ORNL-1515

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ORNL- 1515 T h i s document c o n s i s t s o f 200 pages .

Copy k s - o f 247 c o p i e s . Ser ie s A.

Contrac t No. W- 740 5- eng- 26

AIRCRAFT NUCLEAR PROPULSION PROJECT

QUARTERLY PROGRESS REPORT

for Period Ending March 10, 1953

R. C. Briant, Director J. H. Buck, Associate Director

A. J. Miller, Assistant Director

Edited by: W. B. Cottrell

DATE ISSUED

OAK R I D G E N A T I O N A L LABORATORY Operated by

C A R B I D E A N D CARBON C H E M I C A L S COMPANY A D i v i s i o n of U n i o n C a r b i d e and C a r b o n C o r p o r a t i o n

P o s t O f f i c e B o x P O a k R i d g e , Tennessee

MARTIN MARIETTA ENERGY SYSTEMS LIBRARIES

11 I1 I 1111 Ill1 I I I I 1111 I I 1 Ill I I Ill I 1111 I Ill I II 1111 I1 ' 3 4 4 5 b 0353330 2

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ORNL- 1515 Progress

INTERNAL DISTRIBUTION 1. G. M. Adamson 2. R. G. A f f e l 3. C. R. Baldock 4. C. J. B a r t o n 5. E. S. B e t t i s 6. D. S. B i l l i n g t o n 7. F. F. B l a n k e n s h i p 8. E. P. B l i z a r d 9. M. A. B r e d i g

10. R. C. B r i a n t 11. R. B. B r i g g s E. D. S h i p l e y 1 2 . F. R. Bruce 13. J. H. Buck . L. P. Smi th ( c o n s u l t a n t ) 14. A. D. C a l l i h a n A. H. S n e l l 15. D. W. Ca rdwe l l 16. J. V. C a t h c a r t 17. C. E. C e n t e r 18. J. M. C i s a r 19. G. H. C l e w e t t 20. C. E. C l i f f o r d - 21. W. B. C o t t r e l l 22. D. D. Cowen 23. W. K. E i s t e r 24. L. B. Emlet (Y-12) 25. W. K. Ergen 26. A. P. F r a a s 27. W. R. G a l l 28. C. B. Graham 29. W. W. G r i g o r i e f f 70. J . C. Wilson

30. W. R. G r i m e s 71. C. E. Winters 31. A. H o l l a e n d e r 72-81. ANP L i b r a r y

33. W. B. Humes 34. G. W. K e i l h 35. C, P. K e i 36. M, T. K e l 91. Reactor E x p e r i m e n t a l

E n g i n e e r i n g L i b r a r y

Depar tment (Y- 1 2 )

b

82. B i o l o g y L i b r a r y 83-88. C e n t r a l F i l e s

90. M e t a l l u r g y L i b r a r y

92-96. T e c h n i c a l I n f o r m a t i o n

97-98. C e n t r a l R e s e a r c h L i b r a r y

i

iii

EXTERNAL DISTRIBUTION

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134-138. duPont 1 3 9 - 1 6 0. Ge ne r a 1 161 -164. Genera 1

176-183. K n o l l s Atomic

186-188. Los Alamos S c i e n t

190. M a s s a c h u s e t t 191-193. Mound Labora

A e r o n a u t i c s , Washington

201-202. N o r t h an A v i a t i o n , I n c . lopment Assoc ia tes h , Washington

205-206. Rand r a t i o n (1 copy t o V , G.

t i n g h o u s e E l e c t r i c C o r p o r a t i o n

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216-232. W r i g h t A i r Development C e n t e r 2 c o p i e s t o B. Beaman 1 copy of Co l . P. Le H i l l 1 copy t o L t . C o l e M. J. N i e l s e n 2 c o p i e s t o C o n s o l i d a t e d V u l t e e A i r c r a f t C o r p o r a t i o n 1 copy t o P r a t t and Whitney A i r c r a f t D i v i s i o n 1 copy t o B o e i n g A i r p l a n e Company 1 copy t o K. Campbel l , Wr igh t A e r o n a u t i c a l C o r p o r a t i o n

233-247. T e c h n i c a l I n f o r m a t i o n S e r v i c e , Oak R i d g e , T e n n e s s e e

a Atomic .&s-content J

V

J

SEC ION

ORNL- 528 ORNL-629 ORNL-768 ORNL- 8 5 8 ORNL- 919 ANP- 60 ANP- 65 ORNL- 1154 ORNL- 1170 ORNL- 1227 ORNL- 12 94 ORNL- 1375 ORNL- 1439

Period Ending November 30, 1949 Period Ending February 28, 1950 Period Ending May 31, 1950 Period Ending August 31, 1950 Period Ending December 10, 1950 Period Ending March 10, 1951 Period Ending June 10, 1951 Period Ending September 10, 1951 Period Ending December 10, 1951 Period Ending March 10, 1952 Period Ending June 10, 1952 Period Ending September 10, 1952 Period Ending December 10, 1952

mi t tal -or the-d Eclo h

vi SE

TABLE OF CONTENTS PAGE

1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . FOREWORD

PART I. REACTOR THEORY AND DESIGN

. . . . . . . . . . . . . . . . . . . . . . . . 5 INTRODUCTION AND SUMMARY 7 7 . . . . . . . . . . . . . . . . . . . . . . . . . 7 Stress A n a l y s i s . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 R e a c t o r . ,

11 I n s t r u m e n t a t i o n e . . e . e . a . e e . e . e . . e e . e . e . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Off-Gas S y s t e m . . . . . . . . . . . . . . . . . . . . . . . . 11 R e a c t o r C o n t r o l . . . . . . . . . . . . . . . . . . . . . . . . . 15 E l e c t r i c a l System

2. EXPERIMENTAL REACTOR ENGINEERING e e e e e e o v e 17 Pumps f o r High-Tempera ture L i q u i d s 1 8

C e n t r i f u g a l pump w i t h combina t ion packed and f r o z e n s e a l f o r f l u o r i d e s . . . . . . . . . . . . . . . . . . . . . . . 18

A l l i s - C h a l m e r s c e n t r i f u g a l pump f o r l i q u i d m e t a l s e . e . 18 L a b o r a t o r y - s i z e pump w i t h g a s s e a l e . e e e e e . . e 0 . 1 8

1. CIRCULATING-FUEL AIRCRAFT REACTOR EXPERIMENT . e e , . , . , , F l u i d c i r c u i t . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . .

A R E - s i z e sump pump e . e . e e . . e . 0 e e 0 9 20 ARE c e n t r i f u g a l pump e e e e e . . + e e . a . E l e c t r o m a g n e t i c pump . . . . . . . . . . . . . . . . .

R o t a t i n g - S h a f t and Valve-Stem-Seal Development e e e . e

Mechanica l f a c e s e a l s . e e e e e . e e , . . e

Combinat ion packed and f r o z e n s e a l w i t h MoSz . e e , . Combinat ion packed and f r o z e n s e a l w i t h g r a p h i t e . . . G r a p h i t e packed s e a l . . . . . . . . . . . . . . . . . R o t a t i n g - s h a f t s e a l t e s t . . . . . . . . . . . . . . . Pack ing p e n e t r a t i o n t e s t s , e . . e e e . . e . Frozen-sodium and f r o z e n - l e a d s e a l f o r NaK . . e . A R E v a l v e t e s t . . . . . . . . . . . . . . . . . . . .

Heat Exchanger Sys tems . . . . . . . . . . . . . . . . . S o d i u m - t o - a i r r a d i a t o r t e s t s . . . a . . . . e

B i f l u i d h e a t t r a n s f e r l oop . . . . . . . . . . . . . . ARE F u e l C i r c u i t Mockup . . . . . . . . . . . . . . . . .

V o r t e x e s and bubb les . . . . . . . . . . . . . . . . . O p e r a t i o n a l i n s t a b i l i t i e s . . . . . . . . . . . . . . .

I n s t r u m e n t a t i o n e , , . e . e . e e e e

P r e s s u r e measurement . . . . . . . . . . . . . . . . . ARE l e a k d e t e c t i o n i n d ’ t e s t s . . . . . . . . . .

f h i defined in the Atomic Ene in a

. . . . 21

. e . . 22 e * . . 22 . . * e 22 . . . . 25 . . . . 26 . . e . 26 e e . . 28 . e . . 28 . . . . 2 9 e * . . 29 . . . . 30 . . . . 30 . . . . 30 . . . . 31 . . . . 32 . . . . 33 . . . . 35 . . e . 35 . . . . 36

v i i

/.

Slip rings for temperature ement . ’ * . e . . e e . . 36 Rotameter type of flowmeter . . . . . . . . . . . . . . . . . . . . . . 36

36 Distillation of NaK . . . . . . . . . . . . . . . . . . . . . . 36 Flame tests for NaK vapor in helium 37

3. REACTOR PHYSICS. . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Handling of Fluorides and Liquid Mek/gls . . . . . . . . . . . . . . . . . . . . . . . . . . .

4. REFLECTOR-MODERATED CIRCULATING-FUEL REACTOR e , . , . 41 Staticphysics . . . . . . . . . . . . . . . . . . . . . . . . . 41

Reactors with beryllium reflector-moderators . . . . . . . . . 46 51

Reactors with various reflector-moderators . . . . . . . . . . 44

Summary tables and graphs . . . . . . . . . . . . . . . . . . . Critical Experiments 53

First critical assembly 53 Second critical assembly . . . . . . . . . . . . . . . . . . . 56

Design Characteristics . . . . . . . . . . . . . . . . . . . . . 61 64 Factors affecting core diameter . . . . . . . . . . . . . . . . 66 Temperature, pressure, and str~ss . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 Reflector heating

I . . . . . . . . . . . . . . . . . . . 74 79 Power Plant Design . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Shielding e , , . . . PART 11, SHIELDING RESEARCH

INTRODUCTION AND SUMMARY . . e e e e e . o e e . 87

. . . . . . . . . . . . . . . . . . . . . . . 89 Effective Fast-Neutron Removal Cross Sections . . e . . 0 89 Mockup of the Unit Shield of the Reflector-Moderated Reactor 89

. . . . . . . . . . . . . . . . . . . . . . 91 . . . . . . . . . . . . . . . . . . . 91 . . . . . . . . . . . . . . . . . . . . . 91 92 92 92

5. LIDTANKFACILITY,.

e . 6. BULK SHIELDING FACILITY

Air-Scattering Experiments Irradiation of Animals Neutron Spectroscopy for the Divided Shield e . . e 0 0

Gamma Spectroscopy for the Divided Shield . . e . e . e e e . e

Fission Energy and Power in the Bulk Shielding Reactor e . \

7. TOWER SHIELDING FACILITY e e . . e e e e e e

TowerDesign , , , . . e e , , . , e e e e e

Construction Schedule . . . . . . . . . . . . . . . . . . . . . . Fast-Neutron Scintillation Spectrometer . . e e . e e e 101 Measurements with 6-Mev Van de Graaff 1 0 1

8. NUCLEARMEASUREMENTS . . . . . . . . . . . . . . . . . . . . . . . 101

. . . . . . . . . . . . . .

in the of its c

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PART I I I , MATERIALS RESEARCH

INTRODUCTION AND SUMMARY . . e . . . . . . . . . . . . .

9. CHEMISTRY OF HIGH-TEMPERATURE LIQUIDS . . . . e e . . . , . F u e l M i x t u r e s C o n t a i n i n g UF, e . . . . e e , . . e . .

LiF-ZrF,-UF, . . e . . . . e . . . e e e . . e . . KF-LiF-BeF,-UF, e e . . . . . . . . e e . . . e . e

F u e l M i x t u r e s C o n t a i n i n g ThF, . . e . e e . e . . . . F u e l Mix tu res C o n t a i n i n g UC1, , e . . e . e . e . . .

NaC1-UC1, . e e e . . , . a . e . . . . . . . e . KC1-UC1, . e e e e . . e . . 9 e e e e

F u e l M i x t u r e s C o n t a i n i n g UF, . . e . . e e . . . . . A d d i t i o n of Reducing Agents t o ARE F u e l e . . . . . . . C o o l a n t Development . . e . e e e e . . e . e . . e . . .

LiF-ZrF, . . e * . . . . * . . . . * . . e e * . . . CsF-ZrF, , e , . e e e * . . . * . . . . . . e e e

K F - L i F - Z r F , . . e . . e e . . . . . . . e e e . e e .

RbF-LiF-ZrF, e e e . e e , , e . . . e e e e

KF-LiF-BeF2 e . . . . . . . e . . e . e e . L a b o r a t o r y - s c a l e f u e l p r e p a r a t i o n e . . e . . e . e . P i l o t - s c a l e f u e l p u r i f i c a t i o n e . e . . e e e . . F l u o r i d e p r o d u c t i o n f a c i l i t y . . . e e . . e . . H y d r o f l u o r i n a t i o n of Zr02-NaF m i x t u r e s e . e . . .

10 , CORROSION RESEARCH . . . . e . . e e . e . e . . . . . e

F l u o r i d e C o r r o s i o n o f Meta l s i n S t a t i c , Seesaw, and R o t a t i n g T e s t s . . . e e e . . e e . . . . . e

C r e v i c e c o r r o s i o n e e . . . . . e e . e . e

High- t empera tu re p r e t r e a t m e n t o f I n c o n e l . e e . . e

E f f e c t o f t ime of e x p o s u r e of I n c o n e l t o f l u o r i d e m i x t u r e w i t h and w i t h o u t ZrH, added e . . e . e . .

S t r u c t u r a l m e t a l f l u o r i d e a d d i t i v e s e , e e e e e . e

Hydrogen f l u o r i d e a d d i t i v e e . e . e . e . e . e e

F l u o r i d e c o r r o s i o n i n a r o t a t i n g r i g e e e e e e e e

S t a t i c t es t s on I n c o l o y and I n c o n e l i n f l u o r i d e s . . E f f e c t o f f l u o r i d e b a t c h s i z e . . e e . e e e e e e . F l u o r i d e p r e t r e a t m e n t . e e . . e e . e e . e e e e

Hydr ide a d d i t i v e s e e . e e e e . . . . . . e . e e e e

Meta l a d d i t i v e s . e e e e e e e e . e e . . e . e e . e

Tempera ture dependence , e . e e . . . e e . . . C r e v i c e c o r r o s i o n . e e e . . e e . . e e . e . . e .

P r o d u c t i o n and P u r i f i c a t i o n of F l u o r i d e M i x t u r e s . . .

F l u o r i d e C o r r o s i o n of Metals i n Thermal Convec t ion Loops

. . e . . e . o . . * .

d in the Atomic e of its contents

e . e a 105

. e . 107 e . e e 107 . e . I, 107 . e . 107 e e . 107 e e e 108 . . 0 (I 109 . . . 109 . e e " 109

e . " 110 e . e 0 112 . . . " 112 e 0 e " 112 . . . * 112 . . e a 112 . e e e 113 . . . 113 . . . 113 . . e . 114 e . . . 115 . . e . 115

e . . 117

e . e e 118 e e . a 118 e e e . 118

. e e . 118 . . . e 119 . . e . 120 e * . . 121 . . e . 121 e e . . 121 * e . * 1 2 1 0 . . . 122 e e e e 123 . e e e 123 e . . . 123 . . . . 124 e . e 124

i x

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f a

s EC lr,@ TIQN

E f f e c t of exposure t ime * e . . . . e . . e . . . . . . . Nonuranium b e a r i n g m i x t u r e s e . . . . . . . e e . . .

Liqu id Metal C o r r o s i o n of S t r u c t u r a l M e t a l s e . e . . . . . Seesaw t e s t s o f sod ium- lead a l l o y s . . e e . . e . . . . . S t a t i c t es t s w i t h l i t h i u m . . . . . . . . e . e . I n c o l o y i n sodium, l i t h i u m , and l e a d e . . e . . . . . e

C o r r o s i o n by l e a d i n t h e r m a l c o n v e c t i o n l o o p s . e e . . . C o r r o s i o n of Ceramics by F l u o r i d e s and L i q u i d Metals . . . .

Cermets i n f l u o r i d e s and l i q u i d metals . . . . . . . e

S t a t i c t e s t s of t h e ARE-Be0 b l o c k s i n Na and NaK . e . e . Seesaw tes t s of Be0 i n NaK . e . . e . . . . e . e . e . e

Convect ion l o o p t e s t s of Be0 i n NaK e e e . . . . . e . . e

S o l u b i l i t y of Be0 i n NaK e . . e e a . . . e e . . . . . E f f e c t of Atmosphere on t h e Mass T r a n s f e r o f

N i c k e l i n Hydroxides e . . . . . e . . . e . . e . . e

Fundamental C o r r o s i o n Resea rch . e . . . . e . e . e e e

I d e n t i f i c a t i o n o f c o r r o s i o n p r o d u c t s f rom c o n v e c t i o n loops P r e p a r a t i o n of s p e c i a l complex f l u o r i d e s . . . e . e . e . A i r o x i d a t i o n o f fuel m i x t u r e s e . e . . . . e e e . . .

. . 1 2 4 e . 124 . e 125 . . 125 . . 126 e e 126 . . 128 e e 129 . 129 e . 131 . . 132 . . 132 . . 133

e . 136 e . 136 . . 136 . . 137 . . 137

11. METALLURGY AND CERAMICS e e . . . . . . . . . . e . e e . e 139 Welding and B r a z i n g Resea rch . e a . . . e e . . e . . , e . . e 140

Cone-arc we ld ing e . e e . e e e e . . . . . e . . e e 140 F a b r i c a t i o n of h e a t exchange r u n i t s . e e . . . . . e e . . . 140 B r a z i n g of coppe r t o I n c o n e l e e e e e e . . . . . . . . . . . 142

E v a l u a t i o n Tes t s of B r a z i n g A l l o y s e . . e . e . . e . . e . . e 143 C o r r o s i o n of b r a z i n g a l l o y s by f l u o r i d e s . e . . . . . . . 143 E f f e c t of b r a z i n g t i m e on j o i n t s t r e n g t h . e e e . . . e . . . 143 E f f e c t of s p a c i n g on b razed j o i n t s t r e n g t h e , . e . . . . . . 144 S t r e n g t h of b r a z e d j o i n t s w i t h v a r i o u s b a s e m e t a l s . . . . . . 145

i Creep-Rupture T e s t s of S t r u c t u r a l Metals . . e . e , . e e . 145 P r e o x i d i z e d I n c o n e l i n a rgon . . . . . . . . . . . . e . . 145 $4 Peened I n c o n e l i n a rgon . . . e . a . , . . e e e 146 E f f e c t of I n c o n e l g r a i n s i z e on t i m e t o r u p t u r e . e . . . e . 147 E f f e c t o f e n v i r o n m e n t on s t r a i n vs. t i m e c u r v e s f o r I n c o n e l . e 147 Type 316 s t a i n l e s s s t e e l t u b e b u r s t t e s t s i n a r g o n e . . . 1 4 8

F a b r i c a t i o n of C o n t r o l and S a f e t y Rods e e . e e . , e e . . . . 148 , C o n t r o l - rods f o r t h e G-E R - 1 R e a c t o r . . . e e . . . . . . e ,148

Tower s h i e i d i n g f a c i l i t y s a f e t y r o d s . . e . . . , -. . . . 150 . e . . . . . e . . . . . . . . . 4 . 7 1 5 0 Gaseous r e a c t i o n s . . . e . . . . . e e e e . . . . . . e 150 O x i d a t i o n ,' . e e . . . e , e . . e %. . . , . e , ,, e . e e . '151

F a b r i c a t i o n of Meta l s e . . . . e . e . , . . . e . . e . . e e . 152 H i g h - c o n d u c t i v i t y m e t a l s f o r r a d i a t o r f i n s . . . . . . , e . . 152

i

1

3 1

~ Columbium Reqearch . . 3 1 1

.

1 S o l i d - p h a s e bonding . e e * . e . . . * . . . . . . 152

4 i I I \

- his document conto nod in the Atomic

ure of its contents Energy Act of 1946.

4 \

I i

J 03 X

I

12.

13.

E x t r u s i o n of h i g h - p u r i t y t u b i n g e e . , e e e e . . e e

Hot -Pres sed Pump S e a l s e , . . e . . . e . . . e e e

Ceramics . . e e . . e . e . . e . . . e e . . . .

Ceramic c o a t i n g s , f o r s h i e l d i n g . . . . . e e . . e

Development of cermet f u e l e l e m e n t s e . . . . e . e . Reduc t ion of p o r o s i t y o f ARE b e r y l l i u m o x i d e . e e e

HEAT TRANSFER AND PHYSICAL PROPERTIES e . . e . e . . e . . Thermal C o n d u c t i v i t y of L i q u i d s e e e . . . . e e . . . Heat C a p a c i t y of L i q u i d s e e e e . . . . . . . . . e e

V i s c o s i t y and D e n s i t y of A l k a l i Hydroxides , e . . . . . Vapor P r e s s u r e s of F l u o r i d e s e . . , . . e . . . . P r a n d t l Moduli of V a r i o u s M a t e r i a l s e . . . e e . e . S p e c i f i c Reac tor Heat T r a n s f e r Problems e e e . e e e . T u r b u l e n t Convec t ion i n A n n u l i . e e e . e e e . . . . C i r c u l a t i n g - F u e l Heat T r a n s f e r e e . . . . . e e . High Tempera ture Reac tor C o o l a n t ‘ S t u d i e s e e e . . e e .

RADIATIONDAMAGE e e e . . . . e . . . e e e . . . . . a e

I r r a d i a t i o n o f Fused Mater ia ls e e e . e . e e . In -Reac to r C i r c u l a t i n g Loops e . e e . . e . e . e . e e

C r e e p Under I r r a d i a t i o n e e . . e e . . e . . . . 14. ANALYTICAL STUDIES OF REACTOR MATERIALS . e . e e e . . . e

Chemical A n a l y s i s of Reactor F u e l s and Contaminants e e . Zi rcon ium e e e . e e . e e e e e e . e e e . . . . . . R e d u c t i o n p r o d u c t s e e e e . . e e e . e e . . e . . e

Oxides e . . . e . . . a e . e . . . e e . e e

Hydrogen f l u o r i d e e e e . . . e e e e e e e . e . . .

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C o r r o s i o n p r o d u c t s e e e . e e . . . e e . e e e e

P r e p a r a t i o n of Uran ium T e t r a c h l o r i d e , . . . . . e e e . P e t r o g r a p h i c Examina t ion o f F l u o r i d e s . . e . . e e e

UC14-NaC1 s y s t e m . . . . e e e . e . . e . e . e . UCl,-KCl s y s t e m e e e . . e . . . e . . . . . e e e e

X-Ray D i f f r a c t i o n S t u d i e s . e e . e . e . . . e . e . . Serv ice Chemical Ana lyses e . e e . . e . . . . . .

PART IV. APPENDIXES - 7

15. LIST OF REPORTS ISSUED DURING THE QUARTER . . . . e . e . e

TECHNICAL ORGANIZATION CHAR PROJECT . e e e . .

efined in the Atomic losure of its contents

. . . . 152 . . e . 153 e . . . 154 . * . . 154 e . . . 1 5 4 , e , . 155

. . e . 157 e . e * 157 . e e 157 . . e e 158 e e . . 159 e e . . 160 . . e 160 . e 160 e . e e 162 e . . e 163

. e e 165 e e . . 165 e e . . 167 . e . 167

. . . . 1 7 1 . e . . 171 . e e . 172 e . e 172 . . s . 173 . e . . 173 . . . e 175 e e . . 176 e e e . 176 e e . . 176 . e . . 176 . e e . 177 . e . . 177

.- e . . 183

e . . . 187

! > i i

i

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A N P PROJ GRESS REPORT

T h i s q u a r t e r l y p r o g r e s s e A i r c r a f t N u c l e a r P r o p u l s i o n P r o j e c t a t ORNL r e c o r d s t h e t e c h n i f t h e r e s e a r c h on t h e c i r c u l a t i n g - f u e l r e a c t o r a n d a l l o t h e r ANP r e s e a r c h a t t h e L a b o r a t o r y u n d e r i t s C o n t r a c t W-7405-eng-26. The r e p o r t i s d i v i d e d i n t o t h r e e m a j o r p a r t s : I. R e a c t o r Theory and D e s i g n , 11. S h i e l d i n g R e s e a r c h , and 111. M a t e r i a l s Resea rch . Each p a r t h a s a s e p a r a t e i n t r o d u c t i o n and summary.

The ANP P r o j e c t i s compr ised o f about t h r e e hundred t e c h n i c a l and s c i e n t i f i c p e r s o n n e l e n g a g e d i n many p h a s e s o f r e s e a r c h d i r e c t e d t o w a r d t h e n u c l e a r p r o p u l s i o n o f a i r c r a f t . (The P r o j e c t o r g a n i z a t i o n c h a r t i s i n c l u d e d a s a n append ix . ) A c o n s i d e r a b l e p o r t i o n of t h i s r e s e a r c h i s per formed i n s u p p o r t o f t h e work o f o t h e r o r g a n i z a k i o n s p a r t i c i p a t i n g i n t h e n a t i o n a l ANP e f f o r t ; . How- e v e r , t h e b u l k o f t h e ANP r e s e a r c h a t ORNL i s d i r e c t e d toward t h e deve lopment of a c i r c u l a t i n g - f u e l t y p e of r e a c t o r .

The n u c l e u s of t h e e f f o r t on c i r c u l a t i n g - f u e l r e a c t o r s i s now c e n t e r e d upon t h e A i r c r a f t R e a c t o r Exper iment - a 3-megawat t , h i g h - t e m p e r a t u r e p r o t o t y p e o f a c i r c u l a t i n g - f u e l r e a c t o r f o r t h e p r o p u l s i o n o f a i r c r a f t . T h i s r e a c t o r expe r imen t i s now b e i n g assembled; i t s c u r r e n t s t a t u s i s summarized i n s e c . 1. However, much s u p p o r t i n g r e s e a r c h on m a t e r i a l s and p r o b l e m s p e c u l i a r t o t h e ARE w i l l b e f o u n d i n o t h e r s e c t i o n s of P a r t I and P a r t I11 o f t h i s r e p o r t , a long w i t h t h e g e n e r a l d e s i g n and m a t e r i a l s r e s e a r c h c o n t a i n e d t h e r e i n .

A s u r v e y r e p o r t on a r e f l e c t o r - m o d e r a t e d t y p e o f c i r c u l a t i n g - f u e l r e a c t o r is c o n t a i n e d i n s e c . 2. S i n c e t h e f e a s i b i l i t y o f s u c h a r e a c t o r was i n d i c a t e d by c r i t i c a l e x p e r i m e n t s comple t ed d u r i n g t h e p r e v i o u s q u a r t e r , c o n s i d e r a b l e r e s e a r c h , a s w e l l a s d e s i g n e f f o r t , h a s been d e v o t e d t o p r o b l e m s a s s o c i a t e d t h e r e w i t h .

+The s h i e l d i n g r e s e a r c h r e p o r t , P a r t 11, i s d e v o t e d a l m o s t e n t i r e l y t o problems o f a i r c r a f t s h i e l d i n g . I

- I

1

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INTRODUCTION AND SUMMARY

The A i r c r a f t R e a c t o r E x p e r i m e n t ( s e c . 1 ) i s r a p i d l y t a k i n g f o r m a s e q u i p m e n t i s r e c e i v e d a n d i n s t a l l e d i n t h e ARE B u i l d i n g . T h e r e w e r e n o s i g n i f i c a n t c h a n g e s i n d e s i g n o r c o n c e p t d u r i n g t h e q u a r t e r , and t h e i n s t a l l a t i o n i s p r o c e e d i n g a c c o r d i n g t o s c h e d u l e . T h e f u e l s y s t e m h e a t t r a n s f e r l o o p and t h e f i l l and f l u s h t a n k s a r e c o m p l e t e l y i n s t a l l e d , and t h e s o d i u m h e a t t r a n s f e r l o o p i s n e a r i n g c o m p l e t i o n . I n s t a l l a t i o n o f f u e l a n d s o d i u m p i p i n g i s now i n p r o g r e s s . T h e c o n t r o l a n d g r a p h i c p a n e l s h a v e b e e n c o m p l e t e l y i n s t r u - m e n t e d a n d c h e c k e d . T h e f o r m a l p r e s e n t a t i o n on t h e h a z a r d s i n v o l v e d i n t h e ARE was made t o t h e R e a c t o r S a f e g u a r d s C o m m i t t e e e a r l i e r i n t h e q u a r t e r , and i n view of t h e subsequen t d i s c u s s i o n o f t h e C o m m i t t e e members , i t i s n o t e x p e c t e d t h a t a n y m o d i f i - c a t i o n s o f t h e e x p e r i m e n t w i l l b e r e q u i r e d .

V a l v e s , p u m p s , i n s t r u m e n t a t i o n , and o t h e r components o f t h e f l u o r i d e - f u e l and s o d i u m - c o o l a n t s y s t e m s a r e b e i n g d e v e l o p e d a n d t e s t e d f o r t h e ARE ( s e c . 2 ) . B o t h c e n t r i f u g a l and e l e c t r o m a g n e t i c pumps o f ARE c a p a c i t y h a v e b e e n o p e r a t e d ; t h e l a t t e r w i l l b e e m p l o y e d i n t h e b y - p a s s l o o p f o r p r e l i m i n a r y t e s t s , w i t h NaK, o f t h e e x t e r n a l f u e l sys tem. I m p e l l e r d e s i g n s f o r t h e c e n t r i f u g a l pumps a r e c o n - v e n t i o n a l , b u t t h e pump sea l , p a r t i c u - l a r l y f o r f l u o r i d e f u e l s , r e m a i n s a p rob lem. The p a c k e d - f r o z e n s e a l s on f u e l pumps have w i d e l y v a r y i n g l e a k a g e r a t e s , a n d a d e q u a t e t e m p e r a t u r e c o n t r o l o f t h e f r o z e n zone h a s n o t been o b t a i n e d . B o t h p a c k i n g and f a c e - s e a l m a t e r i a l s a r e b e i n g e x a m i n e d i n a n e f f o r t t o f i n d m a t e r i a l s w i t h t h e d e s i r e d s e r v i c e a n d l i f e c h a r a c - t e r i s t i c s . Gas f a c e s e a l s f o r v e r t i c a l - s h a f t pumps a r e b e i n g i n v e s t i g a t e d . C o n s i d e r a b l e s u c c e s s h a s been e x p e r i - e n c e d w i t h f r o z e n - s o d i u m s e a l s i n s o d i u m pumps , a n d f r o z e n - l e a d s e a l s

a r e b e i n g t e s t e d f o r u s e w i t h f l u o r i d e s . F r o z e n - s o d i u m a n d f r o z e n - l e a d s e a l s have p r o v e d t o be u n s a t i s f a c t o r y f o r u s e on NaK pumps . T h e ARE b e l l o w s t y p e o f v a l v e was t e s t e d a t 1 1 0 0 and 1300°F and f o u n d t o b e s a t i s f a c t o r y , a 1 t h o u g h e x c e s s i v e 1 e a k a g e o c c u r r e d a f t e r o p e r a t i o n a t 1500°F. The i n i t i . a l m o c k u p o f t h e A R E f l u i d c i r c u i t r e v e a l e d i n s t a b i l i t i e s and g a s e n t r a i n - m e n t t h a t were e l i m i n a t e d by m i n o r s y s t e m a l t e r a t i o n s . The r o t a m e t e r s , l e v e l i n d i c a t o r s , and p r e s s u r e t r a n s - m i t t e r s have o p e r a t e d s a t i s f a c t o r i l y f o r l o n g p e r i o d s o f t i m e u n d e r t h e c o n d i t i o n s e x p e c t e d i n t h e A i r c r a f t R e a c t o r Exper iment .

The r e a c t o r p h y s i c s s t u d i e s ( s e c . 3 ) were c o n c e r n e d w i t h t h e s t a t i c s o f t h e r e f l e c t o r - m o d e r a t e d r e a c t o r a n d d a m p i n g o f power o s c i l l a t i o n s . T h e a p p l i c a b i l i t y o f t h e m u l t i g r o u p method t o t h e c a l c u l a t i o n o f t h e r e f l e c t o r - m o d e r a t e d r e a c t o r was d e m o n s t r a t e d by t h e g o o d c o r r e l a t i o n o b t a i n e d w i t h c r i t i c a l e x p e r i m e n t s . The damping o f p o w e r o s c i l l a t i o n s i n a r e a c t o r i s d e m o n s t r a t e d f o r a n o n l i n e a r c a s e , w i t h d e l a y e d n e u t r o n s i n c l u d e d , b y assuming ( 1 ) c o n s t a n t power e x t r a c t i o n o r ( 2 ) a s p e c i a l c a s e o f c o o l i n g w i t h c i r c u l a t i n g f u e l .

T h e r e f l e c t o r - m o d e r a t e d r e a c t o r and an a i r c r a f t power p l a n t a s s e m b l y e m p l o y i n g t h i s r e a c t o r a r e d e s c r i b e d ( s e c . 4). I n g e n e r a l , t h e r e a c t o r c o n s i s t s o f l u m p e d r e g i o n s o f f u e l a n d m o d e r a t o r o r r e f l e c t o r . An e s s e n t i a l e l e m e n t i n t h i s r e a c t o r i s t h e u s e o f a t h i c k b e r y l l i u m r e f l e c t o r t h a t n o t o n l y c o n t r i b u t e s t 0 n e u t r o n economy b u t a l s o c o n s t i t u t e s t h e f i r s t l a y e r o f t h e a i r c r a f t s h i e l d . T h i s r e a c t o r a n d t h e c o m p a c t , s p h e r i c a l a r r a n g e m e n t p e r m i t r e a l i z a t i o n o f what i s p r a c t i c a l l y a u n i t s h i e l d f o r a 2 0 0 - m e g a w a t t r e a c t o r a n d h e a t e x c h a n g e r c o m b i n a t i o n t h a t w e i g h s about 80,000 pounds. C r i t i c a l e x p e r i - m e n t s o n a m o c k u p o f t h i s r e a c t o r

5

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ANP PROJECT QUARTERLY PROGRESS REPORT

a s s e m b l y i n d i c a t e a c r i t i c a l mass o f A p r e l i m i n a r y w e i g h t e s t i m a t e of t h e a b o u t 2 0 l b and a t o t a l u r a n i u m i n - c o m p l e t e p o w e r p l a n t a s s e m b l y , i n - v e s t m e n t o f 1 0 0 l b when t h e c o m p a c t c l u d i n g t h e t u r b o j e t s , i s a b o u t 115,000 e x t e r n a l f u e l s y s t e m i s i n c l u d e d . pounds.

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PERIOD ENDING MARCH 10, 1953

1. CIRCULATING-FUEL AIRCRAFT REACTOR EXPERIMENT J. H. Buck, R e s e a r c h D i r e c t o r ’ s D i v i s i o n ; E. S. B e t t i s , ANP D i v i s i o n

The m a j o r e f f o r t i n t h e ARE p r o j e c t d u r i n g t h e q u a r t e r h a s been i n i n s t a l - l a t i o n o f equipment i n B u i l d i n g 7503. T h e a r r i v a l o f t h e h e a t e x c h a n g e r s p e r m i t t e d t h e i n i t i a t i o n o f a l a r g e amount o f c o n s t r u c t i o n work t h a t h a d b e e n p o s t p o n e d f o r s e v e r a l w e e k s . V a l v e s began t o a r r i v e toward t h e end o f t h e q u a r t e r , and work c o u l d p r o c e e d o n t h e i n s t a l l a t i o n o f t h e m a i n p l u m b i n g s y s t e m . The i n s t a l l a t i o n o f e q u i p m e n t w i l l n o l o n g e r be d e p e n d e n t upon t h e a r r i v a l of c o m p o n e n t s , T h e i n s t a l l a t i o n w o r k i s n o t a h e a d o f s c h e d u l e , b u t t h u s f a r i t a p p e a r s t h a t t h e c o m p l e t i o n g o a l o f J u n e 1953 w i l l b e r e a 1 i zed.

No new t e c h n i c a l c r i s e s h a v e a r i s e n i n t h e p r o j e c t . T e s t s o f v a l v e s , s e a l s , pumps, e t c . c o n t i n u e ( s e c . 2 ) and , t o d a t e , r e v e a l n o i n s u r m o u n t a b l e d i f f i c u l t i e s . S e a l s h a v e o p e r a t e d s a t i s f a c t o r i 1 y , b u t t h e i r p e r f o rmanc e h a s n o t b e e n s o g o o d a s m i g h t b e w i s h e d . T h e same c o n d i t i o n e x i s t s w i t h r e s p e c t t o t h e v a l v e t e s t s , b u t t h e v a l v e s h a v e b e e n s h o w n t o b e u s a b l e .

A 1 t h o u g h d e t a i l i n g o f i n s t a l l a t i o n d r a w i n g s c o n t i n u e s t o b e a p r o b l e m , i t h a s n o t y e t a c t u a l l y r e t a r d e d t h e j o b . T h e r e h a v e b e e n t h e u s u a l m o d i f i c a t i o n s d i c t a t e d by p r o b l e m s a r i s i n g i n t h e f i e l d , b u t t h e y h a v e been n o more numerous or s e r i o u s t h a n would b e e x p e c t e d i n a s y s t e m o f such c o m p l e x i t y a s t h e ARE.

G. A. C r i s t y i n g and Main tenance

s i g n c h a n g e s were made i n t h e f l u i d c i k c u i t . s i n c e i t a p p e a r e d i n a d v i s a b l o n g d r a i n l i n e s i n t h e f u e l c i r c u i t t o s t a n d f u l l o f s t a g n a n t f u e l , two v a l v e s were a d d e d t o p e r m i t d r a i n i n g

t h e s e l o n g l i n e s s o t h a t t h e y w i l l b e e m p t y d u r i n g o p e r a t i o n o f t h e e x p e r i m e n t .

T h e h e a t d i s p o s a l l o o p s f o r t h e f u e l c i r c u i t , t h a t i s , t h e f u e l - t o - h e l i u m h e a t e x c h a n g e r s , t h e h e l i u m - t o - wa te r h e a t e x c h a n g e r s , t h e t h e r m a l b a r r i e r s , t h e h e l i u m d u c t s , and t h e h e l i u m b l o w e r s , a r e now c o m p l e t e l y i n s t a l l e d . F i g u r e 1.1 s h o w s t h e s e l o o p s i n s t a l l e d i n t h e p i t . T h r e e s e c t i o n s o f t h e f u e l p i p e , t o g e t h e r w i t h a n n u l i , t h e r m o c o u p l e s , a n d h e a t e r s ( w h e r e p o s s i b l e 1, h a v e b e e n p r e f a b r i c a t e d and c a n b e w e l d e d i n t o t h e s y s t e m when t h e v a l v e s f o r t h e s e l i n e s a r e r e a d y . F i g u r e 1 . 2 shows one o f t h e s e s e c t i o n s of f u e l p i p e .

A l l t h e f i l l and f l u s h t a n k s h a v e b e e n p u t i n t h e p i t , a n d w o r k h a s been s t a r t e d on i n s t a l l i n g h e a t e r s on t h e s e u n i t s . T h e s e t a n k s a r e shown i n F i g . 1.3.

T h e b y - p a s s , w h i c h e n a b l e s t h e s y s t e m t o b e r u n w i t h o u t t h e r e a c t o r i n t h e c i r c u i t , h a s b e e n d e s i g n e d . T h e e l e c t r o m a g n e t i c pump, which w i l l b e i n s t a l l e d i n t h i s b y - p a s s f o r c i r c u l a t i n g l i q u i d m e t a l , h a s b e e n t e s t e d by t h e E x p e r i m e n t a l E n g i n e e r i n g Group ( s e c . 2 ) .

The s u r g e t a n k s h a v e been c o m p l e t e d , and t e s t s o f t h e mockup o f t h e h y d r a u l i c s y s t e m a r e c o n t i n u i n g ( s e c . 2) .

The h e l i u m - t o - w a t e r h e a t e x c h a n g e r s f o r t h e s o d i u m c o o l a n t c i r c u i t h a v e been r e c e i v e d and a re b e i n g i n s t a l l e d . T h e l i q u i d m e t a l - t o - h e l i u m h e a t e x c h a n g e r s a r e t o b e d e l i v e r e d t h e f i r s t week o f March.

STRESS ANALYSIS R. L. Maxwell J . W. Walker

C o n s u l t a n t s , ANP D i v i s i o n

T h e r e a c t o r b y - p a s s c i r c u i t w a s c h e c k e d t o s e e t h a t p r e v i o u s p r e - s t r e s s i n g c a l c u l a t i o n s w o u l d n o t b e

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F i g . 1 .1 . Fue l System Heat Disposal LOOPS.

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i n v a l i d a t e d by i t s i n c o r p o r a t i o n i n P n e u m a t i c l i n e s h a v e b e e n r u n t o t h e c i r c u i t . A r e p o r t on t h e c o m p l e t e v a l v e s a n d s e n s i n g p o i n t s i n t h e a n a l y s i s o f t h e s t r e i s b e i n g p i t s , b u t a s m a l l amount ( 2 % ) o f work p r e p a r e d . r e m a i n s t o b e d o n e . T h e r m o c o u p l e

A d e s i g n h a s b e e n d e v e l o p e d f o r d e s i g n s h a v e been c o m p l e t e d anld o r d e r s t i n g s t r a i n g a g e s i n t h e h a v e b e e n p l a c e d . S e v e r a l o f t h e

s y s t e m a t t h e a n c h o r p o i n t s t o c h e c k t h e r m o c o u p l e s n e e d e d t o a l l o w i n s t a l - t h e c o m p u t e d s t r e s s e s . T h e s e g a g e s l a t i o n work t o p r o c e e d h a v e been made w i l l b e i n s t a p r i o r t o t h e p r e - b y t h e I n s t r u m e n t D e p a r t m e n t . A l l s t r e s s i n g , an e m a g n i t u d e o f t h e i n s t r u m e n t s and a c t u a t o r s h a v e b e e n p r e s t r e s s i n g f o r c e s w i l l be measured . l a b e l e d . The e n u n c i a t o r p a n e l s h a v e T h e s t r e s s f a s t h e t e m p e r a t u r e b e e n i n s t a l l e d a n d c h e c k e d , e x c e p t

1 t h e f o r c o n n e c t i o n t o t h e s e n s i n g p o i n t s .

O F F - G A S S Y S T E M a b o v e 200'F t h e g a g e s w i l l n o l o n g e r be u s a b l e . T h e r e h a s b e e n n o c h a n g e i n t h e

f f - g a s s y s t e m , and i n s t a l l a t i o n i n he b u i l d i n g i s p r a c t i c a l l y comple ted . h e f i n a l d e s i g n f o r t h e s h i e l d i n g o f

f t h e s e r p e n t i n e t h e r a d i a t i m o n i t o r s h a s n o t b e e n c o i l s and f i n a l a s sembly . F i g u r e s 1.4, c o m p l e t e d , b u t t h i s s h i e l d i n g w i l l b e 1 . 5 , and 1.6 show t h e ' s t a t u s o f p a r t s q u i t e s i m p l e and w i l l be a s s e m b l e d i n o f t h e r e a c t o r . A l l p r e l i m i n a r y work t h e f i e l d by u s i n g a s t a c k i n g o f l e a d on t h e p r e s s u r e s h e l l h a s b e e n com- b r i c k s around t h e m o n i t o r s . p l e t e d . The c o i l s h a v e been r e c e i v e d

R E A C T O R C O N T R O L a n d s a m p l e c o i l s a r e now b e i n g t e s t w e l d e d i n O W L s h o p s . I t i s p l a n n e d The mode l f i s s i o n c h a m b e r f o r u s e

c t o r i n t o a t e s t a t h i g h t e m p e r a t u r e h a s o p e r a t e d c i r c u i t a t a t i s f a c t o r i l y f o r s e v e r a l h u n d r e d

o u r s a t a t e m p e r a t u r e o f 1400'F. a t d e s i g n t e m p e r a t u r e s o t h a t t h e T h i s t e s t h a s proved t h e a c c e p t a b i l i t y

p e n d e n t l y c h e c k e d o f t h e i n s u l a t o r f o r t h i s c h a m b e r . a l l a t i o n . T h i s The l i v e chamber , w i t h a U235 s l e e v e ,

p r e t e s t i n g o f t h e r e a c t o r c o r e w i l l h a s n o t y e t been t e s t e d .

7503, b u t n o been made i n

t h a t s i m u l a t e d v a l v e o p e r a t i o n . t h e assembly .

11

; 1

ANP'.-PRO JECT QUARTERLY

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ESS REPORT

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P E R I O D ENDING MARCH 1 0 , 1953

Fig. 1.5 . Reactor Pressure Shell.

13

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P E R I O D ENDING MARCH 1 0 , 1 9 5 3

ELECTRICAL SYSTEM

The e l e c t r i c a l work i s p r o c e e d i n g L s a t i s f a c t o r i l y . T h e l a r g e j o b o f

c o m p l e t i n g t h e h e a t e r c i r c u i t p a n e l s h a s b e e n a c c o m p l i s h e d . H e a t e r s a r e b e i n g i n s t a l l e d on t h e f i l l and f l u s h

t a n k s , a n d l e a d s h a v e b e e n r u n f rom t h e c o n t r o l p a n e l s t o two o f t h e f i l l and f l u s h t a n k s . Both moto r g e n e r a t o r s e t s h a v e been r e c e i v e d and c h e c k e d . I t was f o u n d t h a t t h e s e s e t s r a i s e d t h e n o i s e l e v e l i n t h e basemen t t p an u n t o l e r a b l e l e v e l ; c o n s e q u e n t l y t h e y w i l l be moved o u t o f t h e b u i l d i n g .

15

2. EXPERIMENTAL REACTOR ENGINEERING

H. W. Savage , ANP D i v i s i o n

The work o f t h e p a s t t h r e e m o n t h s on t h e l i q u i d c i r c u i t s o f t h e ARE h a s been d e v o t e d t o m i n i m i z i n g c o r r o s i o n t o v a l u e s a c c e p t a b l e f o r 1 0 0 0 h r o f c o n t i n u o u s or i n t e r m i t t e n t o p e r a t i o n a t e l e v a t e d t e m p e r a t u r e , d e t e r m i n i n g a n d a p p l y i n g a p r o c e s s o f b l e n d i n g f l u o r i d e s f o r t h e ARE t h a t w i l l y i e l d a p r o d u c t w i t h a q u a l i t y e q u a l t o t h a t o f t h e m i x t u r e u s e d i n t h e most s a t i s - f a c t o r y c o r r o s i o n t e s t s , p r o v i d i n g pumps f o r t h e c i r c u l a t i o n o f f l u o r i d e s and e i t h e r sodium or s o d i u m - p o t a s s i u m a l l o y , d e v e l o p i n g s e a l s f o r t h e pumps t h a t a r e r e l i a b l e f o r 1 0 0 0 h r o f o p e r a t i o n , p r o v i d i n g o t h e r c i r c u i t c o m p o n e n t s , a n d s t u d y i n g c i r c u i t m o d i f i c a t i o n s t h a t w i l l a s s u r e a c c e p t a - b l e a n d o p e r a b l e f l u i d d y n a m i c s . T h i s workwas c a r r i e d o u t c o o p e r a t i v e l y w i t h t h e M e t a l l u r g y D i v i s i o n , t h e M a t e r i a l s C h e m i s t r y D i v i s i o n , and t h e ARE S e c t i o n o f t h e ANP D i v i s i o n .

B o t h c e n t r i f u g a l a n d e l e c t r o - m a g n e t i c pumps o f ARE c a p a c i t y - 50 t o 1 0 0 gpm - h a v e b e e n t e s t e d . T h e c o n v e n t i o n a l pump i m p e l l e r s a r e s a t i s - f a c t o r y , b u t s e a l s f o r m e c h a n i c a l pumps a r e s t i l l a p rob lem, A lOO-gpm, a - c , d o u b l e - c e l l , e l e c t r o m a g n e t i c pump h a s p roved t o be e n t i r e l y s a t i s f a c t o r y f o r pumping s o d i u m - p o t a s s i u m a l l o y a t 1 5 0 0 ° F , a n d i t i s b e i n g t e s t e d f o r pumping sodium.

P a c k i n g s f o r h o r i z o n t a l - s h a f t c e n t r i f u g a l pumps h a v e n o t y e t b e e n p r o v e d r e l i a b l e . T h e m o s t p r o m i s i n g p a c k i n g w a s g r a p h i t e a n d / o r MoS, r e t a i n e d w i t h b r a i d or g r a p h i t e r i n g s , or p o s s i b l y by m a g n e t i c means. Leakage r a t e s have v a r i e d w i d e l y , and f r i c t i o n d e m a n d s , i n some c a s e s , h a v e b e e n e x c e s s i v e . T h e r m a l c o n t r o l o f t h e f r o z e n z o n e , n e e d e d f o r l o w - f r i c t i o n o p e r a t i o n a n d f o r r e m o t e l y s t o p p i n g a n d s t a r t i n g t h e pump, h a s n o t y e t been a c h i e v e d .

O i l - l u b r i c a t e d , 1 ow- t e m p e r a t u r e , f a c e - t y p e , g a s s e a l s have been r e l i a b l y o p e r a t e d f o r t h o u s a n d s o f h o u r s i n h i g h - t e m p e r a t u r e , c e n t r i f u g a l , sump- t y p e pumps , An A R E - s i z e sump pump, s i m i l a r l y s e a l e d , i s u n d e r g o i n g a w a t e r t e s t , a n d t h e r e h a v e b e e n n o ma jo r d i f f i c u l t i e s , t o d a t e .

F r o z e n - s o d i u m or f r o z e n - l e a d s e a l s f o r NaK have p roved t o be i m p r a c t i c a l . Frozen-sodium s e a l s f o r A R E - s i z e sodium pumps ( 2 1 / 2 . - i n . - d i a s h a f t ) a r e now b e i n g t e s t e d , a n d t h e d i f f i c u l t i e s e x p e r i e n c e d t o d a t e a p p e a r t o h a v e b e e n d u e t o t h e r m a l d i s t o r t i o n s . F r o z e n - l e a d s e a l s h a v e b e e n u s e d s a t i s f a c t o r i l y w i t h f l u o r i d e s , and i n s e v e r a l t e s t s w i t h m o l t e n f l u o r i d e i n c o n t a c t w i t h m o l t e n l e a d , t h e r e h a s been no m i x i n g o f t h e f l u o r i d e and t h e l e a d , H i g h - t e m p e r a t u r e f a c e s e a l s f o r u s e w i t h m o l t e n f l u o r i d e s a r e b e i n g i n v e s t i g a t e d , b u t d a t a a r e n o t y e t a v a i l a b l e .

O t h e r c o m p o n e n t s t h a t h a v e b e e n o p e r a t e d s u c c e s s f u l l y f o r l o n g p e r i o d s a r e h i g h - t e m p e r a t u r e r o t a m e t e r s a n d h i g h - t e m p e r a t u r e l i q u i d - l e v e l i n d i - c a t o r s ( b o t h t h e r o t a m e t e r s a n d t h e l i q u i d - l e v e l i n d i c a t o r s u s e v a r i a b l e - i n d u c t a n c e p i c k u p s f o r s i g n a l g e n e r - a t i o n ) ; t h i n - w a l l e d ( 0 . 0 0 5 i n . ) b e l l o w s i n p r e s s u r e @ t r a n s m i t t e r s i n c o n t a c t w i t h f l u o r i d e s ; a p n e u m a t i c a l l y - a c t u a t e d , b e l l o w s - s e a l e d , S t e l l i t e - s e a t e d v a l v e ; a n d t h e s l i p - r i n g a n d b r u s h a r r a n g e m e n t s f o r r emova l o f t h e the rmocoup le s i g n a l s u s e d f o r m e a s u r i n g t e m p e r a t u r e s i n moving p a r t s .

A s t u d y o f t h e p a r a l l e l c i r c u i t s a n d t h e p u m p i n g a n d e x p a n s i o n t a n k a r r a n g e m e n t s o f t h e ARE h a s r e v e a l e d o p e r a t i o n a l s t e p s t h a t w i l l have t o be t a k e n i n t h e e v e n t o f f a i l u r e o f o n e o f t h e pumps s o t h a t l o s s o f c i r c u - l a t i o n f r o m t h e r e m a i n i n g pump a n d e x p a n s i o n t a n k can be p r e v e n t e d . The

17

ANP PROJECT QUARTERLY PROGRESS dEPORT

s t u d y a l s o r e v e a l e d t h e n e e d f o r p i p i n g m o d i f i c a t i o n s t o e l i m i n a t e g a s e n t r a i n m e n t a t t h e f r e e s u r f a c e i n t h e s u r g e t a n k s .

S o d i u m - p o t a s s i u m a l l o y h a s b e e n d i s t i l l e d f r o m c l o s e d s y s t e m s t o s i m u l a t e c i r c u i t c l e a n i n g o f t h e ARE; n e g l i g i b l e q u a n t i t i e s o f a l l o y r ema ined i n i s o l a t e d p o c k e t s .

PUMPS FOR HIGH-TEMPERATURE LIQUIDS W. B. McDonald A. G. G r i n d e l l W. G. Cobb G. D. Whitman W. R. H u n t l e y A . L. S o u t h e r n J . M . Trummel P. W. T a y l o r

ANP D i v i s i o n

Centrifugal Pump with Combination Packed and Frozen Seal for Fluorides. A 50-gpm pump w i t h a S t e l l i t e No. 6 c o a t e d , 2 1 / 2 - i n . - d i a s h a f t w a s o p e r a t e d f o r 85 h r w i t h t h e ARE f u e l , NaF-ZrF4-UF, ( 5 0 - 4 6 - 4 mole % ) . T h e s e a l c o n s i s t e d o f a p a c k i n g o f 1 / 4 - b y 1 / 4 - i n . monel b r a i d wrapped i n n i c k e l f o i l , O p e r a t i o n was u n s a t i s f a c t o r y and t h e t e s t was t e r m i n a t e d b e c a u s e o f s h a f t s e i z u r e i n t h e p a c k i n g a r e a . Examina t ion o f t h e s h a f t a f t e r t h e r u n showed t h a t v e r y s e v e r e s c o r i n g h a d o c c u r r e d , Some g r o o v e s were 0.049 i n . deep.

I t may be c o n c l u d e d from t h i s t e s t t h a t s m a l l p a c k i n g s a l o n e a r e i n - a d e q u a t e . C o m p r e s s i v e l o a d i n g t o min imize l e a k a g e w i l l be h i g h and w i l l r e s u l t i n e x c e s s i v e w e a r b e c a u s e t h e p o o r p e n e t r a t i o n o f l i q u i d f l u o r i d e s w i l l p r e v e n t t h e i r a c t i n g a s a s o r t o f l u b r i c a n t . The p a c k i n g i n s u b s e q u e n t t e s t s i n c l u d e d b r a i d a s a c o m p o n e n t a n d e i t h e r g r a p h i t e o r MoSz, e a c h o f which i s a l u b r i c a n t .

T h e pump h a s b e e n r e p a c k e d w i t h D i x o n ' s M i c r o f y n e f l a k e - g r a p h i t e powder , , w h i c h i s r e t a i n e d by c l o s e - f i t t i n g , s o l i d , A P C - g r a p h i t e r i n g s a t e a c h end o f t h e p a c k i n g g l a n d . I n i t i a l d r y r u n s , w i t h o u t f l u o r i d e s p r e s e n t , s h o w e d t h i s p a c k i n g t o b e q u i t e s e n s i t i v e t o c o m p r e s s i v e l o a d i n g . Approximate ly 35 p s i was found t o be a

18

maximum p a c k i n g l o a d i n g f o r s m o o t h , d r y o p e r a t i o n w i t h o u t t h e s e a l h e a t i n g e x c e s s i v e l y . T h e r e p a c k e d pump h a s now o p e r a t e d a t a s h a f t s p e e d o f 7 0 0 rpm f o r 300 h r a t 1200OF. The p r e s s u r e a g a i n s t t h e s e a l h a s been v a r i e d from 5 t o 18 p s i . L e a k a g e o f s o l i d f u e l from t h e s e a l h a s v a r i e d from 60 t o 75 g/day d u r i n g o p e r a t i o n w i t h p r e s s u r e s i n t h e 5 - t o 1 0 - p s i r a n g e . P o w e r i n p u t t o t h e d r i v i n g m o t o r h a s b e e n q u i t e s m o o t h , w i t h a v a r i a t i o n f r o m 2 . 6 t o 3 . 0 kw, a n d u n d e r t h e s e c o n - d i t i o n s o n l y 1 . 5 t o 1 . 8 kw i s b e i n g l o s t a s f r i c t i o n i n t h e pump s e a l .

Allis-Chalmers Centrifugal Pump for Liquid Metals. T h e A l l i s - C h a l m e r s h y d r o s t a t i c - b e a r i n g pump p r e v i o u s l y r e p o r t e d ( ' ) was s h u t down d u r i n g t h e q u a r t e r f o r a l t e r a t i o n s . A new, o n e - p i e c e s h a f t h a s been f a b r i c a t e d , t h e b e a r i n g s u r f a c e on t h e i m p e l l e r h a s been h a r d c o a t e d w i t h S t e l l i t e , and a f r o z e n - s o d i u m g a s s e a l h a s b e e n i n - c o r p o r a t e d i n t h e pump. A l l f a b r i - c a t i o n i s c o m p l e t e a n d t h e pump i s r e a d y f o r r e a s s e m b l y a n d f u r t h e r t e s t i n g .

Laboratory-Size Pump with Gas Seal. T h e l a b o r a t o r y - s i z e g a s - s e a l e d c e n - t r i f u g a l pump o p e r a t e d 9 9 6 h r w i t h f l u o r i d e f u e l , NaF-ZrF4-UF, ( 4 6 - 5 0 - 4 mole % ) , a t a t e m p e r a t u r e o f 1500°F . The pump has t h u s f a r o p e r a t e d a t o t a l o f 2300 h o u r s . The pump was r u n a t 3 6 0 0 rpm a n d p r o d u c e d a 5 0 - p s i h e a d a t 8 t o 10 gpm.

F i g u r e 2 . 1 shows t h e u p p e r a s sembly o f t h e pump a f t e r 996 h r o f o p e r a t i o n . The ZrF, c o n d e n s a t i o n d o e s n o t a p p e a r t o be e x c e s s i v e ; h o w e v e r , i n t h e o r i g i n a l a s s e m b l y , p r o b e s h o r t i n g was s e r i o u s and t h e two p r o b e s i n t h e pump were r e n d e r e d i n o p e r a b l e a f t e r 5 0 h r o f o p e r a t i o n . T h e s h o r t i n g may h a v e been a r e s u l t o f f u e l f r e e z i n g a r o u n d a n d b r i d g i n g t h e p r o b e and r a d i a t i o n s h i e l d a s s e m b l y , shown i n F i g . 2 . 1 , when an i n a d v e r t e n t l i q u i d - l e v e l s u r g e

("ANP Quur . Prog. R e p . D e c . 1 0 , 1 9 5 2 , ORNL- 1439, p . 19.


J

Fig. 2.1. Gas-Seal Pump Assembly After Operation.

19


o c c u r r e d d u r i n g o p e r a t i o n o r f i l l i n g , T h i s c o n d i t i o n h a s been a l l e v i a t e d by i n c r e a s i n g t h e c l e a r a n c e be tween t h e p r o b e s and r a d i a t i o n b a f f l e s and i n - s e r t i n g a h a l f c y l i n d e r i n t h e cutaway s e c t i o n i n t h e b a f f l e a s sembly .

T h e pump o p e r a t e d q u i t e s a t i s - f a c t o r i l y w i t h o u t p r o b e s , a n d t h e

v e l i n t h e pump bowl w a s d by n o t i n g t h e pump p e r - a n d t e m p e r a t u r e o f t h e

f a c e p l a t e . T h e r e a s o n f o r t e r m i - n a t i o n was a g a i n a b r o k e n q u i d e v a n e i n d i s c h a r g e bowl. The v a n e s have be t o t h e bowl s e v e r a l times, bu f a i l u r e o c c u r r e d i n t h e p a f t h e vane r a t h e r t h a n i n t h e we ld . The r e l i a b i l i t y o f t h i s

t l y i n c r e a s e d bv e m p l o y i n g t h i c k e r v a n e s and a d d i n g a r e i n f o r c i n g r i n g a r o u n d t h e t o p e d g e o f t h e s i x vanes .

An i d e n t i c a l pump h a s b e e n i n - s t a l l e d and has o p e r a t e d a p p r o x i m a t e l y 7 0 0 h r i n a f l u o r i d e s y s t e m t h a t i n - c l u d e s a f l u o r i d e - t o - N a K h e a t e x c h a n g e r . S e v e r a l d e s i g n c h a n g e s were made t o r e d u c e o r n e a r l y e l i m i n a t e t h e o i l l e a k a g e p a s t t h e r o t a r y gas s e a l .

I t w a s f o u n d t h a t w h e n t h e g a s volume above t h e pump was v e n t e d i n t o a s i g h t g l a s s , t h e d i s c h a r g e d h e l i u m was h e a v i l y l a d e n w i t h o i l v a p o r . I t h a s n o t been a s c e r t a i n e d w h e t h e r t h i s vapor is ha rmfu l t o f l u o r i d e s , b u t , a t l e a s t , t h e c o n t a m i n a t i o n w a s u n - d e s i r a b l e ,

I n t h e o r i g i n a l pump, o i l was u s e d t o c o o l t h e d r i l l e d s h a f t and t o f l o o d t h e r o t a r y gas s e a l a s s e m b l y b o t h f o r c o o l i n g and f o r l u b r i c a t i o n . I n t h e p r e s e n t p u m p , t h e s h a f t a n d t h e s t a t i o n a r y s e a l r i n g a r e w a t e r c o o l e d by u s i n g a c l o s e d s y s t e m . The r o t a r y f a c e s e a l c a n b e l u b r i c a t e d , i f n e c e s s a r y , by a d d i n g s m a l l amounts o f o i l , a s l i q u i d o r m i s t , t h r o u g h a n o p e n i n g i n t h e b e a r i n g h o u s i n g .

The r o t a r y , G r a p h i t a r No. 3 0 , g a s - s e a l i n g r i n g w a s r e p l a c e d w i t h a s i l v e r - impregna ted g r a p h i t e (Mor g a n i t e MYIF) r i n g , and an a t t e m p t was made t o

run t h e d r y s e a l a g a i n s t ha rdened t o o l s t e e l . However, a t a b e a r i n g p r e s s u r e o f a p p r o x i m a t e l y 6 0 p s i , t h i s c o m b i - n a t i o n would n o t r u n u n l u b r i c a t e d . I t h a s been n e c e s s a r y t o a d d s m a l l amounts o f o i l t o r e d u c e g a s l e a k a g e a n d t o p r e v e n t s m a l l power e x c u r s i o n s i n t h e r e c o r d e d demand o f t h e pump moto r . The s e a l h a s r e q u i r e d an a v e r a g e o f 6 t o 8 d r o p s o f o i l p e r d a y , a n d t h e g a s l e a k a g e h a s been n e g l i g i b l e .

I t i s p l a n n e d t o u s e a K e l l e r A i r L i n e l u b r i c a t o r t o a t o m i z e t h e l u b r i - c a t i o n i n t o t h e s e a l r e g i o n t h r o u g h t h e b e a r i n g h o u s i n g . T h i s u n i t may be o p e r a t e d r e m o t e l y a s f r e q u e n t l y a s e x p e r i e n c e d i c t a t e s .

ARE-Size Sump Pump. A m o d i f i c a t i o n h a s been made t o t h e e x i s t i n g model DA p u m p ( 2 ) t o c o n v e r t i t t o a sump pump w i t h a s h a f t l a b y r i n t h s e a l from which l e a k a g e w i l l r e t u r n by g r a v i t y t o t h e pump’s sump t a n k . The m o d i f i e d pump i s now b e i n g t e s t e d w i t h w a t e r a n d o t h e r room- tempera tu re l i q u i d s , and i t w i l l b e t e s t e d w i t h l i q u i d s t h a t s i m u l a t e t h e d e n s i t y and v i s c o s i t y o f t h e ARE f u e l . S t u d i e s a r e b e i n g made o f t h e l a b y r i n t h s e a l d u r i n g pump o p e r a t i o n , t h e e f f e c t s o f t h e pump i n l e t s u c t i o n b e l l , and t h e volume o f f l u i d and t h e b a f f l i n g r e q u i r e d i n t h e s u m p t a n k f o r s a t i s f a c t o r y pump o p e r a t i o n .

The o p e r a t i o n o f t h e l a b y r i n t h s e a l ( 0 . 0 0 9 - i n . r a d i a l c l e a r a n c e ) was i n - v e s t i g a t e d by m e a s u r i n g t h e l e a k a g e o f t h e s e a l a t v a r i o u s pump s p e e d s and h e a d s . A s e x p e c t e d , t h e f o u n t a i n i n c r e a s e s w i t h i n c r e a s e i n pump s p e e d and i n pump head . However, t h e amount o f t h e b y p a s s f o u n t a i n f l o w v a r i e d from 2 t o 10% o f pump f l o w , which i s a r e a s o n a b l e f r a c t i o n , A minor problem was e n c o u n t e r e d i n t h a t t h e l a b y r i n t h l e a k a g e s p l a s h e d t h e s u r f a c e o f t h e l i q u i d i n t h e sump t a n k and some o f t h e g a s b u b b l e s were c a r r i e d d e e p e n o u g h t o be e n t r a i n e d i n t h e f l u i d e n t e r i n g t h e i m p e l l e r .

( 2 ) W . G . Cobb. A . G . G r i n d e l l , and G . D. Whitman, ANP Q u a r . P r o g . R e p . S e p t . 1 0 , 1 9 5 2 , ORNL-1375, p . 17.

t

20


T h e pump h a s b e e n t e s t e d i n two t y p e s o f sump t a n k . T h e f i r s t t a n k was a r e c t a n g u l a r , p l e x i g l a s box , 1 4 by 1 6 by 30 i n . , i n w h i c h t h e f l u i d i n l e t t o t h e t a n k was c o n s i d e r a b l y o f f s e t from t h e e y e o f t h e i m p e l l e r . The second t a n k was a p l e x i g l a s c y l i n - d e r , a b o u t 1 2 i n . i n d i a m e t e r and 1 4 i n . h i g h , i n which t h e f l u i d i n l e t i s b e l o w a n d d i r e c t l y i n t o e y e o f t h e impe 1 l e r . When c o n t i n u o u s l y submerged , even i f o n l y t o a s m a l l f r a c t i o n o f an i n c h , t h e pump i n l e t s u c t i o n b e l l a p p e a r e d t o f u n c t i o n s a t i s f a c t o r i l y i n e i t h e r sump t a n k u n d e r a l l c o n d i t i o n s o f pump s p e e d and f l o w ,

Pump p r i m i n g i s n o t d i f f i c u l t t o a c c o m p l i s h i n e i t h e r t a n k . I n t h e i n i t i a l t e s t s e t u p , t h e volume o f g a s i n t h e s y s t e m p i p i n g a t s t a r t u p was a p p r o x i m a t e l y e q u a l t o t h e volume o f l i q u i d ; and i n t h e c y l i n d r i c a l t a n k , t h e pr ime was broken by a sudden s u r g e o f gas i n t o t h e i m p e l l e r e y e . P l a c i n g a n o b s t r u c t i o n o v e r t h e f l u i d i n l e t t o d i v e r t m o s t o f t h e g a s b u b b l e s away from t h e e y e t o t h e f r e e s u r f a c e was s u f f i c i e n t t o m a i n t a i n t h e p r i m e . I n a sys t em i n which t h e r e i s a s m a l l g a s volume compared w i t h t h e l i q u i d volume a t s t a r t u p , p r i m i n g i s a c c o m p l i s h e d by b l e e d i n g t h e t r a p p e d g a s i n t o t h e sump t a n k or by f i l l i n g u n d e r vacuum. I n t h e ARE s y s t e m , t h e t r a p p e d g a s i s f o r c e d o u t .

T e s t s w e r e made i n which t h e f l u i d was g a s s e d by a d m i t t i n g a i r , h e l i u m , o r a r g o n i n t o t h e e y e o f t h e s u c t i o n b e l l u n t i l t h e f l u i d b e c a m e m i l k y . T h e t ime r e q u i r e d f o r t h e f l u i d t o b e c o m e r e l a t i v e l y c l e a r w a s t h e n n o t e d , I n a l l t e s t s , i n c l u d i n g t e s t s w i t h f l o w r a t e s o f up t o 1 0 0 gpm and t e s t s i n w h i c h t h e c y l i n d r i c a l t a n k w i t h o u t b a f f l e s was u s e d , t h e f l u i d d e g a s s e d i n l e s s t h a n 5 min o f o p e r a t i o n . When t h e i n l e t o f t h e c y l i n d r i c a l tank. was o f f s e t a b o u t 1 / 2 i n . w i t h r e s p t o e y e o f t h e i m p e l l e r , t h e e n t i r e h o l d u p volume o f l i q u i d i n t h e t a n k w a s g i v e n a r o t a r y m o t i o n t h a t i n - c r e a s e d i n v e l o c i t y a t h i g h i m p e l l e r

s p e e d s and low f l o w r a t e s . When t h e b a f f l e s were i n p l a c e , t h i s c i r c u l a r m o t i o n o c c a s i o n a l l y c a u s e d t h e f o r - ma t ion o f v o r t e x e s and g a s e n t r a i n m e n t i n t h e l i q u i d . W i t h o u t b a f f l e s i n t h e c y l i n d r i c a l t a n k , t h e r o t a r y m o t i o n w a s p r e s e n t b u t n o v o r t e x e s w e r e o b s e r v e d . The g a s s e a l f o r t h i s pump w i l l b e e i t h e r a f r o z e n - s o d i u m o r f r o z e n - l e a d s e a l o r a m e c h a n i c a l f a c e s e a l .

ARE Centrifugal Pump. An ARE model FP p u m p ( 3 ) h a s b e e n c o n s t r u c t e d a n d i n c o r p o r a t e d i n a t e s t l o o p . The most c r i t i c a l f e a t u r e o f t h i s pump was t h e f r o z e n - s o d i u m s e a l f o r w h i c h s o d i u m from an e x t e r n a l s o u r c e was f e d t o a s e a l i n g a n n u l u s and f r o z e n i n r i n g s on e a c h s i d e o f t h e a n n u l u s ,

T h r e e t e s t s h a v e been r u n i n w h i c h NaK was pumped f o r a b o u t 15 min, 4 h r , and 1 h o u r . Each t e s t was t e r m i n a t e d b e c a u s e o f e x c e s s i v e s e a l l e a k a g e . Chemical a n a l y s e s o f s a m p l e s o f l e a k a g e m a t e r i a l i n d i c a t e d t h e p r e s e n c e o f from 1 t o 7 .5% p o t a s s i u m . S i n c e t h i s pump d o e s n o t o p e r a t e s u c c e s s f u l l y w i t h NaK, i t was m o d i f i e d f o r t e s t i n g w i t h sodium. For o p e r a t i o n w i t h s o d i u m , t h e e x t e r n a l s u p p l y o f s o d i u m t o t h e s e a l w i l l n o t be n e e d e d and a l a r g e r s u r f a c e w i l l be p r e s e n t e d f o r c o o l i n g o f t h e s e a l .

P r i o r t o i n s t a l l a t i o n o f t h e new s e a l i n g g l a n d , a s e r i e s o f t e s t s w a s r u n on t h e e x t e r n a l l y s u p p l i e d s e a l w i t h h e l i u m i n t h e pump l o o p . D u r i n g t h e s e t e s t s , pump s p e e d s a n d s e a l t e m p e r a t u r e s w e r e s y s t e m a t i c a l l y v a r i e d , a n d c o n s i d e r a b l e d a t a were t a k e n t o p r o v i d e more a d e q u a t e u n d e r - s t a n d i n g o f t h e f r o z e n - s e a l mechanism, S u c c e s s f u l o p e r a t i o n , a s a g a s s e a l , was o b t a i n e d o v e r t h e a v a i l a b l e r a n g e o f s p e e d s , 4 0 0 t o 1 9 2 0 r p m , a n d t h e t e m p e r a t u r e o f t h e sodium i n t h e g l a n d g roove v a r i e d from 300 t o 400'F. Speed and p r e s s u r e c o n d i t i o n s were d e t e r m i n e d u n d e r w h i c h t h e s e a l w o u l d f a i l a n d unde r which i t would o p e r a t e r e l i a b l y ,

( 3 ) A N P Q u a r . P r o g . R e p . D e c . 1 0 , 1 9 5 2 , ORNL- 1439, p. 21.

2 1

A N P PROJECT QUARTERLY PROGRESS REPORT

T h e s e a l i n g g l a n d t h a t h a s b e e n i n s t a l l e d i n t h e pump f o r o p e r a t i o n w i t h sodium h a s a l e n g t h - t o - d i a m e t e r r a t i o o f 2 . 3 , i n c o n t r a s t t o t h e r a t i o s o f 0 . 6 and 0 . 2 f o r t h e i n s i d e a n d o u t s i d e g l a n d s o f t h e p r e v i o u s l y u s e d e x t e r n a l l y s u p p l i e d s e a l . A l s o , t h e r a d i a l s h a f t - t o - g l a n d c l e a r a n c e h a s been i n c r e a s e d from 0 .015 i n . f o r t h e e x t e r n a l l y s u p p l i e d g l a n d t o 0.030 i n . f o r t h e l o n g e r g l a n d . I n i t i a l t e s t s o f t h i s g l a n d and s e a l i n d i c a t e a s a t i s f a c t o r y s e a l , b u t t h e y a l s o i n d i c a t e t h e p r e s e n c e o f e x c e s s i v e t h e r m a l d i s t o r t i o n s t h a t w i l l r e s u l t i n d i s p l a c e m e n t o f p a r t s and e v e n t u a l b i n d i n g .

Electromagnetic Pump. T h e t w o - s t a g e e l e c t r o m a g n e t i c pump t h a t w i l l b e u s e d t o c i r c u l a t e NaK i n t e s t i n g a n d c l e a n i n g o p e r a t i o n s o f t h e f u e l c i r c u i t o f t h e ARE h a s b e e n t e s t e d w i t h NaK a t 1500°F and i s u n d e r g o i n g s i m i l a r t e s t s w i t h sodium. With NaK, t h e pump d e l i v e r y i s a p p r o x i m a t e l y 90 gpm a t a p p r o x i m a t e l y 1 0 p s i ; p e r - formance c u r v e s a r e shown i n F i g . 2.2. The pump h a s g i v e n e n t i r e l y s a t i s f a c t o r y p e r f o r m a n c e , e x c e p t f o r a h a r d - s o l d e r e d j o i n t f a i l u r e i n t h e c u r r e n t l o o p , which was e a s i l y r e p a i r e d , and e x c e s s c o o l i n g , which was removed,

ROTATING-SHAFT AND VALVE-STEM-SEAL DEVELOPMENT

W. B. McDonald R . N . Mason W . C. Tunne l1 P. G. S m i t h

W . R . H u n t l e y ANP D i v i s i o n

R . E. E n g b e r g Long Range R e a c t o r P l a n n i n g Group

M e c h a n i c a l F a c e Seals. H i g h - t e m p e r a t u r e m e c h a n i c a l f a c e s e a l s f o r l i q u i d s s u c h a s f l u o r i d e s a r e b e i n g i n v e s t i g a t e d . S u c c e s s f u l o p e r a t i o n o f s u c h s e a l s may be d e p e n d e n t upon d r y - f i l m l u b r i ca t i on, boundary 1 u b r i c a t i o n , o r a d s o r b e d - f i l m l u b r i c a t i o n , b u t r e s e a r c h h a s r e v e a l e d o n l y e m p i r i c a l

22

k n o w l e d g e a b o u t t h e p r i n c i p l e s o f s i m i l a r s e a l s s u c c e s s f u l l y u s e d i n a p p l i c a t i o n s much l e s s s e v e r e t h a n t h o s e i m p o s e d by ANP r e q u i r e m e n t s . T h e p r o b l e m a p p e a r s t o b e o n e o f s e l e c t i n g a p p r o p r i a t e m a t e r i a l s t h a t w i l l r e t a i n o p t i c a l l y f l a t s u r f a c e s a t h i g h t e m p e r a t u r e s a n d w i l l h a v e t h e p r o p e r d e g r e e o f h a r d n e s s and s o f t n e s s r e l a t i v e t o e a c h o t h e r . G r a p h i t e i s b e i n g c o n s i d e r e d f o r t h e s o f t m a t e r i a l and m a t e r i a l s s u c h a s t u n g s t e n c a r b i d e , t i t a n i u m c a r b i d e , a n d c e r m e t s a r e b e i n g c o n s i d e r e d for t h e h a r d m a t e r i a l . T h e m e t h o d s o f f a b r i c a t i o n a n d t h e I

m a i n t e n a n c e o f h i g h a m b i e n t t e m p e r a - t u r e s a n d l o w t h e r m a l g r a d i e n t s t o a v o i d d i s t o r t i o n s a r e a l s o p e r t i n e n t

i

prob lems . I I

The work o f o t h e r s h a s shown t h a t a p r i n c i p a l f a c t o r i n d e t e r m i n i n g w e a r and s u r f a c e damage i n s l i d i n g i s t h e t e n d e n c y o f t h e s l i d i n g or r u b b i n g m a t e r i a l s t o a l l o y . A l t h o u g h o t h e r f a c t o r s , s u c h a s t h e h a r d n e s s e s o f t h e m a t e r i a l s , t h e m e l t i n g p o i n t s , t h e r u b b i n g v e l o c i t y , and t h e t e m p e r a t u r e o f o p e r a t i o n , a r e c o n s i d e r e d a s b e i n g o f s e c o n d a r y i m p o r t a n c e , i n s o m e i n s t a n c e s t h e y may become o f c o n t r o l l i n g i m p o r t a n c e , The u s e o f MoS, a s a h i g h - t e m p e r a t u r e l u b r i c a n t i s i n t r i g u i n g , and c o n s i d e r a b l e work h a s been done t o o b t a i n s u r f a c e s c o a t e d or i m p r e g n a t e d w i t h t h i s m a t e r i a l . T a b l e 2 . 1 l i s t s t h e a t t e m p t s t o e s t a b l i s h a MoS, l a y e r by a d d i n g MoS, t o t h e v e h i c l e t o make a p a s t e . It s h o u l d be n o t e d t h a t MoS, w i l l b e g i n t o o x i d i z e a t a b o u t 700°F i n a i r , b u t i n t h e a b s e n c e o f oxyge-n i t i s s t a b l e t o 2000'F. Tes ts of f a c e s e a l m a t e r i a l s , made by r o t a t i n g them i n c o n t a c t w i t h t h e o t h e r specimen a r e d e s c r i b e d i n T a b l e 2 . 2 . The c h a t t e r i n g n o t e d may h a v e b e e n d u e t o f o r c e s r e s u l t i n g f r o m t h e g e o m e t r y u s e d i n t h e t e s t a p p a r a t u s . T h e s e e x p e r i m e n t s i n d i c a t e t h a t of t h e m a t e r i a l s t e s t e d , g r a p h i t e i s b e s t f o r o n e o f t h e m a t e r i a l s , u n d e r t h e s e t e s t c o n d i t i o n s , when a i r i s p r e s e n t .


a 3 v) v) W

a a

UNCLASSIFIED

0-

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t I I

INPUT VOLTAGE TO CURRENT LOOP

0 25 0 50 A 75 A i o0

0 1 7 5

I 125 0 450

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UNCLASSIFIED DWG. 18712

0 I O 20 30 40 50 60 7 0 80 90

FLOW (gPm)

F i g . 2.2. Performance Curves for Double-Stage Electromagnetic Pump w i t h NaK. I n p u t v o l t a g e t o magnet l oop , 1 2 5 v o l t s .

23


TABLE 2.1. DESCRIPTION OF ATTEMPTS TO OBTAIN A MoS, SURFACE

BASE METAL

1. Type 316

2. Type 316

3. Type 316

s t a i n l e s s s t e e l



4. Type 316

5. Type 316

6. Type 316

7. Type 316

8. Type 316

9. Type 316







10. Lapped t u n g s t e n c a r b i d e

11. Etched t u n g s t e n c a r b i d e

12. Type 316 s t a i n l e s s s t e e l

13. T u n g s t e n c a r b i d e

14. T u n g s t e n c a r b i d e

15. Type 316 s t a i n l e s s s t ee l

16. B r a s s



19. Type 316 s t a i n l e s s s t ee l

VEHICLE

G-E enamel

Co 1 1 o i d a1 s i l v e r

High- t e m p e r a t u r e v a r n i s h

No. 1202 v a r n i s h

K e y s t o n e g r e a s e

P e r m a t e x No. 2

Ruby f l u x

Aquadag No. 200

P e r m a t e x No. 2 t h i n n e d w i t h Seb ac a t e

None

None

None

Handi - f 1 ux

Ruby f l u x

P e r m a t e x No. 2 w i t h S e h a c a t e

Handi- f l u x

Corn s y r u p

C e l l u f l u x

P l i o b o n d

TREATMENT AND APPLICATION

Brushed o n , a i r d r i e d , '

Brushed on , a i r d r i e d ,

Brushed on , a i r d r i e d ,

f u r n a c e h e a t e d t o 700 F

f u r n a c e h e a t e d t o 700'F


Brushed on, a i r d r i e d ,

Base m e t a l h e a t e d t o 700°F,


Base m e t a l h e a t e d t o 700'F,

Base m e t a l h e a t e d t o 7OO0F,



p a s t e b r u s h e d on





H e a t e d t o 700'F, d i p p e d in d r y MoS2

Heated t o 700°F, d r y MoS2

H e a t e d t o 700'F, d i p p e d i n

s p r i n k l e d on

d r y MoS2

t o r c h P a s t e s p p l i e d , h e a t e d w i t h

P a s t e a p p l i e d , h e a t e d w i t h t o r c h

Base m e t a l h e a t e d , b r u s h e d on i n f u r n a c e

Brushed on b a s e m e t a l , h e a t e d i n f u r n a c e




An a t t e m p t h a s been made t o e s t a b l i s h an u p p e r t e m p e r a t u r e l i m i t f o r s i l v e r - i m p r e g n a t e d g r a p h i t e r u b b i n g a g a i n s t t y p e 316 s t a i n l e s s s t e e l . The a s sembly c e a s e d t o s e a l h e l i u m a t a b o u t 450"F, and a l t h o u g h t h e t e m p e r a t u r e was i n - c r e a s e d s l o w l y t o 91O0F, s e a l i n g d i d n o t o c c u r a g a i n . When t h e t e m p e r a t u r e was d e c r e a s e d t o 45OoF, s e a l i n g was

REMARKS

Good c o a t i n g o b t a i n e d ,

Did n o t s t i c k t o b a s e m e t a l

a p p a r e n t l y

V a r n i s h b u r n t o f f , d i d n o t s t i c k

V a r n i s h b u r n t o f f , d i d n o t s t i c k


Showed p r o m i s e , f a i r c o a t i n g

Showed p r o m i s e , f a i r c o a t i n g


o b t a i n e d

o b t a i n e d

Remained s o f t , p o s s i b l y n o t enough h e a t , i n d i c a t e s p r o m i s e

T h i n l a y e r o b t a i n e d , a p p a r e n t l y

Thin l a y e r o b t a i n e d , a p p a r e n t l y

Good l a y e r o b t a i n e d

Adhered t o b a s e m e t a l , b u t uneven

S o f t and f l e x i b l e , a p p a r e n t l y

Good l a y e r , a p p a r e n t l y

B r a s s b u r n t , b u t a p p a r e n t l y some l a y e r r e m a i n e d

F a i r c o a t i n g , shows p r o m i s e

Good c o a t i n g , b u t uneven , shows p r o m i s e

F a i r c o a t i n g , h a r d and b r i t t l e

a g a i n a c c o m p l i s h e d . T h i s e x p e r i m e n t w i l l be c o n t i n u e d , and v a r i o u s s e a l i n g p r e s s u r e s w i l l be t r i e d .

A n o t h e r e x p e r i m e n t i s i n p r o g r e s s i n which an a t t e m p t i s b e i n g made t o s e a l a g a i n s t w a t e r w i t h s i l v e r - i m p r e g n a t e d g r a p h i t e v s . t y p e 316 s t a i n l e s s s t e e l a t v a r i o u s d i f f e r e n t i a l p r e s s u r e s and b e a r i n g p r e s s u r e s . To

24


TABLE 2.2. SUMMARY OF TESTS OF FACE SEAL MATERIALS

BASE METAL NO. ( c f . , Tab le 2 .1 )

11

10

13

16

1 2

14

1 5

MATERIALS

E tched t u n g s t e n c a r b i d e vs. t y p e 316 s t a i n l e s s s tee l

Lapped t u n g s t e n c a r b i d e vs . t y p e 316 s t a i n l e s s s t e e l

Tungs ten c a r b i d e vs. t ungs t e i c a r b i d e

B r a s s vs. t u n g s t e n c a r b i d e

Type 316 s t a i n l e s s s t e e l v s .

t u n g s t e n c a r b i d e

Tungs ten c a r b i d e vs. t y p e 316 s t a i n l e s s s t e e l

Type 316 s t a i n l e s s s t e e l vs. t u n g s t e n c a r b i d e

C-18 g r a p h i t e vs. t u n g s t e n c a r b i d e

G r a p h i t e (No. 40) impregna te , w i t h MoS, vs . t u n g s t e n c a r b i d e

APC g r a p h i t e v s . t u n g s t e n

C-18 g r a p h i t e vs. t u n g s t e n c a r b i d e

C- 18 g r a p h i t e v s . t u n g s t e n c a r b i d e

RESULTS

Opera t ed f o r 2 h r b e f o r e c h a t t e r i n g o c c u r r e d

O p e r a t e d f o r 2 h r b e f o r e c h a t t e r i n g o c c u r r e d

O p e r a t e d f o r o n l y a s h o r t p e r i o d

O p e r a t e d f o r 5 h r b e f o r e c h a t t e r i n g o c c u r r e d

O p e r a t e d f o r 3 h r b e f o r e c h a t t e r i n g o c c u r r e d ; a d d i t i o n o f d r y MoS, s t o p p e d c h a t t e r i n g f o r a b o u t 15 min

O p e r a t e d f o r 7 min b e f o r e c h a t t e r i n g occur r e d

O p e r a t e d f o r 50 min b e f o r e c h a t t e r i n g o c c u r r e d

C h a t t e r e d immedia t e ly , s u r f a c e n o t f l a t

Opera t ed f o r 12 h r a t s e l f - g e n e r a t e d t e m p e r a t u r e of 225'F

At tempted t o c o a t g r a p h i t e w i t h f u e l 27, o p e r a t e d f o r 4 h o u r s

Heated w i t h t o r c h t o 475'F, c h a t t e r d e v e l o p e d

Dry MoS, added , h e a t e d t o 913'F w i t h t o r c h , o p e r a t i o n smooth, e x c e p t between 400 and 450°F, when c h a t t e r i n g o c c u r r e d

d a t e , t h e s e a l h a s n o t been c o n s i s t e n t ; i t h a s l e a k e d a t times and i n v a r y i n g amounts .

O t h e r m a t e r i a l s h a v e been o r d e r e d , s u c h a s b o r o n n i t r i d e c o m p a c t s , MoS,- i m p r e g n a t e d c o p p e r , s i l v e r and s t a i n - l e s s s t e e l c o m p a c t s , a n d a s i n t e r e d m o l y b d e n u m c o m p a c t , t h a t w i l l b e t r e a t e d t o form a MoSz s u r f a c e .

Combination Packed and Frozen Seal with MoS,. B e c a u s e MoS, h a s h i g h - t e m p e r a t u r e l u b r i c a t i n g p r o p e r t i e s , a n a t t e m p t was made t o u s e i t a s a

h i g h - t e m p e r a t u r e p a c k i n g m a t e r i a l f o r s e a l i n g f l u o r i d e s ; f l u o r i d e l e a k a g e was s l i g h t ; o p e r a t i o n was s m o o t h ; and t h e r e were n o power s u r g e s . However, a s i n p r e v i o u s e x p e r i m e n t s , t h e MoSz was t o o f l u i d a n d c o u l d n o t b e c o n - t a i n e d . T h e r e t a i n e r s u s e d w e r e G r a p h i t a r No. 14 r i n g s , The m a t e r i a l s l o w l y l e a k e d o u t o f t h e s t u f f i n g box a n d a r o u n d t h e g l a n d u n t i l t h e g l a n d was c o m p l e t e l y i n s e r t e d .

For t h e n e x t a t t e m p t t o s e a l w i t h t h i s m a t e r i a l , a p a c k i n g o f I n c o n e l

25


b r a i d i m p r e g n a t e d w i t h MoSz was u s e d . T h i s e x p e r i m e n t was t e r m i n a t e d a f t e r a p p r o x i m a t e l y 925 h r o f o p e r a t i o n w i t h f u e l No, 30 a t 1 0 p s i and 1 7 5 0 rpm. Excess i v e 1 eakage o c c u r r e d b e c a u s e t h e s e a l r e a c h e d t o o h i g h t e m p e r a t u r e s when an a t t e m p t was made t o r e s t a r t o p e r a t i o n a f t e r b i n d i n g had o c c u r r e d , The o p e r a t i o n o f t h e s e a l c o r r e s p o n d e d t o o p e r a t i o n o f s e a l s i n o t h e r t e s t s i n t h a t t h e l e a k a g e o f t h e s e a l was a p p a r e n t l y t e m p e r a t u r e s e n s i t i v e . When t h e s e a l w a s t o o h o t o r t o o c o l d , l e a k a g e and power s u r g e s r e s u l t e d , b u t unde r c e r t a i n c o n d i t i o n s o p e r a t i o n was s m o o t h a n d t h e r e was n o d e t e c t a b l e l e a k a g e . T h e r e have been no i n t e n t i o n a l s t a r t - s t o p t e s t s , a l t h o u g h t h e u n i t h a s b e e n a c c i d e n t a l l y s t o p p e d o n s e v e r a l o c c a s i o n s , a n d power s u r g e s h a v e o v e r l o a d e d t h e m o t o r r e l a y s s e v e r a l t i m e s , T h e u n i t h a s b e e n r e s t a r t e d w i t h l i t t l e d i f f i c u l t y on e a c h o c c a s i o n by h e a t i n g t h e p a c k i n g a r e a and u s i n g a wrench t o “ b r e a k ” t h e s h a f t l o o s e .

Combination Packed and Frozen Sea l w i t h Graphite. The c o n t i n u o u s o p e r a t i o n o f t h e g r a p h i t e - p a c k e d s e a l , ment ioned i n t h e p r e v i o u s r e p o r t , was t e r m i n a t e d a f t e r 7 2 5 h o u r s . The s e a l had shown n o s i g n s of f a i l u r e , and a f t e r a n o t h e r 1 5 0 h r o f p e r i o d i c a n d s t o p - s t a r t o p e r a t i o n , t h e t e s t was a g a i n t e r m i - n a t e d . D u r i n g t h e l a t t e r p e r i o d o f o p e r a t i o n , a t t e m p t s w e r e m a d e t o c o n t r o l t h e s e a l t e m p e r a t u r e s a n d , t h e r e b y , t h e z o n e i n w h i c h f r e e z i n g was o c c u r r i n g , s i n c e i t was b e l i e v e d t h a t most s a t i s f a c t o r y o p e r a t i o n would o c c u r i f f r e e z i n g t o o k p l a c e w i t h i n t h e g r a p h i t e r e g i o n . Two f a i r l y s t a b l e t e q p e r a t u r e r a n g e s of o p e r a t i o n were f o u n d ; o n e s e t o f t e m p e r a t u r e s c o r r e s p o n d e d t o t h a t m a i n t a i n e d d u r i n g t h e 7 2 5 - h r p e r i o d o f c o n t i n u o u s o p e r a t i o n and t h e o t h e r s e t was a b o u t 150’F l o w e r . O p e r a t i o n was u n s t a b l e a t i n t e r m e d i a t e t e m p e r a t u r e s . A t t h e l o w e r t e m p e r a t u r e s , o p e r a t i o n w a s s m o o t h ; t h e r e w a s n o d e t e c t a b l e l e a k a g e ; and t h e u n i t c o u l d be s t o p p e d

f o r a s l o n g a s 2 0 m i n a n d s t a r t e d a g a i n by m o t o r power o n l y . The s e a l u s e d i n t h i s t e s t was s i m i l a r t o t h e s e a l s u s e d i n o t h e r t e s t s i n t h a t l e a k a g e o c c u r r e d when t h e s e a l was t o o h o t or t o o c o l d .

Graphite Packed S e a l . I n an a t t e m p t t o d e t e r m i n e t h e b e n e f i t s o f h o l d i n g t h e t r a n s i t i o n f r o m f l u i d t o s o l i d w i t h i n t h e g r a p h i t e , a t e s t was s e t up t h a t i n c l u d e d a l o n g (4 i n . 1, g r a p h i t e - p a c k e d , s t u f f i n g b o x . I n o r d e r t o o b t a i n mor e c o m p l e t e t e m p e r a t u r e d a t a , f o u r t h e r m o c o u p l e s were i n s t a l l e d i n t h e r o t a t i n g s h a f t , and s i g n a l s were t a k e n o f f t h r o u g h s l i p r i n g s . A f t e r a d r y r u n , f l u o r i d e s were i n t r o d u c e d and t h e s e a l i m m e d i a t e l y s t a r t e d l e a k i n g g r a p h i t e . T h e G r a p h i t a r r i n g s u s e d a s r e t a i n e r s d i d n o t c o n t a i n t h e g r a p h i t e a t t h e t o p o f t h e s e a l . Approximate ly 3/4 i n . o f I n c o n e l b r a i d was t h e n a d d e d , and t h e g r a p h i t e was s u c c e s s f u l l y r e t a i n e d . The m o t o r f o r t h i s t e s t was a 5 -hp u n i t . O p e r a t i o n s t a r t e d o f f f a i r l y n o r m a l l y , b u t t h e t e m p e r a t u r e s a d j a c e n t t o t h e s e a l b e g a n t o i n c r e a s e . C o o l i n g o f t h e b e a r i n g h o u s i n g a n d t h e g l a n d w a s s t a r t e d , b u t t h e t e m p e r a t u r e s c o n t i n u e d t o r i s e . T h e t e m p e r a t u r e s n e v e r became s t a b l e ; t h e y f l u c t u a t e d o v e r a r a n g e o f 940 t o 2190’F t h r o u g h o u t t h e s e a l r e g i o n . The h o t t e s t p o i n t was a p p a r e n t l y n e a r t h e m i d d l e o f t h e p a c k i n g , and t h e l o w e s t t e m p e r a t u r e s were i n t h e r e g i o n s o f t h e b e a r i n g s and t h e f l u o r i d e . The m o l t e n f l u o r i d e was a c t i n g a s a c o o l a n t i n t h i s t e s t . The tempera t u res con t i n u e d t o i n c r e a s e u n t i l t h e t e s t h a d t o be t e r m i n a t e d a f t e r a p p r o x i m a t e l y 50 h r o f o p e r a t i o n b e c a u s e t h e s h a f t , f r o z e . T h e s h a f t c o u l d b e r e s t a r t e d b y m o t o r p o w e r a f t e r i t c o o l e d , b u t would n o t c o n t i n u e t o o p e r a t e when h i g h e r t e m p e r a t u r e s were r e a c h e d . A t n o t i m e w a s t h e r e a n y d e t e c t a b l e l e a k a g e ; h o w e v e r , s e v e r e s h a f t s c o r i n g o c c u r r e d .

A p i c t u r e o f t h e s e a l and s h a f t c u t t h r o u g h t h e c e n t e r l i n e i s shown i n F i g . 2 . 3 . The e x t r e m e s c o r i n g o f t h e

k.

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27


1 3 / 1 6 - i n . - d i a s h a f t i s q u i t e e v i d e n t ; o t h e r p o r t i o n s o f t h e s h a f t ( a l s o a t v e r y h i g h t e m p e r a t u r e s ) s h o w e d n o m a r k i n g s w h a t s o e v e r . T h e c o n d i t i o n o f t h e g r a p h i t e i t s e l f i s o f i n t e r e s t , s i n c e i t a p p a r e n t l y p a c k e d i n more or l e s s c o n c e n t r i c ’ ’ r a d i a l l a y e r s t h a t v a r i e d i n t h i c k n e s s a l o n g t h e l e n g t h o f t h e s e a l . T h e l a y e r s a d h e r e d a t times t o t h e s h a f t and r o t a t e d , and a t o t h e r t imes t h e y a d h e r e d t o e a c h o t h e r a n d r e m a i n e d s t a t i o n a r y . The powder w a s e x c e p t i o n a l l y f i n e a n d v e r y “ g r e a s y ” ; t h e “ c o n c e n t r i c ” l a y e r s were v e r y s l i m y ; a n d t h e r e was n o v i s i b l e e v i d e n c e o f f l u o r i d e p e n e t r a t i o n .

R o t a t i n g - S h a f t S e a l T e s t . T h e a p p a r a t u s f o r t h e t e s t s of t h e r o t a t i n g - s h a f t s e a l c o n s i s t s o f a c o n t a i n e r f o r t h e p a c k i n g m a t e r i a l b e i n g t e s t e d , an u p p e r compress ion g l a n d t h a t e x e r t s p r e s s u r e o n t h e p a c k i n g , a l a n t e r n g l a n d l o c a t e d midway i n t h e c o n t a i n e r , a n d a s h a f t e x t e n d i n g t h r o u g h t h e a s s e m b l y . T h e s h a f t r o t a t e s i n a b e a r i n g b e n e a t h t h e a s s e m b l y a n d i s d r i v e n by a moto r mounted above. The p a c k i n g c o n t a i n e r i s m o u n t e d on f o u r r o l l e r s and is r e s t r a i n e d from t u r n i n g w i t h t h e s h a f t by two t e n s i o n s p r i n g s . The t o r q u e n e c e s s a r y t o t u r n t h e s h a f t i s i n d i c a t e d b y a p o i n t e r a n d a c a l i b r a t e d s c a l e o n t h e a s s e m b l y . F l u o r i d e s a r e f o r c e d u n d e r p r e s s u r e f r o m a f i l l t u b e i n t o t h e c o n t a i n e r t h r o u g h t h e l a n t e r n g l a n d . D u r i n g t h e t e s t s , t h e t e m p e r a t u r e o f t h e m i d p o i n t o f t h e p a c k i n g c o n t a i n e r was 1500’F; t h e t e m p e r a t u r e o f t h e l o w e r s h a f t o p e n i n g was 1400’F; t h e p r e s s u r e w a s 20 p s i . T h e p a c k i n g m a t e r i a l s t e s t e d were MoS, andpowdered g r a p h i t e . T h e MoS, p a c k i n g began t o l e a k a f t e r 1 h r o f o p e r a t i o n . The t o r q u e r e q u i r e d t o t u r n t h e s h a f t a t 3 5 0 r p m w a s 2 f t - l b . T h e g r a p h i t e t e s t r a n f o r 8 h r b e f o r e l e a k a g e o c c u r r e d , and t h e same t o r q u e was r e q u i r e d f o r r o t a t i o n . T h e r e w a s c o n s i d e r a b l e w e a r o n t h e u p p e r p a c k i n g g l a n d . T h e s h a f t h a d t o b e s t a r t e d and s t o p p e d a number o f t i m e s b e c a u s e o f s e v e r e v i b r a t i o n .

(1

Packing P e n e t r a t i o n T e s t s . T h e a p p a r a t u s u s e d i n t h e p a c k i n g p e n e - t r a t i o n t e s t s a n d t h e r e s u l t s o f s e v e r a l t e s t s were d e s c r i b e d p r e v i - o u ~ l y . ( ~ ) F u r t h e r t e s t s h a v e b e e n made and t h e r e s u l t s a r e p r e s e n t e d i n t h e f o l l o w i n g .

S t a i n l e s s s t e e l b r a i d i m p r e g n a t e d w i t h MoS, was c o m p r e s s e d a n d h e a t e d t w i c e t o t h e a n n e a l i n g t e m p e r a t u r e , w i t h f u r t h e r c o m p r e s s i o n a f t e r e a c h h e a t i n g . T h i s p a c k i n g h e l d t h e f l u o r i d e s f o r 1 / 2 h r a t 2 p s i , b u t when t h e p r e s s u r e w a s i n c r e a s e d t o 5 p s i , l e a k a g e o c c u r r e d . E x a m i n a t i o n showed t h a t t h e l e a k a g e p a t h was a l o n g t h e w a l l s o f t h e c o n t a i n e r s , t h e s c rew s t e m , a n d t h e s t r a n d s o f t h e b r a i d . I t c o u l d n o t be d e t e c t e d t h a t a n y f l u o r i d e m i x e d w i t h t h e MoS, or p e n e t r a t e d t h r o u g h it .

A s e c o n d b o r o n n i t r i d e t e s t w a s r u n i n an a s s e m b l y w i t h much s m a l l e r c l e a r a n c e s t h a n t h o s e u s e d f o r t h e p r e v i o u s b o r o n n i t r i d e t e s t . I n t h i s t e s t , i t w a s p o s s i b l e t o r a i s e t h e p r e s s u r e t o 30 p s i , and o p e r a t i o n was c o n t i n u e d f o r 2 3 4 h r b e f o r e l e a k a g e o c c u r r e d .

A t e s t w i t h J . T. B a k e r C h e m i c a l C o . p o w d e r e d g r a p h i t e p r e v i o u s l y r e p o r t e d ( 4 ) h a s c o n t i n u e d f o r 240 h r w i t h n o l e a k a g e . A n a l y s i s s h o w e d t h a t t h e p a c k i n g was a p p r o x i m a t e l y 50% a m o r p h o u s c a r b o n . T h r e e m o r e g r a p h i t e s h a v e b e e n t e s t e d , a n d i n a l l c a s e s i t was p o s s i b l e t o r a i s e t h e p r e s s u r e t o 30 p s i w i t h o u t l e a k a g e o c c u r r i n g . The a n a l y s e s and r e s u l t s a r e g i v e n i n T a b l e 2 . 3 . T h e r e s h o u l d b e a minimum o f a m o r p h o u s c a r b o n i n t h e g r a p h i t e b e c a u s e i t w o u l d b e e x p e c t e d t o i n c r e a s e t h e f r i c t i o n b e t w e e n a r o t a t i n g s h a f t a n d t h e p a c k i n g ; h o w e v e r , t h e g r a p h i t e w i t h t h e h i g h e s t amorphous c a r b o n c o n t e n t s e a l e d f o r t h e l o n g e s t p e r i o d s . T h a t t h e p a c k i n g i n t h e f i r s t t e s t d i d n o t l e a k w h e r e a s t h e p a c k i n g i n t h e l a t e r

(4)ANP Quar. P r o g . R e p . D e c . 1 0 . 1 9 5 2 . ORNL- 1439, p . 23 .

28


A N A L Y S I S O F AMORPHOUS

( % I P A C K I N G M A T E R I A L CARBON C O N T E N T

Dixon No. 2 f l a k e g r a p h i t e 10

Dixon Microfyne g r a p h i t e 50

Amer. G r a p h i t e Co. No. 620 powdered g r a p h i t e 50

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22

7 5

6 3

t e s t s d i d , a l t h o u g h t h e p h y s i c a l c h a r a c t e r i s t i c s o f t h e g r a p h i t e s were t h e s a m e , m i g h t b e t h e r e s u l t o f f u e l No. 1 4 b e i n g u s e d i n t h e f i r s t t e s t a n d f u e l No. 3 0 i n t h e l a t e r t es t .

Frozen-Sodium and Frozen-Lead Seal for NaK. I t was r e p o r t e d p r e v i o u s l y ( ' ) t h a t t e s t s were u n d e r way t o d e t e r m i n e t h e f e a s i b i l i t y o f s e a l i n g a NaK pump w i t h an e x t e r n a l l y s u p p l i e d f r o z e n - sodium or f r o z e n - l e a d s e a l . A l t h o u g h t h e p r e l i m i n a r y t es t s were e n c o u r a g i n g , s u b s e q u e n t t e s t s r e v e a l e d t h a t s e a l l i f e ( t h e t i m e b e f o r e f a i l u r e b e c a u s e o f a l l o y i n g ) was, i n g e n e r a l , i n v e r s e l y p r o p o r t i o n a l t o NaK t e m p e r a t u r e and t h a t t h e s e a l s were u n r e l i a b l e f o r p e r i o d s o f o p e r a t i o n g r e a t e r t h a n 100 h o u r s .

I n t h e f r o z e n s o d i u m s e a l , t h e s o d i u m a l l o y s w i t h t h e NaK and f o r m s a l o w - m e l t i n g - p o i n t a l l o y i n t h e s e a l t h a t c a n n o t b e f r o z e n w i t h r o o m - t e m p e r a t u r e c o o l i n g w a t e r ; a s a r e s u l t t h e s e a l i s c o m p l e t e l y l o s t . R e - f r i g e r a t i o n , w i t h t e m p e r a t u r e s b e l o w t h e m e l t i n g p o i n t o f e u t e c t i c NaK (12 'F ) , w o u l d b e r e q u i r e d t o a s s u r e s e a l r e t e n t i o n .

I n t h e f r o z e n - l e a d s e a l , t h e l e a d a l l o y s w i t h t h e NaK and fo rms a h i g h - m e l t i n g - p o i n t a l l o y ; a s a r e s u l t t h e r e i s s h a f t s e i z u r e and i t i s i m p o s s i b l e t o o p e r a t e w i t h r e a s o n a b l e p o w e r r e q u i r e m e n t s .

("AMP Quar. P r o g . R e p . D e c . 1 0 , 1 9 5 2 , ORNL- 1439. p. 2 6 .

A R E Valve Test. P r e l i m i n a r y g a s a n d l i q u i d l e a k a g e t e s t s h a v e b e e n r u n o n t h e ARE p n e u m a t i c a l l y d r i v e n v a l v e s u p p l i e d by F u l t o n - S y l p h o n Co. T h e v a l v e i s c o n s t r u c t e d o f I n c o n e l and h a s a S t e l l i t e - t o - S t e l l i t e v a l v e and s e a t . T h e s h a f t - s e a l i n g member i s a f o u r - p l y I n c o n e l b e l l o w s . T h e v a l v e i s a d a p t a b l e t o b e i n g e i t h e r n o r m a l l y c l o s e d or n o r m a l l y o p e n e d , a n d t h e p o s i t i o n i s r e v e r s e d by a p p l i c a t i o n o f 15 p s i o f a i r p r e s s u r e t o a l a r g e b e l l o w s a c t u a t o r .

F o r t h e i n i t i a l t e s t , t h e v a l v e w a s m o u n t e d v e r t i c a l l y a n d a d a p t e d f o r n o r m a l l y c l o s e d o p e r a t i o n . With t h e v a l v e a t room t e m p e r a t u r e , g a s l e a k a g e was s m a l l w i t h t e s t p r e s s u r e s f r o m 30 t o 6 0 p s i t h a t w e r e f i r s t a p p l i e d u p a g a i n s t t h e v a l v e s e a t a n d t h e n down o n i t . R a i s i n g t h e v a l v e t e m p e r a t u r e t o 1050'F c a u s e d a s l i g h t i n c r e a s e i n g a s l e a k a g e ; however , t h e l e a k a g e r e m a i n e d s m a l l .

T e s t i n g f o r l i q u i d l e a k s w i t h t h e A R E f u e l , N a F - Z r F , - U F , ( 5 0 - 4 6 - 4 mole %), a t 1100'F r e v e a l e d t h a t t h e r e w a s n o l e a k a g e w i t h t e s t p r e s s u r e s o f 30 t o 60 p s i a p p l i e d b o t h above and below t h e s e a t . T h i s t e s t w a s r e p e a t e d s e v e r a 1 t ime s .

I n a t e s t a t 1300°F, s l i g h t l e a k a g e ( 0 . 3 i n . 3 / h r o r l e s s ) o c c u r r e d a t v a r i o u s i n t e r v a l s . H o w e v e r , i t was c o n c l u d e d t h a t t h e l e a k a g e a t t h i s t e m p e r a t u r e w a s n o t s e r i o u s . T h e i n i t i a l c h e c k s a t 1 5 0 0 ' F were v e r y s u c c e s s f u 1. c h e c k s , S u b s e qu e n t

29


however, showed a v e r y s e r i o u s l e a k a g e r a t e , 1 2 0 i n . 3 / h r , t h a t c o u l d n o t be c o r r e c t e d by r e s e a t i n g t h e v a l v e . I t was c o n c l u d e d t h e r e f o r e t h a t t h e v a l v e m i g h t b e u s a b l e f o r s e v e r a l c y c l e s a t 1 5 0 0 ° F b u t t h a t i t c o u l d n o t b e e x p e c t e d t o h o l d t i g h t i f c y c l e d i n d e f i n i t e l y .

D i f f i c u l t y a t t h e e l e v a t e d t empera - t u r e w a s e x p e r i e n c e d i n t h a t t h e v a l v e s t u c k when l e f t c l o s e d f o r s h o r t p e r i o d s . H o w e v e r , i n a l l c a s e s t o d a t e , t h e v a l v e h a s e v e n t u a l l y become o p e r a b l e by i n c r e a s i n g t h e p r e s s u r e u p t o 30 p s i on t h e v a l v e a c t u a t o r . I n o n e i n s t a n c e a t 1100°F and a n o t h e r a t 1500°F, i t was n e c e s s a r y t o v i b r a t e t h e v a l v e body t o g e t t h e v a l v e open. When t h e v a l v e was c u t f o r i n s p e c t i o n , i t was found t h a t some b i n d i n g o f t h e S t e l l i t e f a c e s had o c c u r r e d .

HEAT EXCHANGER SYSTEMS

G. D. Whitman D. F. Salmon ANP D i v i s i o n

S o d i u m - t o - A i r R a d i a t o r T e s t s . T h e s o d i u m - t o - a i r r a d i a t o r t e s t e d

' h a d a c o r e e l e m e n t w i t h 3 0 f i n s p e r i n c h . ( 6 ) T h i s t e s t r a n f o r 2 0 0 h r a n d was t h e n t e r m i n a t e d b e c a u s e o f p o o r h e a t t r a n s f e r p e r f o r m a n c e . The m a x i m u m , o v e r - a l l , h e a t t r a n s f e r c o e f f i c i e n t s o b t a i n e d w e r e o f t h e o r d e r o f 6 B t u / h r * f t 2 * " F , w h i c h i s f a r be low t h e p r e d i c t e d p e r f o r m a n c e . I t was d i s c o v e r e d , a f t e r i n l e t sodium t e m p e r a t u r e s o f 1 5 0 0 ° F were r e a c h e d , t h a t v e r y f e w o f t h e N i c r o b r a z e d f i n - t o - t u b e j o i n t s were g o o d . T h e r a d i a t o r c o u l d b e s e e n t h r o u g h t h e a i r e x h a u s t , and i t was o b s e r v e d t h a t w i t h minimum a i r f l o w l e s s t h a n 10% o f t h e n i c k e l f i n s s h o w e d a n y h e a t c o l o r . T h e s m a l l a m o u n t s o f b r a z e m a t e r i a l u s e d t o a v o i d c l o s i n g t h e 0 . 0 2 5 - i n . f i n - t o - f i n g a p s w e r e a p - p a r e n t l y i n s u f f i c i e n t t o c o m p l e t e l y j o i n t h e f i n s a n d t u b e s . No o x i d e p l u g g i n g o c c u r r e d i n t h e r a d i a t o r

(6)ANP Quar . P r o g . R e p . D e c . 10. 1 9 5 2 , ORNL- 1439, p . 2 7 .

30

t u b e s d u r i n g t h i s r e l a t i v e l y s h o r t r u n , a n d t h e b y p a s s f i l t e r c i r c u i t was o p e r a t e d w i t h o u t d i f f i c u l t y .

A R o o t s C o n n e r s v i l l e g a s pump d r i v e n by a 2 - h p V a r i d r i v e h a s b e e n i n s t a l l e d i n p l a c e o f t h e B u f f a l o c e n t r i f u g a l b l o w e r s o t h a t a w i d e r r a n g e o f a i r f l o w s a n d b e t t e r f l o w r e g u l a t i o n c a n be o b t a i n e d .

B i f l u i d Heat Transfer Loop. T h e b i f l u i d h e a t t r a n s f e r l o o p , ( ' ) w h i c h h a s been i n o p e r a t i o n f o r a p p r o x i m a t e l y two m o n t h s , t r a n s f e r s h e a t f rom f u e l No. 3 0 t o NaK. T h e h e a t t r a n s f e r t a k e s p l a c e i n a c o n c e n t r i c t u b e s e c t i o n ; t h e c e n t e r t u b e c o n t a i n s t h e h o t f l u o r i d e a n d t h e NaK i s i n t h e a n n u l u s . The c e n t e r t u b e h a s an i n s i d e d i a m e t e r o f 0 . 2 6 9 i n . a n d an L / D r a t i o o f 40 , w h e r e a s t h e a n n u l u s has an L/D r a t i o o f 22.

H e a t t r a n s f e r d a t a on t h e f l u o r i d e f u e l h a v e been t a k e n o v e r a R e y n o l d ' s number r a n g e o f from 5 , 0 0 0 t o 2 0 , 0 0 0 , w h i c h c o r r e s p o n d s t o v e l o c i t i e s o f from 8 t o 30 f p s . The maximum f l u o r i d e t e m p e r a t u r e w a s 1 4 0 0 " F , a n d t h e t e m p e r a t u r e d r o p a c r o s s t h e h e a t e x c h a n g e r was v a r i e d from 1 5 t o 40°F. T h e N a K - s i d e d a t a w e r e t a k e n a t R e y n o l d ' s n u m b e r s f r o m 2 0 , 0 0 0 t o 100,000.

The o v e r - a l l h e a t t r a n s f e r c o e f - f i c i e n t f o r h e a t f l u x e s from 3 0 0 , 0 0 0 t o 5 0 0 , 0 0 0 B t u / h r . f t 2 h a s v a r i e d from 1 0 0 0 t o 2 5 0 0 B t u / h r * f t 2 * O F . S a t i s - f a c t o r y s e p a r a t i o n o f t h e i n d i v i d u a l c o e f f i c i e n t s h a s n o t been accompl i shed because o f t h e n e c e s s i t y o f e v a l u a t i n g t h e r m a l e n t r a n c e e f f e c t s a n d b e c a u s e o f what a p p e a r s t o b e f o u l i n g i n t h e e x c h a n g e r . I t i s p o s s i b l e t h a t f o u l i n g o c c u r r e d , b e c a u s e t h e r e w a s f l o w r e s t r i c t i o n when t h e t e m p e r a t u r e o f t h e NaK e n t e r i n g t h e h e a t e x c h a n g e r was l o w e r e d t o t h e f l u o r i d e m e 1 t i n g p o i n t ( a p p r o x i m a t e l y 950'F).

The pump f o r c i r c u l a t i n g f l u o r i d e f u e l h a s o p e r a t e d s a t i s f a c t o r i l y w i t h a minimum o f g a s l e a k a g e . T h i s pump

( 7 ) A N P Quar . P r o g . R e p . D e c . 1 0 , 1 9 5 2 , ORNL- 1439, p. 2 8 .

t


i s a sump pump i n w h i c h t h e l i q u i d l e v e i s c o n t r o l l e d w i t h a s p a r k - p l u g - p r o b e . The s e a l o f t h e pump i s o f t h e w a t e r - c o o l e d , r o t a r y - f a c e t y p e t h a t c o n s i s t s o f s i l v e r - i m p r e g n a t e d g r a p h i t e r u n n i n g a g a i n s t t o o l s t e e l .

ARE FUEL CIRCUIT MOCKUP G. D. Whitman, ANP D i v i s i o n

A mockup o f t h e ARE f u e l c i r c u i t h a s been c o n s t r u c t e d f o r i n v e s t i g a t i n g t h e h y d r o d y n a m i c s t a b i l i t y o f t h e d e s i g n and t h e c h a r a c t e r i s t i c s o f t h e l i q u i d f l o w i n t h e s u r g e t a n k s . The sys t em, shown s c h e m a t i c a l l y i n F i g . 2 . 4 , was c o n s t r u c t e d from b l a c k i r o n p i p e , a n d i t h a s v i e w i n g w i n d o w s i n t h e s u r g e t a n k s and g l a s s s e c t i o n s i n t h e l i n e s l e a v i n g t h e s u r g e t a n k s . T h e s u r g e t a n k s a r e o f t h e s i z e t o b e used i n t h e ARE, and t h e two i d e n t i c a l pumps h a v e c h a r a c t e r i s t i c s i n t h e f l o w r a n g e t o be i n v e s t i g a t e d ( 0 t o 50 gpm)

t h a t a r e q u i t e s i m i l a r t o t h o s e o f t h e p r o p o s e d ARE pumps. S p e e d v a r i a t i o n o f t h e p u m p s i s o b t a i n e d b y u s i n g 5 - h p V a r i d r i v e u n i t s . T h e h e a t e x c h a n g e r s a r e s i m u l a t e d b y g a t e v a l v e s , and t h e r e a c t o r can be s i m u l a t e d by a Globe v a l v e or by t h e g l a s s model t h a t was p r e v i ou s l y d e sc r i bed.

T h u s f a r , w a t e r a n d a w a t e r - g l y c e r i n e solution h a v e b e e n u s e d i n t h e system. The r e s u l t s a re t h e r e f o r e b a s e d on o b s e r v a t i o n s made w i t h w a t e r o f a p p r o x i m a t e l y o n e - t h i r d t h e d e n s i t y a n d o n e - t e n t h t h e v i s c o s i t y o f t h e f u e l a n d w i t h t h e g l y c e r i n e - w a t e r s o l u t i o n o f a p p r o x i m a t e l y o n e - t h i r d t h e d e n s i t y o f t h e f u e l a n d t h e same v i s c o s i t y . T e s t s h a v e b e g u n w i t h 1 - l , 2 - 2 , b r o m o e t h a n e , f o r w h i c h t h e room- t e m p e r a t u r e d e n s i t y and v i s c o s i t y a r e n e a r l y t h e s a m e a s t h o s e o f f u e l No. 30 a t 1400'F.

T h e ARE s y s t e m c o m p r i s e s t w o , s i m i l a r , l i q u i d h e a t e x c h a n g e r a n d

L

I GLASS PIPE-

ANTIVORTEXING AND PROBE ASSEMBLY

ROTAMETER

HEAT EXCHANGER

REACTOR Y ' HEAT EXCHANGER 1 2-in. IPS

PRESSURE GAGE

L \ // -

/ / \ FLUID FLOW -

Fig. 2.4. Sketch of ARE Fuel-Circuit Mockup.

31


s u r g e t a n k c i r c u i t s - one f o r m o d e r a t o r c o o l a n t and t h e o t h e r f o r f u e l . Each

' c i r c u i t i n c l u d e s two p a r a l l e l c i r c u i t s , e a c h o f w h i c h i n c l u d e s , i n s e r i e s , a p a i r o f h e a t e x c h a n g e r s ( i n p a r a l l e l ) , a pump, and a s u r g e t a n k . A s d e s i g n e d , e a c h s u r g e t a n k was t o r e c e i v e a n d d e l i v e r t h e e n t i r e f l o w o f i t s p a r - t i c u l a r pump, H o w e v e r , t h e s u r g e t a n k s of t h e m o d e r a t o r c o o l a n t c i r c u i t s h a v e now b e e n p r o v i d e d w i t h b y p a s s e s t o r e d u c e t h e f l o w t h r o u g h them t o l o w l e v e l s and t h e r e b y r e d u c e g a s - e n t r a i n i n g t u r b u l e n c e t o a c c e p t a b l e v a l u e s . The m o d e r a t o r c o o l a n t f l o w r a t e i s , i n g e n e r a l , s e v e r a l t i m e s h i g h e r t h a n t h e f u e l f l o w r a t e .

However, i n t h e f u e l c i r c u i t t h e r e a r e s t r o n g i n c e n t i v e s t o r e t a i n c o m p l e t e f l o w c o n t r o l o f a l l f u e l , inasmuch a s t h e sys t em w i l l b e f i l l e d i n i t i a l l y w i t h n o n u r a n i u m - b e a r i n g s a l t s and w i l l h a v e U 2 3 5 - b e a r i n g s a l t s a d d e d t o i t u n t i l c r i t i c a l i t y i s r e a c h e d . O n c e a d d i t i o n s t a r t s , n o s a l t c a n be removed o r d r a i n e d , and c o m p l e t e a n d u n i f o r m m i x i n g mus t o c c u r . C o n s e q u e n t l y , t h e e x p a n s i o n or s u r g e t a n k s must p r o v i d e s u f f i c i e n t c a p a c i t y t o r e c e i v e t h e e n r i c h e d f u e l ( a b o u t 15% of t h e sys t em volume) and a l s o t o p r o v i d e f o r f u e l t h e r m a l e x p a n s i o n f r o m 1 0 0 0 t o 1 5 0 0 ' F ( a b o u t 1 0 % o f sys t em volume). The t h e r m a l e x p a n s i o n w i l l b e a b o u t 200'F m o r e t h a n t h a t a n t i c i p a t e d . T h e r e i s a l s o a s t r o n g i n c e n t i v e f o r minimum volume h o l d u p o f e n r i c h e d f u e l i n e a c h s u r g e t a n k .

Vortexes and B u b b l e s . T h e s y s t e m was o p e r a t e d i n i t i a l l y w i t h w a t e r , a n d t h e s u r g e t a n k s were i n v e s t i g a t e d f o r v o r t e x i n g ' a b o v e t h e d i s c h a r g e l i n e s . The s u r g e t a n k s had n o b a f f l e s , and e n t r a i n e d g a s was o b s e r v e d i n t h e d i s c h a r g e s a t a l l f l o w r a t e s a b o v e 10 gpm w i t h t h e t a n k s h a l f f u l l o f l i q u i d . T h i s g a s e n t r a i n m e n t was due t o v o r t e x - i n g o f t h e l i q u i d l e a v i n g t h e t a n k s . A t l o w e r l i q u i d l e v e l s , v o r t e x i n g o c c u r r e d a t f l o w r a t e s o f l e s s t h a n 1 0 gpm.

Many g e o m e t r i e s were t r i e d f o r b r e a k i n g u p t h i s v o r t e x i n g , a n d a

32

b a f f l e d e s i g n was f i n a l l y d e v e l o p e d t h a t a l l o w e d w a t e r f l o w r a t e s o f up t o 4 0 gpm t o be p u t t h r o u g h t h e t a n k s w i t h o u t v i s i b l e g a s e n t r a i n m e n t i f a minimum l e v e l o f a p p r o x i m a t e l y 4 i n . was m a i n t a i n e d i n t h e 1 0 - i n . - d i a t a n k s .

T h i s a n t i v o r t e x i n g b a f f l e c o n s i s t s o f a f l a t p l a t e , 6 by 8 i n . , a t t a c h e d t o t h e b o t t o m o f t h e p r o b e w e l l t h a t i s c e n t e r e d o v e r t h e d i s c h a r g e l i n e . The p r o b e w e l l was c u t o f f s o t h a t t h e p l a t e c o u l d be l o c a t e d 2 i n . from t h e b o t t o m o f t h e t a n k . T h e r e a r e t h r e e v e r t i c a l f i n s a t t a c h e d t o t h e p l a t e , o n e i n t h e c e n t e r a n d o n e n e a r e a c h e d g e , s o t h a t t h e y a r e a p p r o x i m a t e l y 1 / 8 i n . f r o m t h e b o t t o m o f t h e c y - l i n d r i c a l t a n k . T h i s d e v i c e s e r v e s t o g u i d e t h e f l o w f r o m t h e i n l e t t o t h e o u t l e t w i t h l e s s v e l o c i t y l o s s t h a n i n t h e o p e n t a n k , a n d t h e f l o w i s r e - s t r a i n e d from g o i n g i n o n t h e s i d e s and e d g e n e a r t h e end o f t h e t a n k where t h e m o r e s e v e r e v o r t e x i n g a l w a y s o c c u r r e d .

When t h e g l y c e r i n e s o l u t i o n was t r i e d , t h e r e a p p e a r e d t o b e l e s s t e n d e n c y t o e n t r a i n g a s i n t h e s u r g e t a n k s , A t r a t e d f l o w , 4 0 gpm, l o w e r f l u i d l e v e l s c o u l d be m a i n t a i n e d i n t h e s u r g e t a n k s w i t h o u t t h e r e b e i n g v i s i b l e g a s e n t r a i n m e n t i n t h e d i s - c h a r g e .

I t h a d b e e n f e l t t h a t F r o u d e ' s m o d u l u s s h o u l d b e a p p l i c a b l e , s i n c e t h e f l u i d m o c k u p a n d t h e ARE f u e l c i r c u i t s w e r e s i m i l a r , a n d t h a t g r a v i t y f o r c e s s h o u l d p r e d o m i n a t e o n t h e f r e e s u r f a c e s i n t h e t a n k s . S i n c e t h e mockup s u r g e t a n k s a r e f u l l ARE s i z e , t h e ARE f u e l f l o w r a t e s w e r e m a i n t a i n e d w i t h t h e w a t e r a n d t h e g l y c e r i n e - w a t e r s o l u t i o n f o r t h i s i n - v e s t i g a t i o n i n o r d e r t o m a i n t a i n h y d r a u l i c s i m i l a r i t y .

The m o d e r a t o r c i r c u i t i n t h e ARE i s q u i t e s i m i l a r i n d e s i g n t o t h e f u e l c i r c u i t . The Na or N a K f l o w ( a b o u t 100 gpm) c a n n o t be p u t t h r o u g h a s u r g e t a n k o f ARE d i m e n s i o n s w i t h o u t t h e r e b e i n g v e r y s e v e r e g a s e n t r a i n m e n t i n t h e d i s c h a r g e . T h i s c o n d i t i o n c a n be r emed ied by b y p a s s i n g mos t o f t h e f l o w

a round t h e t a n k s or by u s i n g t h e t a n k s a s s t a n d p i p e s o n l y . The f i r s t remedy would be t h e more d e s i r a b l e , s i n c e g a s r emova l would be more e f f e c t i v e .

I t was f o u n d t h a t t h e s u r g e t a n k s r e m o v e d v i s i b l e g a s b u b b l e s i n t h e w a t e r a n d g l y c e r i n e - w a t e r s o l u t i o n . A i r b u b b l e s o f t h e o r d e r o f 1/8 i n . i n d i a m e t e r and l a r g e r were removed i n a v e r y few c y c l e s , and t h o s e s o s m a l l as t o b e b a r e l y v i s i b l e were removed a f t e r a n h o u r or so o f c i r c u l a t i o n a t low or r a t e d f l o w s , When t h e g l y c e r i n e - w a t e r s o l u t i o n was f i r s t t r a n s f e r r e d t o t h e l o o p , i t was n e a r l y opaque b e c a u s e o f t h e f i n e l y d i v i d e d g a s b u b b l e s , b u t t h e s o l u t i o n was c l e a r a f t e r c i r c u - l a t i o n t h r o u g h t h e s u r g e t a n k s f o r a p p r o x i m a t e l y 1 h o u r . T h e s y s t e m t e s t e d f o r g a s r emova l had a c a p a c i t y o f 15 g a l l o n s .

T h e sys t em h a s a l s o been i n v e s t i g a t e d w i t h r e s p e c t topump f a i l u r e s and o p e r a t i o n a l i n s t a b i l i t i e s . D u r i n g o p e r a t i o n w i t h e a c h pump d e l i v e r i n g 30 t o 40 gpm a t a p p r o x i m a t e l y 45 p s i h e a d , i f one pump i s s h u t down t h e r e m a i n i n g pump i m - m e d i a t e l y becomes g a s b o u n d , s t a r t s pumping i n t e r m i t t e n t l y , and s e v e r e l y g a s s e s t h e l o o p . The g a s s i n g o f t h e pump t h a t r e m a i n s o p e r a b l e r e s u l t s f rom t h e t r a n s f e r o f l i q u i d f rom t h e s u r g e t a n k i n t h e o p e r a t i n g l o o p t o t h e s u r g e t a n k i n t h e l o o p t h a t was s h u t down; t h a t i s , when o n e pump i s s h u t o f f , i t s a s s o c i a t e d s u r g e t a n k , w h i c h i s e s s e n t i a l l y a t pump s u c t i o n p r e s s u r e , i s s u b j e c t e d t o t h e d i s - c h a r g e p r e s s u r e o f t h e o p e r a t i n g pump and t h e r e f o r e gas volume i s compressed and c a u s e s t r a n s f e r o f l i q u i d from t h e

i n a loor , t o t h e ~ O O D t h a t was

Opera t iona 1 Ins tab i 1 it i e s .

- s h u t down.

t i n g a t or n e a r o p s , e i t h e r t h e l o o p * -

i m m e d i a t e l y i s o l a t e d from t h e r t h e r e m a i n i n g pump s t o p p e d .

e l o o p c o n t a i n i n g t h e i n o p e r a b l e pump m u s t be v a l v e d o u t o f t h e s y s t e m b e f o r e f l o w i s r e s t a r t e d . A l s o , a t r e l a t i v e l y h i g h f l o w or p r e s s u r e r i s e


a c r o s s t h e pumps, i m p e l l e r s p e e d s must be t h e same f o r b o t h pumps , or e x c e s s i v e amounts o f l i q u i d w i l l be t r a n s f e r r e d from one s u r g e t a n k t o t h e o t h e r .

In an a t t e m p t t o m a i n t a i n e q u i l i b r i u m b e t w e e n t h e two t a n k s i n c a s e o f a pump f a i l u r e , t h e y were c o n n e c t e d by a l i q u i d l i n e . It was n e v e r p o s s i b l e t o o p e r a t e s a t i s f a c t o r i l y w i t h t h i s l i n e open b e c a u s e one pump would d e v e l o p a s l i g h t l y g r e a t e r h e a d a n d takle o v e r t h e e n t i r e l o a d and t h u s i n d u c e b a c k f l o w t h r o u g h t h e o t h e r pump. A t s u c h t i m e s , t h e r e was h e a v y f l o w from o n e t a n k t o t h e o t h e r t h r o u g h t h e l i q u i d l i n e c o n n e c t i n g t h e two s u r g e t a n k s , Flow t h r o u g h t h e h e a t e x c h a n g e r c i r - c u i t s would n o t d r o p o f f a p p r e c i a b l y . The pump c a r r y i n g t h e l o a d c o u l d e a s i l y s u p p l y b o t h h e a t e x c h a n g e r s a n d a s m a l l back f low t h r o u g h t h e o t h e r pump.

The h e a d f l o w c h a r a c t e r i s t i c s o f t h e pumps a r e shown i n F i g . 2 . 5 . I t w i l l be n o t e d t h a t b e t w e e n s h u t - o f f and 5 0 gpm t h e r e i s l i t t l e or no d r o p i n h e a d , a n d a t some s p e e d s is v e r y s l i g h t p u l s a t i o n p o i n t can be d e t e c t e d . T h e s e f l a t c u r v e s e x p l a i n t h e a b i l i t y o f o n e pump t o h a n d l e t h e t o t a l f l o w o f t h e r e a c t o r and h e a t e x c h a n g e r , a s p r e v i o u s l y m e n t i o n e d . One pump r u n - n i n g a t a s l i g h t l y h i g h e r s p e e d c a n e a s i l y buck t h e o t h e r pumps and h a n d l e t h e t o t a l l o o p l o a d w i t h o u t I ! o s i n g s u f f i c i e n t h e a d t o f a l l b e l o w t h e s h u t - o f f head o f t h e o t h e r pump.

D u r i n g o p e r a t i o n be low 25 gpm p e r pump, o s c i l l a t i o n s have been o b s e r v e d i n t h e f l o w . T h e s e h a v e neve:r b e e n s e r i o u s and c o u l d a lways be r e d u c e d t o n e g l i g i b l e a m p l i t u d e by i n c r e a s i n g t h e f l o w r a t e o f t h e s y s t e m . T h e l o s c i l - l a t i o n s a r e e v i d e n c e d by a n i n c r e a s e i n f l o w r a t e a n d l i q u i d l o s s i n o n e pump c i r c u i t a n d a s i m u l t a n e o u s d e - c r e a s e i n f l o w r a t e a n d l i q u i d g a i n i n t h e o t h e r c i r c u i t . T h e c o n l d i t i o n t h e n r e v e r s e s a n d t h e p e r i o d o f t h e o s c i l l a t i o n i s a p p r o x i m a t e l y 2 s e c o n d s . T h e maximum c h a n g e i n f l o w r a t e h a s been f 2 . 5 gpm a t f l o w r a t e s o f 20 gpm p e r pump. T h i s d i s t u r b a n c e c a n b e

33


F i g . 2 . 5 . Head Flow Characterist ics o f Pumps.

34

e x p l a i n e d by t h e pump c h a r a c t e r i s t i c s and t h e a b s e n c e o f check v a l v e s i n t h e d i s c h a r g e l i n e s o f t h e p a r a l l e l pump

I n t h i s p a r t i c u l a r s y s t e m , when one pump t a k e s t h e e n t i r e l o a d , t h e r e i s a s u b s e q u e n t p r e s s u r e r i s e i n t h e s u r g e t a n k o f t h e s t a l l e d pump. T h i s i s t h e n s e e n a s an i n c r e a s e i n d i s c h a r g e p r e s s u r e o f t h e s t a l l e d pump, w h i c h t h e n o v e r p o w e r s th.e pump h a n d l i n g t h e l o a d a n d m o m e n t a r i l y r e v e r s e s t h e s i t u a t i o n ,

The a c t u a l r e v e r s a l o f f l o w o c c u r s o n l y i n t h e l i n e c o n n e c t i n g t h e s u r g e t a n k s t h r o u g h t h e pumps, t h a t i s , t h e s u c t i o n l i n e s a n d t h e common d i s - c h a r g e l i n e . T h e f l o w t h r o u g h t h e h e a t e x c h a n g e r s i s u n s t e a d y b u t d o e s n o t r e v e r s e o r s t o p . The f low t h r o u g h t h e r e a c t o r a p p e a r s t o b e q u i t e s t e a d y , e v e n t h o u g h i t i s b e i n g s u p p l i e d by a l t e r n a t e pumps.

An E s t e r l i n e Angus r e c o r d i n g w a t t - meter w a s i n s t a l l e d on one pump m o t o r , a n d i t was e s t a b l i s h e d t h a t d u r i n g t h e s e o s c i l l a t i o n s t h e pump a l t e r n a t e l y c a r r i e d f u l l l o a d a n d s h u t - o f f h e a d demand. T h i s c o n d i t i o n c a n be e f - f e c t i v e l y c o r r e c t e d by i n s e r t i n g a r e s i s t a n c e i n t h e common pump d i s - c h a r g e l i n e s o t h a t s t a b l e pump c h a r a c - t e r i s t i c s a r e o b t a i n e d . A 2 - p s i i n - c r e a s e in p r e s s u r e i s s u f f i c i e n t t o r e s u l t i n a d i s c h a r g e c u r v e w h i c h s h o w s t h a t t h e h e a d d e c r e a s e s w i t h f l o w f rom s h u t - o f f t o maximum f l o w . T h i s was d e m o n s t r a t e d by p a r t l y c l o s i n g o n e o f t h e t h r o t t l e v a l v e s i n t h e pump d i s c h a r g e l i n e d u r i n g a n o s c i l - l a t i o n ; t h e d i s t u r b a n c e i m m e d i a t e l y s t o p p e d .

o w b e i n g t e s t e d w i t h r o m o e t h a n e , w h i c h h a s p h y s i c a l

r l y t h e same a s t h o s e o f v i s c o s i t y , 9.27 c p s ;

f i c g r a v i t y , 2 , 9 5 a t ??OF). The mockup w i l l a g a i n be used t o check g a s removal and v o r t e x i n g i n t h e s u r g e t a n k s , f i l l i n g and d r a i n i n g t h e r e a c t o r , pump c h a r a c t e r i s t i c s and f l o w i n s t a b i l i t i e s .

. a r r a n g e m e n t .


INSTRUMENTATION W. B. McDonald D. R . Ward P. W . T a y l o r A. L . S o u t h e r n

P. G . S m i t h ANP D i v i s i o n

Pressure Measurement. Two tes t s o f Moore N u l l m a t i c p r e s s u r e t r a n s m i t t e r s , o p e r a t i n g w i t h t h e 0 . 0 0 5 - i n . w a l l b e l l o w s c o m p l e t e l y s u b m e r g e d i n t h e ARE f u e l , NaF-ZrF4 -UF4 ( 50- 46 -4 mole %I, a t 1100”F, have l o g g e d enough o p e r a t i n g time t o make i t seem l i k e l y t h a t t h i s method o f p r e s s u r e measurement i s t h e most a d v a n t a g e o u s o f any t r i e d t o d a t e . The t r a n s m i t t e r s a r e “ u p s i d e down” i n t h e s e n s e t h a t t h e c a v i t y c o n t a i n i n g t h e b e l l o w s a n d t h e l i q u i d u n d e r p r e s s u r e i s open a t t h e t o p . A n i c k e l t r a n s m i t t e r h a s been c y c l e d e v e r y 1 / 2 h r between 10 a n d 3 0 p s i f o r 1900 h o u r s . A t y p e 316 s t a i n l e s s s t e e l t r a n s m i t t e r h a s o p e r a t e d s i m i l a r l y f o r 1500 h o u r s . A t h i r d t r a n s m i t t e r o f t y p e 316 s t a i n - l ess s t e e l f i l l e d w i t h l e a d and topped w i t h a l a y e r o f t h e m o l t e n f u e l h a s 1 5 0 0 h r o f o p e r a t i n g t i m e , t o d a t e , a n d i s r u n n i n g s l i g h t l y c o o l e r t h a n t h e o t h e r s , The i n i t i a l z e r o s h i f t i n e a c h case was a p p r o x i m a t e l y 1% o f f u l l s c a l e a t t h e o p e r a t i n g t e m p e r a t u r e , and d r i f t o v e r t h e 1 5 0 0 - h r p e r i o d was a p p r o x i m a t e l y 2%. However , t h e z e r o p o s i t i o n c a n b e a d j u s t e d e a s i l y , i f n e c e s s a r y .

S e v e r a l o t h e r Moore t r a n s m i t t e r s h a v e been i n s t a l l e d i n d y n a m i c l o o p s f o r c i r c u l a t i n g f l u o r i d e s o r l i q u i d m e t a l s . T h e s e t r a n s m i t t e r s o p e r a t e “ r i g h t s i d e u p , ” and t h e r e i s t r a p p e d h e l i u m a r o u n d t h e b e l l o w s t o p r o t e c t them from t h e l i q u i d . T h i s method o f p r o t e c t i n g t h e b e l l o w s , a l t , h o u g h o p e r a b l e i n mos t c a s e s , d o e s n o t seem a s s a t i s f a c t o r y a s c o m p l e t e s u b m e r s i o n . The ARE f u e l i n t h e n i c k e l t r a n s m i t t e r m e n t i o n e d a b o v e h a s b e e n r a p i d l y f r o z e n and t h e n r a p i d l y r e m e l t e d t h r e e t i m e s , w i t h n o a p p a r e n t damage t o t h e i n s t r u m e n t . T h i s i s n o t p o s s i b l e w i t h t h e t r a p p e d - g a s i n s t r u m e n t b e c a u s e o f f o u l i n g o f t h e b e l l o w s . I t was a l s o

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found t h a t when t h e p r e s s u r e t r a n s m i t t e r i s f i l l e d w i t h s t a t i c f u e l , t h e b e l l o w s t e m p e r a t u r e c a n be m a i n t a i n e d a t 1100°F or below, O p e r a t i o n o f t h e b e l l o w s a t t h e r e d u c e d t e m p e r a t u r e r e d u c e s t h e c o r r o s i o n r a t e .

F a i l u r e o f t h e b e l l o w s i n o n e o f t h e t y p e 3 1 6 s t a i n l e s s s t e e l t r a n s - m i t t e r s a f t e r 500 h r o f o p e r a t i o n a t 1200°F was a p p a r e n t l y c a u s e d by o x i - d a t i o n , Hel ium i n s t e a d o f a i r i s now u s e d a s t h e c o n t i n u o u s - f 1 ow- b a l a n c i n g g a s i n t h e p r e s s u r e t r a n s m i t t e r t e s t s .

ARE Leak Detection Indicator Tests . T h e r e i s i n t e r e s t i n d e v e l o p i n g a s e c o n d a r y method f o r d e t e c t i n g l e a k s i n NaK or f u e l s y s t e m s i n t h e ARE t o s u p p l e m e n t t h e h a l o g e n l e a k d e t e c t o r . E x p e r i m e n t a t i o n r e v e a l e d t h a t a s o - l u t i o n o f p h e n o l r e d can be made v e r y s e n s i t i v e t o c h a n g e s i n pH by a d j u s t - i n g t h e s o l u t i o n t o a r e d d i s h brown. When h e l i u m i s p a s s e d o v e r a s u r f a c e o f h o t f u e l and t h e n o v e r t h e s u r f a c e o f t h e i n d i c a t o r s o l u t i o n , t h e s o l u t i o n changes c o l o r . L i k e w i s e , i t was found t h a t a c o l d lump o f t h e f u e l d r o p p e d i n t o t h e i n d i c a t o r s o l u t i o n c h a n g e d t h e i n d i c a t o r toward t h e a c i d d i r e c t i o n .

S l i p Rings f o r Temperature Measure- ment. T h r e e t e s t s o f s l i p r i n g s f o r m e a s u r i n g t h e t e m p e r a t u r e i n s i d e a r o t a t i n g s h a f t were s t a r t e d . B e c a u s e s i l v e r - g r a p h i t e b r u s h e s were n o t a v a i l - a b l e , c a r b o n b r u s h e s w e r e u s e d . One t e s t was c o m p l e t e d i n w h i c h c o p p e r r i n g s a n d c a r b o n b r u s h e s were u s e d . When t h e b r u s h e s were w e l l r u n - i n , an a c c u r a c y i n t h e t e m p e r a t u r e m e a s u r e - ments o f *P°F a t 1200°F was o b t a i n e d . The c o m b i n a t i o n o f c a r b o n b r u s h e s and c a r b o n r i n g s i s s a t i s f a c t o r y i f a w i p i n g b r u s h i s mounted on t h e r i n g . I f t h e r i n g i s n o t k e p t c l e a n , t h e r e s i s t a n c e a c r o s s t h e c o n t a c t i n c r e a s e s w i t h t i m e , and t h e e r r o r may i n c r e a s e t o +40°F o r more.

A s e c o n d c o m b i n a t i o n o f m a t e r i a l s , c o i n s i l v e r a n d s i l v e r - i m p r e g n a t e d g r a p h i t e , w a s p l a c e d i n o p e r a t i o n b e f o r e b e i n g t e s t e d , and p e r f o r m a n c e h a s b e e n s a t i s f a c t o r y f o r s e v e r a l

h u n d r e d h o u r s . I n a t h i r d t e s t t h a t i s b e i n g c o n d u c t e d w i t h t y p e 3 1 6 s t a i n l e s s s t e e l r i n g s a n d c a r b o n b r u s h e s , a n e r r o r o f + 2 0 " F h a s d e - v e l o p e d , b u t i t i s a c o n s t a n t e r r o r . T h e c a r b o n b r u s h e s w i l l be r e p l a c e d w i t h s i l v e r - i m p r e g n a t e d g r a p h i t e b r u s h e s , which s h o u l d r e d u c e t h e e r r o r s l i g h t l y . C o m m e r i c a l s l i p r i n g a s - s e m b l i e s h a v e b e e n o r d e r e d t h a t w i l l work on e i t h e r a 7 / 8 - o r a 2 1 / 4 - i n . s h a f t .

Rotameter Type of Flowmeter. T e s t i n g h a s c o n t i n u e d on t h e r o t a m e t e r t y p e o f f l o w m e t e r r e p o r t e d p r e v i o u s l y , ( * ) and a p p r o x i m a t e l y 1000 h r o f o p e r a t i o n h a s b e e n l o g g e d i n t h e t e m p e r a t u r e r a n g e o f 1 1 0 0 t o 1 3 0 0 ° F . T h i s i n s t r u m e n t w i l l measure f l o w s o f f u e l No. 30 w i t h 10% a c c u r a c y o v e r t h e r a n g e o f 9 t o 60 gpm. Two i n s t r u m e n t s o f t h i s t y p e h a v e b e e n t e s t e d , a n d t h e r e s u l t s i n d i c a t e t h a t t h i s i n s t r u m e n t w i l l be r e l i a b l e f o r ARE o p e r a t i o n .

,

HANDLING OF FLUORIDES AND LIQUID METALS

L. A . Mann J . M . C' i s a r F. M. G r i z z e l l

ANP D i v i s i o n

D i s t i l l a t i o n of NaK. NaK h a s been c h o s e n a s t h e p r e c l e a n i n g f l u i d f o r t h e ARE b e f o r e i n t r o d u c t i o n o f f l u o r i d e s a l t s . S i n c e o n l y a s m a l l f r a c t i o n o f NaK ( l e s s t h a n 0 . 5 w t %; c f . , s e c . 9 ) c a n be t o l e r a t e d i n t h e f u e l w i t h o u t r e d u c t i o n o f UF, t o UF,, s t u d i e s h a v e b e e n made t o d e t e r m i n e how much NaK r e m a i n s a f t e r t h e s y s t e m i s d r a i n e d and how e f f e c t i v e d i s t i l l a t i o n i s i n removing i t . S i n c e t h e vapor p r e s s u r e o f p o t a s s i u m a t a n y t e m p e r a t u r e i s h i g h e r t h a n t h a t o f s o d i u m , u p o n d i s t i l l a t i o n t h e a l l o y u n d e r g o e s r a p i d d e p l e t i o n o f p o t a s s i u m , and t h e r e i s a c o r r e s p o n d i n g e n r i c h m e n t o f s o d i u m . T h e r e f o r e e a c h d i s t i l l a t i o n i s p r o - g r e s s i v e l y more d i f f i c u l t . The b o i l i n g p o i n t o f s o d i u m i s 1 6 2 1 ° F a t 1 a t m ; h e n c e , vacuum d i s t i l l a t i o n i s u s e d t o a v o i d e x c e s s i v e t e m p e r a t u r e s , An

( * ) A N P Q u a r . P r o g . R e p . D e c . 1 0 . 1 9 5 2 , ORNL- 1439, p . 2 9 .

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a b s o l u t e p r e s s u r e o f 100 mm Hg, which c o r r e s p o n d s t o a sodium b o i l i n g temper- a t u r e o f 1285"F, was s e l e c t e d f o r t h e d i s t i l l a t i o n . A f t e r s o m e i n i t i a l d i f f i c u l t y w i t h g a s l e a k s , s e v e r a l 5 - l b b a t c h e s o f NaK were d i s t i l l e d , and t h e f o l l o w i n g o b s e r v a t i o n s were m a d e :

1. T h e r e w a s n o d i f f i c u l t y i n c o m p l e t e l y d i s t i l l i n g t h e NaK.

2. Most o f t h e d i s t i l l a t i o n o c c u r r e d i n one s u r g e i n e a c h of t h e four r u n s , and a p a r t o f t h e c o n d e n s e r was h e a t e d t o a l m o s t t h e d i s t i l l i n g p o t t e m p e r a - t u r e .

3. The a d j u s t a b l e p r o b e ( a p r o b e w i r e d t h r o u g h a s t u f f i n g b o x o f s i 1 i c o n e - r u b b e r '' w a s h e r s ") w o r k e d e x c e l l e n t l y , a n d g a v e r e p r o d u c i b l e l e v e l r e a d i n g s t h a t c h e c k e d t o w i t h i n 1/32 i n . or c l o s e r .

NaK h a s b e e n d i s t i l l e d f r o m ARE pump l o o p , b u t b e c a u s e o f e x c e s s i v e o x i d a t i o n o f t h e t y p e 316 s t a i n l e s s s t e e l i n t h e l o o p , a s u f f i c i e n t l y low p r e s s u r e c o u l d n o t b e m a i n t a i n e d o n


t h e s y s t e m f o r a g o o d t e s t o f t h e e f f i c i e n c y o f t h e d i s t i l l a t i o n p r o c e s s t o be o b t a i n e d . P o c k e t s o f NaK r e - m a i n e d i n s o m e o f t h e t r a p s , p a r - t i c u l a r l y t h e pump. I n t h e I n c o n e l ARE s y s t e m , s u c h c o r r o s i o n s h o u l d n o t b e e n c o u n t e r e d ; h e n c e , e s s e n t i a l l y comple t e removal o f NaK by d i s t i l l a t i o n s h o u l d be e f f e c t e d .

Flame Tests for N a K Vapor i n Helium ID. R, W a r d , A N P D i v i s i o n ) . T e s t s a r e b e i n g c o n d u c t e d t o d e t e r m i n e t h e r e l i a b i l i t y o f f l ame t e s t s f o r cletect- i n g t h e p r e s e n c e o f NaK i n h e l i u m . One method u s e d was t o i n t r o d u c e h e l i u m , f r o m t h e s y s t e m f r o m w h i c h NaK w a s b e i n g r e m o v e d by t h e d i s t i 1 IL a t i o n p r o c e s s , i n t o a n o t h e r w i s e c o l o r l e s s h y d r o g e n f l a m e ; t h e b r i g h t n e s s o f t h e r e s u l t i n g f l ame was t h e n measured by a p h o t o t u b e c i r c u i t , The r e s u l t s o f s i x t e s t s i n d i c a t e t h a t t h i s method may be u s e d t o d e t e r m i n e t h e d e g r e e o f c l e a n l i n e s s o f a s y s t e m from which NaK h a s been removed by t h e d i s t i l l a t i o n method.

37

i

I

I

I I

i I

I _ I

I = I .

3 . REACTOR PHYSICS

W. K. Ergen , ANP D i v i s i o n

From t h e s t a n d p o i n t o f t h e p h y s i c s o f n u c l e a r r e a c t o r s , t h e main e v e n t d u r i n g t h e p a s t q u a r t e r w a s t h e c o r r e l a t i o n between t h e IBM m u l t i g r o u p c a l c u l a t i o n s and t h e c r i t i c a l e x p e r i - ment on a f a i r l y r e a l i s t i c , r e f l e c t o r - m o d e r a t e d , r e a c t o r mockup. B e c a u s e o f t h e a p p r o x i m a t i o n s i n v o l v e d i n t h e c a l c u l a t i o n s , i t p r e v i o u s l y h a d n o t been c l e a r how c l o s e t h i s c o r r e l a t i o n w o u l d b e . T h a t t h e e x p e r i m e n t a l c r i t i c a l m a s s t u r n e d o u t t o b e o n l y s l i g h t l y h i g h e r t h a n t h e c o m p u t e d v a l u e and w a s w e l l w i t h i n t h e l i m i t s a c c e p t a b l e w i t h r e s p e c t t o u r a n i u m inves tmen t and f u e l c h e m i s t r y , c o n s t i - t u t e s a m i l e s t o n e i n t h e d e v e l o p m e n t o f t h i s t y p e o f r e a c t o r . F u r t h e r m o r e , t h e r e was, e x c e p t a t t h e b o u n d a r i e s , good c o r r e l a t i o n be tween t h e computed and t h e m e a s u r e d f l u x . T h i s a p p l i e s t o t h e f l u x d i s t r i b u t i o n i n s p a c e and i n e n e r g y , b u t t h e o n l y e x p e r i m e n t a l i n d i c a t i o n s o f t h e ene rgy d i s t r i b u t i o n a r e t h e t h e r m a l v a l u e and t h e cadmium r a t i o , which a r e e f f e c t i v e l y o n l y two p o i n t s on t h e e n e r g y d i s t r i b u t i o n

cu rve . Some s i g n i f i c an t d i s c r epanc i e s e x i s t a t t h e b o u n d a r i e s , b u t t h e s i m p l e d i f f u s i o n t h e o r y e m p l o y e d i n t h e c a l c u l a t i o n s o b v i o u s l y c a n n o t b e e x p e c t e d t o h o l d a t t h e i n t e r f a c e s b e t w e e n w i d e l y d i f f e r e n ' t m a t e r i a l s . The n u c l e a r s t u d i e s p e r t i n e n t t o t h e r e f l e c t o r - m o d e r a t e d r e a c t o r a r e i n c l u d e d i n s e c . 4 , " R e f l e c t o r - hl od e r a t e d C i r cu 1 a t i n g- Fu e 1 Re a c t o r .

A s t o r e a c t o r k i n e t i c s , i t w a s s h o w n t h a t t h e d e l a y e d n e u t r o n s i n t r o d u c e d a m p i n g o f r e a c t o r p o w e r o s c i l l a t i o n s , e v e n i n t h e c a s e o f l a r g e i n i t i a l a m p l i t u d e s , and , f u r t h e r - more , one t y p i c a l e x a m p l e i n d i c a t e s t h a t t h i s damping d o e s n o t i n t e r f e r e d e s t r u c t i v e l y w i t h t h e damping c a u s e d by f u e l c i r c u l a t i o n . A l s o , t h e (damping c a n be d e m o n s t r a t e d i n a t y p i c a l c a s e i n which t h e power and f l u x var.y a l o n g t h e p a t h o f a c i r c u l a t i n g f u e l . The t e c h n i q u e s employed a r e v e r y s i m i l a r t o t h o s e r e p o r t e d i n t h e p r e v i o u s ANP q u a r t e r l y r e p o r t s and a r e t h e r e f o r e n o t r e p e a t e d h e r e .

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4. REFLECTOR-MODERATED CIRCULATING-FUEL REACTORS

A. P. F r a a s , ANP D i v i s i o n C. B. Mills, ANP D i v i s i o n

A . D . C a l l i h a n , P h y s i c s D i v i s i o n

Homogeneous r e a c t o r s a r e t h e m o s t s i m p l e n u c l e a r r e a c t o r s w i t h r e s p e c t t o i n t e r n a l s t r u c t u r e b e c a u s e t h e r e a r e n o s t r u c t u r a l e l e m e n t s i n t h e r e a c t o r c o r e . A l t h o u g h t h e c o n - s i d e r a b l e e x p e r i e n c e a c h i e v e d w i t h l i q u i d f l u o r i d e f u e l s i n d i c a t e s t h a t t h e y d o n o t l e n d t h e m s e l v e s t o t h e d e s i g n o f s m a l l , homogeneous r e a c t o r s b e c a u s e o f t h e i r p o o r m o d e r a t i n g p r o p e r t i e s , i t h a s been shown t h a t , by u s i n g t h i c k and e f f i c i e n t r e f l e c t o r s , i t i s p o s s i b l e t o d e s i g n a s m a l l , f l u o r i d e - f u e l r e a c t o r t h a t w i l l b e r e l a t i v e l y f r e e o f s t r u c t u r a l com - p l e x i t i e s . F u r t h e r , t h e c o m b i n a t i o n o f s u c h a r e a c t o r w i t h a s p h e r i c a l - s h e l l h e a t e x c h a n g e r would p r o v i d e a r e a c t o r , h e a t e x c h a n g e r , a n d s h i e l d package t h a t would be much s m a l l e r and l i g h t e r t h a n a n y r e a c t o r now b e i n g c o n s i d e r e d f o r t h e n u c l e a r p r o p u l s i o n o f a i r c r a f t .

T h i s s e c t i o n s u m m a r i z e s t h e work r e c e n t l y c a r r i e d o u t on t h i s t y p e o f power p l a n t . The f i r s t p a r t c o v e r s t h e work done on t h e s t a t i c p h y s i c s o f t h e r e a c t o r , i n c l u d i n g t h e e f f e c t on t h e r e a c t o r o f c o r e s i z e and t h e u s e o f v a r i o u s m a t e r i a l s i n t h e c o r e a n d r e f l e c t o r . The s e c o n d p a r t p r e s e n t s t h e r e s u l t s o f t k e c r i t i c a l e x p e r i - m e n t s a n d c o r r e l a t e s t h e m w i t h t h e m u l t i g r o u p c a l c u l a t i o n s . T h e t h i r d p a r t c o v e r s t h e m e c h a n i c a l d e s i g n e n v i s i o n e d and t h e d e v e l o p m e n t a l work i n i t i a t e d t o p r o v i d e a b a s i s f o r t h e d e t a i l e d d e s i g n o f a f u l l - s c a l e r e a c t o r , The f o u r t h p a r t c o v e r s t h e s h i e l d i n g work t o d a t e , and t h e l a s t p a r t p r e s e n t s some p o s s i b l e f u l l - s c a l e a i r c r a f t power p l a n t a r r a n g e m e n t s , i n c l u d i n g e n g i n e s and r a d i a t o r s .

(I'D. K . Holmes, The Multigrou M e t h o d as U s e d b y t h e ANP P h y s i c s Croup, ANP-58 [Feb. 1 5 , 1 9 5 1 ) .

STATIC PHYSICS

C. B. Mi l l s , ANP D i v i s i o n

The m o s t s i m p l e r e f l e c t e d r e a c t o r i s a s m a l l s p h e r e o f f i s s i o n a b l e ma- t e r i a l s u r r o u n d e d by a c o n c e n t r i c s p h e r e o f m o d e r a t i n g m a t e r i a l . T h e f a s t n e u t r o n s l e a v e t h e f u e l - b e a r i n g r e g i o n e a s i l y a n d d i f f u s e i n t o t h e r e f l e c t o r . I f t h e r e f l e c t o r i s r e l a t i v e l y t h i c k and d o e s n o t c a p t u r e t h e e s s e n t i a l l y t h e r m a l i z e d n e u t r o n s , t h e c h a i n r e a c t i o n c a n be s u p p o r t e d b e c a u s e o f t h e s u f f i c i e n t l y g r e a t p r o b a b i 1 i t y t h a t t h e 1 ow - e n e r gy n e u t r o n s w i l l d i f f u s e b a c k i n t o t h e c e n t r a l f u e l - b e a r i n g r e g i o n . T h e f i s s i o n c r o s s s e c t i o n , a s w e l l a s t h e o t h e r c r o s s s e c t i o n s i n t h e f u e l r e g i o n , i s s o h i g h t h a t t h e s l o w n e u t r o n s r e - e n t e r i n g t h e r e a c t o r c a n n o t e a s i l y r e - e s c a p e .

T h i s r e a c t o r h a s b e e n b r i e f l y e v a l u a t e d w i t h r e s p e c t t o m o d e r a t o r , f u e l , and geometry e f f e c t s t o o b t a i n a q u a l i t a t i v e u n d e r s t a n d i n g o f n e u t r o n d i f f u s i o n a n d l o s s . T h e a n a l y s i s i n v o l v e d t h e u s e o f t h e O R N L - A N P m u l t i g r o u p m e t h o d , ( ' ) s u p p o r t e d by c r i t i c a l e x p e r i m e n t s .

N e u t r o n d i f f u s i o n i n a r e f l e c t o r - modera to r c a n be most e a s i l y d e s c r i b e d by r e f e r r i n g t o t h e r e s u l t s o f t h e f i r s t m u l t i g r o u p c a l c u l a t i o n f o r a 3 2 - i n . - d i a f u e l r e g i o n s u r r o u n d e d by a 1 2 - i n . - t h i c k b e r y l l i u m o x i d e r e f l e c t o r . F i g u r e 4.1 shows t h e l e a k a g e s p e c t r u m a s a f u n c t i o n o f l e t h a r g y f o r n e u t r o n l e a k a g e from t h e c e n t r a l f u e l - b e a r i n g r e g i o n i n t o t h e r e f l e c t o r . T h e n e t c u r r e n t i s v e r y h i g h a c r o s s t h e boundary f o r h i g h - e n e r g y ( l o w - l e t h a r g y ) neu t rons . Most o f t h e f i s s i o n n e u t r o n s move i m m e d i a t e l y i n t o t h e r e f l e c t o r , w h e r e t h e y a r e m o d e r a t e d t o t h e r m a l e n e r g y .

41


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F i g . 4 . 1 . Leakage Spectrum t o R e f l e c t o r vs . Lethargy.

They t h e n e i t h e r d i f f u s e back i n t o t h e f u e l r e g i o n , s i n c e t h e f u e l r e g i o n a t t h e c e n t e r i s a s i n k f o r t h e r m a l n e u t r o n s , or o u t o f t h e r e a c t o r a c r o s s t h e o u t e r r e f l e c t o r boundary.

F i g u r e 4.2 shows t h e s p a t i a l d i s t r i - b u t i o n o f n e u t r o n s a t t h r e e l e t h a r g i e s . The t h e r m a l f l u x i s v e r y h i g h i n t h e n o n a b s o r b i n g b e r y l l i u m o x i d e r e f l e c t o r . The l e t h a r g y d i s t r i b u t i o n of f i s s o n i n g a b s o r p t i o n s and n e u t r o n e s c a p e f o r an a s s u m e d n e u t r o n s o u r c e d i s t r i b u t i o n

( F i g . 4 . 3 ) i s g i v e n on F i g s . 4.4 a n d 4.5. I n t e r m e d i a t e l e t h a r g y f i s s i o n i n g p r o c e s s e s a r e i m p o r t a n t , b u t 50% o f t h e f i s s i o n s r e s u l t s f r o m t h e r m a l n e u t r o n s s t r e a m i n g i n t o t h e c e n t r a l r e g i o n from t h e r e f l e c t o r , The e s c a p e s p e c t r u m , which i s i m p o r t a n t f o r t h e r e a c t o r s h i e l d , shows t h a t a v e r y s m a l l f r a c t i o n o f f a s t n e u t r o n s e s c a p e s from t h e r e f l e c t o r , The r e l a t i v e v a l u e s o f f a s t - n e u t r o n e s c a p e t h r o u g h a 1 - i n . - t h i c k l a y e r o f b o r o n c a r b i d e f o r a

42


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F i g . 4 .2 . Neutron Flux D i s t r i b u t i o n f o r Three Lethargy Values .

be r y 1 1 ium re f 1 e c t o r -moade r a t e d re a c t or a s compared w i t h a r e a c t o r w i t h a 6 - i n . - t h i c k b e r y l l i u m o x i d e r e f l e c t o r a n d a m o d e r a t i n g c o r e a r e shown i n F i g . 4 . 6 . T h e f a s t e s c a p e i s e v e n s m a l l e r f o r some o f t h e s u b s e q u e n t r e f l e c t o r - m o d e r a t e d r e a c t o r d e s i g n s d e s c r i bed be 1 ow.

I n summary, t h e n e u t r o n s a r e b o r n i n t h e c e n t r a l r e g i o n , spend t h e ma jo r

a r t o f t h e i r l i f e i n t h e r e f l e c t o r , n d , a f t e r m o d e r a t i o n , d i f f u s e i n t o

a n d o u t o f t h e f u e l - b e a r i n g r e g i o n . T h e p r o m p t - n e u t r o n l i f e t i m e i s a b o u t 2 x s e c , w h i c h i s a r e l a t i v e l y h i g h v a l u e .

T h e r e i s a p o s i t i v e c o m p o n e n t i n t h e t e m p e r a t u r e c o e f f i c i e n t o f r e - a c t i v i t y o f t h i s r e a c t o r b e c a u s e t h e r e i s s e l f - s h i e l d i n g o f t h e f u e l a n d a

p a r t o f t h e f i s s i o n s i s c a u s e d by f a s t n e u t r o n s i n t h e “ D o p p l e r - r e g i o n . ” The p o s i t i v e component a r i s e s b e c a u s e t h e i n c r e a s e d t h e r m a l m o t i o n o f t h e U235 a toms e f f e c t i ve l y b r o a d e n s and f 1 a t t e n s o u t t h e r e s o n a n c e p e a k s i n t h e f i s s i o n c r o s s s e c t i o n s , p a r t i c u l a r l y t h o s e p e a k s i n t h e h i g h - n e u t r o n - ( e n e r g y r e g i o n . T h i s d e c r e a s e s t h e s e l f - s h i e l d i n g w i t h r e s p e c t t o n e u t r o n s o f e n e r g i e s c o r r e s p o n d i n g t o t h e p e a k s and i n c r e a s e s t h e r e a c t i v i t y .

T h e o r e t i c a l e s t i m a t e s and c : r i t i c a l e x p e r i m e n t s h a v e t h u s f a r f a i l e d t o g u a r a n t e e t h a t t h i s p o s i t i v e component o f t h e t e m p e r a t u r e c o e f f i c i e n t o f r e a c t i v i t y is s m a l l compared w i t h t h e n e g a t i v e component e x p e c t e d f rom t h e f u e l e x p a n s i o n . However, t h i s r e a c t o r i s no worse w i t h r e s p e c t t o t h e ]Doppler

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F i g . 4 . 3 . Spatial Power Distribution.

t e m p e r a t u r e c o e f f i c i e n t o f r e a c t i v i t y t h a n t h e o t h e r r e a c t o r b e i n g s t u d i e d , A s m a l l amount o f U238, a d d e d t o t h e f u e l o r p l a c e d i n t h e s t r u c t u r e n e a r t h e f u e l , w o u l d c o m p e n s a t e f o r a p o s i t i v e t e m p e r a t u r e c o e f f i c i e n t , be- c a u s e w i t h U238 i t i s t h e a b s o r p t i o n t h a t i s s e l f - s h i e l d e d , and t h e d e c r e a s e i n t h e s e l f - s h i e l d i n g w i t h i n c r e a s i n g t e m p e r a t u r e would r e d u c e t h e r e a c t i v i t y ,

Very low a b s o r p t i o n and v e r y good m o d e r a t i o n m u s t be o b t a i n e d i n t h e r e f l e c t o r , S t r u c t u r a l m a t e r i a l a t t h e c o r e - r e f l e c t o r i n t e r f a c e s h o u l d a l s o h a v e a low a b s o r p t i o n c r o s s s e c t i o n , a l t h o u g h t h e i m p o r t a n c e o f t h e c r o s s s e c t i o n a t t h e i n t e r f a c e is r educed by t h e s m a l l p r o b a b i l i t y o f s e v e r a l t h e r m a l - n e u t r o n t r a n s i t s b e c a u s e o f

t h e h i g h a b s o r p t i o n and low a l b e d o o f t h e f u e l r e g i o n , The s t r u c t u r a l ma- t e r i a l i n t h e f u e l - b e a r i n g r e g i o n w i l l compete w i t h t h e u r a n i u m f o r t h e r m a l n e u t r o n s ,

Reactors w i t h Various R e f l e c t o r - Moderators. C o m p u t a t i o n s h a v e b e e n made f o r a number o f p o s s i b l e r e a c t o r c o r e s i z e s a n d r e f l e c t o r - m o d e r a t o r c o m p o s i t i o n s , a n d t h e r e s u l t s a r e summarized i n t h e f o l l o w i n g :

1. The l e a k a g e o f f a s t n e u t r o n s f rom t h e r e f l e c t o r a s a f u n c t i o n o f t h e s l o w i n g - d o w n p o w e r , ex,, o f t h e r e f l e c t o r i s s h o w n i n F i g . 4 . 7 . A f a c t o r o f 1 / 5 i n exs r e s u l t s i n a f a c t o r o f 400 i n t h e t o t a l e s c a p e o f f a s t n e u t r o n s , t h a t i s , n e u t r o n s w i t h l e t h a r g i e s s m a l l e r t h a n 4. F i g u r e 4 . 8

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pectrum to S h i e l d v s . Lethargy.

shows t h e r e f l e c t o r t h i c k n e s s f o r a t e r i z e d by t h e a g e - t o - t h e r m a l i n t h e g i v e n n e u t r o n c u r r e n t e s c a p i n g f r o m r e f l e c t o r m a t e r i a l . t h e r e f l e c t o r a s a f u n c t i o n o f t h e 2 . The a b s o r p t i o n i n t h e r e a c t o r m o d e r a t i n g p r o p e r t i e s o f t h e r e f l e c t o r f u e l i s s e n s i t i v e t o t h e s lowing-down m a t e r i a l . These p r o p e r t i e s a r e c h a r a c - power, c X s , o f t h e r e f l e c t o r only f o r

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p o o r m o d e r a t o r s , The a b s o r p t i o n d e - c r e a s e s r a p i d l y f o r < 0 . 0 8 ( F i g . 4 . 9 )

3. The e s c a p e spec t rum vs . l e t h a r g y i s shown i n F i g . 4 .10 f o r t h e two b e s t r e f l e c t o r s , b e r y l l i u m a n d b e r y l l i u m o x i d e . The d i f f e r e n c e s i n t h e s p e c t r a a r e c h a r a c t e r i s t i c o f t h e d i f f e r e n c e s i n t h e c r o s s s e c t i o n s and t h e modera t - i n g power o f t h e two m a t e r i a l s . B e r y l - l i u m i s a much b e t t e r r e f l e c t o r ma- t e r i a l t h a n b e r y l l i u m o x i d e .

4. The e f f e c t o f r e f l e c t o r m a t e r i a l a n d t h i c k n e s s on t h e e s c a p e o f f a s t n e u t r o n s i s shown i n F i g . 4 . 1 1 . I n o r d e r o f d e s i r a b i l i t y , t h e m a t e r i a l s a r e : b e r y l l i u m , b e r y l l i u m o x i d e , 6 i n . o f b e r y l l i u m p l u s 6 i n . o f c a r b o n , b e r y l l i u m o x i d e a g g r e g a t e , 4 i n . o f b e r y l l i u m p l u s 8 i n . o f c a r b o n , a n d c a r b o n . NaOD i s a good r e f l e c t o r o n l y w i t h r e g a r d t o n e u t r o n e s c a p e . The c r i t i c a l mass w i t h a NaOD r e f l e c t o r i s h i g h ( 6 0 l b ) b e c a u s e o f t h e sodium ab- s o r p t i o n .

5 . T h e e f f e c t o f t h e m o d e r a t o r i n d i c a t e s t h a t t h e r e i s l i t t l e d e - p e n d e n c e o f t h e power d i s t r i b u t i o n on t h e r e f l e c t o r m a t e r i a l i n a s i m p l e s y s t e m . The p r e s e n c e o f s t r u c t u r e and t h e e f f e c t o f o p e r a t i n g t e m p e r a t u r e a r e e x p e c t e d t o f a v o r b e r y l l i u m a s t h e r e f l e c t o r - m o d e r a t o r , i f a m i n i m u m r a t i o o f p e a k - t o - a v e r a g e power d e n s i t y i s t o be o b t a i n e d ,

6. The e f f e c t o f r e f l e c t o r t h i c k - n e s s on r e a c t i v i t y ( F i g . 4 . 1 2 ) shows t h a t t h e b e r y l l i u m or b e r y l l i u m o x i d e r e f l e c t o r s m u s t be o v e r 1 0 i n . t h i c k b u t t h a t l i t t l e i s t o b e g a i n e d by e x c e e d i n g 16 i n , i n t h i c k n e s s .

R e a c t o r s w i t h B e r y l l i u m R e f l e c t o r - M o d e r a t o r s . The r e s u l t s g i v e n a b o v e , a s w e l l a s o t h e r c o n s i d e r a t i o n s , i n d i - c a t e t h a t b e r y l l i u m i s t h e b e s t re - f l e c t o r - m o d e r a t o r . S e v e r a l b e r y l l i u m r e f l e c t o r - m o d e r a t e d r e a c t o r s d i f f e r i n g i n s i z e and d e s i g n were s t u d i e d , and t h e r e a c t i v i t y c o e f f i c i e n t s w e r e e s t i m a t e d . Al though t h e numbers g i v e n

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47


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LETHARGY, u

to t h e S h i e l d for B e r y l l i u m Oxide and

below r e f e r t o t h e s p e c i f i c r e a c t o r s c o n s i d e r e d , t h e g e n e r a l c o n c l u s i o n s a r e b e l i e v e d t o be v a l i d f o r a v a r i e t y o f r e f l e c t o r - m o d e r a t e d r e a c t o r s ,

1. The r a t i o o f t h e p e a k - t o - a v e r a g e power d e n s i t y can be d e c r e a s e d by r e - p l a c i n g t h e c e n t r a l volume o f t h e f u e l w i t h a m o d e r a t o r . T h e r a t i o o f t h e p e a k - t o - a v e r a g e power c a n be r e d u c e d t o a b o u t 1 . 3 , a n d t h e c r i t i c a l m a s s c a n be r educed t o a b o u t 1 / 2 t h e cor res - p o n d i n g v a l u e f o r a comparab le r e a c t o r w i t h o u t a c e n t e r i s l a n d .

2. The e f f e c t o f c h a n g e s i n v a r i o u s c o m p o n e n t s o n t h e r a t i o o f p e a k - t o - a v e r a g e power d e n s i t y i s o f i n t e r e s t . F o r a b a s i c d e s i g n , i n w h i c h t h e d i - a m e t e r s o f c e n t r a l m o d e r a t o r , f u e l r e g i o n , and r e f l e c t o r were 1 4 , 22, and 4 6 i n . , r e s p e c t i v e l y , a n d t h e r e was 2 . 8 v o l % I n c o n e l i n t h e NaF-UF4 f u e l - c o o l a n t ( t o s i m u l a t e s t r u c t u r e between

f u e l a n d r e f l e c t o r ) , t h e r e l a t i v e changes a re i n d i c a t e d by t h e f r a c t i o n s g i v e n below. The d e n o m i n a t o r i s t h e f r a c t i o n a l c h a n g e i n t h e p a r a m e t e r n o t e d , T h e n u m e r a t o r r e f e r s t o t h e r a t i o o f t h e peak power d e n s i t y t o t h e a v e r a g e power d e n s i t y a n d r e p r e s e n t s t h e f r a c t i o n a l c h a n g e o f t h i s r a t i o c a u s e d by t h e c h a n g e i n d i c a t e d i n t h e d e n o m i n a t o r .

PARAMETERS

Amount of U235 i n the fuel - @” = - 0.16 &/M

Fuel layer thickness -- - - 0.34 @/p AT/T

- - -0.067 @/P 4Qh

Structure weight fraction - -

@/P &/R

Radius of central moderator - = -0.117

48

10-1

2

10-2 d

V y 5 0 W-

3 2 W

$10-3 k-

W

L 5

2

2

I 0-4

5

2

IO-^

bnmr OWG 18726

I I I I I !',I I I I I I I ! I I 1 ' 1 I I I I I I ,

I I I I I CARBON I I I I I I k I I I I I I I

\

\

0 4 8 12 16 20 REFLECTOR THICKNESS (in)

F i g . 4 . 1 1 . Fast -Neutron Leakage v s . R e f l e c t o r Thickness .

t C

a

- to

ii.5HeY D W G . 48727

I REFLECTOR 1201

+O 20 REFLECTOR THICKNESS (in)

F i g . 4 . 1 2 . E f f e c t o f R e f l e c t o r Thickness on Mult ip l icat ion Constant.


The computed v a l u e s o f peak- t o - a v e r a g e power d e n s i t y a t t h e two s i d e s and a t t h e c e n t e r o f t h e f u e l - c o o l a n t r e g i o n a r e t a b u l a t e d i n T a b l e 4 . 1 .

3. The r e a c t i v i t y c o e f f i c i e n t s o f d e s i g n i n t e r e s t a r e , where p i s d e n s i t y , M is w e i g h t , and T i s t h i c k n e s s :

For core s t ructure ,

- - -0.17 ; @ k / k &/T

For fuel layer thickness, - -

- 0.52 ; For beryllium re f l ec to r , - = b / k 4??P

For UZJs content, - - - - 0.22 ; &/i4

- 0.106 . 4. The s u b s t i t u t i o n o f 6 or 8 i n .

o f c a r b o n f o r b e r y l l i u m i n t h e r e - f l e c t o r i n c r e a s e s t h e c r i t i c a l mass by 15 and 25%, r e s p e c t i v e l y .

5 . Most o f t h e s t r u c t u r a l m a t e r i a l s t h a t m i g h t be u s e d b e t w e e n t h e f u e l and m o d e r a t o r h a v e a h i g h a b s o r p t i o n c r o s s s e c t i o n , a n d t h e r e f o r e some o f t h e t h e r m a l n e u t r o n s c o m i n g f rom t h e r e f l e c t o r a r e a b s o r b e d , T h e l o s s o f a l l t h e t h e r m a l n e u t r o n s would i n c r e a s e t h e c r i t i c a l mass by a f a c t o r o f a t l e a s t 10 . A 1 / 4 - i n . - t h i c k l a y e r o f I n c o n e l m i g h t r e s u l t i n a r e a c t i v i t y loss o f a s much a s 0 .24 , which i m p l i e s a n i n c r e a s e i n c r i t i c a l m a s s o f t h e o r d e r o f 100%.

6 . A n e g a t i v e c o m p o n e n t o f t h e t e m p e r a t u r e c o e f f i c i e n t o f r e a c t i v i t y i s o b t a i n e d from t h e t h e r m a l e x p a n s i o n o f t h e f u e l , f o r two r e a s o n s : (1) t h e l o s s o f s c a t t e r i n g c e n t e r s f o r f a s t n e u t r o n s and ( 2 ) t h e l o s s o f f u e l from t h e a c t i v e v o l u m e , I f a n e x p a n s i o n c o e f f i c i e n t f o r t h e f u e l o f 2 x 10'4/0F i s a s s u m e d , t h e t e m p e r a t u r e c o e f - f i c i e n t s r e s u l t i n g f r o m t h e s e t w o e f f e c t s a r e , r e s p e c t i v e l y , 0 . 2 x 10 '4 /0F and 0.4 x 10'4/0F, a t o t a l o f 0 . 6 X 1 0 ' 4 / 0 F . T h e f i r s t o f t h e s e r e a c t i v i t y c o e f f i c i e n t s i s s m a l l e r f o r some o t h e r r e a c t o r s ( f o r e x a m p l e , t h e

W k For NaF coolant, -= 4O/P

49

TABLE 4 .1 . S T A T I C P H Y S I C S OF SEVERAL REFLECTOR-MODERATED REACTOR D E S I G N S vl 0 4 z

71 ~ ___

TOTAL IEUTRMY ESCAPE

~

0.397

0.299

0.264

0.299

0.335

0.303

0.222

0.308

0.447

0.345

0.190

0.352

0.473

0.450

0.297

0.488

0.440

0.343

0.367

0.343

-

’10s - Mini- mum- t o -

Average

0.90 ___

0.75

0.83

0.85

0.85

0.86

0.86

0.50

0.85

0.55

0.71

0.90

0.90

0.86

0.65

0.87

0.83

-

POWE1 __ I n s i d e Peak-

t o - herage

IENSITY lu t s i d e Peak-

t o -

~

h e r a g e

ESCAPE 71 s 0 h

OF FAST

10.2 t o 10 Me”) NEUTRONS( )

VITY MEFFICI

UZ3’ Mass Ak/k

M / M __

REA1

Thermal Base A h / k

@(OF) -

S

Over- a1 1 )

A k / k

OB(0F) ~

FUEL Out s ide ) i ame te r

( i n . )

~

GION I n s i d e

D i m e t e r ( i n . 1

REACTOR TYPE

REFLECTOR ( 1 f t t h i c k )

CRITICAL MASS ( I b )

THERMAL FISSIONS (5)

m 0.0002996 4

n

ro 0.0002596 C

4

0.00228 C i r c u l a t i n g fuel, 3 r e g i o n s

C i r c u l a t i n g f v e l (str.(C)), 2 r e g i o n s

c o o l e d ) . 3 r e g i o n s

1 s t r . ) . 3 r e g i o n s

(str.), 3

( s t r . ) . 3 r e g i o n s

(St . . ) . 3 r e g i o n s

3 r e g i o n s

Fuel p l a t e s (Na

3 i r c u l a t i n g f u e l

C i r c u l a t i n g fuel

r e g i o n s C i r c u l a t i n g f u e l

C i r c u l a t i n g f u e l

C i r c u l a t i n g f u e l ,

C i r c u l a t i n g fuel, 2 r e g i o n s

C i r e v l a t i n g f u e l . 2 r e g i o n s

C i r c u l a t i n g fuel. 3 r e g i o n s

C i r c u l a t i n g fuel ( a i r c o o l e d ) , 3 region.

F u e l plates (Ne c o o l e d ) , 3 r e g i o n s

C i r c u l a t i n g f u e l , 3 r e g i o n s

C i r c u l a t i n g f u e l ,


C i r c u l a t i n g fuel,

C i r c u l a t i n g f u e l .


3 r e g i o n s

( s t r . ) , 3

2 r e g i o n s

2 r e g i o n s

( s t = . ) . 3 r e g i o n s

C r i t i c a l e x p e r i - ment, 20-mi1 f o i l and sodium cans, 3 r e g i o n s

R-118 w i t h p(NaF) X 1 /2 , 3 r e g i o n s

r e g i o n s

YaOD

h ( N a c o o l e d )

22

22

19

22

19

22

22

22

16

32

22

48

22

22

32

22

16

16

19

16

19

-

14

9

14

11

11

1 4

14

14

24

14

1 4

20

14

8

10

11

60

25

17

14.8

12

17

13

9

22

18.5

9.4

160

35

35

33

13

31

25.5

23

30

1 5

40

45

38

59 58

52

60

65

28

53

60

40

40

30

40

57

35 38

47

47

56

9.6 x

10.6 x

7.5 x 10-6

6.5 x

17.6 x

6.9 x

11.5 x

8.7 x 10-6

4.4 x 10-6

-2.1 x 10-6

-0.5 x 10-6

1.4 x 10-6

1.9 X

7 x 10-6

-17 X

6.5 X

4.08 X

1.01 Y. 10-6

8.02 x 10-6

10.0 x 10-6

10.5 X

0.20

0.20

0.25

0.42

0.27

0.26

0.25

0.30

0.27

0.47

0.30

0.20

0.20

0.20

0.56

0.20

0.20

0.16

1 .26

2.16

1.19

1.18

1.14

1.14

1.15

1 .14

1.71

1.10

2.34

1.21

1.07

1.3

1.15

1.86

1.93

0.92

1.27

0.96

1.16

0.52

1.59

1.35

1.29

1.29

1.29

1.28

1.95

0.60

1.30

2.11

1.69

1.21

1.2

1.29

0.52

0.49

1.75

1.00

1.34

103

121

124

117

I18

119

120

105

95

97

101

109

108

115

102

122

127

128

129

137

140

-7 x 10-1

-8 x lo-’

-8 X 10”

-7 x 10-s

-12 x 10-5

-8 x 10.’

-9 x 10.’

-5 x 10-1

-4 x 10-5

k 1 N a coo led )

=a m r

0.000291 4

rxl 0.000328

3e(Na c o o l e d )

3e(Na coo led )

0.000280

0.0000149

Be(Na c o o l e d )

Be(Na c o o l e d ) . 16 in . t hzck

Be(Na c o o l e d )

Be0

Be0

Be0

Be0

Be0

0.00029

0.0043

0.0020

0.0025

0.0029

Be0 q g r e g a t e

C

C-Be (h igh p)

Be(4 in . ) C(8 in . )

Be (6 in . ) C(6 in . )

Be(Na c o o l e d )

0.01037

0.040

0.00167

0.010744

0.00436

0.000501

Be 0.001191

Be(Na c o o l e d ) 0.0003866

( a ) D o e s n o t i n c l u d e t h e Doppler e f f e c t . (b )Through 1 i n . o f boron c a r b i d e . ( “ I n t h e s e c a l c u l a t i o n s , s t r u c t u r e was added t o t h e f u e l t o s i m u l a t e s t r u c t u r e be tween f u e l and moderator.

.

ARE) by a f a c t o r o f 1 0 , b u t t h e s e c o n d i s a p p r o x i m a t e l y t h e same.

7. The mean l i f e t i m e o f t h e prompt n e u t r o n s i s a b o u t 4 x l o e 4 sec f o r t h e b e r y l l i u m - r e f l e c t e d r e a c t o r w i t h a c e n t e r i s l a n d . A b o u t 1 / 2 % o f t h e prompt n e u t r o n s h a s a mean l i f e t i m e o f t h e o r d e r o f lo’* s e c b e c a u s e o f t h e low a b s o r p t i o n and l e a k a g e p r o b a b i l i t y i n t h e r e f l e c t o r .

8. A c o o l i n g s y s t e m m u s t b e p r o - v i d e d f o r t h e m o d e r a t o r b e c a u s e o f gamma and n e u t r o n h e a t i n g ; a b o u t 4% o f t h e t o t a l power a p p e a r s i n t h e m o d e r a t o r vo lume. I n s e r t i o n o f s u c h a s y s t e m means an i n c r e a s e d amount o f s t r u c t u r e i n t h e r e f l e c t o r , w h i c h , i n t u r n , c a u s e s a l o s s i n r e a c t i v i t y and a g a i n i n gamma-ray i n t e n s i t y . T h i s p r o b l e m i s b e i n g s t u d i e d .

9. One a s p e c t o f i m p o r t a n c e from t h e s h i e l d i n g s t a n d p o i n t i s t h e e n e r g y s p e c t r u m o f t h e n e u t r o n s e s c a p i n g from bo th t h e s u r f a c e o f t h e t h i c k r e f l e c t o r a n d t h r o u g h t h e f u e l - c i r c u l a t i o n p a s s a g e s a t t h e r e a c t o r e n d s . T h i s s p e c t r u m is s t r o n g l y t h e r m a l f o r t h e r e f l e c t o r s o f i n t e r e s t . The a d d i t i o n o f 1 i n . o f b o r o n c a r b i d e a t t h e r e f l e c t o r b o u n d a r y r e d u c e s t h e t o t a l l e a k a g e t h r o u g h t h e s i d e s o f t h e r e a c t o r t o t h e v a l u e s l i s t e d i n T a b l e 4 . 1 a s “ e s c a p e o f f a s t n e u t r o n s . ” The u s e of a n o n p o i s o n i n g , h e a v y m a t e r i a l ( l e a d o r b i s m u t h ) a s t h e r e f l e c t o r c o o l a n t may be b e n e f i c i a l f r o m t h e s h i e l d i n g s t a n d p o i n t b e c a u s e i t s h o u l d m o d e r a t e f a s t n e u t r o n s by i n e l a s t i c s c a t t e r i n g a n d a l s o s e r v e a s gamma s h i e l d i n g , T h e f a s t l e a k a g e t h r o u g h t h e f u e l p a s s a g e s and from f i s s i o n i n g

p a s s a g e s must be minimized by i o n o f f i s s i o n a n d b y t h e

i o n o f e x t r a s h i e l d i n g m a t e r i a l . T h i s p r o b l e m i s n o t e a s i l y a d a p t a b l e

t i o n , a n d h e n c e c r i t i c a l w i l l b e p e r f o r m e d t o

10 . A f e a s i b l e r o r - m o d e r a t e d r e a c t o r c a n be b u i l t by r e p l a c i n g t h e c i r c u l a t i n g - f u e l c o o l a n t ( f o r example,

a l u a t e l e a k a g e con


NaF-UF,) w i t h u r a n i u m - b e a r i n g s t a i n l e s s s t e e l f u e l p l a t e s and sodium c o o l a n t . A d e s i g n i n c o r p o r a t i n g t h i s f e a t u r e h a s been p r o p o s e d by A . S. Thompson. Shim c o n t r o l f o r s u c h a r e a c t o r can be a c c o m p l i s h e d by v a r y i n g t h e c o n c e n - ‘ t r a t i o n o f p o t a s s i u m i n t h e s o d i u m c o o l a n t . By t h i s means, t h e r e l a t i v e b u r n u p c o u l d b e m a d e v e r y l a r g e . These r e s u l t s imply t h a t t h e goal o f a s i m p l e , s t r u c t u r e l e s s c o r e i s i m - p r a c t i c a l b e c a u s e t h e f u e l s o l v e n t i s i n a d e q u a t e a s a m o d e r a t o r . An i s l a n d o f s o l i d m o d e r a t o r i n t h e c e n t e r o f t h e c o r e seems t o be d e s i r a b l e , a n d t h e u s e f u l n e s s o f s u c h a n i s l a n d i s n o t e n t i r e l y n u c l e a r , As w i l l be shown l a t e r , t h e h y d r o d y n a m i c s o f a r e - f l e c t o r - m o d e r a t e d r e a c t o r a r e a l s o a i d e d by a c e n t r a l i s l a n d .

Summary Tables and G r a p h s . T h e m u l t i p l i c a t i o n c o n s t a n t s o f two- and t h r e e - r e g i o n r e f l e c t o r - m o d e r a t e d r e a c t o r s a s a f u n c t i o n o f u r a n i u m w e i g h t i n t h e f u e l r e g i o n f o r s e v e r a l c o r e a n d i s l a n d s i z e s a n d m o d e r a t o r c o m p o s i t i o n s a r e g i v e n i n F i g . 4 . 1 3 . The v a r i o u s r e a c t o r s r e f e r r e d t q i n t h i s f i g u r e a r e d e s c r i b e d i n T a b l e 4 .1 . The f i g u r e s u m m a r i z e s a nhmber o f p o i n t v a l u e s f o r r e a c t i v i t y . T o f a c i l i t a t e t h e e x t r a p o l a t i o n , t h e c u r v e s d r a w n t h r o u g h p o i n t v a l u e s i n d i c a t e t h e m a n n e r i n w h i c h t h e m u l t i p l i c a t i o n c o n s t a n t v a r i e s w i t h u r a n i u m w e i g h t f o r t h e p a r t i c u l a r r e a c t o r t o w h i c h t h e p o i n t v a l u e r e f e r s . I f o n l y t w o - r e g i o n r e a c t o r s a r e c o n s i d e r e d , t h e s h a p e s o f t h e c u r v e s v a r y s y s t e m a t i c a l l y w i t h t h e p o s i t i o n o f t h e p o i n t v a l u e i n t h e uran ium w e i g h t v s . k , f f p l a n e . Hence, o n l y a few o f t h e c u r v e s were a c t u a l l y computed, and t h e o t h e r s were drawn by a n a l o g y . L i k e w i s e , a few k e f f v s . u r a n i u m w e i g h t c u r v e s c a n be computed f o r t h r e e - r e g i o n r e a c t o r s a n d t h e n s i m i l a r c u r v e s c a n be drawn t h r o u g h t h e p o i n t v a l u e s . The s h a p e s o f t h e c u r v e s f o r t h r e e - r e g i o n r e a c t o r s a r e , o f c o u r s e , d i f f e r e n t f r o m t h o s e f o r

51


1.2

t .1

-I p 0.0 5 2 H

0.7

S m R u D W G . 18728

I I SEE TABLE 4.1 FOR DESCRIPTION OF REACTORS BY NUMBER

t t5

0.6

URANIUM WEIGHT (Ib)

F i g . 4 .13 . Uranium Weight v s . k e f for Several Reflector-Moderated Reactors.

t h e t w o - r e g i o n r e a c t o r s . ( T h r e e - r e g i o n r e a c t o r s have c e n t e r i s l a n d s . )

The c u r v e s d e s c r i b e d a b o v e a r e n o t e x p e c t e d t o b e e x a c t . I t s h o u l d be n o t e d t h a t t h e IBM m u l t i g r o u p method s t a r t s w i t h an assumed power d i s t r i - b u t i o n ; and , i f t h e c a l c u l a t i o n r e s u l t s i n a power d i s t r i b u t i o n d i f f e r e n t from t h e assumed o n e , an i t e r a t i o n must be made by u s i n g t h e c o m p u t e d d i s t r i - b u t i o n a s a s t a r t . S u c h i t e r a t i o n s were c a r r i e d o u t o n l y where e s s e n t i a l . Whenever p o s s i b l e , f u e l - c o o l a n t c o n - s t i t u e n t s w e r e h e l d c o n s t a n t t o emphas ize t h e e f f e c t s o f main i n t e r e s t . I t is t o be n o t e d t h a t any f u e l s e l f - s h i e l d i n g or p o i s o n i n g e f f e c t , or any c h a n g e i n r e a c t o r s i z e , i s r e f l e c t e d by a r a p i d change i n r e a c t i v i t y and a

r a p i d change i n t h e s l o p e o f t h e c u r v e s v s . u~~~ mass.

O f k e f f

. s

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* T y p i c a l r e s u l t s o f t h e m u l t i g r o u p

s o l u t i o n o f t h e n e u t r o n d i f f u s i o n p r o c e s s e s a r e g i v e n i n F i g s . 4 . 1 4 t o 4 . 1 7 . F i g u r e s 4 . 1 4 a n d 4 . 1 5 g i v e s p a t i a l power d i s t r i b u t i o n a n d f l u x s p e c t r a , r e s p e c t i v e l y , f o r one e x t r e m e c a s e - a r e a c t o r w i t h a s m a l l ( 8 - i n . - d i a . ) , c e n t r a l , m o d e r a t o r r e g i o n , a t h i c k ( 5 1 / 2 - i n . ) , f u e l - b e a r i n g r e g i o n , a n d s o d i u m - c o o l e d f u e l p l a t e s . T h e r e l a t i v e l y h i g h p e a k - t o - a v e r a g e r a t i o i n t h e p o w e r d i s t r i b u t i o n c u r v e , F i g . 4 . 1 4 , e m p h a s i z e s t h e v a l u e o f a t h i n f u e l l a y e r . F i g u r e s 4 . 1 6 a n d 4 .17 g i v e t h e computed power and f l u x d i s t r i b u t i o n f o r t h e f i r s t c r i t i c a l

52


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*NORMALIZED TO ONE SOURCE NEUTRON PER cm3 OF CORE

I I I I I I

0 2 4 6 8 i 0 12 14 46 18 20 22 24 26 28 SPACE POINT, n ( r =nAr,crn)

F i g . 4 . 1 4 . S p a t i a l Power D i s t r i b u t i o n f o r a Three -Reg ion R e a c t o r w i t h a Thick Fuel Annulus.

e x p e r i m e n t c a l c u l a t i o n , f o r w h i c h 1- by 3- by 3 - i n . s o d i u m - f i l l e d c a n s and 1 0 - m i l - t h i c k ] 3 - i n . - d i a , U 2 3 5 f u e l d i s k s were u s e d , A c o m p a r i s o n w i t h t h e e x p e r i m e n t a l r e s u l t s i s g i v e n i n t h e n e x t s e c t i o n .

r e p e a t e d h e r e t o g i v e a u n i f i e d p i c t u r e o f t h e f i r s t r e f l e c t o r - m o d e r a t e d r e a c t o r c r i t i c a l e x p e r i m e n t . T h e f u e l c o n s i s t e d o f 0 . 0 2 0 - i n . - t h i c k p i e c e s o f U 2 3 5 m e t a l l u m p e d b e t w e e n 1 - i n . l a y e r s o f s o d i u m c a n n e d i n s t a i n l e s s s t e e l . T h i s a r r a n g e m e n t was shown t o be i n e f f i c i e n t i n n e u t r o n u t i l i z a t i o n b e c a u s e o f t h e s e l f - s h i e l d i n g i n t h e t h i c k uranium l a y e r s . T h e s e l f - s h i e l d i n g o f t h e f u e l w a s m e a s u r e d e x p e r i m e n t a l l y by r e p l a c i n g o n e o f t h e 2 0 - m i l f u e l d i s k s w i t h 10 d i s k s t h a t were e a c h 2 m i l s ; t h i c k w i t h a l u m i n u m c a t c h e r f o i l s b e t w e e n t h e m . T h e a c t i v i t y o f t h e c a t c h e r f o i l s showed t h a t t h e 2 0 - m i l l a y e r s

r e f l e c t o r -mod e r a t e d c i r c u l a t i n g - f u e l

Some i n f o r m a t i o n a l r e a d y r e p o r t e d i s D e c . IO, 1952, ORNL-1439, p. 48.

("D. V. P. Williams, R. C. Keen, J. J. Lynn. D. S c o t t , and C. B. Mills, A N P Quar. P I - o g . R e p . r e a c t o r w a s d e s c r i b e d p r e v i o u s l y . ( 2,

53

a


SeeRPT DWG. 18730

0 2 4 6 8 10 12 14 16 48 20 22 24 26 28 30 SPACE POINT, n ( r - n A r , c m )

F i g . 4 . 1 5 . S p a t i a l F l u x D i s t r i b u t i o n f o r a T h r e e - R e g i o n Reactor w i t h a Thick Fuel Annulus.

were 66% e f f e c t i v e ; t h e c o r r e s p o n d i n g t h e o r e t i c a l es t imate was 63%.

The c r i t i c a l mass was found e x p e r i - m e n t a l l y t o b e 1 5 k g o f U235. With t h i s l o a d i n g , a m u l t i p l i c a t i o n c o n s t a n t o f 1 . 0 3 was c a l c u l a t e d by t h e m u l t i - group method. The u s u a l s e l f - s h i e l d i n g c o r r e c t i o n f o r t h e l u m p e d f u e l w a s u s e d . T h e c a l c u l a t i o n w a s c a r r i e d o u t f o r a s p h e r i c a l s h a p e , w h e r e a s t h e a c t u a l g e o m e t r y was r e c t a n g u l a r . T h i s d i f f e r e n c e was a c c o u n t e d f o r by r e d u c i n g t h e f u e l v o l u m e f o r c a l c u - l a t i o n p u r p o s e s by 10%. The computa t ion d i d n o t i n c l u d e any p o i s o n i n g e f f e c t o f i m p u r i t i e s i n t h e m a t e r i a l s .

54

The n e u t r o n - f l u x t r a v e r s e s measured r a d i a l l y t h r o u g h t h e m i d - p l a n e of t h e

The a c t i v a t i o n s o f b a r e - and cadmium- covered- indium f o i l s and t h e i r d i f f e r - e n c e s were shown. T h e s e r e s u l t s a r e t y p i c a l o f t h o s e o b t a i n e d a l o n g o t h e r t r a v e r s e s , a n d t h e y c o n f i r m t h e p r e d i c t i o h o f h i g h n e u t r o n f l u x i n t h e m o d e r a t o r i s l a n d and r e f l e c t o r . T h i s e f f e c t i s , a s e x p e c t e d , p a r t i c u - l a r l y pronounced f o r t h e r m a l n e u t r o n s .

The cadmium f r a c t i o n , d e r i v e d f rom t h e i n d i u m - f o i l a c t i v a t i o n d a t a and d e f i n e d a s t h e r a t i o of t h e a c t i v a t i o n

r e a c t o r w e r e g i v e n p r e v i o u s l y . ( 3 )

(3)Zbid., Fig . 5 . 3 , p. 51.

I

P E R I O D E N D I N G MARCH 1 0 , 1 9 5 3

S I m DWG. 18731

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0 2 4 6 8 10 12 ( 4 16 18 20 22 24 26 28 30 32 SPACE POINT, n ( r = n A r ,cm)

F i g . 4 .16 . C a l c u l a t e d S p a t i a l Power D i s t r i b u t i o n f o r t h e F i r s t C r i t i c a l Assembly.

by n e u t r o n s of ene rgy below t h e cadmium c u t - o f f t o t h e a c t i v a t i o n by a l l n e u t r o n s , w a s g i v e n p r e v i o u s l y . ( 4 ) The v a l u e s of t h i s cadmium f r ac t i o n , a s c a l c u l a t e d f rom t h e I B c o m p u t a t i o n s , w e r e a l s o p l o t t e d . T h e o r e t i c a l and e x p e r i m e n t a l v a l u e s p r a c t i c a l l y c o i n c i d e i n t h e c e n t e r o f t h e f u e l a n d i n t h e b u l k o f t h e r e f l e c t o r . T h e d i s c r e p a n c y a t t h e f u e l s u r f a c e is n o t s u r p r i s i n g , s i n c e

r a c t i c a l c a l c u l a t i o n m e t h o d s , h e “age” m u l t i g r o u p method, c t n e a r b o u n d a r i e s . i o n i n g d i s t r i bu t i o n th rough - u e l r e g i o n i s s h o w n i n

F i g . 4 . 1 8 . The e x p e r i m e n t a l v a l u e s a r e c a t c h e r - f o i l m e r e m e n t s . S i n c e t h e m e a s u r e m e n t s were n o t n o r m a l i z e d ,

( 4 ) I b i d . , Fig . 5 . 5 , p. 53.

t h e r e i s n o s i g n i f i c a n c e i n t h e c l o s e a g r e e m e n t o f t h e a b s o l u t e v a l u e s o f t h e t h e o r e t i c a l a n d e x p e r i m e n t a l c u r v e s . H o w e v e r , t h e a g r e e m e n t in t h e p e a k - t o - a v e r a g e r a t i o s of power d e n s i t y d o e s seem s i g n i f i c a n t . T h e d i s c r e p a n c y i n t h e shape o f t h e c u r v e s i n s i d e t h e f u e l l a y e r c a n be a t t r i b u t e d t o t h e f a c t t h a t t h e r e i s more m o d e r a t o r i n t h e r e c t a n g u l a r c e n t e r i s l a n d t h a n was assumed i n t h e c o m p u t a t i o n b a s e d on s p h e r i c a l geometry.

To d e t e r m i n e t h e r e a c t i v i t y l o s s e x p e c t e d f r o m s t r u c t u r a l m a t e r i a l a t t h e c o r e - r e f l e c t o r i n t e r f a c e , an e x p e r i m e n t was p e r f o r m e d ( F i g . 4 . 1 9 ) w i t h o n e - h a l f o f o n e o f t h e f o u r o u t s i d e s u r f a c e s of t h e c o r e c o v e r e d w i t h 1 / 4 - i n . s t a i n l e s s s t e e l p l a t e s . The loss i n r e a c t i v i t y was 220 c e n t s , which is c o n s i s t e n t w i th t h e t h e o r e t i c a l

55


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16

14

12

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0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32

SPACE POINT, n ( r = 1.757 n, cm)

Fig . 4.17. C a l c u l a t e d Flux Spectrum f o r t h e F i r s t C r i t i c a l Assembly.

v a l u e o f 24%, f o r an I n c o n e l l a y e r o v e r b o t h t h e i n n e r a n d t h e o u t e r f u e l - r e f l e c t o r i n t e r f a c e s .

A 1 - i n . - t h i c k l a y e r o f l e a d o r bismuth a t t h e c o r e - r e f l e c t o r i n t e r f a c e ( w h e r e i t seems t o b e m o s t u s e f u l ) on one o f t h e f o u r o u t e r s u r f a c e s o f t h e c o r e c o s t 0 . 2 4 % i n k c f f for b i s m u t h and 0.91% f o r l e a d , a s compared w i t h a v o i d .

Second Cr i t ica l Assembly. A second a s s e m b l y w i t h f u e l p r o p e r t i e s t h a t m o r e c l o s e l y r e s e m b l e t h o s e o f a p o s s i b l e f u l l - s c a l e r e a c t o r w a s c o n s t r u c t e d . I n t h i s s e c o n d a s sembly , t h e f u e l w a s a m i x t u r e o f 6 6 w t % Z r O , , 2 4 w t % NaF and 1 0 w t % C ( t h e Zr0 , -C c o m b i n a t i o n s i m u l a t e s Z r F , ) , w i t h s u f f i c i e n t e n r i c h e d UF, a d d e d t o make t h e U 2 3 5 d e n s i t y 0 . 2 g/cm3. The w e l l - h o m o g e n i z e d p o w d e r m i x t u r e was p a c k e d i n 1 1 / 4 - i n . s q u a r e a luminum

t u b e s t h a t were a r r a n g e d a r o u n d t h e c e n t r a l b e r y l l i u m c o r e and were , i n t u r n , s u r r o u n d e d by t h e b e r y l l i u m and g r a p h i t e r e f l e c t o r . T h e s e r e g i o n s may b e s e e n i n F i g . 4 . 2 0 , which shows t h e l o a d i n g i n a p l a n e t h r o u g h t h e a x i s o f t h e r e a c t o r . T h e maximum c r o s s s e c t i o n o f t h e b e r y l l i u m i s l a n d w a s 9 by 9 i n . , a n d t h e m a x i m u m t h i c k n e s s o f t h e f u e l r e g i o n w a s 4 1 / 2 i n c h e s . (With m a t e r i a l s a v a i l a - b l e , i t was n o t p o s s i b l e t o c o m p l e t e l y f i l l t h e f u e l r e g i o n a t a l l a x i a l l o c a t i o n s . ) T h e t h i c k n e s s i n t h e f u e l r e g i o n w a s d e c r e a s e d i n b o t h d i r e c t i o n s from t h e c e n t e r t o s i m u l a t e t h e i n l e t a n d o u t l e t d u c t s o f t h e f u l l - s c a l e r e a c t o r . F i g u r e 4 . 2 1 i s a p h o t o g r a p h o f t h e a s s e m b l y a t s e c t i o n AA o f F i g . 4 . 2 0 . T h i s a s s e m b l y was c r i t i c a l w i t h a l o a d i n g o f 7 . 7 kg o f u 2 3 5

56

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DWG. 18733

1' E XPERl MENTAL 1 (NOT NORMALIZED)

9 10 11 12 13 14 SPACE POINT, n (r=1,757n,cm)

F i g . 4 . 1 8 . Measured t r i b u t i o n i n t h e F u e l R e g i o n o f t h e F i r s t C r i t i c a l Assembly.

Neut ron f l u x d i s t r i b u t i o n w i t h b a r e - and cadmium-covered - ind ium f o i l s a l o n g a h o r i z o n t a l t r a v e r s e l y i n g i n t h e m i d - p l a n e o f t h e assembly a r e shown i n F i g . 4 . 2 2 . N o t e t h e s p a t i a l d i s t r i b u t i o n o f t h e cadmium

h a t i s , t h e f r a c t i o n o f t e d by i n d i u m , t h a t

e l o w t h e c a d m i u m e exper imen t a 1 v a l u e s

f r a c t i o n a n d t h o s e u l t i g r o u p method a r e

The d i f f e r e n c e i s w i t h i n , e x c e p t a t t h e f a c e w h e r e i t is

p e r i m e n t s i n d i c a t e a n e u t r o n e n e r g y lower t h a n t h a t computed f o r t h i s p o i n t . (Recen t d a t a i n d i c a t e t h a t t h i s d i f f e r e n c e may be c a u s e d by


0 6 '18 3/16

THICKNESS OF STAINLESS STEEL (in)

F i g . 4 . 1 9 . R e a c t i v i t y L o s s v s . T h i c k n e s s o f S t a i n l e s s S t e e l a t t h e Fuel -Ref 1 ec t o r I n t e r f a c e o f th'e F i r s t C r i t i c a l Assembly.

t h e v o i d a t t h e i n t e r f a c e , w h i c h i s p e c u l i a r t o t h e s t r u c t u r e o f t h e c r i t i c a l expe r imen t . 1

T h e e x p e r i m e n t a l cadmium f r a c t i o n c u r v e shown i n F i g . 4 . 2 1 i s r e p e a t e d a s c u r v e A i n F i g . 4 . 2 3 , w h i c h g i v e s t h e d i s t r i b u t i o n o f t h e f r a c t i o n of n e u t r o n s , d e t e c t e d by i n d i u m , w i t h e n e r g i e s b e l o w t h e cadmium c u t - o f f . C u r v e B o f F i g . 4 . 2 3 w a s o b t a i n e d f rom t h e f i r s t c r i t i c a l e x p e r i m e n t . C o m p a r i s o n o f t h e t w o c u r v e s s h o w s t h e s i m i l a r i t y o f t h e s p e c t r a i n t h e c e n t e r o f t h e f u e l i n t h e two a s s e m b l i e s . I t i s t o b e remembered t h a t t h e f u e l l a y e r i n t h e f i r s t mockup w i 3 s o n l y 3 i n . t h i c k .

A p r e l i m i n a r y m e a s u r e m e n t o f t h e n e u t r o n l e a k a g e s p e c t r u m g a v e v a l u e s o f t h e cadmium f r a c t i o n f o r i n d i u m - d e t e c t e d n e u t r o n s a t t h e o u t s i d e edge o f t h e r e f l e c t o r , b o t h on t h e a x i s a n d a t t h e s i d e a t t h e m i d - p l a n e . T h e r e s p e c t i v e v a l u e s were 0 . 4 and

57


seeul3 DWG (8735

L A

F i g . 4 .20. Vertical Cross-Section o f the Second Cri t ica l Assembly.

AXIS

0 . 9 . A m e a s u r e o f t h e f i s s i o n r a t e o r p o w e r d i s t r i b u t i o n i n a d i r e c t i o n p a r a l l e l t o t h e r e a c t o r a x i s h a s been o b t a i n e d f r o m t h e i m p r o v i s a t i o n i l l u s t r a t e d i n F i g . 4.24 . U r a n i u m m e t a l d i s k s , 1 . 4 i n . i n d i a m e t e r a n d 0. 002 i n . t h i c k , i n c o n t a c t w i t h aluminum d i s k s , 0.005 i n . t h i c k , were p l a c e d a d j a c e n t t o o n e o f t h e f u e l c o n t a i n e r s ; and t h e a c t i v i t y on t h e

58

aluminum, c a u s e d by r e c o i l i n g f i s s i o n f r a g m e n t s , was coun ted . The low v a l u e a t t h e 1 7 - i n . a b s c i s s a p o i n t p r o b a b l y r e s u l t e d f r o m t h e s h i e l d i n g o f e x - t e r n a l l y r e f l e c t e d n e u t r o n s by t h e l a y e r of f u e l t h a t was t h i c k e r t h e r e t h a n a t t h e 20 - in . a b s c i s s a p o i n t .

I n a s i m i l a r m a n n e r , an a t t e m p t was made t o d e t e r m i n e t h e f i s s i o n r a t e p a t t e r n i n a d i r e c t i o n p e r p e n d i c u l a r

,PERIOD ENDING MARCH 10, 1953 /

I

F i g . 4 .21. Photograph o f Second C r i t i c a l Assembly a t S e c t i o n AA of F i g . 4 . 2 0 .

59


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I BERYLLIUM -GRAPHITE -C REFLECTOR TO 27

- BERYLLIUM --&- ISLAND

0 BARE INDIUM, EXPERIMENTAL

A CADMIUM-COVERED INDIUM, EXPERIMENTAL EXPERIMENTAL CADMIUM FRACTION

A CALCULATED C4DMIUM FRACTION

1 .o z 0 a 5 E LL

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0 0 5 10 15 20 25

DISTANCE FROM REACTOR AXIS (in.)

k

Fig. 4.22. Radial Indium Activation and Cadmium Fr the Second Critical Assembly.

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Fig. 4.23. Comparison of the Cadmium Fractions in the Two Critical Assemblies.

i .

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.

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PERIOD ENDING MARCH 1 0 1 9 5 3

?rcmcl- DWG 1873

BERYLLIUM REFLECTOR

' 0.002-in. URANIUM DISK AND ALUMINUM CATCHER FOIL

0 5 IO 15 20 2 5 30 35 DISTANCE FROM REACTOR INTERFACE (in.)

F i g . 4 .24 . Measured Power D i s t r i b u t i o n P a r a l l e l to A x i s o f Second Crit ical Assembly.

t o t h e a x i s a l o n g a h o r i z o n t a l l i n e l y i n g i n t h e m i d - p l a n e . U r a n i u m d i s k s and s m a l l (5/16 in . i n d i a m e t e r ) a l u m i n u m c a t c h e r f o i l s w e r e p l a c e d b e t w e e n t h e f u e l c o n t a i n e r s . T h e r e s u l t s show a c e n t e r - t o - e d g e a c t i v i t y r a t i o o f 0 .45, t h a t i s , a 55% d e p r e s s i o n i n t h e p o w e r a c r o s s a f u e l l a y e r 3.75 i n . wide. By d i r e c t measurement w i t h 2 0 - m i l c a d m i u m i n t h e f i r s t c r i t i c a l a s s e m b l y , i t was found t h a t 7 0 % o f t h e f i s s i o n s w a s c a u s e d by n e u t r o n s wi th ene rgy below t h e cadmium c u t - o f f . From t h e s i m i l a r i t y o f t h e s D e c t r a . i t i s s u s p e c t e d t h a t a b o u t t h e same d i s t r i b u t i o n o c c u r s i n t h e

o d i r e c t m e a s u r e m e n t

A. P. F r a a s , ANP D i v i s i o n

t h e d e s i g n o f t h e f u l l - s c a l e r e a c t o r shown i n F i g . 4 . 2 5 s h o u l d l o g i c a l l y p r e c e d e a d e t a i l e d d e s c r i p t i o n , an e x p o s i t i o n o f t h e s e c o n s i d e r a t i o n s w i l l be g r e a t l y s i m p l i f i e d by e a r l y r e f e r e n c e t o a f a i r l y s p e c i f i c s y s t e m . T h e r e f o r e , t h i s s e c t i o n b e g i n s w i t h a d e s c r i p t i o n o f t h e r e f l e c t o r -molder a t e d r e a c t o r d e s i g n and s u b s e q u e n t l y t a k e s up t h e more s i g n i f i c a n t o f t h e many f a c t o r s t h a t h a v e e n t e r e d i n t o t h a t d e s i gn .

Much w o r k r e m a i n s t o b e d o n e on r e f l e c t o r - m o d e r a t e d r e a c t o r s to g i v e b e t t e r b a s e s f o r d e t a i l e d d e s i g n s , b u t t h e c o n s t r u c t i o n i n d i c a t e d by F i g . 4.25 seems t o be t h e most p romis ing o n e c o n s i d e r e d , t o d a t e , f o r a n a i r c r a f t p o w e r p l a n t . T h i s c r o s s s e c t i o n t h r o u g h t h e r e a c t o r c o r e , m o d e r a t o r , and h e a t e x c h a n g e r shows a

I

A l t h o u g h t h e many c o m p l e x a n d s e r i e s of f o u r c o n c e n t r i c s h e l l s , each o f which i s a s u r f a c e of r e v o l u t i o n . i n t e r r e l a t e d c o n s i d e r a t i o n s u n d e r l y i n g

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The two i n n e r s h e l l s s u r r o u n d t h e f u e l r e g i o n a t t h e c e n t e r , t h a t i s , t h e c o r e o f t h e r e a c t o r , and s e p a r a t e i t f r o m t h e b e r y l l i u m i s l a n d a t t h e c e n t e r and f rom t h e o u t e r b e r y l l i u m r e f l e c t o r . T h e f u e l c i r c u l a t e s downward t h r o u g h t h i s r e g i o n i n which t h e f i s s i o n i n g t a k e s p l a c e and t h e n downward and o u t w a r d t o t h e e n t r a n c e o f t h e s p h e r i c a l s h e l l h e a t e x c h a n g e r t h a t l i e s be tween t h e m o d e r a t o r o u t e r s h e l l and t h e m a i n p r e s s u r e s h e l l . T h e f u e l f l o w s u p w a r d b e t w e e n t h e t u b e s i n t h e h e a t e x c h a n g e r i n t o two m i x e d f l o w pumps a t t h e t o p . From t h e pumps, i t i s d i s c h a r g e d inward t o t h e top of t h e a n n u l a r p a s s a g e l e a d i n g back t o t h e r e a c t o r c o r e . The t o t a l f u e l v o l u m e i n t h e s y s t e m f o r t h i s d e s i g n would b e a p p r o x i m a t e l y 7 f t 3 , of which a p p r o x i m a t e l y 1 1 / 3 f t 3 would b e i n t h e r e a c t o r c o r e . Most o f t h e r e m a i n i n g f u e l w o u l d b e i n t h e i n - t e r s t i c e s b e t w e e n t h e t u b e s i n t h e h e a t e x c h a n g e r . The m o d e r a t o r was d e s i g n e d t o b e c o o l e d b y s o d i u m f l o w i n g downward t h r o u g h t h e a n n u l a r s p a c e b e t w e e n t h e b e r y l l i u m and t h e e n c l o s i n g s h e l l s a n d b a c k u p w a r d t h r o u g h p a s s a g e s i n t h e b e r y l l i u m . Two c e n t r i f u g a l p u m p s a t t h e t o p c i r c u l a t e t h e s o d i u m f i r s t t h r o u g h t h e m o d e r a t o r a n d t h e n t h r o u g h t h e s m a l l t o r o i d a l s o d i u m - t o - N a K h e a t e x c h a n g e r s around t h e o u t e r p e r i p h e r y of t h e pump and e x p a n s i o n t a n k r e g i o n . A h o r i z o n t a l s e c t i o n t h r o u g h t h e pump and e x p a n s i o n t a n k r e g i o n i s shown i n F i g . 4 . 2 6 . N o t e t h a t sump p u m p s w i t h g a s s e a l s a r e u s e d . A pump o f t h i s t y p e r e c e n t l y c o m p l e t e d 1000 h r of v e r y s u c c e s s f u l o p e r a t i o n i n a f l u o r i d e s y s t e m , w i t h pump i n l e t t e m p e r a t u r e s of a b o u t 1400'F.

The p r i m a r y c o n s t r u c t i o n m a t e r i a l i s I n c o n e l b e c a u s e i t seems t o be t h e m a t e r i a l t h a t i s m o s t r e s i s t a n t t o f l u o r i d e c o r r o s i o n . B e r y l l i u m was c h o s e n a s t h e m o d e r a t o r m a t e r i a l , p a r t l y b e c a u s e i t s e e m e d t o b e t h e b e s t m a t e r i a l o b t a i n a b l e , f rom b o t h s h i e l d i n g and c r i t i c a l m a s s s t a n d - p o i n t s , and p a r t l y because i t s p h y s i c a l


p r o p e r t i e s seem t o b e s u p e r i o r t o t h o s e of any o t h e r m a t e r i a l t h a t migh t be u s e d i n t h a t l o c a t i o n , o t h e r t h a n g r a p h i t e . I t was d e c i d e d t h a i t t h e v a s e - s h a p e d i s l a n d i n t h e c e n t e r s h o u l d b e u s e d , p a r t l y b e c a u s e i t reduced t h e c r i t i c a l mass and improved t h e p o w e r d i s t r i b u t i o n i n t h e f u e l r e g i o n , a n d p a r t l y b e c a u s e h y d r o - d y n a m i c a l l y i t p r o m i s e d t o g i v e t h e s i m p l e s t a n d m o s t d e s i r a b l e f u e l p a s s a g e . T h e 1 2 - i n . - t h i c k b e r y l l i u m r e f l e c t o r f o l l o w e d by 1 i n . o f b o r o n c a r b i d e w a s c h o s e n o r i g i n a l l y t o k e e p t h e n e u t r o n s e s c a p i n g t o t h e h e a t e x c h a n g e r r e g i o n t o a l e v e l a p p r o x i m a t e l y e q u a l t o t h a t o f t h e d e l a y e d - n e u t r o n f l u x f rom t h e c s i r cu - l a t i n g f u e l i n t h a t r e g i o n . I t h a s s i n c e p r o v e d t o be n e a r l y a n optimum c o n f i g u r a t i o n from b o t h c r i t i c a l mass and s h i e l d i n g s t a n d p o i n t s .

The s p h e r i c a l s h e l l h e a t e x c h a n g e r , w h i c h m a k e s p o s s i b l e t h e c o m p a c t l a y o u t o f t h e r e a c t o r - h e a t e x c h a n g e r a s s e m b l y , i s based on t h e u s e o f t u b e b u n d l e s c u r v e d i n such a way t h a t t h e t u b e s p a c i n g i s u n i f o r m , i r r e s p e c t i v e o f l a t i t u d e . ( ) The i n d i v i d u a 1 t u b e b u n d l e s t e r m i n a t e i n h e a d e r s t h a t r e s e m b l e s h o w e r h e a d s b e f o r e t h e t u b e s a r e w e l d e d i n p l a c e . T h i s a r r a n g e m e n t f a c i l i t a t e s a s s e m b l y b e c a u s e a l a r g e n u m b e r o f s m a l l t u b e - t o - h e a d e r a s s e m b l i e s i s made l e a k t i g h t much more e a s i l y t h a n o n e l a r g e u n i t . F u r t h e r m o r e , t h e s e t u b e b u n d l e s g i v e a r u g g e d f l e x i b l e c o n - s t r u c t i o n t h a t r e s e m b l e s s t e e l c a b l e a n d i s a d m i r a b l y a d a p t e d t o m e r v i c e i n which l a r g e amounts of d i f f e r e n t i a l t h e r m a l e x p a n s i o n m u s t b e exp lec t ed . T h i s b a s i c t u b e b u n d l e a n d s p a c e r c o n s t r u c t i o n w a s u s e d i n a s m a l l NaK-to-NaKheat exchange r t h a t o p e r a t e d s a t i s f a c t o r i l y f o r 3000 h r w i t h a NaK i n l e t t e m p e r a t u r e o f 1500'F. ( 6 , Two

(5)A. P. F r a a s and M . E . L a v e r n e , H e a t E x -

(6 )G. H. Cohen, A. P. Fraas , and EA. E. Laverne , H e a t T r a n s f e r and P r e s s u r e L o s s i n T u b e B u n d l e s for H i g h P e r f o r m a n c e H e a t E x c h a n g e r s crnd Fue 1 E l e m e n t s , OWL-1215, Aug. 12 , 1952 .

c h a n g e r D e s i g n C h a r t s , OWL-1330, Dec. 7 , 1952.

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s o d i u m pumps a n d t w o s o d i u m - t o - N a K h e a t e x c h a n g e r s a r e p r o v i d e d s o t h a t f a i l u r e o f o n e p u m p o r o n e h e a t e x c h a n g e r w i l l n o t c o m p l e t e l y d i s a b l e t h e r e a c t o r .

Factors A f f e c t i n g Core Diameter. T h e f i r s t f a c t o r c o n s i d e r e d i n e s - t a b l i s h i n g t h e r e a c t o r c o r e d i a m e t e r ( t h e f u e l r e g i o n ) was t h e e f f e c t o f d i a m e t e r on c r i t i c a l mass . A l t h o u g h m u c h w o r k r e m a i n s t o b e d o n e t o e s t a b l i s h t h e c o r e d i a m e t e r , i t a p p e a r s , a t t h i s t ime, t h a t t h e c r i t i c a l m a s s i s e s s e n t i a l l y i n d e p e n d e n t o f t h e c o r e d i a m e t e r . A more i m p o r t a n t f a c t o r a f f e c t i n g c r i t i c a l mass i s t h e

64

p r e s e n c e and s i z e o f t h e i s l a n d . I t a p p e a r s t h a t t h e u s e o f a b e r y l l i u m i s l a n d w i t h a d i a m e t e r o n e - h a l f t h a t o f t h e f u e l r e g i o n c u t s t h e c r i t i c a l mass a p p r o x i m a t e l y i n h a l f . A t t h e same t i m e , t h e i s l a n d r e d u c e s t h e r a t i o o f t h e p e a k - t o - a v e r a g e p o w e r d e n s i t y by a f a c t o r o f a b o u t 1 . 5 . F u r t h e r work on t h e e f f e c t s o f i s l a n d s i z e a n d f u e l r e g i o n t h i c k n e s s i s unde r way.

A c a r e f u l s c r u t i n y o f t h e d a t a t h a t h a v e been o b t a i n e d on t h e m e l t i n g p o i n t , v i s c o s i t y , and t h e r m a l conduc- t i v i t y o f v a r i o u s f l u o r i d e m e l t s i n d i c a t e s t h a t i t w i l l p r o b a b l y n o t

i r


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b e p o s s i b l e t o o b t a i n a f l u o r i d e f u e l w i t h more t h a n 4 m o l e % u r a n i u m t h a t h a s c l o s e t o o p t i m u m p h y s i c a l p r o p e r t i e s f r o m t h e h e a t t r a n s f e r s t a n d p o i n t ; i n f a c t , f r o m t h e s t a n d p o i n t o f p h y s i c a l p r o p e r t i e s , t h e r e a p p e a r s t o be an i m p o r t a n t i n c e n t i v e f o r k e e p i n g t h e u r a n i u m c o n c e n t r a t i o n l e s s t h a n 2 m o l e %. On t h e b a s i s o f c r i t i c a l m a s s d a t a f r o m t h e c a l c u l a t i o n s a n d t h e c r i t i c a l e x p e r i m e n t s , i t a p p e a r s t h a t a f u e l - r e g i o n d i a m e t e r o f a t l e a s t 18 i n . w i l l b e r e q u i r e d t o s a t i s f y t h i s c o n d i t i o n .

A m a j o r c o n s i d e r a t i o n i n e s - t a b l i s h i n g t h e c o r e d i a m e t e r i s t h e p o w e r d e n s i t y . Work i s c u r r e n t l y u n d e r way t o d e t e r m i n e t h e e f f e c t o f p o w e r d e n s i t y on r a d i a t i o n d s m a g e . A 1 though t h e e x p e r i m e n t a l r e s u l t s a r e d i f f i c u l t t o i n t e r p r e t and t h e r e f o r e n o c l e a r l y d e f i n e d l i m i t t o t h e a l l o w a b l e p o w e r d e n s i t y h a s b e e n e s t a b l i s h e d , i t i s e n t i r e l y c o n c e i v a b l e t h a t r a d i a t i o n damage c o n s i d e r a t i o n s w i l l n o t be t h e l i m i t i n g f a c t o r .

T h e k i n e t i c s o f r e a c t o r c o n t r o l a r e v e r y c o m p l e x . Work c a r r i e d o u t t h u s f a r on c o n t r o l o f t h e r e a c t o r i n d i c a t e s t h a t t r a n s i e n t power s u r g e s may c a u s e u n a c c e p t a b l y l a r g e t e m p e r a - t u r e e x c u r s i o n s i f t h e t e m p e r a t u r e o f t h e c i r c u l a t i n g f l u o r i d e f u e l e x c e e d s 1000 t o 2000'F p e r second. A t empera - t u r e r i s e o f 2 0 0 0 ° F / s e c i n t h e f u e l would i m p l y a p o w e r d e n s i t y o f a p p r o x i - m a t e l y 3 kw/cm3. T h i s , i n t u r n , would mean t h a t a c o r e d i a m e t e r o f a b o u t 2 1 i n . would be r e q u i r e d f o r a 200,000- kw r e a c t o r .

The problem o f c o o l i n g t h e m o d e r a t o r becomes more s e v e r e a s power d e n s i t y i s i n c r e a s e d . A s t h e p o w e r d e n s i t y i s i n c r e a s e d f o r a g i v e n r e a c t o r power o u t p u t , t h e p e r c e n t a g e o f t h e f i s s i o n e n e r g y t h a t a p p e a r s a s h e a t i n t h e m o d e r a t o r i s i n c r e a s e d and t h e i n t e n s i t y o f h e a t g e n e r a t i o n i n t h a t p o r t i o n o f t h e m o d e r a t o r c l o s e s t t o t h e f u e l r e g i o n i s e s s e n t i a l l y d i r e c t l y p r o p o r t i o n a l t o t h e power d e n s i t y i n t h e f u e l . A l though i t seems p r a c t i c a b l e

t o d e s i g n a n d b u i l d t h e m o d c e r a t o r c o o l i n g s y s t e m f o r a r e a c t o r h a v i n g power d e n s i t i e s of up t o 8 or 10 I t w / c m 3 , m o d e r a t o r c o o l i n g c o n s i d e r a t i o n s seem t o i n d i c a t e t h a t power d e n s i t i e s h i g h e r t h a n 10 kw/cm3 would b e i n a d - v i s ab1 e.

T e m p e r a t u r e v a r i a t i o n s i n t h e f l u i d f u e l i n t h e c o r e w i l l b e a f u n c t i o n o f b o t h t h e v e l o c i t y d i s t r i b u t i o n and t h e p o w e r d e n s i t y . W i t h a g i v e n v e l o c i t y d i s t r i b u t i o n , i t w o u l d b e e x p e c t e d t h a t c e r t a i n l o c a l i t i e s s u c h a s t h e b o u n d a r y l a y e r or t h e c e n t e r s o f e d d i e s w o u l d r u n s u b s t a n t i a l l y h o t t e r t h a n t h e b u l k mean t e m p e r a t u r e o f t h e f u e l . T h e m a g n i t u d e o f t h i s t e m p e r a t u r e d i f f e r e n t i a l w i l l d e p e n d , t o some e x t e n t , on t h e t h e r m a l conduc- t i v i t y o f t h e f l u i d , b u t t h e r a t e a t which h e a t i s d i s p e r s e d by t u r b u l e n t i n t e r c h a n g e o f p a r t i c l e s b e t w e e n h o t a n d c o l d r e g i o n s w i l l p r o b a b l y be much more i m p o r t a n t . The R e y n o l d ' s number f o r a h i g h - p o w e r r e a c t o r will\- b e s o m e w h e r e b e t w e e n l o 5 a n d l o 6 , depend ing on f u e l v i s c o s i t y and d e s i g n v a l u e s f o r t h e r e a c t o r c o r e d i a m e t e r a n d t h e f u e l t e m p e r a t u r e r i s e . A t p r e s e n t , i t i s n o t p o s s i b l e t o make more t h a n t h e r o u g h e s t s o r t of e s t i m a t e o f t h e m a g n i t u d e o f t h e t e m p e r a t u r e d i f f e r e n t i a l b e t w e e n t h e s e h o t s p o t s a n d t h e f r e e s t r e a m . The p r o b l e m i s b e i n g a t t a c k e d b o t h t h e o r e t i c a l l y a n d e x p e r i m e n t a l l y , a n d i t i s h o p e d t h a t r e s u l t s f rom a t l e a s t t h e l a t t e r w i l l p l a c e a n u p p e r l i m i t o n t h e m a g n i t u d e o f t h e e f f e c t s t o be e x p e c t e d . One p o s s i b l e i l l e f f e c t w i t h r e s p e c t t o c o n t r o l c o u l d a r i s e f r o m t h e s e h o t s p o t s . I f b o i l i n g were t o t a k e p l a c e , i r r e g u l a r f l u c t q a t i o n s i n p o w e r l e v e l t h a t w o u l d p r o b a b l y b e s i m i l a r t o t h o s e e x p e r i e n c e d i n b o i l i n g e x p e r i m e n t s m a d e w i t h t h e LITR( ' ) would be e x p e c t e d t o r e s u l t . T h e r e i s a l s o a p o s s i b i l i t y t h a t

( 7 ) W . M. B r e a z e a l e , T. E. C o l e , and J. A. Cox, J o u r n a l o f R e a c t o r S c i e n c e and T e c h n o l o g y , Vol. 11,

(1952). NO. 2, TID-2002 11952); Vol. 11, NO. 4, TID-2004

65


A T 1400'F

27,500

17,000

8,500

5,500

3,500

1,700

15,500

c o u p l i n g o f t h e o s c i l l a t i o n s i n power w i t h t h e p e r i o d i c f l u c t u a t i o n s i n f l u i d f l o w t h a t c a u s e d t h e e d d i e s o r o t h e r h o t s p o t s migh t t a k e p l a c e .

A f t e r t h e v a r i o u s c o n s i d e r a t i o n s o u t l i n e d a b o v e w e r e e x a m i n e d , i t a p p e a r e d t h a t o n l y i n a f u l l - s c a l e expe r imen t can t h e maximum, a l l o w a b l e , power d e n s i t y i n a f l u i d - f u e l r e a c t o r c o r e b e d e f i n i t e l y e s t a b l i s h e d . T h i s , i n t u r n , i m p l i e s t h a t t h e f i r s t e x p e r i m e n t o f t h i s s o r t s h o u l d b e r u n w i t h t h e s m a l l e s t p r a c t i c a l c o r e s i z e b e c a u s e t h e c o s t o f t h e e x p e r i m e n t w o u l d b e l a r g e l y a f u n c t i o n o f t h e t o t a l amount o f h e a t t o be d i s s i p a t e d . H e n c e , t h e c h e a p e s t e x p e r i m e n t t o y i e l d a d e f i n i t i v e answer w i l l b e t h e o n e c a r r i e d o u t w i t h t h e s m a l l e s t r e a c t o r c o r e t h a t m i g h t r e a s o n a b l y be e x p e c t e d t o y i e l d a p o w e r p l a n t o f a d e q u a t e s i z e . S i n c e f u e l c h e m i s t r y a n d c r i t i c a l m a s s c o n s i d e r a t i o n s i n d i c a t e t h a t an 1 8 - i n . - d i a c o r e i s t h e s m a l l e s t t h a t c a n b e u s e d w i t h f l u o r i d e f u e l s t h a t h a v e d e s i r a b l e p h y s i c a l p r o p e r t i e s , mos t d e s i g n work h a s b e e n b a s e d on r e a c t o r c o r e s i z e s r a n g i n g from 18 t o 21 i n . i n d i a m e t e r .

T e m p e r a t u r e , Pressure, and S tres s . Two m a j o r t e n e t s o f t h e d e s i g n p h i - l o s o p h y h a v e been t h a t t h e p r e s s u r e s t h r o u g h o u t t h e f l u i d sys t ems s h o u l d b e k e p t l o w , p a r t i c u l a r l y i n t h e h o t

A T 1600'F A T 1800'F

15,000 7,500

9,000 4,000

4,500 2,800

2,700 1,700

2,000 560

1,700 340

10,000 7,000

z o n e s , and t h a t a l l s t r u c t u r e s h o u l d

25,000

i L b e c o o l e d t o a t e m p e r a t u r e a p p r o x i - m a t e l y e q u a l t o o r b e l o w t h a t o f t h e s e c o n d a r y c o o l a n t l e a v i n g t h e h e a t

20,000

: r

exchanger . The t e m p e r a t u r e , p r e s s u r e , a n d s t r e s s v a l u e s c a l c u l a t e d f o r v a r i o u s s t a t i o n s i n t h e r e a c t o r a r e i n d i c a t e d i n F i g . 4 . 2 7 . The s t resses i n t h e s t r u c t u r a l p a r t s h a v e b e e n k e p t t o a minimum. T h e r m a l s t r e s s e s w e r e n o t i n c l u d e d i n t h i s d i a g r a m , s i n c e i t i s f e l t t h a t t h e y w i l l a n n e a l o u t a t t h e s e t e m p e r a t u r e s a n d , a t w o r s t , w i l l c a u s e a l i t t l e d i s t o r t i o n t h a t s h o u l d n o t be s e r i o u s . T a b l e 4 . 2 g i v e s s t r e n g t h d a t a on I n c o n e l and c o l u m b i u m . R e c e n t t e s t s i n d i c a t e t h a t i n t h e a b s e n c e o f o x y g e n t h e c r e e p r a t e o f I n c o n e l may be t w o o r

P

t h r e e t i m e s t h e r a t e g i v e n i n t h e t a b l e f o r a g i v e n s t r e s s l e v e l . E x a m i n a t i o n o f F i g . 4 . 2 7 w i l l s h o w t h a t t h e s t r e s s e s h a v e b e e n k e p t s o l o w t h a t t h e c r e e p r a t e s h o u l d n o t p r o v e t o b e a s e r i o u s p r o b l e m . N o t e t h a t t h e h i g h e s t s t r e s s e s a r e i n t h e h e a t e x c h a n g e r t u b e s .

A s m a l l , e x p e r i m e n t a l , h e a t e x - c h a n g e r h a s b e e n d e s i g n e d f o r i n - v e s t i g a t i n g t h e problem o f f a b r i c a t i n g t u b e b u n d l e s and h e a d e r c o n n e c t i o n s o f t h e t y p e r e q u i r e d . A l t h o u g h s m a l l , t h e h e a t e x c h a n g e r s h o u l d b e c a p a b l e o f t r a n s m i t t i n g 1 . 5 m e g a w a t t s o f h e a t

TABLE 4 . 2 . STRENGTH OF INCONEL AND COLUMBIUM AT ELEVATED TEMPERATURES

U1 t ima te tens i le s t rength

Yield s t rength (0.2% o f f s e t )

Stress-rupture a t 100 hr

Stress-rupture a t 1,000 h r

1% creep i n 10,000 h r

0.1% creep i n 10,000 h r

Endurance l i m i t (10 cycles) a

A T 1200'F

65,000

26,500

21,000

12,000

9,300

5,500

26,500

STRENGTH OF COLUMBIUM ( p s i )

A T 1600'F A T 1800°F I 6,000+

66


+l?me DWG 483094

FUEL TO HEAT EXCHANGER TEMP = 1590'F PRESS : 40 psi

t h e Reflector-


f r o m t h e f l u o r i d e t o NaK. I t i s The t e m p e r a t u r e s s p e c i f i e d i n F i g . 4 .27 e x p e c t e d t h a t , u l t i m a t e l y , s i x , s m a l l , were based on t h e h i g h e s t t e m p e r a t u r e s h e a t e x c h a n g e r s w i l l b e b u i l t f o r t h a t appea r r e a s o n a b l e from t h e s t a n d - i n v e s t i g a t i n g t h e e f f e c t s on endurance p o i n t o f c o m p a t i b i l i t y o f t h e b e r y l l i u m - l i f e o f o p e r a t i o n a t v a r i o u s t empera - sodium-Inconel s y s t e m . H i g h e r t empera - t u r e and p r e s s u r e l e v e l s . F i g u r e 4.28 t u r e s would b e l i k e l y t o g i v e t r o u b l e s h o w s o n e t u b e b u n d l e f o r t h i s h e a t b e c a u s e o f mass t r a n s f e r and b e c a u s e exchange r . S i x o f t h e s e b u n d l e s w i l l o f a t t a c k o f t h e I n c o n e l c a n n i n g b e u s e d i n a 5 - i n . - d i a c y l i n d r i c a l m a t e r i a l b y t h e b e r y l l i u m . T h e a n n u l u s i n s t e a d o f i n t h e l a r g e r and t e m p e r a t u r e l e v e l s r e q u i r e d s h o u l d more c o m p l e x s p h e r i c a l s h e l l a r r a y n o t be d i f f i c u l t t o a t t a i n , s i n c e t h e e n v i s a g e d for t h e f u l l - s c a l e r e a c t o r . m o d e r a t o r h e a t would b e removed a t a

T h e d e s i g n t e m p e r a t u r e l e v e l i n h i g h t e m p e r a t u r e l e v e l . Two e n g i n e s t h e s o d i u m c i r c u i t f o r c o o l i n g t h e c o u l d b e f i t t e d w i t h s m a l l a u x i l i a r y m o d e r a t o r r e g i o n i s q u i t e t e n t a t i v e . r a d i a t o r s p l a c e d between t h e compressor

and t h e main r a d i a t o r s . T h e s e c o u l d Y-E893 b e e m p l o y e d t o s u b c o o l a p o r t i o n o f

t h e secondary c i r c u i t NaK t o , p e r h a p s , 900°F. T h i s c o o l e r NaK c o u l d t h e n b e f e d t o t h e Na- to-NaK h e a t e x c h a n g e r a t t h e t o p o f t h e r e a c t o r . T h e r e , by c o o l i n g t h e sodium from t h e m o d e r a t o r c o o l i n g c i r c u i t , i t w o u l d b e h e a t e d t o a b o u t 1100°F s o t h a t i t would t h e n f l o w t o t h e m a i n h e a t e x c h a n g e r a t t h e same t e m p e r a t u r e a s t h a t o f t h e NaK from t h e o t h e r r a d i a t o r c i r c u i t s . T h u s t h e w e i g h t p e n a l t y a t t a c h e d t o c o o l i n g t h e m o d e r a t o r r e g i o n would be o n l y a b o u t 4 0 0 l b o f r a d i a t o r c o r e p l u s p o s s i b l y 200 l b o f e x t r a r e a c t o r s h i e l d and 1 0 0 l b o f pump a n d l i n e

Lead, b i smuth , a nonuranium b e a r i n g f l u o r i d e , s o d i u m , and NaK w e r e a l l g i v e n s e r i o u s c o n s i d e r a t i o n a s cool a n t s f o r t h e b e r y l l i u m m o d e r a t o r . T h e m e t a l l u r g i s t s f e l t t h a t l e a d o r b i s m u t h w o u l d b e l i k e l y t o p o s e a s e r i o u s m a s s t r a n s f e r p r o b l e m . T h e r e l a t i v e l y h i g h n e u t r o n a b s o r p t i o n c r o s s s e c t i o n o f t h e p o t a s s i u m i n t h e NaK made i t q u i t e u n d e s i r a b l e f r o m t h e c r i t i c a l mass s t a n d p o i n t . Rubidium m i g h t b e u s e d i n p l a c e o f p o t a s s i u m

(6) b u t , b e c a u s e o f l i t t l e demand, i t i s c u r r e n t l y v e r y expens ive . Thus sodium

F i g . 4 .28. Tube BundleforSpherical s e e m e d t o b e t h e b e s t c h o i c e f o r a Reactor Heat Exchanger. la) One e n d m o d e r a t o r c o o l a n t . S i n c e c o r r o s i o n of a comple t ed t u b e bund le a n d " s h o w e r and mass t r a n s f e r a r e l i k e l y t o o c c u r h e a d " a s s e m b l y . ( b ) T u b e - t o - h e a d e r i n a B e - N a K - N a s y s t e m , i t s e e m e d welded c o n n e c t i o n s . e s s e n t i a l t h a t t h e b e r y l l i u m b e c l ad

4 i i

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i n some f a s h i o n . Work a t B a t t e l l e ( * ) i n d i c a t e s t h a t b e r y l l i u m c a n b e c h r o m e - p l a t e d t o g i v e s a t i s f a c t o r y r e s i s t a n c e t o sodium a t t a c k a t 932'F. However, t h i s work w a s c a r r i e d o u t o n s m a l l s p e c i m e n s , a n d t h e r e i s a q u e s t i o n a s t o w h e t h e r a d e q u a t e p r o t e c t i o n t o t h e v e r y l a r g e s u r f a c e a r e a s r e q u i r e d w o u l d b e p r a c t i c a l . An a l t e r n a t e p o s s i b i l i t y would b e t o c a n t h e b e r y l l i u m i n t h i n - w a l l e d I n c o n e l c a n s a n d t o f i l l t h e s m a l l i n t e r s t i c e s be tween t h e b e r y l l i u m and t h e c a n w i t h s t a g n a n t s o d i u m . T h i s a r r a n g e m e n t a p p e a r s t o b e t h e m o r e p r o m i s i n g o f t h e two, b u t b o t h p o s s i - b i l i t i e s a r e b e i n g i n v e s t i g a t e d , T h e r e f l e c t o r c o u l d b e c o n s t r u c t e d o f two l a r g e h e m i s p h e r e s o f b e r y l l i u m i f t h e c a n n i n g t e c h n i q u e were u s e d . C o o l i n g p a s s a g e s c o u l d be r i f l e - d r i l l e d t h r o u g h t h e b e r y l l i u m a n d l i n e d w i t h t h i n - w a l l e d t u b e s , w h i c h c o u l d b e w e l d e d i n t o h e a d e r s a t t h e e n d s . T h e B r u s h B e r y l l i u m Co. h a s i n d i c a t e d t h a t t h e f a b r i c a t i o n o f t h e s e 1 a r g e h e m i s p h e r i c a l s h e l l s w o u l d p r o b a b l y b e n o m o r e d i f f i c u l t t h a n t h e f a b r i c a t i o n o f l a r g e f l a t s l a b s . T h e p e r s o n n e l o f t h e Y - 1 2 b e r y l l i u m shop s t a t e t h a t i t w o u l d n o t b e d i f f i c u l t t o r i f l e - d r i l l h o l e s 3 / 1 6 t o 1/4 i n . i n d i a m e t e r and a s much a s 40 i n . d e e p , w i t h t h e h o l e d i a m e t e r h e l d t o w i t h i n 0 . 0 0 1 i n . a n d t h e h o l e c e n t e r l o c a t i o n h e l d t o w i t h i n 0.010 i n c h . S i n c e i t would b e v e r y d i f f i c u l t t o p l a t e t h e i n s i d e s o f h o l e s , an a l t e r n a t e c o n s t r u c t i o n t h a t a p p e a r s a t t r a c t i v e , i f c h r o m e - p l a t e d b l o c k s p r o v e p r a c t i c a b l e , i s t h e u s e o f a l a r g e n u m b e r o f w e d g e - s h a p e d s e g m e n t s , which would b e s h a p e d much l i k e t h e s e c t i o n s o f an o range . These

c o u l d w i t h s h a l l o w g r o o v e s i n t h e i t would - form p a s s a g e s f o r c o o l i n g s t r e a m s o f sodium i n t h e a s sembly .

The c h o i c e o f a s e c o n d a r y c o o l a n t was d i f f i c u l t . C a r e f u l e x a m i n a t i o n of t h e components i n t h e e x t e r n a l s y s t e m

(*)J. G . Beach and C. L. F a u s t , E l e c t r o p l a t i n g o n B e r y l l i u m , BMI-732 (Apr. 1. 1 9 5 2 ) .

, P E R I O D ENDING MARCH 1 0 , 1 9 5 3

i n d i c a t e s t h a t a b o u t 40 f t 3 o f f l u i d would be r e q u i r e d a s a minimum,, T h i s m e a n s t h a t i f l e a d o r b i s m u t h were u s e d , t h e w e i g h t r e q u i r e d would be i n t h e r a n g e o f 30 ,000 pounds . A number o f mol t en s a l t m i x t u r e s w a s c o n s i d e r e d , b u t t h e m e l t i n g p o i n t s i n a l l c a s e s were above 300"F, which i s o b j e c t i o n a b l y h i g h . O t h e r media were r e j e c t e d b e - c a u s e o f c o r r o s i o n c o n s i d e r a t i o n s . Sodium or NaK seemed t o be d e f i n i t e l y s u p e r i o r t o a n y o t h e r c o o l a n t c o n - s i d e r e d e x c e p t f o r t h e o b j e c t i o n a b l e n e u t r o n a c t i v a t i o n and r e s u l t a n t gamma a c t i v i t y o f s o d i u m , a n d t h e f i r e h a z a r d a s s o c i a t e d w i t h a p o s s i b l e l e a k . S h i e l d i n g c h a r a c t e r i s t i c s i n d i c a t e t h a t f o r t h e m o s t p r o ~ m i s i n g d i s t r i b u t i o n o f s h i e l d i n g m a t e r i a l between t h e r e a c t o r and t h e crew, gamma a c t i v i t y from t h e sodium would be l e s s t r o u b l e s o m e t h a n t h e p r o m p t -gamma a c t i v i t y from t h e r e a c t o r core . Con- s i d e r a b l e e x p e r i e n c e w i t h s o d i u m h a s i n d i c a t e d t h a t i f t h e p l u m b i n g i s d e s i g n e d t o k e e p t h e s t r e s s e s l o w s o t h a t b u r s t t y p e s o f f a i l u r e w i l l n o t r e s u l t , l e a k s t h a t d o o c c u r a s t h e r e s u l t o f f a t i g u e c r a c k s o r c o r r o s i o n p i t s d e v e l o p s l o w l y a n d do n o t r e s u l t i n s e r i o u s f i r e s . I n f a c t , s i n c e sodium does n o t e x p l o d e ( s o l o n g a s n o w a t e r i s p r e s e n t ) , i n many w a y s i t seems n o more h a z a r d o u s t h a n g a s o l i n e . A f t e r a l l t h e f a c t o r s were w e i g h e d , t h e m o s t p r o m i s i n g s e c o n d a r y f l u i d a p p e a r e d t o be NaK. A 56% sodium and 44% p o t a s s i u m a l l o y , which h a s a m e l t - i n g p o i n t o f 56"F, was c h o s e n f o r t h e a n a l y s i s . I t s l o w m e l t i n g p o i n t , e x c e l l e n t h e a t t r a n s f e r c h a r a c t e r i s t i c s , g o o d c o r r o s i o n c h a r a c t e r i s t i c s i n i r o n - c h r o m e - n i c k e l a l l o y s , a n d l o w d e n s i t y made i t a p p e a r t o b e t h e b e s t c h o i c e .

Reflector Heating (A. H. Fox, R. W. B u s s a r d , ANP D i v i s i o n ) . T h e h e a t i n g o f t h e r e f l e c t o r o f a r e a c t o r by t h e a b s o r p t i o n o f gamma r a d i a t i o n and t h e s l o w i n g down o f n e u t r o n s o r i g i n a t i n g i n t h e c o r e p r e s e n t s a h e a t r e m o v a l t a s k t h a t is o n l y an o r d e r o f m a g n i t u d e

69

ANP P R O J E C T QUARTERLY PROGRESS REPORT

s m a l l e r t h a n t h a t o f c o o l i n g t h e c o r e i t s e l f .

T h e d i s t r i b u t i o n o f t h e h e a t g e n e r a t e d i n t h e m o d e r a t o r d e p e n d s on t h e s t r e n g t h a n d l o c a t i o n o f t h e s o u r c e s and on t h e a t t e n u a t i o n o f t h e r a d i a t i o n between t h e s o u r c e s and t h e p o i n t i n q u e s t i o n . F o r t h e gamma-ray e n e r g i e s o f i n t e r e s t , t h e mechanism o f d e g r a d a t i o n i n v o l v e s p r i n c i p a l l y t h e Compton c o l l i s i o n s . The mechanism o f d e g r a d a t i o n o f e n e r g y o f t h e c o r e gammas i s c o m p l i c a t e d , e v e n w i t h t h e m o s t s i m p l e g e o m e t r y o f s o u r c e a n d r e f l e c t o r ; f o r a m o r e complex g e o m e t r y , s u c h a s t h a t o f t h e r e f l e c t o r - m o d e r a t e d r e a c t o r , many s i m p l i f y i n g a s s u m p t i o n s a r e n e c e s s a r y b e f o r e even an a p p r o x i - m a t e e s t i m a t e o f t h e r a t e o f h e a t g e n e r a t i o n i n t h e b e r y l l i u m may b e o b t a i n e d .

T h e f i r s t a p p r o x i m a t i o n u s e d i n - v o l v e d t h e s t r a i g h t - a h e a d t h e o r y o f gamma a b s o r p t i o n f o r which i t is assumed t h a t Compton c o l l i s i o n s mere ly d e g r a d e i n e n e r g y a n d d o n o t s c a t t e r t h e p h o t o n s . Only e x p o n e n t i a l a t t e n u a t i o n w i t h a c o e f f i c i e n t t h a t i s c h a r a c - t e r i s t i c o f t h e m a t e r i a l t h r o u g h which t h e p h o t o n s p a s s n e e d be c o n s i d e r e d . When a p h o t o n p a s s e s f rom o n e medium t o a n o t h e r , n o r e f r a c t i o n i s c o n - s i d e r e d . Use o f a b u i l d u p f a c t o r t o a l l o w f o r o r d i n a r y s c a t t e r i n g i s b e i n g i n ves t i ga t e d .

A n o t h e r s i m p l i f y i n g a s s u m p t i o n c o n c e r n e d t h e s o u r c e d i s t r i b u t i o n . O n l y t h e t o t a l amount o f gamma f l u x w a s c o n s i d e r e d , a n d v a r i a t i o n s f rom p o i n t t o p o i n t i n t h e c o r e w e r e n e g l e c t e d , T h u s a n a v e r a g e p o w e r d e n s i t y f o r t h e c o r e was d e t e r m i n e d s i m p l y by d i v i d i n g t h e t o t a l r e a c t o r power o u t p u t by t h e volume o f t h e f u e l r e g i o n o f t h e c o r e . (An i n v e s t i g a t i o n o f s o u r c e s d i s t r i b u t e d a s i n d i c a t e d by t h e c r i t i c a l e x p e r i m e n t s showed o n l y a s m a l l v a r i a t i o n i n r e s u l t s . )

The p a r t i c u l a r c a s e c o n s i d e r e d was t h a t o f a n 1 8 - i n . - d i a , s p h e r i c a l , f l u o r i d e - f u e l r e g i o n s u r r o u n d i n g a 9 - i n . - d i a , c e n t r a l , b e r y l l i u m i s l a n d

and e n c l o s e d by a 1 2 - i n . - t h i c k b e r y l l i u m r e f l e c t o r , A 3 / 1 6 - i n . - t h i c k l a y e r o f I n c o n e l was c o n s i d e r e d a s b e i n g t h e s e p a r a t i n g m a t e r i a l b e t w e e n t h e f u e l r e g i o n and e a c h o f t h e two m o d e r a t o r r e g i o n s . The f e a c t o r power o u t p u t was t a k e n a s 200 megawa t t s , and t h e e n e r g y e v o l v e d i n t h e gammas was t a k e n a s 1 2 M e v / f i s s i o n , w h i c h g a v e a t o t a l power from gammas o f 1 2 m e g a w a t t s and a gamma s o u r c e d e n s i t y i n t h e f u e l r e g i o n o f 275 w a t t s / c m 3 . The a v e r a g e gamma e n e r g y was assumed t o be 1 M e V ,

and t h e r e c i p r o c a l a t t e n u a t i o n l e n g t h s f o r t h e f u e l , I n c o n e l , and b e r y l l i u m - m o d e r a t o r r e g i o n s were t a k e n a s 0 . 0 9 , 0.3'0, and 0 .16 cm" , r e s p e c t i v e l y .

The power d e n s i t y was computed a t p o i n t s s p a c e d a b o u t 1 i n . a p a r t a l o n g a r a d i u s from t h e c e n t e r o f t h e i s l a n d t o t h e o u t s i d e o f t h e r e f l e c t o r . The r e s u l t i n g v a l u e s a r e g i v e n i n T a b l e 4 .3 ( c a s e A ) and F i g . 4 .29. T a b l e 4.4 ( c a s e A ) shows t h e i n t e g r a t e d v a l u e s o f t h e p o w e r , i n t h e v a r i o u s r e g i o n s o f i n t e r e s t , o b t a i n e d by g r a p h i c a l i n t e g r a t i o n o f t h e power d e n s i t y c u r v e . The f a c t t h a t t h e t o t a l gamma h e a t i n g i n d i c a t e d by T a b l e 4 . 3 i s o n l y 1 0 . 6 megawat t s i n s t e a d o f t h e 1 2 m e g a w a t t s a s s u m e d i s d u e , i n p a r t , t o l e a k a g e f r o m t h e r e f l e c t o r a n d , i n p a r t , t o t h e a p p r o x i m a t i o n s m a d e f o r t h e c o m p u t a t i o n s . However, i t i s b e l i e v e d t h a t t h e d i s t r i b u t i o n o f t h e gamma h e a t i n g i s a p p r o x i m a t e d q u i t e w e l l by F i g . 4 . 2 9 . One i m p o r t a n t r e s u l t o f t h i s work i s t h a t f o r t h i s c o n f i g u r a t i o n more t h a n 60% of t h e gamma e n e r g y goes i n t o h e a t i n g t h e f u e l . A s e c o n d c o m p u t a t i o n was made w i t h d i f f e r e n t v a l u e s f o r t h e r e c i p r o c a l a t t e n u a t i o n l e n g t h s , t h a t i s , 0 . 0 6 an'd 0 . 1 3 c m - ' f o r t h e f u e l a n d b e r y l l i u m , r e - s p e c t i v e l y , and t h e r e s u l t s a r e shown i n T a b l e 4 . 3 a s c a s e B. A s c a n b e s e e n , t h i s r e l a t i v e l y l a r g e change had n o g r e a t e f f e c t on t h e d i s t r i b u t i o n o f t h e gamma h e a t i n g . T h e t o t a l power f o r bo th c a s e A and c a s e B i s g i v e n i n T a b l e 4.4.

. _

70


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450

4 0 0

350

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\ 5 fn + +

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t

ln z r-

200 a W : P

I 5 0

too

50

0 0 2 4 6 8 i o 12 i 4 16 18 20

RADIAL DISTANCE FROM REACTOR CENTER LINE, f (in.)

F i g . 4 .29. Radial Power Density

F. ( c o r r e c t i o n gy l o s s f o r e a c h

c o l l i s i o n s i n t h a t g r o u p a t a g i v e n r a d i u s or s p a c e p o i n t , T h e s p a t i a l d i s t r i b u t i o n ,

from Neutron and Gamma Heating.

i s n o r m a l i z e d t o t h e t o t a l power l o s t by m o d e r a t i o n ( 2 1 / 2 % o f r e a c t o r power) by t h e u s e o f t h e i n t e g r a t i o n o p e r a t o r

The power d e n s i t i e s r e s u l t i n g from n e u t r o n m o d e r a t i o n a n d f r o m gamma h e a t i n g , a s o b t a i n e d by t h e m e t h o d s d e s c r i b e d a b o v e , a s w e l l a s t h e r e s u l t a n t t o t a l p o w e r d e n s i t y , a r e shown i n F i g . 4 .29 , S e v e r e p e a k s i n t h e I n c o n e l s h e l l s a n d a r a p i d d r o p w i t h d i s t a n c e from t h e f u e l r e g i o n a re shown.

A number o f f a c t o r s m u s t lbe c o n - s i d e r e d i n t h e d e s i g n o f a s y s t e m o f

*

7 1


R E G I O N

I s l a n d b e r y l l i u m I s l a n d I n c o n e l Fue 1 R e f l e c t o r I n c o n e l R e f l e c t o r b e r y l l i u m

TABLE 4 . 3 . POWER D E N S I T Y I N V A R I O U S R E G I O N S

TOTAL POWER ( m e g a w a t t s )

C a s e A C a s e B

0.46 0. 51 0.24 0 .29 6 .71 5.58 0.57 0 .85 3 .14 3.44

R E G I O N

I s l a n d b e r y l l i u m

I s l a n d Incone l

Fue 1

R e f l e c t o r I n c o n e l

Re f 1 e c t o r be r y 1 1 i urn

R A D I A L D I S T A N C E FROM CENTER OF

REACTOR CORE

r (in.)

0 2 3 4 4 .31

4 .31 4 .5

4 . 5 5 5 . 5 6. 0 6 .75 8 8 . 5 9

9 9.19

9 .19 9 . 5

10 1 0 . 5 11 12 1 3 14 15 2 1

72

r ( c m )

0 5.08 7.62

10.16 10.95

10 .95 1 1 . 4

11.4 12.7 14 15 .2 1 7 . 1 20.3 21.6 22.9

22.9 23 .3

23.3 2 4 . 1 25.4 26 .7 27.9 30.5 33.0 35.6 38.1 53.3

RATE OF HEAT G E N E R A T I O N FROM GAMMAS ( w a t t s / c m ) 3

C a s e A

47 .5 60 80

101 120

223 3 54

106 167 186 182 184 157 141 73

215 150

80 53.7 37.7 25.4 19 .0 10.3

5 . 4 2.9 1 .67 0.066

C a s e B

61.9 65 74 93

142

330 497

99 137 148 152 151 132 116

65

325 227

98 57 44.6 31.9 2.4.4 14 .0

8 . 3 4.9 3 .0 0.19

m o d e r a t o r c o o l i n g p a s s a g e s . The volume o f b o t h t h e sodium a n d , e s p e c i a l l y , t h e I n c o n e l m u s t b e m i n i m i z e d t o k e e p p a r a s i t i c n e u t r o n a b s o r p t i o n s w i t h i n r e a s o n a b l e l i m i t s . T h e n e u t r o n f l u x c u r v e s s h o w t h a t f r o m t h e n e u t r o n economy s t a n d p o i n t c o o l a n t p a s s a g e s i n t h e b e r y l l i u m a r e much more i m p o r t a n t s e v e r a l i n c h e s f r o m t h e f u e l r e g i o n t h a n a t t h e f u e l - m o d e r a t o r i n t e r f a c e . T h e r m a l s t r e s s e s w i l l be s e t u p by t e m p e r a t u r e v a r i a t i o n s i n t h e b e r y l - l i u m . S i n c e an e l o n g a t i o n o f a b o u t

. . .


30% c a n be o b t a i n e d i n b e r y l l i u m a t t h e o p e r a t i n g t e m p e r a t u r e s e n v i s i o n e d , t h e r m a l s t r e s s e s s h o u l d n o t l e a d t o c r a c k i n g b u t m i g h t c a u s e d i s t o r t i o n t h a t c o u l d become a p r o b l e m a f t e r a number o f t h e r m a l c y c l e s o f t h e s y s t e m , F o r t h i s r e a s o n , t h e t e m p e r a t u r e v a r i a t i o n i n t h e b e r y l l i u m b e t w e e n a d j a c e n t c o o l a n t p a s s a g e s was h e l d t o SOOF. T h e p r e s s u r e d r o p t h r o u g h t h e v a r i o u s c o o l a n t p a s s a g e s w a s l i m i t e d t o 40 p s i t o k e e p p r e s s u r e - i n d u c e d s t resses low. The maximum b e r y l l i u m - sodium i n t e r f a c e t e m p e r a t u r e was h e l d

be low 1200°F t o r e d u c e mass t r a n s f e r i n t h e B e - s t a g n a n t - N a - I n c o n e l s y s tern,

S e v e r a l d e t a i l d e s i g n s were i n - v e s t i g a t e d t h a t f a v o r e d f i r s t one and t h e n a n o t h e r of t h e v a r i o u s r e q u i r e - men t s , t h a t i s , minimum p o i s o n , minimum v a r i a t i o n i n b e r y l l i u m t e m p e r a t u r e , m i n i mu m b e r y 1 1 i u m - s o d i ~1 m i n t e r f a c e t e m p e r a t u r e , minimum s o d i u m s y s tem p r e s s u r e d r o p , e t c . F i g u r e 4.30 shows t h e h o l e p a t t e r n i n t h e b e r y l l i u m f o r a p r o m i s i n g a r r a n g e m e n t , and t h e r e - s u l t i n g t e m p e r a t u r e d i s t r i b u t i o n i s shown i n F i g . 4.31.

Sf!t%Pl DWG 48744

PASSAGE FOR INLET No TO REFLECTOR (2 REQ'D)

0.26- in. - DIA HOLES IN Be, CONTAINING 0.25-in. -OD TUBES FOR No COOLANT FLOW

REFLECTOR-MODERATOR

-__Et__-

F i g . 4 . 3 0 . Cooling Hole Distribution i n Reflector-Moderator.

7 3


1600

1400

1200

1000 - lL

W a 2

e

800 W Q z W c

600

400

200

0 0 2 4 6 8 10 12 14 16 18 20

RADIAL DISTANCE FROM REACTOR CENTER L INE (in.)

F i g . 4 . 3 1 . Temperature D i s t r i b u t i o n Across Midplane o f 200-Megawatt Reflector-Moderated Reactor. Sodium i n l e t , 100O0F.

SHIELDING A. P. F r a a s , ANP D i v i s i o n

J. B. T r i c e , S o l i d S t a t e D i v i s i o n

The s h i e l d d e s i g n p h i l o s o p h y t h a t h a s b e e n the_ b a s i s o f t h e w o r k o n t h . r e f l e c t o r - m o d e r a t e d r e a c t o r s h i e l d h a s been t h a t a n o p e r a t i o n a l a i r p l a n e , i n t h e m i l i t a r y s e n s e o f t h e word , c a n h a r d l y be a c h i e v e d w i t h a s h i e l d d i - v i d e d t o s u c h a d e g r e e t h a t a n u n - p r o t e c t e d man 5 0 f t f rom t h e r e a c t o r r e c e i v e s a l e t h a l d o s e i n 1 5 s e c ( a s e n v i s i o n e d f o r t h e a i r c y c l e ) . Those e x p e r i e n c e d i n a i r c r a f t o p e r a t i o n and m a i n t e n a n c e know t h a t p e r h a p s 50% of t h e m a i n t e n a n c e w o r k i n v o l v e s n o n -

s c h e d u l e d o p e r a t i o n s , t h e c h a r a c t e r a n d d e t a i l e d n a t u r e o f w h i c h a r e i t n p o s s i b 1 e t 0,' p r e d i c t w i t h o u t a n e x t e n s i v e b a c k g r o u n d o f e x p e r i e n c e . P r o v i s i o n of an a d e q u a t e s e t of e q u i p - ment and f a c i l i t i e s t o t a k e c a r e 0' a l l c o n t i n g e n c i e s p r o m i s e s t o i n v o l v e e x p e n d i t u r e s o f t h e s a m e o r d e r a s t h o s e r e q u i r e d f o r t h e n u c l e a r power p l a n t i t s e l f , I t w a s f e l t t h a t i f t h e r a d i a t i o n d o s e a t f u l l p o w e r c o u l d be c u t t o a b o u t 1 0 r / h r a t 5 0 f t from t h e r e a c t o r , t h e g r e a t e r m a j o r i t y o f t h e n o n s c h e d u l e d m a i n t e n a n c e j o b s t h a t migh t d e l a y a f l i g h t a t t h e l a s t minu te o r r e q u i r e emergency a t t e n t i o n i m m e d i a t e l y f o l l o w i n g a l a n d i n g c o u l d

74


be h a n d l e d w i t h o u t s p e c i a l equ ipmen t . F o r t h i s r e a s o n , e f f o r t h a s b e e n d i r e c t e d t o w a r d t h e d e v e l o p m e n t o f s o m e t h i n g c l o s e l y a p p r o a c h i n g a u n i t s h i e l d , I t i s f u l l y r e a l i z e d t h a t a we igh t p e n a l t y i s i n e v i t a b l e .

I t w a s f o u n d t h a t t h e i n i t i a l s t a r t u p and warmup o f t h e r e a c t o r c a n p r o b a b l y b e c a r r i e d o u t a t p o w e r l e v e l s t h a t , i n g e n e r a l , do n o t exceed 10% of t h e f u l l power of t h e r e a c t o r ; t h u s t h e r a d i a t i o n dose d u r i n g s t a r t u p a n d warmup w o u l d be 1 0 % o f t h a t a t f u l l power. I f i n t h e t u n e u p p r o c e s s t h e o p e r a t i o n s m u s t b e c a r r i e d o u t c l o s e t o t h e r e a c t o r , t h e r e a c t o r m i g h t b e i d l e d d o w n f r o m 1 0 % t o p e r h a p s 1% o f f u l l p o w e r o u t p u t s o t h a t t h e r a d i a t i o n ' d o s e a t any p a r t i - c u l a r p o i n t w o u l d be o n l y 1% o f t h e f u l l - p o w e r dose . I t is t r u e , however , t h a t a f t e r a l o n g f l i g h t t h e accumu- l a t i o n o f f i s s i o n p r o d u c t s w i l l c o n s t i t u t e a s u b s t a n t i a l gamma d o s e e v e n a f t e r t h e r e a c t o r i s s h u t down c o m p l e t e l y . T h i s d o s e w i l l s t i l l be o n l y o f t h e o r d e r o f 1 or 2% o f t h e t o t a l r a d i a t i o n d o s e a t f u l l p o w e r o u t p u t b e c a u s e t h e d e c a y gammas a r e f e w e r i n number and s o f t e r t h a n t h e prompt gammas. A d r a i n v a l v e w i l l be p r o v i d e d a t t h e bo t tom of t h e r e a c t o r s o t h a t t h e f l u o r i d e f u e l c a n b e d r a i n e d i n t o u n d e r g r o u n d t a n k s . I t i s hoped t h a t a b o u t 9 8 % o f t h e f u e l c a n b e removed by a s i m p l e d r a i n i n g o p e r a t i o n and t h a t m o s t o f t h e r e m a i n i n g f u e l c a n b e f l u s h e d o u t by u s i n g a n o n -

a r i n g f l u o r i d e . P r e c i s e l y w h a t c a n b e d e i n t h i s d i r e c t i o n i s d i f f i c u l t p r e d i c t , b u t o n e o f t h e m a j o r i t e m s o f i n f o r m a t i o n e x - p e c t e d f r o m A R E t e s t w o r k i s t h e e x t e n t t o w h i c h t h e r a d i a t i o n f rom a c i r c u l a t i n g - f l u o r i d e - f u e 1 r e a c t o r can be r e d u c e d by d r a i n i n g and f l u s h i n g . T h e d e g r e e t o w h i c h t h e I n c o n e l s t r u c t u r e w i l l be a c t i v a t e d and w i l l r e p r e s e n t a n i m p o r t a n t s o u r c e o f r a d i a t i o n a f t e r shutdown i s d i f f i c u l t t o e s t i m a t e , I f t h e s h i e l d i s n o t d i s a s s e m b l e d , rough e s t i m a t e s i n d i c a t e

t h a t t h e I n c o n e l a c t i v a t i o n s h o u l d n o t b e a p r o b l e m . H e r e a g a i n , t h e ARE w i l l y i e l d much v a l u a b l e i n f o r m a t i o n .

T h e s h i e l d f o r t h e 2 0 0 - m e g a w a t t r e f l e c t o r - m o d e r a t e d r e a c t o r h a s some c h a r a c t e r i s t i c s t h a t a r e p e c u l i a r t o t h i s p a r t i c u l a r r e a c t o r c o n f i g u r a t i o n . A s i n d i c a t e d i n an e a r l i e r s e c t i o n , t h e t h i c k r e f l e c t o r was s e l e c t e d on t h e b a s i s o f s h i e l d i n g c o n s i d e r a - t i o n s . ( ' ) The two m a j o r r e a s o n s f o r u s i n g a t h i c k r e f l e c t o r a r e t h a t a r e f l e c t o r a b o u t 12 i n , t h i c k f o l l o w e d by a l a y e r o f b o r o n - b e a r i n g m a t e r i a l w i l l a t t e n u a t e t h e n e u t r o n f l u x t o t h e p o i n t w h e r e t h e s e c o n d a r y gamma f l u x can be r e d u c e d t o an u n i m p o r t a n t l e v e l f o r a q u a s i - u n i t s h e l l . T h i s t h i c k n e s s a l s o r e d u c e s t h e n e u t r o n l e a k a g e f l u x f r o m t h e r e f l e c t o r t o t h e h e a t e x c h a n g e r t o t h e l e v e l o f t h a t f r o m t h e d e l a y e d n e u t r o n s a p - p e a r i n g i n t h e i n t e r m e d i a t e h e a t e x c h a n g e r a s d e l a y e d n e u t r o n s f r o m t h e c i r c u l a t i n g f u e l . An addi t i 'onal a d v a n t a g e o f t h e t h i c k r e f l e c t o r i s t h a t 99.98% o f t h e e n e r g y d e v e l o p e d i n t h e c o r e w i l l a p p e a r a s h e a t i n t h e h i g h - t e m p e r a t u r e zone i n s i d e t h e p r e s s u r e s h e l l . T h i s m e a n s t h a t v e r y l i t t l e o f t h e e n e r g y p r o d u c e d by t h e r e a c t o r m u s t b e d i s p o s e d o f w i t h a p a r a s i t i c c o o l i n g s y s t e m a t a low t e m p e r a t u r e l e v e l . The m a t e r i a l i n t h e s p h e r i c a l - s h e l l i n t e r m e d i a t e h e a t exchange r is a b o u t 7 0 % a s e f f e c t i v e a s w a t e r f o r t h e r e m o v a l o f f a s t n e u t r o n s ; s o i t t o o i s o f v a l u e f rom t h e s h i e l d i n g s t a n d p o i n t . The d e l a y e d n e u t r o n s a n d t h e d e c a y gammas f r o m t h e c i r c u l a t i n g f u e l i n t h e h e a t e x c h a n g e r r e g i o n migh t a p p e a r t o pose a s e r i o u s h a n d i c a p . H o w e v e r , e a c h h a s an a t t e n u a t i o n l e n g t h t h a t i s much s h o r t e r t h a n t h e c o r r e s p o n d i n g a t t e n u - a t i o n l e n g t h f o r r a d i a t i o n f rom t h e c o r e . T h u s , f r o m t h e o u t e r s u r f a c e o f t h e s h i e l d , t h e i n t e r m e d i a t e h e a t e x c h a n g e r a p p e a r s a s a much l e s s

(')A. P. F r a a s , T h r e e R e a c t o r - H e a t E x c h a n g e r - S h i e l d A r r a n g e r e n t s f o r U s e w i t h F u s e d F l u o r i d e C i r c u l a t i n g F u e l , OWL Y-F15-10 (June 30, 1952).

7 5


i n t e n s e s o u r c e o f r a d i a t i o n t h a n t h e more d e e p l y b u r i e d r e a c t o r c o r e .

I t i s t r u e t h a t t h i s a r r a n g e m e n t v i o l a t e s one o f t h e p r e c e p t s o f t h e m a t c h e d s h i e l d , n a m e l y , t h a t e a c h l a y e r o f h e a v y m a t e r i a l s h o u l d b e p l a c e d a s c l o s e t o t h e r e a c t o r c o r e a s p o s s i b l e . H o w e v e r , t h e l o s s i n w e i g h t a s s o c i a t e d w i t h t h e d i s p a r i t y between t h i s i d e a l c a s e and t h e s h i e l d l a y o u t o f F i g . 4 . 3 2 i s n o t t o o g r e a t , w h e r e a s t h e e n g i n e e r i n g a d v a n t a g e s d e r i v e d a r e o f c r u c i a l impor t ance .

A s e r i e s o f L i d T a n k e x p e r i m e n t s i s i n p r o g r e s s t o d e t e r m i n e t h e optimum a r r a n g e m e n t and t h i c k n e s s o f t h e v a r i o u s b e r y l l i u m , b o r o n c a r b i d e , i r o n , l e a d , and b o r a t e d w a t e r l a y e r s f o r a s h i e l d o f t h e t y p e s h o w n i n F i g . 4 . 3 2 , w h i c h r e p r e s e n t s t h e b e s t c o n f i g u r a t i o n t e s t e d t o d a t e . When t h i s s e r i e s o f t e s t s i s c o m p l e t e d , t h e r e s u l t i n g s h i e l d w i l l be u s e d a s a b a s i s f o r compar i son , F u r t h e r t e s t s w i l l b e r u n w i t h m o r e u n u s u a l m a t e r i a l s . Rough c a l c u l a t i o n s i n d i c a t e t h a t a s much a s 1 0 , 0 0 0 l b o f s h i e l d w e i g h t m i g h t b e s a v e d t h r o u g h t h e u s e o f some o f t h e s p e c i a l m a t e r i a l s . When

. t h e t e s t w o r k i s c o m p l e t e d , i t i s h o p e d t h a t a f a i r l y s o u n d b a s i s f o r a d e c i s i o n on t h e u s e o f t h e s e s p e c i a l m a t e r i a l s w i l l be p r o v i d e d b y a com- p a r i s o n o f t h e i r c o s t a n d a t t e n d a n t w e i g h t s a v i n g s r e l a t i v e t o t h e s i m p l e r s h i e l d c o n f i g u r a t i o n o f F i g u r e 4 . 3 2 .

One o f t h e m a j o r p i e c e s o f i n - f o r m a t i o n o b t a i n e d f rom t h e L i d Tank e x p e r i m e n t s h a s been t h e c o n f i r m a t i o n o f t h e o r i g i n a l e s t i m a t e s o f t h e d e g r e e o f a c t i v a t i o n o f sodium i n t h e h e a t e x c h a n g e r r e g i o n . I t h a d b e e n s u s p e c t e d t h a t i n a r e l a t i v e l y t h i n s l a b o f m a t e r i a l h a v i n g t h e p o o r m o d e r a t i n g p r o p e r t i e s o f t h e h e a t e x c h a n g e r m a t r i x , n e u t r o n s o f 0 . 1 Mev o r h i g h e r w o u l d t e n d t o e s c a p e f r o m t h e s l a b l o n g b e f o r e t h e y c o u l d be s lowed down. A l t h o u g h i t i s n o t p o s s i b l e t o s i m u l a t e t h e e f f e c t s o f t h e c i r - c u l a t i n g f u e l i n t h e L i d Tank e x p e r i -

m e n t s , t h e s p e c t r u m o f t h e d e l a y e d n e u t r o n s i s n o t t o o d i f f e r e n t f r o m t h a t o f t h e b u l k o f t h e n e u t r o n s t h a t e s c a p e f r o m t h e f u e l r e g i o n t h r o u g h t h e t h i c k b e r y l l i u m r e f l e c t o r and t h e h e a v y b o r o n c a r b i d e c u r t a i n b e t w e e n t h e r e f l e c t o r a n d t h e h e a t e x c h a n g e r . F o r t h i s r e a s o n , i t i s f e l t t h a t t h e s o d i u m a c t i v a t i o n d a t a f r o m t h e L i d Tank e x p e r i m e n t s g i v e a good b a s i s f o r e s t i m a t i n g t h e a c t i v a t i o n o f t h e sodium i n a f u l l - s c a l e r e a c t o r o f t h e t y p e shown i n F i g . 4 . 2 5 . On t h i s b a s i s , i t a p p e a r s t h a t t h e s o d i u m a c t i v i t y a f t e r a l o n g p e r i o d o f f u l l - p o w e r o u t p u t w i l l g i v e a d o s e o f a b o u t 1 r / h r a t 50 f t f rom t h e r e a c t o r . The a c t i v i t y of t h e p o t a s s i u m i n t h e N a K w o u l d b e much l e s s t h a n t h a t o f t h e sodium.(" ) The NaK c o u l d be d r a i n e d a f t e r o p e r a t i o n a n d t h e a c t i v a t e d s o d i u m a l l o w e d t o d e c a y . S e v e r a l w e e k s s h o u l d s u f f i c e t o b r i n g t h e a c t i v i t y o f t h e s o d i u m d o w n t o a n e g l i g i b l e l e v e 1.

The d e s i g n d e s c r i b e d i s b e l i e v e d t o g i v e e n o u g h s h i e l d i n g a l l a r o u n d t h e r e a c t o r t o g i v e a d o s e o f 5 r / h r a t 50 f t f rom t h e c e n t e r o f t h e r e a c t o r a t f u l l p o w e r . An a d d i t i o n a l l e a d l a y e r w o u l d be employed a t t h e f r o n t o f t h e r e a c t o r t o a c t a s a l i g h t shadow s h i e l d f o r t h e crew. F u r t h e r s h a d o w s h i e l d i n g w o u l d b e e m p l o y e d a t t h e b a c k o f t h e c r e w c o m p a r t m e n t t o a t t e n u a t e t h e r a d i a t i o n f r o m b o t h t h e r e a c t o r a n d t h e NaK r a d i a t o r s t o g i v e a d o s e o f a p p r o x i m a t e l y 1 r / h r i n s i d e t h e c r e w c o m p a r t m e n t . T a b l e s 4 . 5 a n d 4 . 6 g i v e d e t a i l e d d a t a f o r s u c h a c o n f i g u r a t i o n f o r s e v e r a l r e a c t o r c o r e d i a m e t e r s , p o w e r o u t - p u t s , a n d power d e n s i t i e s . F u r t h e r work c o v e r i n g t h e e f f e c t s on s h i e l d w e i g h t o f v a r i o u s d o s e l e v e l s f o r b o t h g r o u n d and f l i g h t crews i s u n d e r way.

('O'W. K. Ergen, P o t a s s i u m as C o o l a n t in C o n - n e c t i o n w i t h Ground-Safe S h i e l d s , ORNL Y - F 2 0 - 4 (Dec. 6 , 1950).

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T A B L E 4 . 5 . D O S A G E S A T V A R I O U S L O C A T I O N S F O R T H E S H I E L D O F T A B L E 4 . 6

LOCATION

50 f t from r e a c t o r ( e x c e p t i n f r o n t c o n e )

Crew compartment 1 6 f t from r e a c t o r ( e x c e p t

i n f r o n t c o n e )

S h i e l d s u r f a c e ( e x c e p t i n f r o n t cone )

'Ten p e r cent o f f u l l power.

A t S t a r t u p *

0.5 0.1

6

60

DOSE ( r / h r )

A t F u l l Power

6 1

60

600

A t S h u t d o w n * *

NaK n o t D r a i n e d

1 0.2

1 0

30

NaK D r a i n e d

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* * F i f t e e n m i n u t e s a f t e r shutdown from long p e r i o d a t f u l l power.

T A B L E 4 . 6 . P R E L I M I N A R Y S H I E L D WEIGHT E S T I M A T E S S H O W I N G E F F E C T S O F V A R I A T I O N S I N R E A C T O R POWER, C O R E D I A M E T E R , AND POWER D E N S I T Y I N T H E F U E L R E G I O N *

Power, megawatts

R e a c t o r c o r e d i a m e t e r , i n .

Power d e n s i t y , kw/cm3

P r e s s u r e s h e l l o u t s i d e d i a m e t e r , i n .

d i a m e t e r , i n .

d i a m e t e r , i n .

h e a t e x c h a n g e r , a n d s h i e l d , l b

Shadow d i s k a t crew (7 f t d i a l , l b

Lead l a y e r o u t s i d e

R e a c t o r s h i e l d o u t s i d e

T o t a l w e i g h t , r e a c t o r ,

200 18

5.5

59

72

120

74,000

3,600

2 00

22.7 2.79

62.3

75.3

119

84,000

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400 22.7

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82

128

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140

147,000

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*Computed from L i d Tank d a t a for the b e s t Be-B4C-NaF-B4C-Fe-Pb-HZ0 l a y e r c o n f i g u r a t i o n t e s ted up t o l a r c h 13. 1953.

POWER P L A N T D E S I G N

A . P. F r a a s , ANP D i v i s i o n

Some e a r l y work on n u c l e a r power p l a n t s i n v o l v e d d e t a i l e d d e s i g n s o f power p l a n t s i n which t h e e n g i n e s were w i d e l y s e p a r a t e d from t h e r e a c t o r . The a c u t e problems of d i f f e r e n t i a l t h e r m a l

e x p a n s i o n , t h e r m a l l a g a n d s y s t e m c o n t r o l , a n d t h e p l u m b i n g w e i g h t a s s o c i a t e d w i t h t h e s e a r r a n g e m e n t s i n d i c a t e d t h a t i t w o u l d be advan tageous t o u s e c o m p a c t u n i t s . T h u s , t h e c u r r e n t t r e n d t o w a r d c o m p a c t p o w e r packages , f o l l o w e d by b o t h t h e G e n e r a l E l e c t r i c Co. and t h e P r a t t and Whitney A i r c r a f t D i v i s i o n , seems i n o r d e r .

79


I n c o n s i d e r i n g t h e t y p e s o f a p p l i - c a t i o n o f g r e a t e s t i n t e r e s t , i t a p p e a r e d t h a t t h e r e a r e t h r e e r e p r e - s e n t a t i v e c a s e s : namely, a B-36 f l i g h t - t e s t - b e d i n s t a l l a t i o n , a Mach 0.9 s e a - l e v e l b o m b e r , a n d a Mach 1 . 5 h i g h - a l t i t u d e bomber . I n s k e t c h i n g p r e - l i m i n a r y l a y o u t s , i t a p p e a r e d t h a t t h e r e w a s l i t t l e d i f f e r e n c e i n t h e r e q u i r e m e n t s f o r t h e f i r s t t w o , a n d t h e t h i r d d i f f e r e d i n n o t t o o s e r i o u s a f a s h i o n . A s a r e s u l t , t h e l a y o u t o f F i g , 4 . 2 5 w a s p r e p a r e d f o r t h e M a c h 0 . 9 s e a - l e v e l b o m b e r o n t h e b a s i s t h a t i t would r e q u i r e a r e a c t o r h e a t o u t p u t of 200 megawa t t s . I t was p r e s u m e d t h a t t h e same p o w e r p l a n t m i g h t b e u s e d f o r p r e l i m i n a r y t e s t w o r k a t a r e d u c e d p o w e r , s a y 1 3 0 m e g a w a t t s , i n a B-36 f l i g h t - t e s t - b e d i n s t a l l a t i o n .

T a b l e 4 . 7 g i v e s t h e w e i g h t of v a r i o u s components of t h e i n s t a l l a t i o n shown i n F i g . 4 . 3 3 . ' I f a n i n c r e a s e i n power were made, t h e w e i g h t o f t h e r e a c t o r - h e a t - e x c h a n g e r - s h i e l d a s sembly would i n c r e a s e a s i n d i c a t e d i n T a b l e 4 . 6 , a n d t h e w e i g h t o f e n g i n e s , r a d i a t o r s , pumps, and l i n e s w o u l d b e r o u g h l y p r o p o r t i o n a l t o t h e p o w e r o u t p u t . I f t h e same power o u t p u t were

t o be r e q u i r e d a t a n a l t i t u d e a t which t h e a i r - s w a l l o w i n g c a p a c i t y o f t h e e n g i n e s was c u t i n h a l f , t h e t u r b o j e t e n g i n e w e i g h t would be d o u b l e d . The w e i g h t o f t h e r a d i a t o r s w o u l d b e i n c r e a s e d by, p e r h a p s , 5 0 % , b u t t h e w e i g h t o f t h e pumps a n d l i n e s w o u l d r e m a i n s u b s t a n t i a l l y t h e same. T h e power p l a n t o f F i g . 4 . .33 r e p r e s e n t s o n l y a p r e l i m i n a r y l a y o u t f o r showing t h e p r o p o r t i o n s t h a t might be e x p e c t e d . The t h r u s t t h a t c a n be o b t a i n e d f r o m t h i s power p l a n t is h e a v i l y d e p e n d e n t o n t h e a l l o w a b l e r e a c t o r o p e r a t i n g t e m p e r a t u r e . By c a r e f u l d e s i g n of t h e m o d e r a t o r - c o o l i n g s y s t e m , i t w i l l b e p a s s i b l e t o k e e p t h e t e m p e r a t u r e o f a l l s t r u c t u r a l p a r t s d o w n t o t h e t e m p e r a t u r e o f t h e s e c o n d a r y f l u i d l e a v i n g t h e i n t e r m e d i a t e h e a t e x - c h a n g e r . T h i s s h o u l d make i t p o s s i b l e t o o p e r a t e s u c h a power p l a n t , c o n - s t r u c t e d o f I n c o n e l , a t NaK o u t l e t t e m p e r a t u r e o f a b o u t 1500 'F f o r 5 0 0 h o u r s . A t a k e - o f f o r w a r - e m e r g e n c y r a t i n g o f 1600'F m i g h t b e p e r m i t t e d f o r p e r h a p s 2 0 t o 5 0 h r o f t h e 5 0 0 h o u r s .

A b r i e f d e s c r i p t i o n o f t h e e s s e n t i a l f e a t u r e s o f t h e d e s i g n shown i n F i g . 4.33 f o l l o w s , The r e a c t o r i s t h e same

TABLE 4 . 7 . MAJOR WEIGHT COMPONENTS OF THE 200-MEGAWATT AIRCRAFT POWER PLANTOFFIG. 4 . 3 3

NO. OF UNITS

4

1 6

1 6

1 6

4

COMPONENTS

T u r b o j e t e n g i n e s

R a d i a t o r s ( f i l l e d w i t h NaK)

NaK pumps, h e a d e r t a n k s , and t u r b i n e d r i v e a s s e m b l i e s

P i p i n g f o r N a K c i r c u i t s

Thermal i n s u l a t i o n f o r NaK c i r c u i t s

NaK i n NaK c i r c u i t s ( e x c e p t i n r a d i a t o r s )

F u e l and sodium pump d r i v e s

T u r b o j e t i n l e t and o u t l e t d u c t s and s u p p o r t s t r u c t u r e

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WEIGHT ( l b )

1 2 , 4 0 0

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FUEL PUMP DRIVE TURBINE BLEED-OFF AIR

No PUMP DRIVE TURBIN

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ENGINE DATA NoK-TO-AIR RADIATOR

MODIFIED WRIGHT TURBOJET HELICAL BAFFLE COMPRESSION RATIO 4 I (CORRECTED FOR SEA LEVEL) AIR FLOW 220 Ib/sec (CORRECTED FOR SEA LEVEL) DIAMETER = 44 v2 in. LENGTH = 140 in COMPRESSOR

ENGINE WEIGHT = 3100 Ib (WITHOUT RADIATOR) RADIATOR WEIGHT = 4500 Ib (WITH NaK) INLET AIR

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a s t h a t s h o w n i n F i g . 4 . 2 5 . T h e s h i e l d was d e s i g n e d s o t h a t i t m i g h t b e i n s e r t e d t h r o u g h a n o p e n i n g 6 f t 8 i n . w ide i n t h e b o t t o m o f t h e f u s e - l a g e , T h u s i t w o u l d l e n d i t s e l f t o i n s t a l l a t i o n i n t h e bomb b a y o f t h e B-36 j u s t a f t o f t h e main s p a r . Two c a n t i l e v e r beams p l a c e d o n 6 - f t c e n t e r s were employed a s t h e p r i m a r y s t r u c t u r e . The f r o n t e n d s o f t h e s e beams c o u l d be b o l t e d or p inned t o f i t t i n g s on t h e r e a r s p a r , a n d t h e r e a c t o r a n d t h e s h i e l d s t r u c t u r e c o u l d be a t t a c h e d t o t h e r e a r e n d s . The s h i e l d s t r u c t u r e w o u l d b e d i v i d e d i n t o s i x m a j o r s e c t i o n s , e a c h of w h i c h would c o n s i s t o f a n i n n e r l a y e r o f l e a d a n d a n o u t e r t a n k o f r u b b e r t h a t w o u l d be f i l l e d w i t h b o r a t e d w a t e r . The t o p and bo t tom s e c t i o n s would be s e p a r a t e d f r o m t h e f o u r s e c t i o n s i n t h e c e n t r a l r e g i o n by s u r f a c e s o f r e v o l u t i o n f o r e n c l o s i n g t h e NaK d u c t s t h r o u g h t h e s h i e l d , A l a r g e , b o w l - s h a p e d , r u b b e r t a n k w o u l d be p l a c e d a t e a c h s i d e . T h e s e t a n k s c o u l d be d e f l a t e d w h i l e t h e power p l a n t was b e i n g i n s e r t e d i n t h e a i r p l a n e and c o u l d be f i l l e d w i t h w a t e r a f t e r t h e power p l a n t w a s i n p l a c e . The t o p s e c t i o n o f t h e s h i e l d w o u l d b e p e n e t r a t e d by f i v e t u b e s . Four o f t h e s e t u b e s would c a r r y q u i l l s h a f t s t o t r a n s m i t power f rom b l e e d - o f f a i r t u r b i n e s t o t h e pumps a t t h e t o p o f t h e r e a c t o r , a n d t h e f i f t h t u b e w o u l d c a r r y t h e c o n t r o l r o d a c t u a t i n g mechanism.

E a c h of t h e e n g i n e r a d i a t o r s would be c o u p l e d t o a s e p a r a t e t u b e b u n d l e i n t h e i n t e r m e d i a t e h e a t e x c h a n g e r i n s u c h a way t h a t t h e r e w o u l d b e 1 6 s e p a r a t e s e c o n d a r y f l u i d c i r c u i t s . The e x p a n s i o n t a n k , f i l t e r , and pump f o r e a c h o f t h e s e c i r c u i t s w o u l d b e l o c a t e d a t t h e p o i n t o f g r e a t e s t e l e v a t i o n a n d l o w e s t t e m p e r a t u r e i n t h e s y s t e m , t h a t i s , a t t h e t o p o f t h e s h i e l d and j u s t o u t s i d e i t . Thus t h e NaK w o u l d l e a v e t h e pumps a n d p a s s i n t o t h e s h i e l d , t h r o u g h t h e i n t e r m e d i a t e h e a t e x c h a n g e r , back o u t

t h r o u g h t h e s h i e l d down t o t h e r a d i a t o r , a n d b a c k up t o t h e pump. T h e p i p e s p a s s i n g t o a n d f r o m t h e r a d i a t o r w o u l d b e a p p r o x i m a t e l y 3 1 / 2 i n . i n d i a m e t e r . T h e p r e s s u r e d r o p t h r o u g h t h e r a d i a t o r s would be a b o u t 3 5 p s i , and t h a t t h r o u g h p i p e s from t h e r e a c t o r would be a b o u t 7 p s i , I n a l l c a s e s , t h e p r e s s u r e h a s b e e n k e p t l o w t o k e e p t h e s t r e s s e s low a n d , h e n c e , t o m i n i m i z e t h e l i k e l i h o o d o f a b u r s t t y p e o f f a i l u r e . T h u s , e v e n t h o u g h s m a l l l e a k s m i g h t o c c u r a s a r e s u l t o f f a t i g u e c r a c k s o r s m a l l c o r r o s i o n p i t s i n w e l d e d o r b r a z e d j o i n t s , i t seems l i k e l y t h a t a ma jo r l e a k ( e x c e p t f o r g u n f i r e ) c o u l d be a v o i d e d .

The t u r b o j e t e n g i n e s i n d i c a t e d i n F i g . 4 . 3 3 a r e m o d i f i c a t i o n s o f a new e n g i n e b e i n g d e v e l o p e d by t h e W r i g h t A e r o n a u t i c a l C o r p . T h e o r i g i n a l e n g i n e i s a h i g h - c o m p r e s s i o n - r a t i o two-spoo l machine. S i n c e f u e l economy i s l e s s i m p o r t a n t t h a n e n g i n e w e i g h t f o r a power p l a n t of t h e t y p e s h o w n , ( ’ ’ ) a n e s t i m a t e o f t h e w e i g h t o f a m o d i f i e d e n g i n e w a s p r e p a r e d b y t h e W r i g h t A e r o n a u t i c a l C o r p O , a n d e s t i m a t e d p e r f o r m a n c e c u r v e s f o r t h e s e e n g i n e s a r e g i v e n i n F i g . 4.34. The r a d i a t o r s u s e d i n t h e s e t u r b o j e t s a r e o f t h e s a m e t y p e a s t h o s e t h a t h a v e b e e n t e s t e d a t ORNL i n t h e f o r m o f c o r e e l e m e n t s d u r i n g t h e p a s t y e a r . One o f t h e s e r a d i a t o r c o r e s o p e r a t e d f o r o v e r 1000 h r a t 1500°F, o r a b o v e , i n c l u d i n g o v e r 4 0 h r a t 1 7 0 O 0 F . ( ” ) I t i s e x p e c t e d t h a t d e v e l o p m e n t a l work now i n p r o c e s s w i l l p r o d u c e l i g h t e r u n i t s w i t h b e t t e r h e a t t r a n s f e r p e r f o r m a n c e t h a n t h e r a d i a t o r s o f t h i s p r e l i m i n a r y d e s i g n e

The p r o c e d u r e t h a t might be f o l l o w e d t o a s s e m b l e t h e c o m p l e t e power p l a n t would be t o modnt t h e r e a c t o r on t h e c a n t i l e v e r beams t h a t s u p p o r t i t a n d t h e s h i e l d a s s e m b l y . T h e t u r b o j e t e n g i n e s w o u l d t h e n b e m o u n t e d t o

(‘”W. S. F a r m e r , A . P. F r a a s , H. J . Stumpf, a n d G . D. Whi tman, P r e l i m i n a r y D e s i g n a n d P e r - f o r n a n c e S t u d i e s o f S o d i u n - t o - A i r R a d i a t o r s , OWL-1509 ( t o b e p u b l i s h e d ) .

i .

82


I 1 I I I 1 I I I CORRECTED C O M P R E S S I O N R A T I O = 4.0 : 1

320

280

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64,000

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48,000

40,000

32,000

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12,000

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I

0 0.3 0.6 0.9 1.2 1.5 MACH N U M B E R

F i g . 4 . 3 4 . E s t i m a t e d Turbo j e t Engine Per formance Curves .

83

s t r u c t u r e a t t a c h e d t o t h e s e s a m e c a n t i l e v e r beams, The p i p e s c o n n e c t i n g t h e e n g i n e r a d i a t o r t o t h e r e a c t o r and h e a t exchange r a s sembly c o u l d t h e n b e w e l d e d i n t o p o s i t i o n , a l o n g w i t h theNaK pump and h e a d e r t a n k a s s e m b l i e s , T h e e n t i r e s y s t e m c o u l d t h e n b e p r e s s u r e checked c a r e f u l l y a n d examined c l o s e l y f o r l e a k s . I t would p r o b a b l y p rove d e s i r a b l e t o i n s t a l l NaK i n t h e s e c o n d a r y c i r c u i t , s o d i u m i n t h e m o d e r a t o r c i r c u i t , o p e r a t e t h e pumps, and c h e c k a l l components c a r e f u l l y f o r l e a k s b e f o r e t h e t h e r m a l i n s u l a t i o n w a s i n s t a l l e d . An a u x i l i a r y s u p p l y o f c o m p r e s s e d a i r w o u l d be r e q u i r e d t o r u n t h e s o d i u m a n d NaK pumps a t p e r h a p s h a l f s p e e d f o r t h i s c h e c k . T h e s y s t e m t e m p e r a t u r e s i n t h e N a K c i r c u i t s would n o t have t o exceed room t e m p e r a t u r e , b u t a n a u x i l i a r y b u r n e r a r r a n g e m e n t s h o u l d be p r o v i d e d t o h e a t t h e two r a d i a t o r s c o u p l e d t o t h e two s o d i u m - t o - N a K h e a t e x c h a n g e r s f o r t h e m o d e r a t o r c o o l i n g s y s t e m . T h e s e h e a t e r s c o u l d b e u s e d t o b r i n g t h e s o d i u m s y s t e m t e m p e r a t u r e u p t o 300 or 400°F. Upon s a t i s f a c t o r y c o m p l e t i o n o f t h i s t e s t work, t h e r m a l i n s u l a t i o n c o u l d be i n s t a l l e d a r o u n d t h e r e a c t o r p r e s s u r e s h e l l a n d t h e c o n n e c t i n g l i n e s and pumps o f t h e sodium c i r c u i t . By u s i n g t h e s a m e h e a t s o u r c e , t h e sodium s y s t e m c o u l d be b r o u g h t u p t o p e r h a p s 1 0 0 0 ° F a n d a n o n u r a n i u m - b e a r i n g f l u o r i d e s a l t c o u l d be pumped i n t o t h e r e a c t o r . The f l u o r i d e - f u e l s y s t e m c o u l d t h e n b e c h e c k e d a n d d r a i n e d , a n d t h e l e a d s h i e l d i n g a n d t h e r u b b e r t a n k s f o r t h e b o r a t e d w a t e r c o u l d b e i n s t a l l e d t o c o m p l e t e t h e a s s e m b l y , A f t e r t h e power p l a n t u n i t h a d b e e n i n s t a l l e d i n t h e a i r p l a n e , t h e r u b b e r t a n k s c o u l d be f i l l e d w i t h b o r a t e d w a t e r , a n d t h e n e c e s s a r y c o n n e c t i o n s c o u l d b e made f o r t h e i n s t r u m e n t s and c o n t r o l s ,

I n s t a r t i n g u p t h e r e a c t o r , i t i s e x p e c t e d t h a t t h e NaK c i r c u i t s would be u s e d t o h e a t t h e s o d i u m t o b r i n g t h e r e a c t o r t e m p e r a t u r e u p t o a b o u t 1 0 0 0 ° F . A f l u o r i d e f u e l m e l t c o n - t a i n i n g l e s s t h a n t h e d e s i r e d amount o f u r a n i u m would t h e n be p o u r e d i n t o t h e f u e l s y s t e m a n d c i r c u l a t e d . G r a d u a l a d d i t i o n s o f a f l u o r i d e m e l t c o n t a i n i n g a r a t h e r h i g h p e r c e n t a g e o f U235 c o u l d be made u n t i l t h e r e a c t o r became c r i t i c a l . The t e m p e r a t u r e o f t h e r e a c t o r c o u l d t h e n b e a l l o w e d t o i n c r e a s e t o t h e d e s i r e d v a l u e - p r o b a b l y a n a v e r a g e t e m p e r a t u r e o f 1300'F - a n d t h e l o a d c o u l d b e g r a d u a l l y i n c r e a s e d b y s t a r t i n g u p f i r s t o n e a n d t h e n a n o t h e r o f t h e t u r b o j e t e n g i n e s . I t w i l l p r o b a b l y be p o s s i b l e t o d e p e n d u p o n t h e s e l f - s t a b i l i z i n g c h a r a c t e r i s t i c s i n h e r e n t i n t h e f l u o r i d e f u e l r e a c t o r t o k e e p t h e mean f l u o r i d e t e m p e r a t u r e e s s e n t i a l l y c o n s t a n t s o t h a t , i n e f f e c t , t h e r e a c t o r w o u l d become a s l a v e t o t h e t u r b o j e t e n g i n e s a n d w o u l d a c t a s a c o n s t a n t - t e m p e r a t ur e h e a t s o u r c e . C o n t r o l o f t h e i n d i v i d u a l t u r b o j e t e n g i n e s c o u l d b e a c c o m p l i s h e d b y v a r y i n g t h e amount o f a i r a l l o w e d t o b y p a s s t h e r a d i a t o r s t h r o u g h a d j u s t a b l e l o u v e r s i n t h e h e l i c a l b a f f l e s between r a d i a t o r banks. I n e f f e c t , t h i s would g i v e a v a r i a b l e , m e a n , t u r b i n e - a i r - i n l e t t e m p e r a t u r e . Coupled w i t h t h i s c o n t r o l , it would p r o b a b l y be n e c e s s a r y t o have a n a d j u s t a b l e j e t e x i t n o z z l e t o g i v e good p e r f o r m a n c e and t o a v o i d c o m p r e s s o r s t a l l o v e r a w i d e r a n g e o f o p e r a t i n g c o n d i t i o n s . F i n e c o n t r o l o f r e a c t o r t e m p e r a t u r e c o u l d b e a c c o m p l i s h e d t h r o u g h t h e u s e o f o n e or t w o c o n t r o l r o d s i n t h e c e n t r a l i s l a n d o r i n t h e r e f l e c t o r r e g i o n . C o a r s e s h i m c o n t r o l c o u l d be o b t a i n e d b y v a r y i n g t h e u r a n i u m c o n c e n t r a t i o n i n t h e f l u o r i d e f u e l .

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- . ..-.

. .

INTRODUCTION AND SUMMARY E . P. B l i z a r d J. L. M e e m , A s s o c i a t e

P h y s i c s D i v i s i o n

With t h e d e v e l o p m e n t o f a r e a c t o r d e s i g n i n w h i c h t h e f i s s i o n s a r e c o n f i n e d t o a s m a l l v o l u m e , a n d i n w h i c h i t i s h o p e d t h e r a d i a t o r s c a n b e k e p t r e l a t i v e l y n o n r a d i o a c t i v e , t h e h o p e s f o r a l i g h t u n i t s h i e l d h a v e b e e n r e v i v e d . A c c o r d i n g l y , a u n i t - s h i e l d m o c k u p w a s r e c e n t l y i n s t a l l e d i n t h e L i d Tank F a c i l i t y and is now b e i n g o p t i m i z e d w i t h r e g a r d t o t h e l o c a t i o n o f t h e s h i e l d com- p o n e n t s . I n a d d i t i o n , an i n t e n s i v e s e a r c h i s b e i n g c a r r i e d o u t f o r p r o m i s i n g m a t e r i a l s t h a t c o u l d b e u s e d i n t h e u n i t s h i e l d . Measurements o f r e l a t i v e s h i e l d i n g e f f e c t i v e n e s s i n d i c a t e l i t h i u m t o b e a p r o m i s i n g component f o r n e u t r o n s h i e l d i n g , and i n q u i r i e s h a v e b e e n i n i t i a t e d t o d e t e r m i n e w h e t h e r u r a n i u m c o u l d b e made a v a i l a b l e a n d f a b r i c a t e d a s a gamma s h i e l d ( s e c . 5 ) .

The a i r - s c a t t e r i n g e x p e r i m e n t s a t t h e B u l k S h i e l d i n g F a c i l i t y h a v e been c o m p l e t e d . E a r l i e r d i f f i c u l t i e s h a v e b e e n a s c r i b a b l e p r i m a r i l y t o u n s u s p e c t e d b a c k g r o u n d e f f e c t s , and i n d i c a t i o n s now a r e t h a t t h e w e i g h t s d e s c r i b e d i n t h e r e p o r t o f t h e S h i e l d i n g B o a r d ( 1 9 5 0 ) w e r e a p p r o x i m a t e l y c o r r e c t . The n e u t r o n s were somewhat l ow and t h e gam'ma r a y s somewhat h i g h , w i t h t h e w e i g h t d i f f e r e n c e s a p p r o x i - m a t e l y c a n c e l l i n g . T h e i r r a d i a t i o n o f a n i m a l s i n t h e B u l k S h i e l d i n g F a c i l i t y i s now c o m p l e t e , a n d t h e

a n i m a l s i n v o l v e d h a v e b e e n r e t u r n e d f o r l o n g - r a n g e o b s e r v a t i o n o f t h e b i o l o g i c a l e f - f e c t s of t h e s e e x p o s u r e s . N e u t r o n s p e c t r o s c o p y on t h e d i v i d e d s h i e l d i n t h e Bulk S h i e l d i n g F a c i l i t y h a s now commenced, a n d t h e f i r s t few s p e c t r a h a v e b e e n m e a s u r e d w i t h t h e p r o t o n - r e c o i l s p e c t r o m e t e r . T h e r e s u l t s a r e o n l y p r e l i m i n a r y ; h e n c e , n o d a t a a r e y e t a v a i l a b l e . However , t h e gamma s p e c t r a l m e a s u r e m e n t s f rom t h e d i v i d e d - s h i e l d mockup a r e b e i n g t a b u l a t e d f o r m a c h i n e c a l c u l a t i o n s ( s e c . 6 ) .

The Tower S h i e l d i n g F a c i l i t y d e s i g n i s b e i n g d e v e l o p e d r a p i d l y . T h e t o w e r s t r u c t u r e d e s i g n i s f i n a l and a b u i l d i n g i s f a i r l y c o m p l e t e l y l a i d o u t . The R e a c t o r d e s i g n f e a t u r e s and some o f t h e i n s t r u m e n t a t i o n a:re y e t t o b e deve loped . I n d i c a t i o n s a re t h a t t h e f a c i l i t y w i l l b e g i n o p e r a t i o n by t h e e n d o f t h e c a l e n d a r y e a r , and t e s t s w i t h t h e f i r s t s h i e l d s w i l l commence s h o r t l y t h e r e a f t e r ( s e c . 7 ) .

A n e u t r o n s p e c t r o m e t e r i s b e i n g d e v e l o p e d t h a t , u t i li z e s s c i n t i 11 a t i o n i n a l i t h i u m f l u o r i d e c r y s t a l . T h i s a p p a r a t u s g i v e s p r o m i s e o f a p p r e c i a b l y g r e a t e r s e n s i t i v i t y t h a n r e c o i l - p r o t o n s p e c t r o m e t e r s i f d e v e l o p m e n t a l d i f f i - c u l t i e s c a n b e o v e r c o m e . No c r o s s - s e c t i o n m e a s u r e m e n t s were c o m p l e t e d on t h e 6-Mev Van d e G r a a f f d u r i n g t h e q u a r t e r b e c a u s e t h e machine was b e i n g moved t o i t s pe rmanen t l o c a t i o n i n t h e X-10 Area ( s e c . 8).

87

f

. 6

5 . LID TANK FACILITY

J . D. F lynn J . N. Miller G. T. Chapman F. N. Watson

Ph ys i c s D i v i s i on

T h e L i d T a n k F a c i l i t y h a s b e e n u s e d d u r i n g t h e p a s t q u a r t e r p r i m a r i l y f o r m e a s u r i n g t h e f a s t - n e u t r o n remova 1 c r o s s s e c t i o n s o f a n u m b e r o f c o n - v e n t i o n a l a n d p o t e n t i a l s h i e l d i n g m a t e r i a l s . I n a d d i t i o n , a mockup o f t h e u n i t s h i e l d o f t h e r e f l e c t o r - m o d e r a t e d r e a c t o r h a s been a s sembled .

EFFECTIVE FAST-NEUTRON REMOVAL CROSS SECTIONS

T h e f o l l o w i n g e f f e c t i v e f a s t - n e u t r o n r e m o v a l c r o s s s e c t i o n s h a v e been measured:

A 1 1.19 ba rns / a tom Be 1.12 ba rns / a tom c u 2.08 barns/atom

Fe 1 . 9 3 barns/atom

L i F w 3 . 0 8 b a r n s / a tom

2.8 0 b a r n s /m o 1 ecu 1 e

The d a t a on l i t h i u m f l u o r i d e a r e p a r t i c u l a r l y i n t e r e s t i n g . I f f l u o r i n e i s a s s i g n e d a c r o s s s e c t i o n o f 1 b a r n , a s w o u l d b e i n d i c a t e d f r o m a c o m p a r i s o n w i t h p r e v i o u s l y m e a s u r e d v a l u e s for o x y g e n a n d c a r b o n , i t w o u l d a p p e a r t h a t l i t h i u m e x h i b i t s a c r o s s s e c t i o n o f 1 . 8 b a r n s . T h i s i s e x c e p t i o n a l l y h i g h f o r such a l i g h t n u c l e u s , a n d , i f v e r i f i e d , r e v e a l s a r e a l i n c e n t i v e f o r u s i n g t h i s e l e m e n t i n a i r c r a f t s h i e l d s . A c c o r d i n g l y , i t i s p l a n n e d t o measure t h e c r o s s s e c t i o n o f f l u o r i n e a s s o o n a s p o s s i b l e by u s i n g s l a b s o f a s a t u r a t e d f l u o r o c a r b o n .

M e a s u r e m e n t s h a v e a l s o b e e n made on t h e e f f r e p l a c i n g w a t e r n e a r t h e s o u r c e w i t h a s l a b o f t r a n s f o r m e r o i l ( C H , ) . By c o m p a r i s o n o f t h e s e measurements w i t h t h o s e f o r g r a p h i t e , i t i s p o s s i b l e t o d e t e r m i n e t h e e f f e c t o f t h e o x y g e n t h a t t h e o i l r e p l a c e d i n t h e w a t e r c l o s e t o t h e s o u r c e .

T h i s r e p r e s e n t s t h e f i r s t measurement o f t h e t r u e e f f e c t i v e removal. c r o s s s e c t i o n f o r t h i s e l e m e n t . P r e v i o u s e s t i m a t e s h a v e b e e n d e p e n d e n t upon a somewhat d i f f e r e n t d e f i n i t i o n , b e c a u s e t h e o x y g e n t h a t w a s m e a s u r e d w a s s p r e a d t h r o u g h o u t t h e s h i e l d a s i n w a t e r . I t i s i n t e r e s t i n g t o n o t e t h a t , a s might be e x p e c t e d , t h e oxygen e x h i b i t s a somewhat g r e a t e r e f f e c t i v e r emova l c r o s s s e c t i o n i n t h e l o c a t i o n n e a r t h e s o u r c e .

It had been p r o p o s e d by S l e e p e r o f B r o o k h a v e n N a t i o n a l L a b o r a t o r y t h a t d e u t e r i u m might p r o v e a more e f f e c t i v e s h i e l d component t h a n hydrogen b e c a u s e o f t h e more n e a r l y i s o t r o p i c s c a t t e r i n g ( l a b o r a t o r y s y s t e m ) i t e x h i b i t s b e c a u s e o f i t s i n c r e a s e d m a s s . To e x p l o r e t h i s p o i n t , a t a n k o f D,O was i n s e r t e d n e x t t o t h e s o u r c e i n t h e L i d Tank F a c i l i t y , a n d a n e f € e c t i v e r e m o v a l c r o s s s e c t i o n w a s m e a s u r e d . R e s u l t s i n d i c a t e a d i f f e r e n c e i n e f f e c t i v e r e m o v a l c r o s s s e c t i o n b e t w e e n n o r m a l and h e a v y hydr ' ogen o f 0 . 1 b a r n . T h i s c o r r e s p o n d s v e r y c l o s e l y t o t h e d i f f e r e n c e i n t h e i r t o t a l c r o s s s e c t i o n s i n t h e r a n g e o f a b o u t 2 t o 5 Mev and i n d i c a t e s t h a t n o a d d e d p r e m i u m a c c r u e s f r o m , t h e i n c r e a s e d a n g l e o f s c a t t e r i n g o r , a t l e a s t , t h a t t h i s i s c o u n t e r b a l a n c e d by t h e g r e a t e r e n e r g y d e g r a d a t i o n o f t h e l i g h t hydrogen.

MOCKUP OF THE UNIT SHIELD OF THE REFLECTOR-MODERATED REACTNOR

R e c e n t l y a mockup h a s been i n s t a l l e d i n t h e L i d Tank F a c i l i t y t o s i m u l a t e t h e r e f l e c t o r h e a t e x c h a n g e r and t h e u n i t s h i e l d o f t h e F i r e b a l l r e a c t o r . The b e r y l l i u m r e f l e c t o r i s s i m u l a t e d by a l a r g e s l a b o f m a t e r i a l s u p p l i e d by KAPL p l u s some a d d i t i o n a l m a t e r i a l

89


t h a t w a s a v a i l a b l e a t t h e Y-12 s i t e . T h e h e a t e x c h a n g e r i s s i m u l a t e d by sodium f l u o r i d e and i r o n ; t h e sodium f l u o r i d e i s l o a d e d i n t o l a r g e , t h i n , i r o n b o x e s . T h e p r o t o t y p e f o r t h e s h i e l d w i l l b e o f l e a d and w a t e r , and t e s t s c u r r e n t l y u n d e r way a r e d e s i g n e d t o d e t e r m i n e t h e optimum l o c a t i o n o f t h e l e a d w i t h i n t h e w a t e r .

An i n v e s t i g a t i o n w i l l a l s o be made o f t h e d e s i r a b i l i t y o f b o r a t i n g p a r t o f t h e w a t e r . T h e s e e x p e r i m e n t s h a v e j u s t begun, and t h e r e f o r e n o f i r m d a t a a r e y e t a v a i l a b l e ; however , t h e r e a r e i n d i c a t i o n s t h a t t h e o v e r - a l l r e a c t o r - s h i e l d w e i g h t w i l l b e v e r y low. T h i s i s a d i r e c t r e s u l t o f t h e s m a l l volume t o w h i c h t h e f i s s i o n s a r e c o n f i n e d .

.

90 f


6. BULK SHIELDING FACILITY

J . L. Meem E. B. J o h n s o n R. G . Cochran J. K . Les l i e M. P. Haydon T. A. Love K . M. Henry F. C. M a i e n s c h e i n H. E. H u n g e r f o r d G . M. McCammon


The a i r - s c a t t e r i n g e x p e r i m e n t s and t h e p r o g r a m o f i r r a d i a t i n g m o n k e y s h a v e b e e n c o n c l u d e d . I n a d d i t i o n , s o m e p r e l i m i n a r y n e u t r o n s p e c t r a l m e a s u r e m e n t s h a v e b e e n m a d e , b u t f u r t h e r work w i l l b e p o s t p o n e d u n t i l m e a s u r e m e n t s h a v e b e e n c o m p l e t e d on t h e m o c k u p o f t h e t o p p l u g o f t h e S I R s h i e l d . T h e gamma s p e c t r a l m e a s u r e m e n t s on t h e r e a c t o r p a r t o f t h e d i v i d e d s h i e l d a r e b e i n g a p p l i e d t o c a l c u l a t i o n s of a d i v i d e d s h i e l d .

AIR-SCATTERING EqPERIMENTS The a i r - s c a t t e r i n g e x p e r i m e n t a t

t h e Bulk S h i e l d i n g F a c i l i t y , o r i g i n a l l y c a r r i e d o u t l a s t s u m m e r , ( l o 2 , h a s b e e n e x t e n d e d a n d i m p r o v e d i n a n e f f o r t t o u n d e r s t a n d t h e s e r i o u s d i s c r e p a n c y t h a t a p p e a r e d t o be e x t a n t between t h i s e x p e r i m e n t and t h e c a l c u - l a t i o n s o f t h e S h i e l d i n g B o a r d . ( 3 ) With t h e i n c r e a s e d power now a v a i l a b l e , 1 0 0 kw h a v i n g r e c e n t l y b e e n a p p r o v e d f o r t h e BSR, i t i s now p o s s i b l e t o e l i m i n a t e much o f t h e e x t r a p o l a t i o n p r e v i o u s l y r e q u i r e d . I n a d d i t i o n , i t was d i s c o v e r e d t h a t t h e r a d i o a c t i v i t y i n t h e D O O ~ w a t e r was r e s p o n s i b l e f o r a l a r g e p a r t of t h e o b s e r v e d d o s e i n t h e mocked-up crew p o s i t i o n . Measure-

wer e n t o d e t e r m i n e t h e o f u s r a d i a t i o n s s c a t t e r -

i n g f r o m t h e p o o l w a l l s , a s w e l l a s f r o m t h e r e a c t o r s u p p o

("ANP Quar. P r o g . Rep . June 10, 1952, O W L - 1 2 9 4 , p. 46.

( 2 ) J . L , Meem a n d H. E. H u n g e r f o r d , A i r - S c a t t e r i n g E x p e r i m e n t s a t t h e B u l k S h i e l d i n g F a c i l i t y , OWL CF-52-7 -37 ( J u l y 8. 1 9 5 2 ) .

( 3 ) R e p o r t o f t h e S h i e Z d i n g B o a r d f o r t h e A i r c r a f t N u c l e a r P r o p u l s i o n P r o g r a m , A N P - 5 3 . p . 6 4 f f . ( O c t . 16, 1950) .

T h e s e were f o u n d t o c o n t r i b u t e o n l y n e g l i g i b l y t o t h e o b s e r v e d n e u t r o n and gamma d o s e s .

A l t h o u g h t h e e x p e r i m e n t hiIs b e e n c o m p l e t e d s o r e c e n t l y t h a t i t i s i m p o s s i b l e a t t h i s t i m e t o g i v e a c o m p l e t e r e p o r t , t h e f o l l o w i n g c o n - c l u s i o n s can be drawn :

1. T h e n e u t r o n d o s e i n t h e c r ew c o m p a r t m e n t a p p e a r s t o b e l o w e r by a f a c t o r o f 5 t h a n t h e ANP-53 c a l c u - l a t i o n s i n d i c a t e . T h e a d v a n t a g e a c c r u i n g f r o m t h i s a m o u n t s t o a b o u t 5000 l b f o r t h e s t a n d a r d c r e w - s h i e l d d e s i g n .

2. The gamma-ray d o s e i n t h e crew compartment a p p e a r s t o b e highler t h a n i n d i c a t e d by t h e ANP-53 d e s i g n by a f a c t o r o f 3 . 5 . T h e w e i g h t p e n a l t y a s s o c i a t e d w i t h t h i s i s a b o u t 6 0 0 0 pounds.

T h e c o n c l u s i o n s d i f f e r f r o m t h e e a r l i e r o n e s b o t h i n t h e m a g n i t u d e o f t h e d i s c r e p a n c i e s and i n t h e amount o f m a t e r i a l r e q u i r e d t o make u p t h e added a t t e n u a t i o n . S i n c e t h i s e x p e r i - m e n t i s b a s i c a l l y s o v e r y c r u d e , f u r t h e r e x p l o i t a t i o n o f t h e B u l k S h i e l d i n g F a c i l i t y i n t h i s t y p e o f w o r k i s n o t c o n s i d e r e d w o r t h w h i l e ; t h e p r e s e n t compar i son w i t h t h e ANP-53 c a l c u l a t i o n s i s c o n s i d e r e d a d ' e q u a t e .

IRRADIATION OF ANIMALS I n a d d i t i o n t o t h e t w o g r o u p s o f

m o n k e y s m e n t i o n e d i n a p r e v i o u s q u a r t e r l y r e p o r t , C 4 ) a t h i r d g roup h a s been i r r a d i a t e d by t h e B u l k S h i e l d i n g R e a c t o r . T h e c o m p l e t e s e r i e s o f e x p e r i m e n t s i s summarized in T a b l e 6 .1 .

( 4 ) A N P Q u a r . P r o g . R e p . S e p t . 1 0 , 1 9 5 2 , ORNL-1375, p. 6 6 .

91


TABLE 6.1. IRRADIATION OF MONKEYS IN THE BULK SHIELDING FACILITY

Number of e x p o s u r e s

Time p e r e x p o s u r e , h r

Time between e x p o s u r e s , days

T o t a l e x p o s u r e , rem

Number o f a n i m a l s u s e d

* O n e - h a l f d o s e i n n e u t r o n s and o n e - h a l f d o s e i n gamma r a y s .

A l l e x p o s u r e s h a v e b e e n c o m p l e t e d and t h e a n i m a l s h a v e been r e t u r n e d t o t h e USAF S c h o o l of A v i a t i o n M e d i c i n e a t A u s t i n , T e x a s , where t h e y w i l l b e h e l d f o r o b s e r v a t i o n . I t i s e x p e c t e d t h a t t h e t h i r d g r o u p , which r e c e i v e d 512 r e m , w i l l d e v e l o p e y e c a t a r a c t s , b u t t h a t t h e f i r s t a n d s e c o n d g r o u p s w i l l n o t . I f t h e e x p e r i m e n t t u r n s

n t i c i p a t e d , t h e t h r e s h o l d f o r c a t a r a c t s s h o u l d b e d e f i n i t e l y b r a c k e t e d .

A r e p o r t i s b e i n g p r e p a r e d i n c o o p e r a t i o n w i t h t h e H e a l t h P h y s i c s D i v i s i o n t h a t g i v e s d e t a i l s o f t h e d o s i m e t r y d u r i n g t h e e x p e r i m e n t . F i g u r e 6. 1 s h o w s o n e o f t h e a n i m a l s r e a d y t o b e p l a c e d i n a w a t e r t i g h t c a g e f o r s u b m e r s i o n i n t h e p o o l .

NEUTRON SPECTROSCOPY FOR THE DIVIDED SHIELD

Some p r e l i m i n a r y n e u t r o n s p e c t r a k lave b e e n r u n w i t h t h e p r o t o n - r e c o i l s p e c t r o m e t e r d e v e l o p e d b y C o c h r a n and H e n r y . ( ' ) F a s t - n e u t r o n d a t a h a v e a l s o b e e n t a k e n w i t h n u c l e a r p l a t e s and t h r e s h o l d d e t e c t o r s . A l l r e s u l t s a r e i n p r e l i m i n a r y f o r m a n d a r e n o t y e t s u i t a b l e f o r r e p o r t i n g . T h e e x p e r i m e n t s w i l l b e c o n t i n u e d a s r e a c t o r t ime p e r m i t s .

(5)R. G . C o c h r a n and K . M . H e n r y , A P r o t o n Reco i 1 T y p e Fas t - N e u t r o n S p e c t r o m e t e r , ORNL- 1479 ( i n p r e s s ) .

GAMMA SPECTROSCOPY FOR THE DIVIDED SHIELD

The d a t a on t h e e n e r g y and a n g u l a r d i s t r i b u t i o n o f g a m m a r a y s f r o m t h e d i v i d e d - s h i e l d m o c k u p a r e b e i n g t a bu 1 a t ed f o r mac h i n e c a 1 c u 1 a t i on s . The e n e r g y , a n g u l a r d i s t r i b u t i o n , and t o t a l i n t e n s i t y o f t h e d i r e c t , a s w e l l a s s c a t t e r e d , p h o t o n s a r r i v i n g a t t h e c r e w c o m p a r t m e n t w i l l b e c o m p u t e d .

FISSION ENERGY AND POWER IN THE BULK SHIELDING REACTOR

A r e p o r t on t h e power d i s t r i b u t i o n i n t h e r e a c t o r w i t h a b e r y l l i u m o x i d e r e f l e c t o r h a s been c o m p l e t e d , ( 6 ) and a r e p o r t on t h e d e t e r m i n a t i o n o f t h e e n e r g y r e l e a s e d p e r f i s s i o n i s b e i n g p r e p a r e d . F i g u r e s 6 . 2 and 6 . 3 i l l u s - t r a t e t h e t i m e d e c a y o f n e u t r o n s a n d gamma r a y s f r o m t h e r e a c t o r a f t e r shutdown. The d a t a a r e n o r m a l i z e d t o u n i t y f o r o p e r a t i o n s a t 1 a n d 1 0 0 kw and p l o t t e d a g a i n s t t i m e a f t e r scramming t h e r e a c t o r . I t i s i n t e r e s t i n g t o n o t e h o w t h e ( y , n > r e a c t i o n on b e r y l l i u m k e e p s t h e n e u t r o n l e v e l f a i r l y h i g h . W i t h o u t t h e b e r y l l i u m o x i d e r e f l e c t o r , t h e n e u t r o n s d e c a y w i t h p e r i o d s t h a t a r e c h a r a c t e r i s t i c o f t h e d e l a y e d - n e u t r o n emi t t e r s .

("J. L . Meem and E. B. J o h n s o n , D e t e r m i n a t i o n o f t h e P o w e r o f t h e B u l k S h i e l d i n g R e a c t o r , P a r t 11, ORNL-1438 ( i n p r e s s ) .

f


Fig. 6.1. Monkey and Irradiation Cage forthe Bulk Shielding Facility Experiment.

93

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I I I I I I I I I I I \ I I I I I I ', 1 I I I I I I I I I I I I

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2 I \I I I I I I I I I I I I I I I I

10-5 I dNEUTRON DECAY AFTER 100-kw OPERATION FOR 46 hr I I I I I I I I

1 I ., I I U P I I I I 1- I I I I I I I I I I I 1

5

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io= 0 20 40 60 80 1 0 0 120 140 160 180 200 220 240 260 280 300 320 340 360

TIME AFTER SHUTDOWN (min)

1 hr 2 hr 3 hr 4 hr 5 hr 6hr .

F i g . 6 .2 . Decay o f Neutrons and Gamma Rays from 0 t o 6 hr After Shutdown.

!a

0 20 40

F i g .

60

1 min

6.3.

*! N

80 100 120 140 2 min

Decay of Neutron

x 160 180 200 220 240 260 280 300 320 340 360 380 400 3 min 4 min 5 min 6 min

TIME AFTER SHUTDOWN ( s e d CI 0

and Gamma Rays from 0 t o 400 sec After Shutdown.

W ul

7 . TOWER S H I E L D I N G F A C I L I T Y

C. E. C l i f f o r d T. V. B l o s s e r


J. Y. E s t a b r o o k , ANP D i v i s i o n

T h e p r e l i m i n a r y d e s i g n o f t h e T o w e r S h i e l d i n g F a c i l i t y p r o p o s e d b y t h e f i r m o f K n a p p e n - T i p p e t t s - Abbet t -McCar thy (KTAM), a r c h i t e c t u r a l e n g i n e e r s , was a c c e p t e d by ORNL e a r l y i n J a n u a r y . Some d e l a y was n e c e s s i t a t e d by t h e d i s c o v e r y t h a t t h e tower d e s i g n f i r s t c o n s i d e r e d b y K T A M p r o v e d e x c e p t i o n a l l y h e a v y i n s t r u c t u r a l s t e e l , p a r t i c u l a r l y i n t h e l o n g o v e r h e a d members from which t h e l o a d s were s u p p o r t e d by a v e r t i c a l h o i s t . S i n c e t h e h e a v i e r members r a i s e d t h e background f rom s t r u c t u r a l s c a t t e r i n g beyond r e a s o n a b l e l imits , a d e s i g n was p r o p o s e d t h a t e 1 i m i n a t e d t h e o v e r h e a d s t r u c t u r e and r e d u c e d t h e w e i g h t o f t h e l e g s by a f a c t o r o f a p p r o x i m a t e l y 2. The d e s i g n s a n d s p e c i f i c a t i o n s o f t h e t o w e r a n d a s s o c i a t e d b u i l d i n g s a r e now s c h e d u l e d f o r c o m p l e t i o n by KTAM a n d t h e ORNL E n g i n e e r i n g D e p a r t m e n t on March 1.

D e s i g n , p r o c u r e m e n t , a n d c o n - s t r u c t i o n o f t h e r e a c t o r and i n s t r u - m e n t s , a s w e l l a s e n g i n e e r i n g o f t h e s i t e , r o a d , and u t i l i t i e s , a r e b e i n g done by ORNL. T h i s work i s p r o c e e d i n g ahead of s c h e d u l e , a t p r e s e n t .

TOWER DESIGN

T h e t o w e r d e s i g n i s s h o w n i n F i g s . 7 . 1 a n d 7 . 2 . T h e s t r u c t u r e i s 315 f t h i g h and h a s a 2 0 0 - f t i n s i d e c l e a r a n c e i n t h e n o r t h - s o u t h d i r e c t i o n a n d a 1 0 1 - f t i n s i d e c l e a r a n c e i n t h e e a s t - w e s t d i r e c t i o n . The f o u r t o w e r c o l u m n s a r e 9 f t s q u a r e a n d w e i g h a p p r o x i m a t e l y 400 l b p e r r u n n i n g f o o t .

T h e l o a d s w i l l b e r a i s e d b y s i x i n d i v i d u a l h o i s t s - t w o f o r t h e

r e a c t o r s h i e l d and f o u r f o r t h e c r e w s h i e l d . T h e r e a c t o r s h i e l d c a n b e r a i s e d 200 f t o f f t h e g r o u n d , a n d i t may b e moved l a t e r a l l y t o a p p r o a c h t h e tower l e g s . T h i s l a t e r a l movement w i l l p e r m i t m e a s u r e m e n t o f t h e r a d i - a t i o n s s c a t t e r e d by t h e tower s t r u c t u r e . T h e f o u r h o i s t s s u p p o r t i n g t h e c r e w c o m p a r t m e n t w i 11 a 1 1 ow c on s i d e r a b l e f l e x i b i l i t y i n t h e crew c o m p a r t m e n t p o s i t i on and o r i e n t a t i on , i n c l u d i n g t h e p o s s i b i l i t y o f a v a r i a t i o n o f f rom 35 t o 1 0 0 f t i n t h e r e a c t o r - t o - crew s e p a r a t i o n d i s t a n c e .

CONSTRUCTION SCHEDULE

The t e n t a t i v e s c h e d u l e f o r o u t s i d e e n g i n e e r s and c o n t r a c t o r s f o r c o m p l e t i n g t h e i r v a r i o u s p h a s e s o f d e s i g n a n d c o n s t r u c t i o n o f t h e Tower S h i e l d i n g F a c i l i t y h a v e been somewhat o p t i m i s t i - c a l l y e s t i m a t e d as f o l l o w s :

February 24 Design comple ted and s u b m i t t e d

March 17 B i d s r e c e i v e d

March 20 C o n t r a c t s awarded

J u n e 15 C o n s t r u c t i o n o f t h e r o a d s , tower f o u n d a t i o n , a n d guy a n c h o r s comple ted

November 15 A 1 1 o u t s i d e c o n s t r u c t i o n c o m - p l e t e d

December 31 , R e a c t o r c r i t i c a l

t o b i d d e r s

I t a p p e a r s t h a t ORNL w i l l e i t h e r meet or b e a h e a d o f t h e t ime s c h e d u l e i n i t s s h a r e o f t h e Tower S h i e l d i n g F a c i l i t y w o r k . T h e f o l l o w i n g i s a l i s t o f O R N L ’ s f u n c t i o n s , t o g e t h e r w i t h t h e p r e s e n t s t a t u s of accon ip l i sh - ment .

97

ANP PROJECT QUARTERLY P R O G R E S S REPORT

F U N C T I O N

Eng ineer ing of s i t e , b u i l d i n g , and p o o l

E n g i n e e r i n g of r e a c t o r , tank, and mechanica l c o n t r o l s

E n g i n e e r i n g of r e a c t o r c o n t r o l s ( e l e c t r i c a l p o r t i o n )

E n g i n e e r i n g of i n s t rumentat ion (mechanica l )

E n g i n e e r i n g of i n s t r u m e n t a t i o n ( e l e c t r i c a l )

C o n s t r u c t i o n of r e a c t o r , tank, and mechanica l c o n t r o l s

C o n s t r u c t i o n o f r e a c t o r c o n t r o l s ( e l e c t r i c a l p o r t i o n )

C o n s t r u c t i o n of i n s t r u m e n t a t i o n (mechanica l )

Cons truc t i o n of i n s t r u m e n t a t i o n ( e l ec t r i c a l )

T A R G E T D A T E

3/1/53 3/1/53 7 / 1/5 3 5/1/53 3/ 1/5 3 9 /1 /53 12/1/53 8/ 1/53 2/ 1/51 3

PER C E N T COMPLETE

100 100 20 50

10 0 5

20 5

2 0

.

i i


AEsscuGsEB- DWG. c - IZ I I~B

F i g . 7 . 1 . Tower S h i e l d i n g F a c i l i t y ( P e r s p e c t i v e ) .

99


aeJrmffee DWG. C-121188

Fig. 7.2. Tower Shielding Facility (Plan V i e w ) .

100

PERIOD ENDING MARCH lo,, 1953

8 . NUCLEAR MEASUREMENTS

A f a s t - n e u t r o n s c i n t i l l a t i o n s p e c t r o m e t e r e m p l o y i n g UF c r y s t a l s , w h i c h h a v e l o w g a m m a - r a y r e s p o n s e , i s b e i n g d e v e l o p e d , The 6-Mev Van de G r a a f f h a s b e e n s e t u p i n t h e H i g h - V o l t a g e L a b o r a t o r y , b u t no r e s e a r c h h a s y e t b e e n u n d e r t a k e n i n t h e new l o c a t i o n .

FAST-NEUTRON SCINTILLATION SPECTROMETER

J . Schenck F. J . M u c k e n t h a l e r P h y s i c s D i v i s i o n

The work on t h e d e v e l o p m e n t o f a s c i n t i l l a t i o n s p e c t r o m e t e r f o r f a s t n e u t r o n s h a s a p p e a r e d s o p r o m i s i n g f o r s h i e l d i n g work t h a t two r e s e a r c h p e r s o n n e l h a v e b e e n a s s i g n e d t o t h e p r o j e c t t o a c c e l e r a t e t h e w o r k . A l t h o u g h e u r o p i u m - a c t i v a t e d l i t h i u m

i o d i d e c r y s t a l s h a v e b e e n u s e d t o d a t e , l i t h i u m f l u o r i d e would b e much m o r e d e s i r a b l e b e c a u s e o f i t s l o w e r gamma-ray r e s p o n s e . The work i s now c o n c e n t r a t e d i n a n e f f o r t t o g r o w a 1 i t h i u m f l u o r i d e c r y s t a l w i t h s u i t a b 1 e sc i n t i 1 1 a t i on p rop e r t i e s .

MEASUREMENTS WITH THE 6-MEV VAN de GRAAFF

H. B. W i l l a r d , P h y s i c s D i v i s i o n

The 6-Mev Van d e G r a a f f was moved d u r i n g t h e q u a r t e r from i t s t e m p o r a r y l o c a t i o n i n B u i l d i n g 9 2 0 1 - 2 , Y - 1 2 s i t e , t o i t s permanent q u a r t e r s i n t h e H i g h - V o l t a g e L a b o r a t o r y , B u i l d i n g 4 5 0 0 , X-10 s i t e . A beam was f i r s t o b t a i n e d l a t e i n t h e q u a r t e r , b u t n o c r o s s - s e c t i o n m e a s u r e m e n t s w e r e u n d e r t a k e n .

10 1

4

-.. . . . . . . - . . . . ...... - * * . . . . ~. _ . . . . . . . . .

INTRODUCTION AND SUMMARY

T h e r e s e a r c h o n f u s e d f l u o r i d e s y s t e m s ( s e c . 9 ) h a s b e e n l a r g e l y c o n c e r n e d w i t h t h e d e v e l o p m e n t o f t e c h n i q u e s f o r p u r i f y i n g and p r e p a r i n g e n r i c h e d ARE f u e l and f u e l c a r r i e r . T h e f 1 u o r i d e t r e a t m e n t p r o c e d u r e i n v o l v e s s u c c e s s i v e p u r g i n g o f t h e l i q u i d w i t h HF, H , , HF, and f i n a l l y H e . T h e t r e a t e d f u e l t h e n c o n t a i n s o n l y t r a c e s o f H F , N i F , , a n d F e F , , which a r e p r i m a r y f a c t o r s i n f l u o r i d e c o r r o s i o n . The b e n e f i c i a l e f f e c t on t h e c o r r o s i o n o f t h e r e d u c i n g a g e n t s h a s b e e n s u b s t a n t i a t e d , a n d t h e q u a n t i t y o f t h e v a r i o u s r e d u c t a n t s t h a t may b e t o l e r a t e d i n t h e f u e l h a s b e e n d e f i n e d . T h e c o n s e q u e n c e s o f t h e a t t e n d a n t r e d u c t i o n o f some UF, t o UF, a r e b e i n g i n v e s t i g a t e d . F o r t h e l o n g e r - r a n g e f u e l d e v e l o p m e n t program, s e v e r a l t e r n a r y and q u a t e r n a r y f l u o r i d e s y s t e m s c o n t a i n i n g L i F a r e b e i n g i n v e s t i g a t e d , a s w e l l a s some b i n a r y c h l o r i d e m i x t u r e s c o n t a i n i n g

The c o r r o s i o n r k s e a r c h ( s e c . 1 0 ) h a s been p r i m a r i l y o n t h e d e t e r m i n a t i o n o f t h e c o r r o s i o n c h a r a c t e r i s t i c s o f f l u o r i d e m i x t u r e s . T h e i n c r e a s e d a t t a c k e x p e r i e n c e d i n r e c e n t t e s t s w i t h t h e ARE f u e l m i x t u r e i s b e l i e v e d t o b e d u e t o f a u l t y p u r i f i c a t i o n r a t h e r t h a n t o h a n d 1 i n g t e c h n i q u e s . Z i r c o n i u m h y d r i d e a s a n a d d i t i v e t o t h e f u e l m i x t u r e r e d u c e s t h e f l u o r i d e a t t a c k o n I n c o n e l by a f a c t o r o f 2. A p p a r e n t l y t h e m e c h a n i s m i s t h e r e d u c t i o n o f t h e m e t a l l i c f l u o r i d e s NiF , a n d FeF, , w h i c h a r e p r e s e n t i n t h e f u e l , b e c a u s e a d d i t i o n o f t h e s e f l u o r i d e s t o t h e f u e l i n c r e a s e s t h e c o r r o s i o n . Measurements o f t h e concen- t r a t i o n o f N iF , , FeF,, and CrF, a s a f u n c t i o n o f e x p o s u r e t i m e o f I n c o n e l i n t h e f u e l h a v e b e e n m a d e a s a n i n d e x o f c o r r o s i o n . T h e n i c k e l c o n t e n t r e m a i n s a p p r o x i m a t e l y c o n s t a n t and t h e i r o n c o n t e n t d r o p s s h a r p l y t o a c o n s t a n t v a l u e ; however , t h e chromium

uc1,.

c o n t e n t r i s e s d u r i n g t h e f i r s t 100 h r a n d t h e n l e v e l s o f f . A f t e r t h e a d d i t i o n o f Z r H , , t h e o n l y s i g n i f i c a n t c h a n g e i n t h e s e c o n c e n t r a t i o n s was i n t h e c h r o m i u m c o n t e n t , w h i c h t h e n changed i n t h e same manner a s t h e i r o n c o n t e n t . T h e a d d i t i o n o f c h r o m i u m m e t a l was n o t e f f e c t i v e i n inhibiting f l u o r i d e c o r r o s i o n , a p p a r e n t l y because o f t h e low s o l u b i l i t y o f chroniium i n t h e f l u o r i d e . A l t h o u g h I n c o n e l a n d s t a i n l e s s s t e e l a r e s e v e r e l y a1, tacked by l e a d i n t e s t s i n c o n v e c t i o n l o o p s , molybdenumand columbium a r e r e l a t i v e l y immune. H o w e v e r , s t a t i c t e s t s o f l e a d - s o d i u m a l l o y s show t h a t s o d i u m a d d i t i o n s o t h 13 r w i s e s e v e r e l y c o r r o s i v e a c t i o n o f t h e l e a d o n b o t h I n c o n e l and s t a i n l e s s s t e e l . The s t a b i l i t y o f Be0 i n NaK i s , s t i l l b e i n g i n v e s t i g a t e d . I t a p p e a r s t h a t t h e r e i s some s o l u b i l i t y o f Be0 i n NaK.

The m e t a l l u r g y and c e r a m i c s r e s e a r c h ( s e c . 11) i n c l u d e s t h e f a b r i c a t i o n o f v a r i o u s r e a c t o r components f o r u s e a t h i g h t e m p e r a t u r e s ; c r e e p r u p t u r e t e s t s o f s t r u c t u r a l m e t a l s ; t h e d e v e l o p m e n t o f s p e c i a l a l l o y s , c e r m e t s , and (ceramic c o a t i n g s ; a n d t e s t s o f w e l d i n g a n d b r a z i n g a l l o y s . C o n t r o l o r s a f e t y r o d i n s e r t s a r e b e i n g p r e p a r e d f o r t h e G-E r e a c t o r a n d f o r t h e Tower S h i e l d i n g F a c i l i t y . C h r o m e - p l a t e d , h i g h - c o n d u c t i v i t y f i n s h a v e n o t p r o v e d a d e q u a t e f o r h i g h - t e m p e r a t u r e r a d i a t o r u s e , b u t I n c o n e l o r s t a i n l e s s - s t e e l - c l a d c o p p e r f i n s may now b e s a t i s f a c t o r i l y b r a z e d . R e c e n t c r e e p t e s t s o f s t a i n - l e s s s t e e l and I n c o n e l h a v e shown t h a t s u r f a c e o x i d a t i o n i s n o t the c o n t r o l l i n g f a c t o r i n t h e l o n g e r r u p t u r e t i m e s o b s e r v e d i n a i r a s compared w i t h t h e r u p t u r e t imes i n h y d r o g e n and a r g o n . T h e c o n e - a r c w e l d i n g t e c h n i q u e i s b e i n g a d a p t e d t o t h e w e l d i n g o f d i s h e d h e a d e r s € o r h e a t e x c h a n g e r s b e c a u s e o f t h e u n e q u a l a r c d i s t a n c e s e n c o u n t e r e d . B e c a u s e o f d i l u t i o n and e m b r i t t l e m e n t o f t h e N i c r o b r a z u s e d i n

d e c r e a s e t h e

105


b r a z i n g a h e a t e x c h a n g e r e l e m e n t o t h e r a l l o y s h a v e been c o n s i d e r e d f o r t h i s a p p l i c a t i o n . The e v a l u a t i o n o f h i g h - t e m p e r a t u r e a l l o y s w i t h r e s p e c t t o t e m p e r a t u r e , s t r e n g t h , and c o r r o s i o n r e s i s t a n c e i s c o n t i n u i n g .

The p h y s i c a l p r o p e r t y measurements were made p r i m a r i l y f o r t h e d e t e r m i - n a t i o n o f v a r i o u s p r o p e r t i e s o f s e v e r a l f l u o r i d e m i x t u r e s , a n d t h e h e a t t r a n s f e r s t u d i e s were c o n c e r n e d w i t h e x p e r i m e n t a l s y s t e m s , a s w e l l a s a i r c r a f t c o m p o n e n t s ( s e c . 1 2 ) . T h e h e a t c a p a c i t y o f t h e ARE f u e l w a s found t o b e 0 . 3 1 c a l / g o o C from 550 t o 850OC. Vapor p r e s s u r e measurements o f t h e e n r i c h e d f u e l m i x t u r e were l o w e r t h a n e x p e c t e d a n d i n d i c a t e d t h e f o r m a t i o n o f c o m p l e x i o n s a t h i g h t e m p e r a t u r e s . P r e l i m i n a r y measurements were made o f b o t h t h e t h e r m a l conduc- t i v i t y a n d t h e v i s c o s i t y o f s o d i u m h y d r o x i d e a t e l e v a t e d t e m p e r a t u r e s . A minimum-weight a n a l y s i s w a s c o m p l e t e d f o r a n a i r c r a f t r a d i a t o r w i t h t h e optimum f i n s p a c i n g and t h i c k n e s s and t h e optimum t u b e s p a c i n g and d i a m e t e r . E x p e r i m e n t a l a p p a r a t u s t o d e t e r m i n e t h e f l u i d v e l o c i t y p r o f i l e s and t h e f l u i d t e m p e r a t u r e s t r u c t u r e i s b e i n g a s sembled . One s t u d y i s u n d e r way t o d e t e r m i n e t e m p e r a t u r e d i s t r i b u t i o n i n e n t r a n c e r e g i o n s , w h e r e a s a n o t h e r s t u d y w i l l compare t h e v a r i o u s h i g h - t e m p e r a t u r e h e a t t r a n s f e r f l u i d s .

C r e e p u n d e r i r r a d i a t i o n and c o r r o s i o n by s o d i u m i n a n i n - r e a c t o r l o o p a r e

b e i n g i n v e s t i g a t e d ; however, i r r a d i a t i o n o f f l u o r i d e m i x t u r e s c o m p r i s e s t h e g r e a t e r p a r t o f t h e r a d i a t i o n damage s t u d i e s ( s e c . 1 3 ) . I n r e c e n t i r - r a d i a t i o n s o f t h e ARE f u e l m i x t u r e i n t h e MTR, i n which t h e power g e n e r a t i o n i s 20 t imes t h a t e x p e c t e d i n t h e ARE, c o r r o s i o n a n d c h a n g e s i n t h e f u e l c o m p o s i t i o n o c c u r r e d t h a t w e r e i n e x c e s s o f t h o s e o b s e r v e d i n c o n t r o l t e s t s . However , t h e I n c o n e l and t h e f u e l were a t t e m p e r a t u r e s i n e x c e s s o f 1 5 0 0 ' F d u r i n g t h e t e s t s . T h e r e c e n t i n - r e a c t o r c r e e p m e a s u r e m e n t s c o n f i r m e d p r e v i o u s c o n c l u s i o n s t h a t i r r a d i a t i o n h a d l i t t l e e f f e c t on t h e c r e e p s t r e n g t h .

A n a l y t i c a l s t u d i e s o f r e a c t o r m a t e r i a l s ( s e c . 1 4 ) i n c l u d e d c h e m i c a l , p e t r o g r a p h i c , a n d x - r a y d i f f r a c t i o n i d e n t i f i c a t i on o f i m p u r i t i e s , c o r r o s i o n p r o d u c t s , r e d u c t i o n p r o d u c t s , a n d c o n s t i t u e n t s o f r e a c t o r f u e l s . Vo lu - m e t r i c m e t h o d s f o r t h e d e t e r m i n a t i o n o f z i r c o n i u m i n t h e p r e s e n c e o f u r a n i u m a n d f o r t h e s i m u l t a n e o u s d e t e r m i n a t i o n o f u r a n i u m t r i f 1 u o r i . d e and z i r c o n i u m m e t a l h a v e b e e n d e v e l o p e d . An a p p a r a t u s h a s b e e n b u i l t t o a i d i n t h e d e t e r m i n a t i o n o f t r a c e s o f o x i d e s i n f l u o r i d e s . With p e t r o g r a p h i c and x - r a y - d i f f r a c t i o n s t u d i e s , i t h a s been p o s s i b l e t o d e t e r m i n e a n d d e f i n e c o m p o s i t i o n s o f t h e c o m p o u n d s a n d e u t e c t i c s p r e s e n t i n U C 1 4 - N a C 1 , UCl,-KCl, a n d NaF-ZrF,-UF, s y s t e m s .

106

A

http://1uori.de

PERIOD ENDING MARCH l o ! , 1953

9. CHEMISTRYOFHIGH-TEMPERATURE LIQUIDS W. R. G r i m e s , M a t e r i a l s C h e m i s t r y D i v i s i o n

The major e f f o r t o f t h e ANP C h e m i s t r y g r o u p c o n t i n u e s t o be d e v o t e d t o t h e s t u d y o f f l u o r i d e m i x t u r e s f o r u s e a s a i r c r a f t r e a c t o r f u e l s and c o o l a n t s . A l a r g e f r a c t i o n o f t h i s e f f o r t h a s been d e v o t e d t o t h e s p e c i f i c m a t e r i a l s t h a t c o m p r i s e t h e f u e l s o l v e n t , t h e c o n c e n t r a t e d f u e l , and t h e f i n a l f u e l m i x t u r e f o r t h e ARE.

T h e f i n a l p r o c e s s i n g p l a n s f o r p r e p a r a t i o n o f t h e f l u o r i d e m i x t u r e s i n p u r e f o r m a r e n e a r l y f i n i s h e d . P r o c e d u r e s f o r r e m o v i n g a l l e x c e p t t r a c e s o f HF, NiF, and FeF, from t h e s e m a t e r i a l s a r e i n t h e f i n a l d e v e l o p - men t a l s t a g e s . C o n t r a r y t o p r e v i o u s b e l i e f s , h y d r o g e n d o e s c a u s e p a r t i a l r e d u c t i o n o f UF, t o UF, i n t h e s e m e l t s a t 800°C. T h e b e n e f i c i a l e f f e c t o f r e d u c i n g a g e n t s o n t h e c o r r o s i o n o f f l u o r i d e m i x t u r e s h a s been w e l l sub - s t a n t i a t e d , a n d t h e q u a n t i t i e s o f v a r i o u s r e d u c t a n t s t h a t may b e t o l e r a t e d i n t h e f u e l s h a s been d e f i n e d .

P h a s e e q u i l i b r i u m and o t h e r s t u d i e s of s y s t e m s i n which a l l o r p a r t o f t h e UF, h a s been r e p l a c e d by UF, a r e s t i l l b e i n g c a r r i e d o u t a s a p a r t o f t h e s t u d y o f t h e e f f e c t o f added r e d u c i n g a g e n t s and a s an a i d i n t h e i d e n t i f i - c a t i o n of c o r r o s i o n p r o d u c t s . A d d i - t i o n a l m a t e r i a l s h a v e been s y n t h e s i z e d t h a t c o n t a i n t r i v a l e n t u r a n i u m a n d seem t o b e i d e n t i c a l w i t h s p e c i e s p r o d u c e d d u r i n g c o r r o s i o n . I n t h e hope o f d e v e l o p i n g O t h e r and s u p e r i o r f u e l m i x t u r e s f o r f u t u r e a p p l i c a t i o n s , an e x t e n s i v e s t u d y o f p h a s e e q u i l i b r i a i n s y s t e m s c t a i n i n g l i t h i u m f l u o r i d e i s b e i n g c a r r i e d o u t . Some s t u d y o f UC1, s y s t e m s i s a l s o i n p r o g r e s s .

FUEL MIXTURES CONTA

L. M. B r a t c h e r C. J. B a r t o n M a t e r i a l s C h e m i s t r y D i v i s i o n

L i F - Z r F , - U F , . The L i F - Z r F , -UF, s y s t e m was i n v e s t i g a t e d w i t h UF, c o n -

c e n t r a t i o n s o f u p t o 4 5 m o l e % a n d ZrF, c o n c e n t r a t i o n s o f u p t o 5 0 m o l e %. The l o w e s t m e l t i n g p o i n t o l ~ s e r v e d was 440°C f o r t h e m i x t u r e c o n t , a i n i n g 68.5 mole % L i F , 2 6 . 5 mole % UI:,, and 5 . 0 m o l e % ZrF , . T h e r m a l h a l t s were n o t e d w i t h t h i s c o m p o s i t i o n , als w e l l a s w i t h o t h e r c o m p o s i t i o n s n e a r l y t h e s a m e , a t a b o u t 400 t o 415°C; h o w e v e r , i t c a n n o t b e a s c e r t a i n e d d e f i n i t e l y from t h e d a t a t h a t h a v e been o b t a i n e d w h e t h e r t h i s e f f e c t i s d u e t o a e u t e c t i c o f unknown c o m p o s i t i o n o r t o a s o l i d t r a n s i t i o n .

K F - L i F - B e F , - U F , . The e f f e c t on t h e m e l t i n g p o i n t o f v a r y i n g t h e UI: c o n - c e w t r a t i o n o f one c o m p o s i t i o n i n t h e K F - L i F - B e F , -UF, s y s t e m h a :3 b e e n d e t e r m i n e d , The d a t a show t h a t when UF, i s added t o t h e 40% BeF,, 20% KF, a n d 20% L i F m i x t u r e t h e m e l t i n g p o i n t g o e s t h r o u g h a minimum a t a l o w c o n - c e n t r a t i o n o f UF, and then r ises r a t h e r r a p i d l y w i t h i n c r e a s i n g UF, c o n c e n - t r a t i o n . The t h e r m a l e f f e c t n o t e d a t 330 t o 340°C may i n d i c a t e t h e e x i s t e n c e o f a l o w - m e l t i n g - p o i n t e u t e c t i c i n t h e f o u r - c o m p o n e n t s y s t e m ; a g r e a t d e a l o f w o r k w i l l b e r e q u i r e d t o d e t e r m i n e t h e c o m p o s i t i o n o f t h e e u t e c t i c , The l o w e s t m e l t i n g t e m p e r a - t u r e o b s e r v e d t o d a t e i s 38OOC a t 2 . 5 mole % o f UF,.

?

FUEL MIXTURES CONTAINING ThF, L. M. B r a t c h e r C. J . B a r t o n

Ma t e r i a1 s C h e m i s t r y D i v i s ion

O t h e r i n v e s t i g a t o r s ( ) h a v e shown t h a t t h e LiF-ThF, e q u i l i b r i u m d i a g r a m i s q u i t e s i m i l a r t o t h a t o f t h e LiF-UF, s y s t e m , a n d u n p u b l i s h e d d a t a o b t a i n e d i n t h i s l a b o r a t o r y i n d i c a t e d t h a t t h e BeF,-ThF, s y s t e m i s s i m i l a r t o t h e BeF,-UF, s y s t e m . S i n c e t h e LiF-BeF, b i n a r y i s common t o b o t h s y s t e m s , i t

( l ) J . 0 . Blomeke, An I n v e s t i g a t i o n o f ThF,- F u s e d S a l t S o l u t i o n s f o r H o m o g e n e o u s B r e e d e r R e a c t o r s , O R N L - 1 0 3 0 (June 19, 1951).

107

A N P P R O J E C T QUARTERLY PROGRESS REPORT

seemed r e a s o n a b l e t o assume t h a t t h e L i F - B e F , - T h F , e q u i l i b r i u m d i a g r a m would be comparab le t o t h e d i ag ram f o r t h e LiF-BeF,-UF4 s y s t e m d e s c r i b e d i n t h e p r e v i o u s r e p o r t . ( 2 ) T h e d a t a shown i n F i g . 9 . 1 c o n f i r m t h i s e x - p e c t a t i o n . The h i g h e r me1 t i n g p o i n t o f t h e LiF-ThF, e u t e c t i c (550°C com- p a r e d w i t h 490OC f o r L i F - U F , ) i s r e f l e c t e d i n t h e c o n t o u r s . A com- p o s i t i o n c o n t a i n i n g 5 mole % ThF,, 6 7 mole % L i F , a n d 28 m o l e 7% BeF, m e l t s

( 2 ) L . M . B r a t c h e r and C. J . B a r t o n , ANP Quar. Prog. Rep. D e c . 1 0 , 1 9 5 2 , OWL-1439, p. 105.

a t a p p r o x i m a t e l y 4 3 0 ° C . F r o m t h e l i m i t e d d a t a o b t a i n e d w i t h t h e l o w e r ThF, c o n c e n t r a t i o n s , i t a p p e a r s t h a t c o m p o s i t i o n s i n t h i s s y s t e m t h a t mel t b e l o w 4 0 0 ° C w i l l c o n t a i n a l o w c o n - c e n t r a t i o n o f ThF, a n d a h i g h concen- t r a t i o n o f BeF,.

FUEL MIXTURES CONTAINING UC1, R. J . S h e i l C. J. B a r t o n M a t e r i a l s C h e m i s t r y D i v i s i o n

The p r o b l e m o f o b t a i n i n g p u r e UC1, h a s n o t y e t b e e n c o m p l e t e l y s o l v e d . E f f o r t s t o p r e p a r e t h e p u r e m a t e r i a l

._

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F i g . 9 . 1 . The System L i F - B e F , - T h F , .

108

PERIOD ENDIIYG MARCH 1 0 , 1 9 5 3

b y s u b l i m a t i o n f r o m t h e a v a i l a b l e c r u d e UC1, h a v e n o t b e e n s u c c e s s f u l . S y n t h e s i s o f UC1, b y l i q u i d - p h a s e c h l o r i n a t i o n w i t h h e x a c h l o r o p r o p y l - e n e ( , ) h a s b e e n u s e d t o p r o v i d e m a t e r i a l f o r r e c e n t s t u d i e s . A l t h o u g h a n a l y t i c a l d a t a from which to e v a l u a t e t h i s m a t e r i a l a r e n o t y e t a v a i l a b l e , i t a p p e a r s t h a t t h e m a t e r i a l i s n o t o f g o o d q u a l i t y . T h e d a t a r e p o r t e d b r i e f l y below may t h e r e f o r e be r e v i s e d when p u r e r UC1, becomes a v a i l a b l e .

N a C 1 - U C I , . Thermal d a t a on 18 com- p o s i t i o n s i n t h e NaC1-UC1 s y s t e m have b e e n r e p o r t e d by K r a u s . 4 , ) H e c o n - c l u d e d , on t h e b a s i s o f t h e d a t a o b t a i n e d f r o m c o o l i n g c u r v e s , t h a t t h e compound 2NaCl.UC1, was t h e o n l y compound f o r m e d i n t h i s s y s t e m a n d t h a t i t m e 1 t e d i n c o n g r u e n t l y a t 4 3 0 rt 5 ° C . I t a l s o a p p e a r e d f r o m h i s d a t a t h a t t h e r e was o n l y o n e e u - t e c t i c , which m e l t e d a t 370 f 5°C. The p r e s e n t , i n c o m p l e t e i n v e s t i g a t i o n seems t o show t h e e x i s t e n c e o f two e u t e c t i c s and two compounds i n t h i s sys tem. The f i r s t e u t e c t i c i s b e l i e v e d t o b e a t a b o u t 3 0 m o l e % U C l , , a n d i t a p p e a r s t o m e l t a t 4 2 0 rt 1 0 ° C . O n e o f t h e c o m p o ~ n d s , Na2UC1,, i s b e l i e v e d t o m e l t c o n g r u e n t l y a t 440 + 10°C. The s e c o n d e u t e c t i c i s b e l i e v e d t o b e a t a p p r o x i m a t e l y 45 mole % UCl, , a n d i t a p p e a r s t o m e l t a t 37OoC, i n good a g r e e m e n t w i t h K r a u s ' r e s u l t s . I n t h e 6 5 t o 9 0 m o l e % UC1, r a n g e , a s e r i e s o f b r e a k s a t 420 rt 10°C p r o b a b l y r e p r e s e n t s t h e i n c o n g r u e n t m e l t i n g p o i n t o f a compound s u c h a s NaU2C1, or NaU3C1 3 . T h e p u r e compound h a s n o t y e t b e e n p r e p a r e d , a n d i t c a n n o t b e d e f i n i t e l y i d e n t i f i e d o n t h e b a s i s of i n f o r m a t i o n a v a i l a b l e a t t h i s t i m e .

rmal d a t a on 1 4 com- p o s i t i o n s i n t h e KC1-UC1, s y s t e m , i n t h e 2 0 t o 7 e % UC1, r a n g e , h a v e a l s o been r e p o r t e d by K r a u s . ( , ) These

K C 4.'

( 3 ) B . M . Pitt e t a l . , The P r e p a r a t i o n of T C l , w i t h H e r a c h l o r o p r o p y l e n e , C-2.350.3 ( J u l y 2 7 , 1945).

("C. A. K r a u s , P h a s e D i a g r a m of Some Complex S a l t s of U r a n i u m w i t h H a l i d e s of t h e A l k a l i and A l k a l i n e E a r t h M e t a l s , M-251 ( J u l y 1, 1943).

d a t a s h o w e d t h a t t h e r e was o n e compound, K2UC1,, which m e 1 t e d c o n g r u e n t l y a t 6 5 0 rt 5"C, and two e u t e c t i c s i n t h e s y s t e m . The KCL-K2UC1, e u t e c t i c w a s s t a t e d t o b e a t 2 5 mole % UCll,, a n d i t s m e l t i n g p o i n t w a s g i v e n a s 5 6 0 + 5°C; t h e K2UC1 ,-UCl, e u t e c t i c was i n d i c a t e d t o be a t 5 3 m o l e % UC1 , a n d i t s m e l t i n g p o i n t was 3 5 0 k 5 C. The rma l d a t a a n d p e t r o g r a p h i c e x a m i n a t i o n o f t h e s o l i d p h a s e s show s t r o n g e v i d e n c e f o r t h e e x i s t e n c e o f t h r e e compounds a n d t h r e e e u t e c t i c s i n t h i s s y s t e m . The p r e s e n t r e s u l t s a r e i n f a i r a g r e e - m e n t w i t h t h o s e o f K r a u s o n t h e l o c a t i o n a n d m e l t i n g p o i n t o f t h e KC1-K2UC1, e u t e c t i c , t h e m e l t i n g p o i n t o f K2UC1,, a n d t h e m e l t i n g p o i n t o f t h e h i g h e r e u t e c t i c . H o w e v e r , i t a p p e a r s t h a t a K2UC1,-KUClS e u t e c t i c w i t h 4 2 . 5 k 2 . 5 m o l e % UC1, o c c u r s i n t h i s s y s t e m a n d t h a t i t m e l t s a t 3 2 0 k 1 0 ° C . T h e c o m p o u n d KUC1, p r o b a b l y m e l t s c o n g r u e n t l y , b u t a r e l i a b l e v a l u e f o r i t s m e l t i n g p o i n t h a s n o t y e t been o b t a i n e d . The t h e r m a l e v i d e n c e f o r t h e e x i s t e n c e o f a com- p o u n d w i t h m o r e t h a n 1 mole % UC1, p e r m o l e o f KC1 i s a s e r i e s o f b r e a k s i n t h e 7 0 t o 85 mole % UC1, r e g i o n a t 400 rt 5°C. The the rma l e f f e c t a t t h i s t e m p e r a t u r e may i n d i c a t e t h e i n c o n g r u e n t m e l t i n g p o i n t o f t h i s c o m p o u n d o f unknown c o m p o s i t i o n . A s m e n t i o n e d i n t h e s e c t i o n on NaC1-UCl,, a n d i n l i n e w i t h e x p e r i e n c e w i t h f l u o r i d e stys t e m s , i t h a s been found r a t h e r d i f f i c u l t t o p r e p a r e i n c o n g r u e n t l y m e 1 t i n g compounds i n s u f f i c i e n t l y p u r e s t a t e t o p e r m i t t h e i r p o s i t i v e i d e n t i f i ca t i o n . T h e c o m p o s i t i o n o f t h e KUC1, -KUI: C l 4 * + e u t e c t i c h a s n o t b e e n a c c u r a t e l y d e t e r m i n e d .

04

F U E L - M I X T U R E S C O N T A I N I N G U F ,

V. S. Coleman C. J . B a r t o n Ma t e r i a l s Ch e m i s t r y D i v i s i on

Work on t h e NaF-UF, a n d KF-UF3 s y s t e m s h a s n o t y e t r e v e a l e d com- p o s i t i o n s t h a t m e l t b e l o w 7 0 0 a n d 680°C, r e s p e c t i v e l y . C o m p l i Ica t i o n s

109


f r o m UO, a n d UF, i n t h e m e l t s h a v e been minimized by u s i n g a l k a l i f l u o r i d e s t h a t h a v e b e e n t r e a t e d w i t h HF a t h i g h t e m p e r a t u r e s a n d b y m i n i m i z i n g t h e t o p t e m p e r a t u r e t o which t h e m e l t i s h e a t e d t o d e c r e a s e d i s p r o p o r t i o n a - t i o n o f t h e UF,.

T h e s e s y s t e m s a r e s t u d i e d , a t p r e s e n t , i n n i c k e l c a p s u l e s w e l d e d u n d e r a n a r g o n a t m o s p h e r e . T h e e x a m i n a t i o n i s h a m p e r e d b e c a u s e t h e KF-UF, compounds decompose r e a d i l y i n t h e l a b o r a t o r y a i r . P e t r o g r a p h i c e x a m i n a t i o n i s a c c o m p l i s h e d by g r i n d i n g t h e m a t e r i a l i n a d r y , i n e r t a t m o s p h e r e a n d t r a n s f e r r i n g i t t o m i c r o s c o p e s l i d e s u n d e r o i l . Al though t h e t h e r m a l d a t a a r e a s y e t i n c o n c l u s i v e , i t a p p e a r s t h a t t h e compound f o r m e d i n NaF- b e a r i n g m e 1 t s i s 3NaF-2UF3.

A D D I T I O N O F R E D U C I N G A G E N T S T O A R E F U E L

J . D. Redman V. S. Coleman L. G. O v e r h o l s e r D . C. Hoffman K. J. K e l l y F. F. B l a n k e n s h i p

M a t e r i a l s C h e m i s t r y D i v i s i o n

D e c r e a s e d c o r r o s i o n o f I n c o n e l i n t h e r m a l c o n v e c t i o n l o o p s h a s b e e n d e m o n s t r a t e d t o r e s u l t f r o m s m a l l a d d i t i o n s o f N a K , Z r H z , o r Z r " t o f l u o r i d e m i x t u r e s o f i n t e r e s t a s ARE f u e l s . When t h e s e r e d u c i n g a g e n t s a r e a d d e d i n l a r g e q u a n t i t i e s t o m a t e r i a l s c o n t a i n i n g UF,, t h e y p r o d u c e UF,, w h i c h i s o n l y s p a r i n g l y s o l u b l e i n t h e m e l t a t 600°C. T h e r e f o r e t h e r e a c t i o n s o f p o s s i b l e ARE f u e l s w i t h v a r i o u s r e d u c i n g a g e n t s h a v e b e e n s t u d i e d i n a n e f f o r t t o d i s c o v e r a s a f e u p p e r l i m i t t o t h e amount o f such a d d i ti ves .

P r e v i o u s e x p e r i m e n t s h a d d e m o n - s t r a t e d t h a t a d d i t i on o f s u f f i c i e n t r e d u c t a n t r e s u l t e d i n s e p a r a t i o n o f UF, a s a d i s c r e t e ' p h a s e , w h i c h c o u l d b e r e m o v e d by f i l t r a t i o n a t 6 0 0 ° C . T h e r e s u l t i n g f i l t r a t e s r e v e a l e d n o t r a c e o f t h e e a s i l y d e t e c t a b l e UF, a f t e r s o l i d i f i c a t i o n , b u t t h e y showed c o n s i d e r a b l e q u a n t i t i e s o f v a r i o u s

c o m p l e x compounds o f UF,. I d e n t i c a l m i x t u r e s ( w i t h t h e s a m e r e d u c i n g a g e n t s ) t h a t were n o t f i l t e r e d showed c o n s i d e r a b l e q u a n t i t i e s o f UF,. I f a s u f f i c i e n t l y s m a l l q u a n t i t y o f r e d u c i n g a g e n t w a s a d d e d s o t h a t n o UF, c o u l d b e f i l t e r e d a t 600"C, t h e r e w a s n o UF, d e t e c t e d i n t h e c o o l , s o l i d i f i e d m a t e r i a l .

V a r i o u s ZrF4 - b e a r i n g m i x t u r e s , w i t h a n d w i t h o u t a d d e d U F , , h a v e b e e n e q u i l i b r a t e d w i t h p r e d e t e r m i n e d s m a l l q u a n t i t i e s o f NaK ( 7 8 w t % K ) , Z r H , , and Zr" i n s e a l e d c a p s u l e s o f I n c o n e l by r o c k i n g f o r 16 h r a t 4 cpm w i t h t h e ends o f t h e c a p s u l e s a t 800 and 650°C, r e s p e c t i v e l y . The c a p s u l e s were th:n h e a t e d a t 800°C i n a v e r t i c a l p o s i t i o n f o r 2 t o 6 h r t o p e r m i t s e t t l i n g o f i n s o l u b l e m a t e r i a l a n d , e s p e c i a l l y , u n r e a c t e d r e d u c i n g a g e n t . C o o l e d s a m p l e s were s e c t i o n e d l o n g i t u d i n a l l y f o r p e t r o g r a p h i c e x a m i n a t i o n .

T h e u p p e r t o l e r a n c e l i m i t s i n number o f e q u i v a l e n t s ( o n e e q u i v a l e n t i s t h e q u a n t i t y o f r e d u c t a n t n e e d e d t o r e d u c e a l l UF, t o UF,) a r e l i s t e d i n T a b l e 9 .1 .

R e d u c i n g a g e n t s added t o NaZrF5 i n a m o u n t s i n e x c e s s o f 0 . 2 w t % showed opaque nonmagnet ic m a s s e s , and c h e m i c a l and x - r a y t e s t s i n d i c a t e d t h e m a t e r i a l t o b e , a t l e a s t i n p a r t , Z r " . Appar- e n t l y , t r i v a l e n t z i r c o n i u m d o e s n o t e x i s t i n f l u o r i d e m e l t s u n d e r t h e s e

c .

c

c i r c u m s t a n c e s . V e r i f i c a t i o n o f t h e t o l e r a n c e v a l u e s

f o r Z r H , i n t h e ARE f u e l m i x t u r e h a s been o b t a i n e d b y e q u i l i b r a t i o n o f ZrH, w i t h t h e f u e l m i x t u r e a t 8 0 0 ° C i n n i c k e l e q u i p m e n t , f o l l o w e d by e q u i l i - b r a t i o n a t 600°C and f i l t r a t i o n o f t h e r e s u l t i n g m e l t a t 6 0 0 ° C t h r o u g h s i n t e r e d n i c k e l . T h e d a t a o b t a i n e d b y c h e m i c a l a n a l y s i s o f t h e f i l t r a t e and by p e t r o g r a p h i c e x a m i n a t i o n of t h e f i l t e r e d r e s i d u e a r e shown i n T a b l e 9.2.

The d a t a i n d i c a t e t h a t n o s o l i d m a t e r i a l e x i s t s i n t h e l i q u i d a t 600°C i f l e s s t h a n 0 . 9 w t % Z r H , i s a d d e d t o t h e m i x t u r e . A g r e e m e n t b e t w e e n t h e da: ta s h o w n i s p r o b a b l y

L

*

110


FLUORIDE USED

w i t h i n t h e e r r o r of s u c h e x p e r i m e n t s . The f a i l u r e t o o b s e r v e UF,, a s s u c h , i n any o f t h e f i l t r a t e s a f f o r d s con- f i r m a t i o n o f t h e a s s u m p t i o n s u s e d t o i n t e r p r e t t h e p r e v i o u s d a t a .

When s m a l l q u a n t i t i e s (up t o a b o u t 0 . 4 e q ) o f r e d u c i n g a g e n t a r e a d d e d , an olive-drab phase ( a v e r a g e r e f r a c t i v e i n d e x of 1 .558) o c c u r s i n t h e NaF-ZrF4- UF, m i x t u r e s .

R e d u c i n g a g e n t s a d d e d t o compo- s i t i o n s i n t h e NaF-ZrF , -UF , s y s t e m p roduced an o l i v e - d r a b p h a s e ( a v e r a g e

AMOUNT TOLERABLE

NaK ZrH, Z r o

r e f r a c t i v e i n d e x o f 1 . 5 5 8 ) a t t h e 0 . 2 - e q c o n c e n t r a t i o n . The q u a n t i t y o f o l i v e - d r a b p h a s e g e n e r a l l y i n c r e a s e d u p o n a d d i t i o n o f 0 . 4 e q of r e d u c i n g a g e n t . W i t h l a r g e r a d d i t i o n s o f r e d u c i n g a g e n t , a d e c r e a s e i n t h e o l i v e - d r a b p h a s e was o b s e r v e d , , a l o n g w i t h an i n c r e a s e i n t h e r e d - o r a n g e p h a s e ( U F 3 * 2 Z r F 4 ) . S y n t h e s i s a n d p e t r o - g r a p h i c e x a m i n a t i o n h a v e i n d i c a t e d t h a t t h e o l i v e - d r a b p h a s e may b e UF3-2ZrF4, i n w h i c h t e t r a v a l e n t uranium h a s b e e n p a r t i a l l y s u b s t i t u t e d f o r

NaZrF5

NaF-Zr F, -UF4 (46-50-4 mole %)

NaF-ZrF4-UF, (50-46-4 mole %)

L

E q u i v a l e n t

0.6

0 . 4

W e i g h t % E q u i v a l e n t . W e i g h t % E q u i v a l e n t W e i g h t %

0 . 5

'Hydrogen c o n s i d e r e d n e u t r a l i n c a l c u l a t i o n of e q u i v a l e n t w e i g h t .

f

TABLE 9.2. DATA OBTAINED BYCHEMICAL ANALYSIS AND PETROGRAPHIC EXAMINATION OF ARE FUEL* AFTER TREATMENT WITH ZrH,

0 . 8 0 . 7 1 . 2 1 1 . 0

Z r H , ADDED ( w t sa)

0

0.2 0.5 0 . 7

0.9 1.0 1 .5

1.5

URANIUM CONTENT O F F I L T R A T E

( w t % )

8.62

8.72 8 .68 8.65

6.58 7.12 5.95

8 .64

PETROGRAPHIC O B S E R V A T I O N S

Uranium r e d u c t i o n o c c u r r e d ; no d i s c r e t e UF, obse rved

UF, found on f i l t e r and i n r e a c t i o n chamber

P r e s e n c e of Z r O z i n d i c a t e d an oxygen l e a k

*NaF-ZrF4-UF4 (50 -46 -4 mole Sf.

111


t r i v a l e n t u r a n i urn. P e t r o g r a p h i c e x a m i n a t i o n s r e v e a l e d t h a t UF,-UF,- 4ZrF, was an o l i v e - d r a b , p l e o c h r o i c p h a s e , w i t h a n a v e r a g e r e f r a c t i v e i n d e x o f 1 . 5 6 4 , a b i r e f r i n g e n c e o f a b o u t 0 , 0 0 8 , a n d a n o p t i c a n g l e o f 80 d e g r e e s . A n o t h e r o l i v e - d r a b m a t e r i a l ( r e f r a c t i v e i n d e x o f 1 . 5 7 4 ) was o b t a i n e d when t h e s e m a t e r i a l s were mixed t o c o r r e s p o n d t o UF3-3UF,- 8ZrF4. A m i x t u r e c o r r e s p o n d i n g t o 3 U F 3 - U F , - 8 Z r F 4 p r o d u c e d s t r i a t e d c r y s t a l s of o l i v e - d r a b and r e d - o r a n g e m a t e r i a l s .

T h e 5 0 m o l e % NaF c o m p o s i t i o n d e v e l o p e d f r e e UF, upon a d d i t i o n o f 1 . 2 e q of Z r o o r ZrH, . The 46 mole % NaF c o m p o s i t i o n formed f r e e UF, upon t h e a d d i t i o n o f 1 . 6 e q Z r " o r Z r H , . The u s u a l o l i v e - d r a b and o r a n g e - r e d p h a s e s w e r e o b s e r v e d i n t h e s e com- p o s i t i o n s w i t h l e s s t h a n 1 . 2 e q o f r e duc t a n t s .

It was n o t e d t h r o u g h o u t t h i s s t u d y t h a t t h e 4 6 m o l e % NaF, 5 0 m o l e % ZrF,, 4 m o l e % UF, c o m p o s i t i o n t o l e r - a t e d s l i g h t l y more r e d u c t i o n w i t h o u t p r e c i p i t a t i n g UF, t h a n d i d t h e 50 mole % NaF, 46 mole % ZrF, , 4 mole % UF, c o m p o s i t i o n . F u r t h e r , i t w a s n o t e d t h a t b o t h c o m p o s i t i o n s a r e more t o l e r a n t t o Z r " and ZrH, t h a n t o NaK. These o b s e r v a t i o n s s u p p o r t t h e mecha- n i s m s u g g e s t e d p r e v i o u s l y , ( 5 ) w h i c h p o s t u l a t e s t h a t NaF and UF, c o m p e t e f o r t h e ZrF, p r e s e n t . T h e N a ( K ) F fo rmed by t h e NaK r e d u c t i o n r e a c t i o n i s c a p a b l e o f b r e a k i n g t h e U F 3 * 2 Z r F 4 c o m p l e x t o f o r m N a ( K ) Z r F 5 a n d f r e e UF,. On t h e o t h e r h a n d , ZrF, f o r m e d by t h e Z r " o r Z r H z r e d u c t i o n r e a c t i o n i s c a p a b l e o f c o m p l e x i n g m o r e UF,. T h i s s u g g e s t s t h a t a f l u o r i d e com- p o s i t i o n w i t h a Z r F , - t o - N a F r a t i o l a r g e r t h a n u n i t y would b e d e s i r a b l e i f o n l y b e c a u s t o f i t s c a p a c i t y t o complex UF,.

("F. F . B l a n k e n s h i p , D . C. H o f f m a n , K . J . K e l l y , a n d T. N. McVay, A N P Q u a r . P r o g . R e p . D e c . 10, 1 9 5 2 , ORNL-1439, p . 1 1 9 .

COOLANT DEVELOPMENT

L. M. B r a t c h e r C. J . B a r t o n M a t e r i a l s Chemis t ry D i v i s i o n

L i F - Z r F , . S t u d y o f t h e L i F - Z r F , s y s t e m , m e n t i o n e d i n t h e p r e v i o u s p r o g r e s s r e p o r t , ( ) h a s been c o n t i n u e d by t h e r m a l a n a l y s i s a n d b y p e t r o g r a p h i c and x- r a y - d i f f r a c t i on e x a m i n a t i o n o f s o l i d i f i e d m e l t s . Al though Li,ZrF6 i s t h e o n l y c o m p o u n d t h a t h a s b e e n p o s i t i v e l y i d e n t i f i e d , t h e r e i s some e v i d e n c e f o r one a d d i t i o n a l compound w i t h l e s s t h a n 33 mole % ZrF, and one w i t h more t h a n 50 mole % ZrF,.

C s F - Z r F , . B o t h Cs,ZrF, and CsZrFS have b e e n i d e n t i f i e d by p e t r o g r a p h i c e x a m i n a t i o n o f m e l t s i n t h e CsF-ZrF, s y s t e m , and t h r e e e u t e c t i c s have b e e n shown t o e x i s t . The l o w e s t - m e l t i n g - p o i n t ( 4 1 2 f. 10°C) e u t e c t i c c o n t a i n s a b o u t 40 mole % ZrF,. F u r t h e r work i s i n p r o g r e s s t o c o m p l e t e t h e e q u i - l i b r i u m d i a g r a m f o r t h e s y s t e m .

KF-L i F - Z r F , . The KF- L i F- Z r F, sys t em h a s been examined o v e r a ZrF, concen- t r a t i o n r a n g e o f 5 t o 6 0 m o l e %. A t e r n a r y e u t e c t i c m e l t i n g a t a b o u t 3 8 5 ° C a p p e a r s c l o s e t o t h e KF-ZrF, e u t e c t i c . T h e e x a c t c o m p o s i t i o n o f t h i s e u t e c t i c h a s n o t y e t been e s t a b - l i s h e d .

Me 1 t i n g - p o i n t de t e r - m i n a t i o n s h a v e b e e n made f o r com- p o s i t i o n s i n t h e RbF-LiF-ZrF, s y s t e m t h a t h a v e 5 t o 60 m o l e % ZrF,. The r e s u l t s were s i m i l a r t o t h o s e o b t a i n e d w i t h KF-LiF-ZrF, m i x t u r e s . The l o w e s t m e l t i n g p o i n t shown t o d a t e was 370°C f o r a m i x t u r e c o n t a i n i n g 45 mole % RbF, 45 m o l e % Z r F , , a n d 1 0 m o l e % L i F ; t h i s c o m p o s i t i o n i s p r o b a b l y c l o s e t o a t e r n a r y e u t e c t i c . T h e r m a l e f f e c t s a t a b o u t 550°C were o b s e r v e d w i t h a number of c o m p o s i t i o n s i n t h i s r e g i o n . T h e s e e f f e c t s a r e b e l i e v e d t o b e d u e t o t h e p r e s e n c e i n t h e f u s e d m i x t u r e o f c o m p l e x o x y f l u o r i d e s t h a t may r e s u l t f rom t h e h y g r o s c o p i c n a t u r e of t h e RbF.

R b F -L i F - ZrF, .

( 6 ) L . M. B r a t c h e r and C. J . B a r t o n , ANP Q u a r . P r o g . R e p . D e c . I O , 1 9 5 2 , ORNL-1439, p. 1 1 3 .

112


K F - L i F - B e F , . T h e d a t a o b t a i n e d t h u s f a r w i t h c o m p o s i t i o n s i n t h e 4 t o 5 7 m o l e % B e F , r ange o f t h e KF-LiF-BeF, s y s t e m s e e m t o i n d i c a t e t h a t o n l y s l i g h t l o w e r i n g of t h e m e l t i n g p o i n t r e s u l t s f r o m t h e a d d i t i o n o f KF t o LiF-BeF, m i x t u r e s . The l o w e s t m e l t i n g p o i n t t h a t h a s been c o n f i r m e d by b o t h h e a t i n g and c o o l i n g c u r v e s i s 3 5 0 ° C f o r t h e m i x t u r e w i t h 54 m o l e % BeF2 , 10 mole % KF, and 36 mole % L i F , and i t i s o n l y s l i g h t l y l o w e r t h a n t h e m e l t i n g p o i n t (365OC) o f t h e 50 mole % LiF, 50 mole % BeF, c o m p o s i t i o n .

P R O D U C T I O N AND P U R I F I C A T I O N O F F L U O R I D E M I X T U R E S

F. F. B l a n k e n s h i p G. J. N e s s l e M a t e r i a l s Chemis t ry D i v i s i o n

H. W. Savage , Ai" D i v i s i o n

S t u d y o f t h e h y d r o g e n a t i o n - h y d r o - f l u o r i n a t i o n p r o c e d u r e p r e v i o u s l y d e s c r i b e d ( ' ) f o r f u e l p r e p a r a t i o n h a s been c o n t i n u e d on l a b o r a t o r y and p i l o t s c a l e s . O p e r a t i n g c o n d i t i o n s t o p r o v i d e optimum p u r i t y of t h e m o l t e n m i x t u r e s a r e now r e a s o n a b l y w e l l d e f i n e d .

C o n s t r u c t i o n o f t h e p r o d u c t i o n - s c a l e equ ipmen t f o r p r o d u c i n g 3000 l b o f ARE f u e l s o l v e n t (NaZrF5) h a s b e e n d e l a y e d t o s o m e e x t e n t b y l a c k o f manpower. T h i s e q u i p m e n t s h o u l d be a v a i l a b l e f o r t e s t i n g e a r l y i n A p r i l , and t h e m a t e r i a l s h o u l d be p r e p a r e d d u r i n g May and June . A l l raw m a t e r i a l s f o r t h i s o p e r a t i o n have been r e c e i v e d , a n d c h e m i c a l a n d s p e c t r o g r a p h i c a n a l y s e s o f e a c h b a t c h i n d i c a t e t h a t t h e m a t e r i a l s a r e o f s a t i s f a c t o r y p u r i t y .

Laboratory-Scale Fuel Preparation. (C. M. B lood , F. P. Boody, R. E . Thoma, J r . , M a t e r i a l s C h e m i s t r y D i v i s i o n ) . C o r r o s i o n b y s e l e c t i v e r e m o v a l o f c h r o m i u m f r o m I n c o n e l i n f l u o r i d e m e l t s may o c c u r by a n y c o m b i n a t i o n o f s e v e r a l mechanisms. T h r e e o f t h e

( 7 ) F . F. B l a n k e n s h i p and G. J . N a s s l e . ANP Quar. P r o g . R e p . D e c . 1 0 . 1 9 5 2 , ORNL-1439. p. 122.

most l i k e l y of t h e s e p r o c e s s e s a r e :

Cr" + 3UF, CrF, + 3UF3 ; ( 1 )

( 2 1 d 2Cr" + 3HF 2CrF, + 3H, ; - and 2Cr" + 3NiF2 3Ni0 + 2CrF, , 2Cr0 + 3FeF, - 3Fe0 + 2CrF, , ( 3 ) - Cr" + FeF, f-- Feo + CrF, .

A d d i t i o n o f t h e s t r o n g r e d u c i n g a g e n t Z r H , w o u l d b e e x p e c t e d t o m i n i m i z e t h e c o r r o s i o n , r e g a r d l e s s o f w h i c h mechanism was e f f e c t i v e .

C o r r o s i o n by t h e f i r s t m e c h a n i s m c a n be m i n i m i z e d by r e d u c t i o n of UF, t o UF, by some r e d u c t a n t s u c h (3s ZrH, t o t h e e x t e n t t o l e r a b l e w i t h o u t e x c e s s i v e d e t e r i o r a t i o n o f t h e p h y s i c a l p r o p e r t i e s of t h e f u e l . C o r r o , s i o n by t h e o t h e r mechanisms c a n , i n p r i n c i p l e , be e l i m i n a t e d by t h e p r o p e r t e c h n i q u e s f o r removing t h e r e a g e n t m a t e r i a l s .

The h y d r o g e n a t i o n - h y d r o f l u o r i n a t i o n p r o c e s s f o r f u e l p u r i f i c a t i o n w a s o r i g i n a l l y c h o s e n a s t h e o n e m o s t l i k e l y t o p r o d u c e v e r y p u r e f l u o r i d e l i q u i d s . The s c h e d u l e f o r t h i s p r o c e s s was p r e s c r i b e d t o p r o v i d e w h a t was c o n s i d e r e d t o b e l a r g e e x c e s s e s o f t i m e f o r r e a c t i o n a n d s t r i p p i n g a t e a c h s t a g e . I n r e c e n t e x p e r i m e n t s , a t t e m p t s were made t o q u a n t i t a t i v e l y e v a l u a t e t h e c h e m i c a l c h a n g e s d u r i n g each p r o c e s s s t a g e . The need f o r s u c h d a t a i s obvious . Incomple t e t r e a t m e n t a t a n y s t a g e i s r e f l e c t e d b y p o o r c o r r o s i o n c h a r a c t e r i s t i c s ; h o w e v e r , l o n g t r e a t m e n t t i m e s a r e u n e c o n o m i c a l i n terms of equipment l i f e , p r o d u c t i o n r a t e , m a t e r i a l consumed, and manpower r e q u i r e d a n d , i n a d d i t i o n , r e s u l t i n s l i g h t a l t e r a t i o n i n f u e l c o m p o s i t i o n because of v o l a t i l i z a t i o n of t h e ZrF,.

S t r i p p i n g w i t h i n e r t g a s s h o u l d s e r v e a s a r a p i d and r e a s o n a b l y com- p l e t e method f o r r e m o v i n g HF, b e c a u s e t h e a c i d f l u o r i d e s a r e u n s t a b l e a t t e m p e r a t u r e s above 500°C. S i n c e a n y r e s i d u a l HF s h o u l d l e a d t o e n h a n c e d c o r r o s i o n , t h e p r o g r e s s o f HF removal

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h a s b e e n s t u d i e d i n t e n s i v e l y b y a n a l y z i n g t h e e x i t g a s s t r e a m f o r HF.

I n i t i a l e x p e r i m e n t s r e v e a l e d t h a t p l o t s of t h e l o g a r i t h m o f HF c o n c e n - t r a t i o n i n t h e h e l i u m v s . vo lume o f he l ium p a s s e d were e s s e n t i a l l y l i n e a r , w i t h h a l f - l i f e volumes be tween 40 and 70 l i t e r s when 0 . 5 t o 1 . 2 l i t e r s / m i n o f h e l i u m was p a s s e d t h r o u g h a b o u t 1 l i t e r ( 3 k g ) o f t h e m e l t . From t e s t s o f t h e s t r i p p i n g o f t h e HF by He, i t may be c o n c l u d e d t h a t t y p i c a l b a t c h e s o f f u e l p r e p a r e d by t h e s t a n d a r d p r o c e d u r e d e s c r i b e d p r e v i o u s l y s h o u l d have been s t r i p p e d t o a b o u t lo ' , mole of HF p e r l i t e r of He and s h o u l d have c o n t a i n e d a b o u t 1 0 ppm o f HF i n t h e me l t . The re i s no d e t e c t a b l e d i f f e r e n c e i n s t r i p p i n g r a t e w i t h He be tween t h e NaZrF, and t h e NaF-ZrF,-UF, m i x t u r e c o n t a i n i n g 4 mole % U F , . The e f f e c t o f f l o w r a t e on a t t a i n m e n t o f e q u i - l i b r i u m v a p o r c o n c e n t r a t i o n h a s been o n l y p a r t l y e x p l o r e d .

When h y d r o g e n i s used t o sweep t h e m e l t a f t e r p a s s a g e o f HF, t h e a c i d c o n t e n t of t h e e f f l u e n t g a s i s c o n - s i d e r a b l y h i g h e r t h a n when h e l i u m i s u s e d . T h e f o l l o w i n g r e a c t i o n s a r e a lmos t c e r t a i n l y r e s p o n s i b l e :

NiF, + H, + N i " + 2HF, AFolooooK = -65 kcal , 2FeF3-+ H, + 2FeF, + 2HF, & o l O O O ~ K = -31.5 kcal , FeF, + H, + Feo + 2HF, ~ o l o o o ~ K = 1 . 5 kcal , ZUF, + H, + ZUF, + ZHF, ~ o l o o o o K = 22.0 kcal .

I n t r e a t m e n t of NaZrF, w i t h hydrogen a t 800°C h a l f - l i f e v o l u m e s o f a b o u t 70 l i t e r s a r e f o u n d . S i n c e m o s t o f t h e s e e x p e r i m e n t s a r e p e r f o r m e d i n n i c k e l c o n t a i n e r s , a p p r e c i a b l e amounts t h e HF r e s u l t from r e d u c t i o n of NiF,.

I n s t r i p p i n g o f t h e ARE f u e l m i x t u r e w i t h H, , t h e c o n t r a s t b e t w e e n H e and H, i s e v e n more n o t i c e a b l e . When H, i s u s e d , t h e HF c o n t e n t o f t h e g a s d r o p s s h a r p l y , a s e x p e c t e d , b u t i t l e v e l s o f f a t a b o u t l o e 4 mole HF p e r l i t e r of H,. The r e d u c t i o n of UF, t o UF, i n t h e s o l i d s t a t e i s c o n s i d e r e d n e g l i g i b l e below 900°C. However, UF,

h a s been shown by p e t r o g r a p h i c t e c h - n i q u e s t o b e p r e s e n t i n A R E f u e l b a t c h e s a f t e r p r o l o n g e d H, t r e a t m e n t a t 700 t o 800OC. T h e r e seems t o b e n o d o u b t t h a t t h e h i g h v a l u e s f o r HF i n t h e e x i t g a s a r e a c o n s e q u e n c e o f t h i s r e a c t i o n . From t h e r a t e o f HF e v o l u t i o n , it a p p e a r s t h a t t h e r a t e o f r e d u c t i o n i s a b o u t 3% o f t h e UF, p r e s e n t p e r hour .

F i l t r a t i o n o f t h e m e l t a f t e r h y d r o g e n t r e a t m e n t and HF s t r i p p i n g s e r v e s t o r e d u c e t h e n i c k e l c o n t e n t o f t h e f u e l b a t c h t o l e s s t h a n 1 5 0 ppm. I t h a s n o t b e e n p o s s i b l e , t o d a t e , t o b r i n g t h e i r o n c o n t e n t o f t h e m e l t t o s u c h a l o w l e v e l . I t a p p e a r s , however , t h a t l o w v a l u e s f o r N i F , , F e F , , a n d HF c a n b e a c h i e v e d w i t h o u t e x c e s s i v e e x p o s u r e t i m e s and w i t h o u t undue r e d u c t i o n of t h e UF,.

P i l o t - S c a l e Fuel P u r i f i c a t i o n (G. J . N e s s l e , J . E. E o r g a n , M a t e r i a l s C h e m i s t r y D i v i s i o n ) . D u r i n g t h e p a s t q u a r t e r , a t o t a l o f 3 2 6 . 4 kg o f mixed f l u o r i d e s , c o m p r i s i n g 24 s m a l l b a t c h e s of a p p r o x i m a t e l y 2 kg e a c h and 11 l a r g e b a t c h e s o f a p p r o x i m a t e l y 25 kg e a c h , h a s b e e n p r o c e s s e d b y t h e g r o u p i n B u i l d i n g 9 9 2 8 a n d d i s p e n s e d t o r e - q u e s t i n g p e r s o n n e l i n t h e ANP D i v i s i o n . H e a t i n g t h e c o n t r o l p a n e l s t o 125°F h a s r e s u l t e d i n marked improvement i n t h e s m o o t h n e s s a n d e f f i c i e n c y o f o p e r a t i o n . T h e a d d i t i o n o f t w o p r e s s u r e g a g e s , o n e d i r e c t l y on t h e r e a c t o r c a n and one d i r e c t l y on t h e r e c e i v e r c a n , h a s e l i m i n a t e d t h e d i f f i c u l t y i n d i s c o v e r i n g p o s s i b l e d a n g e r p o i n t s , a n d m i n o r f a i l u r e s d u r i n g a r u n a r e now p r a c t i c a l l y n o n e x i s t e n t .

The p r o c e s s f o r t r e a t m e n t o f mixed f l u o r i d e s h a s been m o d i f i e d t o p e r m i t 1 . 5 h r o f s t r i p p i n g w i t h H, and 1 . 5 h r o f s t r i p p i n g w i t h He a f t e r t h e HF t r e a t m e n t and b e f o r e t r a n s f e r o f t h e mol ten f l u o r i d e s . A g a s t h r o u g h p u t of a b o u t 15 l i t e r s / m i n i s a c c o m p l i s h e d by p r e s s u r i z i n g t o 10 l b ( g a g e ) and r e l e a s i n g t o 0 l b ( g a g e ) 30 t i m e s p e r h o u r . T h e HF c o n t e n t o f t h e s t r i p

*

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g a s i s u s u a l l y a b o u t lo ' , m o l e / l i t e r a t t h e t i m e o f f u e l t r a n s f e r . T h i s p r o b a b l y c o r r e s p o n d s t o a b o u t 1 0 ppm o f HF i n t h e m e l t . The c o m b i n a t i o n o f H, t r e a t m e n t and f i l t r a t i o n t h r o u g h s i n t e r e d n i c k e l h a s r e d u c e d t h e s o l u b l e n i c k e l i n t h e m e l t f rom 900 t o l e s s t h a n 150 ppm.

F l u o r i d e P r o d u c t i o n F a c i l i t y (G . J. Nessle, M a t e r i a l s C h e m i s t r y D i v i s i o n ; H. W . S a v a g e , ANP D i v i s i o n ) . T h e p r o d u c t i o n f a c i l i t y f o r p r e p a r i n g i n e x c e s s o f 3000 l b o f f u e l s o l v e n t i s s c h e d u l e d f o r c o m p l e t i o n d u r i n g t h e month o f March. Shakedown r u n s and o t h e r p r e l i m i n a r y t e s t s of t h e a p p a r a - t u s s h o u l d r e q u i r e l e s s t h a n f o u r weeks; t h e p r o d u c t i o n o p e r a t i o n c o u l d , i f n e c e s s a r y , be f i n i s h e d by mid-June.

The low-hafnium ZrC1, h a s been con- v e r t e d t o ZrF,, and t h e equ ipmen t f o r t h i s p r o c e s s h a s been c l e a n e d and p u t i n t o s t a n d b y c o n d i t i o n f o r f u t u r e u s e , i f n e e d e d . A t p r e s e n t , t h e s t o c k p i l e c o n t a i n s 3000 l b of ZrF,.

A l l b a t c h e s o f t h e ZrF, h a v e b e e n s a m p l e d a n d a n a l y z e d by c h e m i c a l m e t h o d s f o r z i r c o n i u m and f l u o r i n e . C o m p l e t e s p e c t r o g r a p h i c a n a l y s e s , w i t h s p e c i a l s h o t s o f e a c h b a t c h , f o r h a f n i u m and b o r o n a r e a v a i l a b l e . T h e b o r o n c o n t e n t o f t h e b a t c h e s r a n g e s f r o m 1 . 8 t o 0 . 3 ppm, w i t h a n a v e r a g e o f 0 .8 ppm, and s e v e n o f t h e n i n e b a t c h e s show l e s s t h a n 8 5 ppm h a f n i u m . T h e o t h e r t w o b a t c h e s , c o m p r i s i n g a b o u t 2 5 % o f t h e t o t a l , show 150 and 550 ppm hafnium.


A b o u t 1 0 0 0 l b o f NaF f r o m o n e p r o d u c t i o n l o t h a s b e e n s t o c k p i l e d for u s e i n f u e l p r o d u c t i o n . Chemica l a n d s p e c t r o g r a p h i c e x a m i n a t i o n s o f samples from t h r e e c o n t a i n e r s i n d i c a t e t h a t t h e m a t e r i a l i s s a t i s f a c t o r y f o r u se .

H y d r o f l u o r i n a t i o n o f Z r 0 , - N a P M i x t u r e s ( R . E . T h o m a , J r . , C . M . B lood , Ma t e r i a1 s C h e m i s t r y D i v i s i o n ) . The f e a s i b i l i t y o f p r o d u c i n g NaZrFs by a s h o r t t r e a t m e n t o f N a F - Z r O , m i x t u r e w i t h HF a t a h i g h tempi- = r a t u r e h a s been d e m o n s t r a t e d . B e s t r e s u l t s a r e o b t a i n e d when some p r e v i o u s l y p r e p a r e d NaZrFS i s added t o t h e c h a r g e s o t h a t a l i q u i d p h a s e i s p r e s e n t d u r i n g t h e i n i t i a l s t a g e s . An amount o f NaZrFS t h a t i s e q u i v a l e n t t o 10% of t h e t o t a l c h a r g e a p p e a r s t o b e s u f f i - c i e n t t o b r i n g a b o u t c o m p l e t e c o n - v e r s i o n o f t h e m i x t u r e i n 4 h r a t 800°C. U t i l i z a t i o n of abou t 30% of t h e HF d e l i v e r e d h a s been a t t a i n e d .

T h e r e a r e s t i l l some p r o b l e m s i n c o n n e c t i o n w i t h t h e equipment f o r t h i s o p e r a t i o n . F r e q u e n t r u p t u r e o f t h e HF i n p u t l i n e o c c u r r e d when n i c k e l t u b i n g w a s u s e d . M e t a l l o g r a p h i c e x a m i n a t i o n r e v e a l e d t h a t t h e a t t a c k was due t o s u l f u r , which w a s p r o b a b l y p r e s e n t i n t h e Z r O , f e e d . G r a p h i t e l i n e r s i n t h e n i c k e l r e a c t o r s h a v e b e e n u s e d s a t i s f a c t o r i l y ; h o w e v e r , t h e r e h a s been d i f f i c u l t y i n t h e use o f g r a p h i t e d i p l i n e s f o r HF I l e c a u s e o f b reakage d u r i n g r u n s .

F u r t h e r s t u d y o f t h i s p r o c e d u r e , w h i c h p r o m i s e s t o r e d u c e m a t e r i a l l y t h e c o s t of ZrF, a s NaZrFS, i s p lanned .

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W. D. Manly, M e t a l l u r g y D i v i s i o n W. R. G r i m e s , M a t e r i a l s C h e m i s t r y D i v i s i o n

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C o r r o s i o n p h e n o m e n a a r e u s u a l l y e x a m i n e d f i r s t i n s t a t i c or s e e s a w t e s t s , and t h e n s e l e c t e d s y s t e m s o r phenomena a re examined i n t h e c o n v e c t i o n l o o p s . C r e v i c e c o r r o s i o n , e f f e c t o f e x p o s u r e t i m e , a n d t h e e f f e c t s o f a d d i t i v e s h a v e b e e n s t u d i e d i n b o t h s t a t i c and d y n a m i c t e s t s d u r i n g t h e p a s t q u a r t e r . No s i g n i f i c a n t i n c r e a s e i n c o r r o s i o n w a s n o t e d i n s t a t i c t e s t s . However, t h e c r e v i c e c o r r o s i o n f o u n d i n t h e r m a l c o n v e c t i o n l o o p s was a b o u t t h r e e t i m e s t h a t f o u n d i n a d j a c e n t t u b i n g ; t h e m e c h a n i s m by w h i c h c r e v i c e s i n c r e a s e c o r r o s i o n i s n o t y e t u n d e r s t o o d . C o r r o s i o n , a s e v i d e n c e d by t h e chromium m e t a l c o n t e n t o f t h e f l u o r i d e , h a s been shown t o b e f a i r l y c o n s t a n t a f t e r t h e f i r s t 100 h r o f e x p o s u r e . C o n v e c t i o n l o o p s t h a t were r u n f o r 1000 h r a t 1500°F i n d i c a t e d t h a t t h e amount o f c o r r o s i o n d e c r e a s e d w i t h t i m e , a l t h o u g h t h e r e was a s m a l l i n c r e a s e i n t h e d e p t h a n d i n t e n s i t y o f a t t a c k .

The work on t h e dynamic t e s t i n g o f t h e f l u o r i d e f u e l s i n I n c o n e l t h e r m a l c o n v e c t i o n loops h a s c o n t i n u e d , w i t h a m a j o r e f f o r t b e i n g made t o d e t e r m i n e why t h e c o r r o s i o n i n t h e I n c o n e l - f l u o r i d e s y s t e m s h a s b e e n i n c r e a s i n g . I t h a s b e e n shown t h a t n e i t h e r t h e i n c r e a s e i n f l u o r i d e b a t c h s i z e n o r p o o r h a n d l i n g t e c h n i q u e s d u r i n g f i l l i n g were r e s p o n s i b l e ; r e t r e a t i n g t h e f u e l b a t c h e s h a s p r o d u c e d c o n t r a - d i c t o r y r e s u l t s . E v i d e n c e i n d i c a t e s t h a t t h e i n c r e a s e i n c o r r o s i o n i s b e i n g c a u s e d by f a u l t y p u r i f i c a t i o n , s i n c e t h e c o r r o s i o n w a s d e e p e r i n l o o p s i n w h i c h h y d r o f l u o r i n a t e d f l u o r i d e m i x t u r e s were c i r c u l a t e d t h a n i t was i n t h e l o o p s t h a t u s e d a s - m e l t e d f l u o r i d e a s t h e f u e l . One I n c o n e l t h e r m a l c o n v e c t i o n l o o p was

o p e r a t e d w i t h a h o t - l e g t e m p e r a t u r e o f 1650"F , and n o l a r g e i n c r e a s e i n t h e d e p t h of a t t a c k was n o t e d i n c o m p a r i s o n w i t h t h a t f o u n d i n l o o p s : r u n a t 1500°F . A w h i r l i g i g r i g , p a t t e r n e d a f t e r o n e d e v e l o p e d b y NACA, w i t h w h i c h f l u o r i d e f l o w v e l o c i t i e s o f 1 0 f p s c a n b e o b t a i n e d , h a s b e e n p l a c e d i n o p e r a t i o n . P r e l i m i n a r y t e s t s w i t h t h i s a p p a r a t u s w i t h f l u o r i d e f u e l s i n I n c o n e l show o n l y a s l i g h t i n c r e a s e i n c o r r o s i v e a t t a c k compared w i t h t h a t f o u n d i n s t a t i c c a p s u l e t e s t s . I t was c o n f i r m e d t h a t ZrH, i s a n e f f e c t i v e c o r r o s i o n i n h i b i t o r when u s e d w i t h NaF-ZrF4-UF4 (46 -50-4 m o l e % ) ; TiH, w i l l a l s o i n h i b i t c o r r o s i o n , b u t n o t q u i t e s o e f f e c t i v e l y a s Z r H 2 . I t now a p p e a r s t h a t t h e s o l u b i l i t y o f chromium i n NaF-KF-LiF-UF4 ( 10 .9 -43 .5 - 4 4 . 5 - 1 . 1 m o l e %) i s a b o u t 3 0 0 0 ppm, w h i c h i s n o t s o h i g h a s o r i g i n a l l y e x p e c t e d . C o n s i d e r a b l e a t t a c k w a s found i n an I n c o n e l l o o p i n which t h e f l u o r i d e h a d b e e n s a t u r a t e d w i t h chromium m e t a l p r i o r t o c i r c u l a t i o n .

T h e c o m p a t i b i l i t y o f Be0 i n NaK c o n t i n u e s t o b e e x a m i n e d , a n d a c o r r e l a t i o n b e t w e e n t h e d e n s i t y o f t h e Be0 and t h e c o r r o s i o n b e h a v i o r i s b e i n g s t u d i e d . V a r i o u s s u r f a c e t r e a t m e n t s f o r t h e B e 0 a r e b e i n g e v a l u a t e d . T h e r e i s some e v i d e n c e t h a t B e 0 i s s o l u b l e i n NaK t o a n e x t e n t t h a t i s d e p e n d e n t o n t h e t e m p e r a t u r e o f t h e s y s t e m . T h e c o r r o s i o n o f two cermets was examined i n b o t h f l u o r i d e s and l i q u i d m e t a l s . A l t h o u g h t h e t e s t s i n l i q u i d m e t a l s showed l i t t l e or n o a t t a c k , a t l e a s t one f l u o r i d e t e s t r e s u l t e d i n s i g n i f i - c a n t c o r r o s i o n .

The m a s s - t r a n s f e r c h a r a c t e r i s t i c s o f v a r i o u s m e t a l s i n h i g h - p u r i t y l e a d a r e b e i n g s t u d i e d b y u s i n g

117


q u a r t z t h e r m a l c o n v e c t i o n l o o p s . The r e s u l t s show t h a t b o t h columbium a n d m o l y b d e n u m h a v e v e r y g o o d r e - s i s t a n c e t o mass t r a n s f e r and c o r r o s i o n i n l i q u i d l e a d . On t h e o t h e r h a n d , s e v e r e c o r r o s i o n a n d m a s s t r a n s f e r were f o u n d i n l e a d - I n c o n e l s y s t e m s , even though t h e l e a d had been c a r e f u l l y d e o x i d i z e d . M a t e r i a l s t o b e t e s t e d i n l i q u i d l e a d i n c l u d e t y p e 304 , h i g h a n d l o w c a r b o n , s t a i n l e s s s t e e l s , t y p e 410 s t a i n l e s s s t e e l , a n d Armco i r o n . T e s t s o f s t a i n l e s s s t e e l and I n c o n e l i n s o d i u m - l e a d a l l o y s c o n t i n u e t o show t h a t a d d i t i o n s o f s o d i u m t o l e a d d e c r e a s e t h e s e v e r e c o r r o s i v e a c t i o n .

The e f f e c t o f a hydrogen a t m o s p h e r e i n m i n i m i z i n g mass t r a n s f e r o f n i c k e l i n sodium h y d r o x i d e was d e m o n s t r a t e d by u s i n g a 50-50 m i x t u r e o f h e l i u m and hydrogen . However, t h e u s e o f a tmos - p h e r e s o f C O , , f o r m i n g g a s , w e t h y d r o g e n , o r d r y a i r u n d e r a h y d r o g e n p r e s s u r e o f o n e - h a l f a t m o s p h e r i c p r e s s u r e r e s u l t e d i n c o n s i d e r a b l e mass t r a n s f e r .

A n u m b e r o f s i m p l e a n d c o m p l e x f l u o r i d e s o f t h e s t r u c t u r a l m e t a l h a s b e e n p r e p a r e d f o r s t u d i e s o f t h e i r e f f e c t o n c o r r o s i o n b y f l u o r i d e m i x t u r e s . T h e c o m p l e x f l u o r i d e s f o r m e d i n c o r r o s i o n t e s t s a r e i d e n t i f i e d b y e i t h e r p e t r o g r a p h i c o r x - r a y - d i f f r a c t i o n t e c h n i q u e s , o r b o t h . The o x i d a t i o n o f m o l t e n NaUF, y i e l d e d n o UO,F,, UO, , o r UF,. H o w e v e r , i t i s e v i d e n t f r o m t h e r e s u l t i n g p r o d u c t s t h a t t h e c o n t a i n e r p l a y s an i m p o r t a n t p a r t i n t h e mechanism o f a i r o x i d a t i o n o f u r a n i u m i n t h e m o l t e n f l u o r i d e s .

FLUORIDE CORROSIONOF METALS IN STATIC, SEESAW, AND ROTATING TESTS

D. C. V r e e l a n d J . E. Pope E. E. Hoffman L. R. T r o t t e r

M e t a l l u r g y D i v i s i o n

F. K e r t e s z C. R. C r o f t H. J. Bu t t r am R. E. Meadows


Crevice Corrosion. I n c o n n e c t i o n w i t h t h e c r e v i c e c o r r o s i o n t e s t s

b e i n g r u n , i t w a s s u g g e s t e d t h a t a m o r e r e a l i s t i c m e t h o d o f t e s t i n g w o u l d e m p l o y a t a p e r e d o r V - s h a p e d c r e v i c e i n t h e b o t t o m o f t h e t e s t i n g tube . A c c o r d i n g l y , a j i g w a s d e s i g n e d f o r p u t t i n g t a p e r e d c r i m p s i n t e s t t u b i n g . With t h i s j i g , c r e v i c e s c a n b e made t h a t a r e a p p r o x i m a t e l y 1 1 / 4 i n . l o n g a n d v a r y i n w i d t h u p t o a p p r o x i m a t e l y 0 . 3 i n c h . S e v e r a l s t a t i c t e s t s w i t h v a r i o u s m a t e r i a l s f o r c o n t a i n i n g t h e N a F - Z r F, - UF, ( 4 6 - 5 0 - 4 m o l e X ) h a v e b e e n r u n t o t e s t t h e c r e v i c e s . C o r r o s i o n i n t h e c r e v i c e s s e e m e d t o be somewhat e r r a t i c , w i t h some s u r f a c e s b e i n g a p p a r e n t l y u n a t t a c k e d a n d o t h e r s h a v i n g t h e u s u a l s u b s u r f a c e I v o i d s . H o w e v e r , a c c e l e r a t e d c o r r o s i o n i n t h e s e c r e v i c e s was n o t n o t e d ; t h e a t t a c k t h a t was f o u n d i n t h e c r e v i c e s was n o t beyond what m i g h t b e e x p e c t e d f o r t h e m a t e r i a l s t e s t e d .

High-Temperature Pretreatment o f I n c o n e l . On t h e b a s i s o f r e s u l t s f rom some p r e v i o u s t e s t s w i t h NaF-KF- LiF-UF, ( 1 0 . 9 - 4 3 . 5 - 4 4 . 5 - 1 . 1 m o l e %) a t h i g h t e m p e r a t u r e s (1200 t o 13OO0C), i t w a s r e p o r t e d t h a t t h e r e w a s n o s u r f a c e l a y e r a t t a c k o n I n c o n e l . I t w a s t h o u g h t t h a t p e r h a p s a p r e - t r e a t m e n t a t h i g h t e m p e r a t u r e would r e n d e r I n c o n e l immune f r o m c o r r o s i o n a t t h e u s u a l t e m p e r a t u r e o f 816OC. A c c o r d i n g l y , two I n c o n e l t u b e s were l o a d e d w i t h t h e f l u o r i d e , h e a t e d f o r 4 h r a t 125OoC, a n d t h e n h e a t e d f o r 2 5 0 h r a t 816OC. L i g h t a t t a c k w a s n o t e d i n e a c h t u b e i n t h e f o r m o f s u b s u r f a c e v o i d s t h a t e x t e n d e d t o a d e p t h o f 1 m i l i n one t u b e and 0 . 5 m i l i n t h e o t h e r t u b e .

E f f e c t o f Time o f Exposure o f Inconel t o Fluoride Mixture w i t h and Without ZrH, Added. When t h e A R E f u e l m i x t u r e NaF-ZrF,-UF, ( 5 0 - 4 6 - 4 m o l e X ) , w i t h o u t a d d e d m a t e r i a l , i s t e s t e d i n I n c o n e l u n d e r a n a t m o s p h e r e o f h e l i u m , t h e s e v e r i t y o f a t t a c k and t h e d e p t h o f p e n e t r a t i o n seem t o i n c r e a s e v e r y s l i g h t l y w i t h e x p o s u r e t i m e s o f b e t w e e n 1 0 0 a n d 250 h o u r s . D i f f e r e n c e s between c o r r o s i o n o b s e r v e d

. .

118

a f t e r 25 and 100 h r seem t o be r e a l , A p l o t o f t h e s t r u c t u r a l me ta l c o n t e n t o f t h e f l u o r i d e m i x t u r e v s . e x p o s u r e t i m e i s shown i n F i g . 1 0 . 1. I t i s o b v i o u s t h a t t h e c h r o m i u m c o n t e n t shows a r a p i d i n i t i a l r i s e and t h e n t e n d s t o l e v e l o f f a t a h i g h v a l u e , whereas t h e i r o n c o n t e n t f a l l s r a p i d l y a t f i r s t a n d t h e n v e r y s l o w l y . I t seems c e r t a i n t h a t r e a c t i o n s s u c h a s

FeF3 -t Cr - CrF3 -t F e , w i t h c o n s e q u e n t d e p o s i t i o n o f t h e m e t a l l i c i r o n o n t h e w a l l s , a r e r e s p o n s i b l e f o r a p a r t of t h e c o r r o s i o n o b s e r v e d .

When t h i s f u e l m i x t u r e , w i t h 0 . 5 w t % Z r H , a d d e d , w a s t e s t e d i n I n c o n e l , t h e c o r r o s i o n o b t a i n e d was c o n s i d e r a b l y l e s s s e v e r e , b u t t h e c o r r o s i o n c h a n g e s w i t h e x p o s u r e t i m e

1600

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s J

5 800 W z -1 a a 3 600 t 0 3 a t v) 400

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were s i m i l a r . F i g u r e 1 0 . 2 shows t h e r e s u l t s o f a n a l y s i s o f t h e f u e l m i x t u r e f o r t h e s t r u c t u r a l m e t a l s . I n t h i s c a s e , FeF, a n d NiF, c o n t e n t s d r o p p e d t o v e r y low v a l u e s b e c a u s e o f t h e s t r o n g r e d u c i n g a g e n t , a n d , a p p a r e n t l y , m o s t o f t h e C r F , w a s a l s o r e d u c e d . However, w i t h i n c r e a s e d e x p o s u r e t i m e , t h e CrF, c o n c e n t r a t i o n i n c r e a s e d s l i g h t l y .

T h e s e r e s u l t s a r e e n c o u r a g i n g i n t h a t t h e y i n d i c a t e t h a t t h e r e l a t i v e l y l a r g e c o r r o s i o n r a t e s i n i t i a l l y o b s e r v e d a r e d r a s t i c a l l y r e d u c e d a t l o n g e r e x p o s u r e t imes.

S t r u c t u r a l Metal F l u o r i d e Addl i t ives . Chemical a n a l y s e s o f f l u o r i d e m a t e r i a l s b e f o r e and a f t e r c o r r o s i o n t e s t i n g i n I n c o n e l h a v e r e p e a t e d l y d e m o n s t r a t e d t h a t t h e i r o n and n i c k e l c o n t e n t s o f t h e m i x t u r e a r e r e d u c e d a n d t h e

F i g . 10 .1 . S t r u c t u r a l Metal Content of NaF-ZrF,-UF, (50 -46-4 mole %) A s F u n c t i o n of Exposure Time.

119


0 100 200 300 EXPOSURE TIME (hr)

400 500

Fig. 10.2. Structural Metal Content NaF-ZrF,-UF4 (50-46-4 mole %), with 0.5 wt % ZrH,, As a Function of Exposure T i m e .

chromium c o n t e n t i s i n c r e a s e d . The r e a c t i o n s

3FeF, -t 2Cr + 2CrF, -t 3Fe and

3NiF, -t 2Cr - 2CrF, -t 3Ni a r e o b v i o u s l y i n v o l v e d i n t h e c o r r o s i o n m e c h a n i s m . S i n c e b o t h i r o n a n d n i c k e l f l u o r i d e s a r e l i k e l y t o b e p r e s e n t t o some e x t e n t i n t h e f i n a l A R E f u e l a n d s i n c e c o n s i d e r a b l e a m o u n t s o f t h e s e compounds h a v e been p r e s e n t i n some o f t h e b a t c h e s t e s t e d , a s e r i e s o f e x p e r i m e n t s h a s b e e n c o n d u c t e d t o d e m o n s t r a t e t h e e f f e c t s o f t h e f l u o r i d e s o f i r o n , c h r o m i u m , and n i c k e l i n c o n s i d e r a b l e amounts on t h e c o r r o s i o n o f I n c o n e l by t h e ARE f u e l and t h e ARE f u e l s o l v e n t .

A d d i t i o n o f e i t h e r FeF, or NiF, i n c r e a s e s t h e s e v e r i t y o f a t t a c k and d e p t h o f p e n e t r a t i o n . T h e a d d i t i o n o f CrF, a p p a r e n t l y h a s n o e f f e c t on t h e c o r r o s i o n r a t e . When i r o n o r chromium f l u o r i d e s a r e added , m e t a l l o - g r a p h i c e x a m i n a t i o n r e v e a l s m e t a l l i c d e p o s i t s on t h e c a p s u l e w a l l s .

Chemical a n a l y s e s of t h e s o l i d i f i e d m e l t s , a f t e r e x p o s u r e , r e v e a l t h a t t h e

a d d i t i o n o f CrF, d o e s n o t a p p r e c i a b l y a l t e r t h e amoun t s o f i r o n and n i c k e l n o r m a l l y f o u n d i n t h e m i x t u r e . T h e a d d i t i o n o f NiF , , h o w e v e r , g r e a t l y i n c r e a s e s t h e amount o f CrF, found i n t h e m e l t ; t h e v e r y l a r g e q u a n t i t i e s o f s o l u b l e n i c k e l a d d e d a r e n e a r l y c o m p l e t e l y r e d u c e d and a re a p p a r e n t l y d e p o s i t e d on t h e w a l l s o f t h e c a p s u l e s o t h a t t h e y a r e n o t removed w i t h t h e f l u o r i d e mass. The a d d i t i o n o f FeF, a l s o s e r v e s t o r a i s e t h e c h r o m i u m c o n t e n t o f t h e f l u o r i d e m i x t u r e , b u t o n l y a p a r t o f t h e F e F , s e e m s t o b e

.

r educed t o m e t a l .

l y t i c a l t e c h n i q u e s a r e n o t s u f f i c i e n t l y p r e c i s e t o p e r m i t o b t a i n i n g a c c u r a t e m a t e r i a l b a l a n c e s f rom t h e e q u a t i o n s shown a b o v e ; i n g e n e r a l , however , t h e b a l a n c e i s w i t h i n +20%, from which i t a p p e a r s t h a t a c o n 2 i d e r a b l e f r a c t i o n o f t h e c o r r o s i o n i s , a s was e x p e c t e d , d u e t o o t h e r a c t i o n s .

Hydrogen Fluoride Additive. Hydro- f l u o r i c a c i d i s o n e o f t h e r e a g e n t s u s e d i n t h e p r o c e s s f o r p u r i f y i n g t h e f l u o r i d e m e l t s . T h i s r e a g e n t may b e p r e s e n t i n t h e m e l t s a t l o w

- The h a n d l i n g , s a m p l i n g , a n d a n a

120


c o n c e n t r a t i o n s , e v e n t h o u g h c o n - s i d e r a b l e c a r e is u s e d i n t h e s t r i p p i n g o p e r a t i on I

S t u d y o f c o r r o s i o n o f I n c o n e l by a b a t c h o f ARE f u e l , N a F - Z r F 4 - U F , ( 5 0 - 4 6 - 4 m o l e % ) , t o w h i c h HF h a d b e e n a d d e d a s NaHF, , s h o w e d t h a t h e a v y s u b s u r f a c e v o i d f o r m a t i o n r e s u l t e d when as much a s 0 . 3 w t % HF w a s p r e s e n t . T h i s a t t a c k w a s shown t o b e a s much a s 3 m i l s d e e p , w h i c h i s a t l e a s t t w i c e t h e d e p t h e x p e c t e d w i t h o u t a d d i t i o n . H o w e v e r , t h e u s e o f 0 . 1 w t % HF r e s u l t e d i n l e s s s e v e r e a t t a c k , w i t h p e n e t r a t i o n t o o n l y 1 .5 m i l s , and t h e a d d i t i o n o f 0 . 0 4 w t % HF y i e l d e d a l i g h t m e t a l l i c d e p o s i t and r e l a t i t v e l y l i g h t c o r r o s i v e a t t a c k .

T h e f u e l m i x t u r e u s e d i n t h e s e e x p e r i m e n t s h a d b e e n t r e a t e d w i t h H, a n d , p r e s u m a b l y , c o n t a i n e d s m a l l a m o u n t s o f UF,. I t i s p o s s i b l e t h a t t h e r e a c t i t on

A 2UF,, i- 2HF \-’ 2UF, -t H ,

may h a v e m a s k e d t h e d e l e t e r i o u s e f f e c t o f smal l HF a d d i t i o n s .

F l u o r i d e C o r r o s i o n i n a R o t a t i n g R i g . T h e w h i r l i g i g r i g ( ’ ) i s n o w r u n n i n g and o p e r a t i o n a l “ b u g s ” a r e g r a d u a l l y b e i n g worked o u t . I n t h i s d e v i c e i t w i l l b e p o s s i b l e t o r u n r e l a t i v e l y h i g h - v e l o c i t y c o r r o s i o n t e s t s w i t h t h e f l u o r i d e m i x t u r e s c o n t a i n e d i n I n c o n e l and o t h e r s u i t a b l e t u b i n g . , 4 t t h e p r e s e n t t i m e , a f l u i d v e l o c i t y o f a p p r o x i m a t e l y 1 0 f p s i s b e i n g employed . Upon m e t a l l o g r a p h i c e x a m i n a t i o n a f t e r a 1 0 0 - h r t e s t w i t h N a F - Z r F , - U F , ( 4 6 - 5 0 - 4 m o l e % ) i n I n c o n e l a t a t e m p e r a t u r e o f 816OC ( n o a p p r e c i a b l e g r a d i e n t e m p l o y e d ) , i t w a s n o t e d t h a t t h e a t t a c k w a s n o m o r e s e v e r e t h a n t h a t o f t e n e n c o u n t e r e d i n o r d i n a r y s t a t i c c o r r o s i o n t e s t s . T h e a t t a c k w a s q u i t e u n i f o r m and was i n t h e f o r m o f s u b s u r f a c e v o i d s t o a d e p t h o f 2 m i l s .

t h e r m a 1

( l ) L . C. Desmon and D. R. Mosher , P r e l i m i n a r y S t u d y o f C i r c u l a t i o n i n a n A p p a r a t u s S u i t a b l e f o r D e t e r m i n i n g C o r r o s i v e E f f e c t s o f H o t F l o w i n g L i q u t d s , NACA-RM-E-51D12 (June 2 9 , 1 9 5 1 ) .

C h e m i c a l a n a l y s i s o f t h e f l u o r i d e a f t e r t h e t e s t r e v e a l e d t h e p r e s e n c e of 0.025% Fe, 0.003% N i , and 0. 141% Cr. O t h e r t e s t s a r e b e i n g r u n w i t h v a r i o u s a d d i t i o n s t o t h e f l u o r i d e m i x t u r e s , a n d a t t e m p t s a r e b e i n g made t o v a r y t h e h e a t i n g a r r a n g e m e n t s on t h e t u b i n g s o t h a t s i z e a b l e t e m p e r a t u r e g r a d i e n t s c a n be a t t a i n e d .

S t a t i c Tests on I n c o l o y and I n c o n e l i n F l u o r i d e s . I n c o l o y ( 3 2 % N i - 2 1 % Cr-47% Fe ) w a s t e s t e d i n NaF-ZrF, -UF, ( 4 6 - 5 0 - 4 mole %) f o r 100 h r a t 816OC. I n a f e w p l a c e s , s u b s u r f a c e v o i d s t o a d e p t h o f 2 m i l s c o u l d b e n o t e d . A p h o t o m i c r o g r a p h o f t h e I n c o l o y , t a k e n a f t e r t e s t i n g , i s s h o w n i n F i g . 10.3.

T h e d e s c a l i n g p r o p e r t i e s o f t h e f l u o r i d e o n o x i d i z e d I n c o n e l w e r e t e s t e d a t 816OC, and i t was found t h a t t h e o x i d i z e d I n c o n e l was c l e a n e d v e r y w e l l a t t h e 1 - , 4 - , a n d 8 - h r t e s t t imes t h a t were t r i e d .

FLUORIDE CORROSION OF METALS I N THERMAL CONVECTION LOOPS

G. M. Adamson, M e t a l l u r g y D i v i s i o n

E f f e c t o f F l u o r i d e B a t c h S i z e . A s d i s c u s s e d i n t h e p r e v i o u s r e p o r t , ( 2 ,

t h e c o r r o s i o n h a s b e e n i n c r e a s i n g i n t h e I n c o n e l l o o p s c i r c u l a t i n g NaF- Z r F , - U F , ( 4 6 - 5 0 - 4 m o l e % ) . T h e i n c r e a s e s i n t h e m s e l v e s w e r e n o t enough t o c a u s e t r o u b l e , b u t t h e y a r e d a n g e r o u s when r e g a r d e d a s a t r e n d ‘ t h a t i s n o t u n d e r s t o o d . C o n s e q u e n t l y , a s e r i e s o f l o o p s was r u n t o d e t e r m i n e w h e t h e r t h e i n c r e a s e i n b a t c h s i z e i n t h e p r o d u c t i o n o f t h e f l u o r i d e m i x t u r e w a s r e s p o n s i b l e f o r t h e c o r r o s i o n i n c r e a s e . Loops were r u n w i t h f l u o r i d e m i x t u r e s p r e p a r e d i n 5 - a n d 5 0 - l b b a t c h e s f o r 1 0 0 - and 5 0 0 - h r p e r i o d s . I n b o t h t h e 1 0 0 - a n d 5 0 0 - h r t e s t s , more c o r r o s i o n was c a u s e d by t h e s m a l l b a t c h e s t h a n by t h e l a r g e b a t c h e s . O b v i o u s l y , t h e i n c r e a s e i n b a t c h s i z e w a s n o t t h e r e a s o n f o r t h e

(2)C. M. Adamson, ANP Q u a r . P r o g . R e p . D e e . I O . 1 9 5 2 , ORNL-1439, p . 133 f f .

12 1


I

Fig. 10.3. Static Test of Incoloy hr at 816OC.

i n c r e a s e i n a t t a c k . F u r t h e r m o r e , e v e n t h o u g h e x t r e m e c a r e was t a k e n d u r i n g f i l l i n g o f t h e l o o p , t h e a t t a c k was s t i l l e x t e n s i v e ; t h e r e f o r e p o o r h a n d l i n g d u r i n g f i l l i n g w a s a l s o e l i m i n a t e d a s t h e cause .

Fluoride Pretreatment. Two s m a l l b a t c h e s o f N a F - Z r F , - U F , ( 4 6 - 5 0 - 4 m o l e 7%) w e r e t a k e n € r o m t h e 5 0 - l b b a t c h and g i v e n a c o m p l e t e r e t r e a t - m e n t . ( 3 ) When t h e s e b a t c h e s w e r e c i r c u l a t e d i n I n c o n e l l o o p s , t h e a t t a c k i n one i n s t a n c e was c o n s i d e r a b l y g r e a t e r t h a n a v e r a g e , w h e r e a s i n t h e o t h e r i t was l e s s ; t h e r e f o r e i t may be c o n c l u d e d t h a t some m a j o r v a r i a b l e s t i l l h a s n o t been c o n t r o l l e d .

(3 )C . M . B l o o d , A. J . Weinberger , F. P. Boody, and G . J. N e s s l e , ANP Q u a r . P r o g . R e p . J u n e 1 0 , 1 9 5 2 , OWL-1294, p. 97 .

in NaF-ZrF4-UF, (46-50-4 mole %) for 100

The a t t a c k f o u n d i n I n c o n e l l o o p s i n which NaF-ZrF,-UF, (46-50-4 mole %) c i r c u l a t e d was much l e s s t h a n h a d been found when NaF-KF-LiF-UF, ( 1 0 . 9 - 43.5-44.5-1. l m o l e %) was t h e c i r c u l a t e d m a t e r i a l . (,) S i n c e t h e NaF-ZrF4-UF, h a d r e c e i v e d m o r e e x t e n s i v e p r e - t r e a t m e n t w i t h H, and HF, i t s h i g h e r p u r i t y i s a l o g i c a l e x p l a n a t i o n f o r i t s lower c o r r o s i v e n e s s . A c c o r d i n g l y , two s p e c i a1 b a t c h e s o f t h e NaF-KF-LiF- UF, m i x t u r e w e r e g i v e n t h e s a m e s p e c i a l p r e t r e a t m e n t . T h e s e b a t c h e s p r o d u c e d a t t a c k on I n c o n e l t h a t was a l m o s t t w i c e t h a t h e r e t o f o r e obse rved . Two a d d i t i o n a l b a t c h e s o f t h e same f l u o r i d e were t h e n s p e c i a l l y p r e p a r e d and c i r c u l a t e d i n I n c o n e l l o o p s , and

(4 )G. M. Adamson, ANP Q u a r . P r o g . R e p . S e p t . 1 0 , 1952, ORNL-1375, p. 103 f f .

122

t h e a t t a c k w a s e v e n w o r s e t h a n i n t h e f i r s t t e s t .

I n a l l t h e t e s t s w i t h p r e t r e a t e d f u e l , t h e o p e r a t o r r e p o r t e d a s t r o n g o d o r o f h y d r o g e n f l u o r i d e d u r i n g t h e f i l l i n g o f t h e l o o p s . S i n c e h y d r o g e n f l u o r i d e , a s a n a d d i t i v e i n s t a t i c t e s t s , h a s b e e n s h o w n t o i n c r e a s e c o r r o s i o n , i t i s m o s t p r o b a b l e t h a t t h e HF u s e d a t o n e s t e p i n t h e f u e l p r e t r e a t m e n t , a s w e l l a s t h e N i F p r o d u c e d d u r i n g t h i s t r e a t m e n t , i s n o t b e i n g c o m p l e t e l y r e m o v e d and i s c a u s i n g t h e i n c r e a s e d c o r r o s i o n . T h e s e t e s t s show t h a t p o o r p u r i f i - c a t i o n may do more harm t h a n good.

Hydride Additives. I t h a s b e e n c o n f i r m e d t h a t z i r c o n i u m h y d r i d e w i l l r e d u c e t h e a t t a c k o f N a F - Z r F , - U F , ( 4 6 - 5 0 - 4 m o l e % ) o n I n c o n e l . An a d d i t i o n o f 1 / 2 % z i r c o n i u m h y d r i d e i n one t h e r m a l c o n v e c t i o n l o o p r e d u c e d t h e d e p t h o f a t t a c k t o b e t w e e n 1 and 4 m i l s . T h i s a t t a c k i s l o w e r t h a n n o r m a l b u t i s d e e p e r t h a n t h a t f o u n d when z i r c o n i u m h y d r i d e i s a d d e d t o NaF-KF-LiF-UF4 ( 1 0 . 9 - 4 3 . 5 - 4 4 . 5 - 1 . 1 m o l e % ) . T h e c o o l a n t u n d e r w e n t c o n s i d e r a b l e t r a n s f o r m a t i o n , a s e v i d e n c e d by t h e p r e s e n c e o f a brown m a t e r i a 1.

T i t a n i u m h y d r i d e ( 1 / 2 % ) was a d d e d t o t h e N a F - K F - L i F - U F 4 m i x t u r e a n d c i r c u l a t e d i n I n c o n e l . T h e maximum p e n e t r a t i o n o f 2 . 5 m i l s , a l t h o u g h much l e s s t h a n t h a t f o u n d when n o a d d i t i v e was u s e d , was n o t q u i t e s o low a s t h a t o b t a i n e d when z i r c o n i u m h y d r i d e was a d d e d . S u r f a c e l a y e r s were f o u n d i n b o t h t h e h o t a n d c o l d l e g s . T h e s e l a y e r s m u s t r e c e i v e a d d i t i o n a l s t u d y i f a n y h y d r i d e i s t o be usefd a s an i n h i b i t o r .

Metal Additives. The t h r e e m o s t common i m p u r i t i e s f o u n d i n t h e f u e l a r e n i c k e l , i r o n , and chromium. One l o o p i n w h i c h chromium me ta l p o w d e r h a d b e e n a d d e d t o NaF-KF-LiF-UF, ( 1 0 . 9 - 4 3 . 5 - 4 4 . 5 - 1 . 1 mo le % ) w a s

T h i s t e s t was r e p e a t e d , a n d a g a i n n o c h a n g e i n t h e a v e r a g e d e p t h o f a t t a c k

d i s c u s s e c l i n t h e p r e v i o u s r e p o r t . ( 2 )


w a s f o u n d , n o u n u s u a l l a y e r s w e r e found, and t h e chromium c o n t e n t o f t h e f l u o r i d e s f r o m t h e l o o p was n o r m a l ; s o a g a i n t h e chromium m e t a l d i d n o t go i n t o s o l u t i o n . Chromium m e t a l powder, i n s u f f i c i e n t q u a n t i t y t o make 0 . 5 % i n t h e s o l u t i o n , was t h e n a d d e d t o a t r a n s f e r p o t b e f o r e t h e f l u o r i d e s were p l a c e d i n t o i t . A f t e r t h e f l u o r i d e s had been a d d e d , t h e p o t was k e p t h o t and h e l i u m w a s blown t h r o u g h i t f o r 30 m i n u t e s . A g a i n , a v e r a g e a t t a c k was f o u n d a f t e r t h i s m a t e r i a l h a d b e e n c i r c u l a t e d i n a n I n c o n e l l o o p . T h e c h e m i c a l a n a l y s i s o f t h i s f l u o r i d e s h o w e d a c h r o m i u m c o n c e n - t r a t i o n o f 2500 ppm, w h i c h i s a b o u t t w i c e t h e n o r m a l c o n c e n t r a t i o n . F u r t h e r work i s s c h e d u l e d t o d e t e r m i n e w h e t h e r t h e s o l u b i l i t y o f chromium i s much l o w e r t h a n w a s e x p e c t e d . Th.is i s l i k e l y , s i n c e t h e c h r o m i u m c o n t e n t d i d n o t i n c r e a s e g r e a t l y d u r i n g c i r c u l a t i o n a n d y e t a t t a c k had t a k e n p l a c e .

As a n o t h e r a p p r o a c h t o t h i s p rob lem, a s e c t i o n of I n c o n e l p i p e was chromium p l a t e d a n d w e l d e d i n t o t h e h o t l e g o f a l o o p . A f t e r t h e NaF-KF-LiF-UF, m i x t u r e had been c i r c u l a t e d , t h e d e p t h o f a t t a c k w a s t h e s a m e i n a d j a c e n t p l a t e d a n d u n p l a t e d s e c t i o n s . No t r a c e s o f t h e chromium p l a t e r e m a i n e d on t h e w a l l s . A m e t a l l i c a p p e a r i n g l a y e r w a s f o u n d in t h e c o l d leg. The c h r o m i u m c o n t e n t o f t h e f l u o r i d e s v a r i e d from 2500 t o 3 0 0 0 ppm, w h i c h , a l t h o u g h h i g h e r t h a n n o r m a l , is a b o u t t h e same a s t h a t f o u n d i n t h e l o o p d i s c u s s e d above.

Temperature Dependence. A l o o p f i l l e d w i t h t h e f l u o r i d e f u e l , NaF- ZrF,-UF, (50 -46 -4 m o l e % ) , was o p e r a t e d f o r 500 h r w i t h a minimum c o l d - l e g t e m p e r a t u r e o f 1500'F a n d a h o t - l e g t e m p e r a t u r e o f 1650'F. T h e h o t - l e g a t t a c k was m o d e r a t e t o l i g h t , w i t h a m a x i m u m d e p t h o f 11 m i l s a n d a n a v e r a g e d e p t h o f 8 m i l s . A c o n c e n - t r a t i o n o f v o i d s i n t h e g r a i n b o u n d a r i e s h a d t a k e n p l a c e . The r e s u l t s may b e c o m p a r e d w i t h t h o s e o f a s i m i l a r

123


l o o p t e s t i n which t h e h o t - l e g temper- a t u r e was 1500'F. The h o t - l e g a t t a c k i n t h i s l o o p was f r o m 3 t o 10 m i l s d e e p . C o m p a r i s o n o f t h e s e two l o o p s i n d i c a t e s t h a t t h e c o r r o s i o n mechanism i s n o t e x t r e m e l y t e m p e r a t u r e s e n s i t i v e . One d i s t u r b i n g f a c t i s t h a t w i t h t h e h o t t e r l o o p t h e r e was some e v i d e n c e o f u r a n i u m s e g r e g a t i o n i n t h e c o l d l e g . T h i s i s now b e i n g c h e c k e d i n a n o t h e r l o o p .

Crev ice Corros ion. A n o t h e r l o o p o p e r a t e d i n t h e s t u d y o f c r e v i c e c o r r o s i o n ( 2 ) w a s a n I n c o n e l l o o p , w i t h two c r e v i c e s b u i l t i n t o t h e h o t l e g , i n w h i c h NaF-ZrF4-UF, ( 4 6 - 5 0 - 4 m o l e % ) w a s c i r c u l a t e d . T h e u p p e r h o t - l e g s e c t i o n s h o w e d a maximum a t t a c k o f 16 m i l s a n d a n a v e r a g e

. a t t a c k o f 1 2 m i l s , w h e r e a s t h e a t t a c k i n t h e l o w e r h o t - l e g s e c t i o n h a d a maximum d e p t h o f 9 m i l s . The maximum a t t a c k i n t h e c r e v i c e s was 1 9 m i l s a n d t h e a v e r a g e w a s 1 2 m i l s . T h e i n t e n s i t y o f a t t a c k i n t h e c r e v i c e was s e v e r a l times t h a t i n t h e s t r a i g h t s e c t i o n . T h i s c o n f i r m s p r e v i o u s l y o b t a i n e d r e s u l t s i n t h a t t h e a t t a c k i n t h e c r e v i c e i s o n l y s l i g h t l y d e e p e r b u t t h e i n t e n s i t y o f a t t a c k i s g r e a t l y i n c r e a s e d .

I n s e r t e d Corros ion Samples. Me- t a l l o g r a p h i c d a t a r e c e i v e d f o r t h e p r e v i o u s l y d i s c u s s e d ( 2 , l o o p s i n which t h e r m o c o u p l e t u b e s were i n s e r t e d i n t o t h e c e n t e r o f t h e h o t a n d t h e c o l d l e g s c o n f i r m t h e r e s u l t s o b t a i n e d w i t h f l a t s a m p l e s . W i t h b o t h NaF- ZrF , -UF , a n d N a F - K F - L i F - U F 4 , t h e a t t a c k on t h e l o o p w a l l s i n t h e h o t l e g w a s n o r m a l , b u t t h e h o t - l e g i n s e r t s were a t t a c k e d t o a d e p t h o f o n l y 1 m i l ; n o s a t i s f a c t o r y e x p l a n a t i o n h a s been o f f e r e d f o r t h i s phenomenon.

E f f e c t o f E x p o s u r e T i m e . An I n c o n e l l o o p was u s e d t o c i r c u l a t e NaF-ZrF4-UF, (50-46-4 mole %) 1000 h r , and t h e r e s u l t i n g h o t - l e g a t t a c k was m o d e r a t e t o h e a v y i n i n t e n s i t y a n d e x t e n d e d t o d e p t h s o f 5 t o 11 m i l s . The a t t a c k was p r e s e n t b o t h a s g e n e r a l a t t a c k and a s a c o n c e n t r a t i o n o f t h e

v o i d s i n t h e g r a i n b o u n d a r i e s . F o r c o m p a r a t i v e p u r p o s e s , t h e s e d a t a a r e s u m m a r i z e d i n T a b l e 10. 1, a l o n g w i t h s i m i l a r d a t a f o r l o o p s p r e v i o u s l y o p e r a t e d f o r 1 0 0 a n d 5 0 0 h o u r s . A l t h o u g h t h e d e p t h a n d i n t e n s i t y o f t h e a t t a c k i n c r e a s e s w i t h t h e e x p o s u r e t i m e , t h e r a t e o f a t t a c k d e f i n i t e l y d e c r e a s e s .

TABLE 10.1. EFFECT OF EXPOSURE TIME ON DYNAMIC CORROSION OF INCONEL BY

NaF-ZrF,-UF,

o ~ ~ ~ ~ ~ ~ N MAXIMUM ATTACK ( m i l s ) ( h r ) I CORROSION IN TENS1 TY

L i g h t t o moderate

L i g h t t o moderate

Moderate t o heavy

Nonu r an ium Bearing NaF-ZrF4 ( 5 0 - 5 0 mole d u r i n g t h e i n i t i a l

Mixtures. S i n c e %) w i l l b e u s e d t e s t i n g o f t h e

ARE, s e v e r a l l o o p s h a v e been o p e r a t e d t o s t u d y i t s e f f e c t s . T h e s e a r e s t a n d a r d l o o p s , t h a t i s , I n c o n e l l o o p s o p e r a t e d f o r 5 0 0 h r w i t h a h o t - l e g t e m p e r a t u r e o f 1500'F. T h e u p p e r s e c t i o n o f t h e h o t l e g o f o n e loop showed l i g h t a t t a c k t h a t e x t e n d e d t o d e p t h s o f 4 t o 8 m i l s , w h e r e a s t h e l o w e r s e c t i o n w a s p r a c t i c a l l y u n a t t a c k e d . The s e c o n d l o o p i s s t i l l o p e r a t i n g . A t h i r d l o o p , i n w h i c h NaF-ZrF, (52 -48 mole %) was c i r c u l a t e d , y i e l d e d s c a t t e r e d i n t e r g r a n u l a r a t t a c k o f from 3 t o 8 m i l s i n t h e t o p s e c t i o n o f t h e h o t l e g . T h e l o w e r s e c t i o n s h o w e d g e n e r a l p i t t i n g 1 m i l d e e p , w i t h an o c c a s i o n a l p a t c h o f p i t s u p t o 6 m i l s d e e p . No d e p o s i t was found i n t h e c o l d l e g .

Z i r c o n i u m h y d r i d e ( 1 / 2 % ) was a d d e d t o a n o t h . e r b a t c h o f t h i s c o o l a n t , which was t h e n s u b j e c t t o t h e s t a n d a r d l o o p t e s t . T h e h o t - l e g s u r f a c e o f t h i s l o o p was p i t t e d , b u t t h e a t t a c k , a s s h o w n by t h e s u b s u r f a c e v o i d s , e x t e n d e d t o a maximum d e p t h o f o n l y

124


1 . 5 m i l s . A t w o - p h a s e l a y e r 1 m i l - t h i c k was p r e s e n t o n t h e h o t - l e g

s u r f a c e , a n d a t i g h t l y a d h e r i n g m e t a l l i c - a p p e a r i n g l a y e r 0 . 1 m i l

A g a i n t h e z i r c o n i u m h y d r i d e a c t e d a s a n i n h i b i t o r , b u t h o t - l e g d e p o s i t s were formed.

I

b t h i c k w a s f o u n d i n t h e c o l d l e g .

One I n c o n e l l o o p c i r c u l a t e d 500 h r w i t h NaF-BeF, ( 5 7 - 4 3 m o l e % ) . T h e maximum h o t - l e g a t t a c k was 9 m i l s and t h e a v e r a g e was 4 m i l s . More v o i d s were c o n c e n t r a t e d i n t h e g r a i n bounda- r i e s t h a n a r e n o r m a l l y f o u n d , and t h e v o i d s w e r e l a r g e r . A n o n m e t a l l i c d e p o s i t was f o u n d i n t h e c o l d l e g . With b o t h NaF-ZrF4 a n d NaF-BeF2, t h e a t t a c k mechanism seems t o b e t h e same as f o r t h e o t h e r f l u o r i d e s . '

L I Q U I D METAL CORROSION OF STRUCTURAL METALS

G . P. S m i t h E. E. Hoffman J . V. C a t h c a r t L. R. T r o t t e r D. C. V r e e l a n d J . E. Pope


Seesaw Tests of Sodium-Lead Al loys . A s e r i e s o f s e e s a w t e s t s o f s o d i u m - l e a d m i x t u r e s h a s b e e n r u n i n I n c o n e l and t y p e s 430 and 304 s t a i n l e s s s t e e l t u b i n g f o r 1 0 0 h o u r s . T h e l e a d f o r t h e s e t e s t s was p u r i f i e d by b u b b l i n g h y d r o g e n t h r o u g h m o l t e n l e a d a t 750°C f o r 1 1 / 2 h o u r s . A l l I n c o n e l t u b e s were a t t a c k e d i n t h e h o t zone. S e v e r i t y o f t h e a t t a c k d e c r e a s e d w i t h i n c r e a s i n g sodium a d d i t i o n s , b u t t h e a t t a c k was s t i l l a p p r e c i a b l e w i t h a 3 0 w t 7% sodium a d d i t i o n , a s shown i n F i g . 10.4,

T

F i g . 10 .4 . Inconel After a Seesaw Test i n a 30 w t % Na-70 w t % Pb Mixture for 100 hr a t 85OoC. 1OOX.

12 5


which i l l u s t r a t e s t h e t y p e and e x t e n t o f a t t a c k of t h e s e sod ium- lead m i x t u r e s . I n no c a s e was a t t a c k or d e p o s i t i o n o f c r y s t a l s n o t e d i n t h e c o l d zone upon me t a l l o g r a p h i c e x a m i n a t i o n ; however , i n s e v e r a l o f t h e t u b e s , c r y s t a l s c o u l d b e d e t e c t e d i n t h e b a t h m a t e r i a l . I n t h e t e s t w i t h t h e t y p e 430 s t a i n - l e s s s t e e l t u b i n g , t h e r e w a s v e r y l i t t l e c o r r o s i v e a t t a c k by t h e sodium- l e a d m i x t u r e s . T y p e 3 0 4 s t a i n l e s s s t e e l s h o w e d e x c e p t i o n a l l y g o o d r e s i s t a n c e t o t h e s e c o r r od a n t s . A s e c t i o n o f t h e h o t z o n e o f a t u b e a f t e r e x p o s u r e t o 5% Na-95% P b i s shown i n F i g . 1 0 . 5 . T h e r e was e s - s e n t i a l l y n o a t t a c k i n a n y o f t h e t e s t s w i t h t y p e 3 0 4 s t a i n l e s s s t e e l . A summary o f t h e s e t e s t s i s g i v e n i n T a b l e 10.2.

S t a t i c T e s t s w i t h L i t h i u m . Two- c o m p o n e n t s t a t i c t e s t s o f s e v e r a l m a t e r i a l s h a v e b e e n r u n w i t h l i t h i u m a t 1 0 0 0 ° C t o f u r n i s h a b a s i s o f compar i son w i t h t h r e e - c o m p o n e n t t e s t s r u n p r e v i o u s l y . S e v e r e a t t a c k h a d b e e n n o t e d i n t h e t h r e e - c o m p o n e n t t e s t s , 1 0 t o 1 5 m i l s p e n e t r a t i o n b e i n g q u i t e common. I t s h o u l d b e e m p h a s i z e d , h o w e v e r , t h a t t h e m o r e r e c e n t t e s t s w e r e s t a t i c t e s t s and t h e a t t a c k m i g h t be l e s s s e v e r e t h a n i n t h e d y n a m i c s y s t e m s . R e s u l t s o f t h e s e t e s t s a r e p r e s e n t e d i n T a b l e 10.3.

I n c o l o y i n S o d i u m , L i t h i u m , a n d Lead. I n c o l o y (32% N i - 2 1 % Cr-47% F e ) w a s t e s t e d f o r 1 0 0 h r a t 816OC i n sodium, l i t h i u m , and l e a d . No a t t a c k was n o t e d i n e i t h e r sodium or l i t h i u m , a l t h o u g h some c r y s t a l d e p o s i t i o n was

F i g . 10 .5 . Type 304 S t a i n l e s s S t e e l After a s e e s a w Test i n a 5 w t % Na-95 w t % Pb Mixture f o r 100 hr a t 830OC. 1 O O X .

126

PERIOD ENDING MARCH 1 0 , 1953

TABLE 10.2. SEESAW TESTS OF VARIOUS MATERIALS RUN IN SODIUM-LEAD MIXTURES FOR 100 HOURS

M ATERI AL

I n c o n e l

Type 304 s t a i n l e s s s t e e l

.

Type 430 s t a i n l e s s s t e e

BATH COMPOSITION ( %)

Na

5

10

15

20

25

30

5

10

15

20

25

30

5

10

15

20

25

30

Pb

95

90

85

80

75

70

95

90

85

80

75

70

95

90

85

80

75

70

AVERAGE 1 (

5 1 d Zone

5 30

330

3 15

39 5

47 0

48 5

560

57 5

545

58 5

600

600

565

580

57 5

57 5

550

6 10

'ERATURE

Hot Zone

8 20

870

8 60

855

8 50

8 50

8 30

8 40

8 30

8 25

835

835

8 50

845

8 20

8 10

805

835

METALLOGRAPHIC NOTES

l e r m i n a t e d a f t e r 18 h r , no c i r c u l a t i o n ; 12 mils of i n t e r g r a n u l a r a t t a c k in h o t zone

35-mil w a l l i n h o t zone

i n h o t zone

h t e r g r a n u l a r a t t a c k e n t i r e l y t h r o u g h

15 mils o f heavy i n t e r g r a n u l a r a t t a c k

12 m i l s o f i n t e r g r a n u l a r a t t a c k i n h o t

i m i l s o f i n t e r g r a n u l a r a t t a c k i n h o t

i mils o f i n t e r g r a n u l a r a t t a c k i n h a t

zone

zone

zone

h s e n t i a l l y no a t t a c k i n e i t h e r h o t o r c o l d zone i n any o f t h e t y p e 304 s t a i n - less s t ee l t e s t s

E s s e n t i a l l y no a t t a c k in e i t h e r h o t o r c o l d zone i n any o f t h e t y p e 430 s t a i n - l e s s s t ee l t e s t s

127


TABLE 10.3. RESULTS OF TWO-COIPONENT STATIC TESTS WITH LITEIUM AT 100O'C __

MATERIAL

Type 316 s t a i n l e s s steel

Inconel

Type 304 s t a i n l e s s s t e e l

TIME OF TEST (hr )

100

loa

400


No s i g n o f a t tack on s e c t i o n s exposed t o l i q u i d phase; 2 . 5 m i l s o f in tergranular a t t a c k on s e c t i o n s exposed t o vapor phase

Some m a s s - t r a n s f e r c r y s t a l s cou ld be noted on the sur face ; no a t t a c k i n vapor zone; 3 t o 4 m i l s o f subsurface v o i d s on tube i n bath zone

1 t o 2 m i l s o f i n t e r g r a n u l a r p e n e t r a t i o n and transformation from a u s t e n i t e t o f e r r i t e

a p p a r e n t i n t h e t e s t w i t h l i t h i u m . I n t h e t e s t w i t h l e a d , 1 t o 2 m i l s o f i n t e r g r a n u l a r p e n e t r a t i o n c o u l d b e no ted .

C o r r o s i o n b y L e a d i n T h e r m a l Convection LOOPS. A s e r i e s o f t e s t s h a s been made t o d e t e r m i n e t h e e x t e n t o f m a s s t r a n s f e r a n d c o r r o s i o n i n t h e r m a l c o n v e c t i on 1 o op s c o n t a i n i ng l i q u i d l e a d . The s y s t e m s l e a d - I n c o n e l , l e a d - n i o b i u m , a n d l e a d - m o l y b d e n u m h a v e been s t u d i e d . R e s u l t s a r e a l s o a v a i l a b l e f o r t h e l e a d - t y p e 3 0 4 s t a i n l e s s s t e e l s y s t e m , b u t a r e incomple t e .

S i n c e t h e r e s u l t s o f p r e v i o u s i n v e s t i g a t i o n s o f mass t r a n s f e r and c o r r o s i o n i n l e a d t h e r m a l c o n v e c t i o n l o o p s h a v e b e e n s u b j e c t t o c r i t i c i s m b e c a u s e o f o x i d e i n t h e l e a d o r on t h e m e t a l t u b i n g , i n t h e p r e s e n t s e r i e s o f e x p e r i m e n t s , t h e l i q u i d l e a d w a s d e o x i d i z e d w i t h h y d r o g e n p r i o r t o c o n t a c t w i t h t h e t e s t m e t a l . C a r e w a s a l s o t a k e n t o a v o i d h e a v y o x i d a t i o n o f t h e m e t a l s e c t i o n s o f t h e l o o p s . The a p p a r a t u s and e x p e r i - m e n t a l p r o c e d u r e were d e s c r i b e d i n t h e p r e v i o u s r e p o r t . ( '1

T h e q u a r t z t u b i n g u s e d i n t h e l o o p i s v i r t u a l l y i n s o l u b l e i n l e a d a t t h e t e s t t e m p e r a t u r e s ; t h e concen- t r a t i o n o f S i O , i n t h e l e a d a f t e r o n e

t5)ANP Quar. P r o g . R e p . D e c . 1 0 , 1 9 5 2 , ORNL- 1439, p. 148.

t e s t was o n l y 17 ppm, a n d t h e S i O , c o n c e n t r a t i o n i n a l e a d s a m p l e t h a t had n o t been i n c o n t a c t w i t h g l a s s o r q u a r t z w a s 15 ppm.

Loop t e s t s were r u n w i t h I n c o n e l , c o l u m b i u m , molybdenum a n d t y p e 3 0 4 s t a i n l e s s s t e e l s a m p l e s s u s p e n d e d i n t h e c i r c u l a t i n g l e a d . The r e s u l t s f o r I n c o n e l h a v e b e e n r e p o r t e d p r e v i - ~ u s l y ; ( ~ ) t h e r e s u l t s f o r t h e o t h e r m e t a l s a r e summar ized i n T a b l e 10 .4 .

The columbium s p e c i m e n s e x h i b i t e d n o m a s s t r a n s f e r a n d v i r t u a l l y n o c o r r o s i o n e v e n a f t e r a l m o s t 6 0 0 h r o f l o o p o p e r a t i o n . The s m a l l d e c r e a s e i n w a l l t h i c k n e s s was p r o b a b l y due t o t h e s o l u t i o n o f t h e s m a l l a m o u n t o f c o l u m b i u m r e q u i r e d t o s a t u r a t e t h e l e a d . No mass t r a n s f e r o c c u r r e d w i t h molybdenum, b u t t h e c o r r o s i o n , a l t h o u g h s l i g h t , w a s a l i t t l e g r e a t e r t h a n t h a t f o u n d f o r columbium. L i t t l e or n o i n t e r g r a n u l a r p e n e t r a t i o n w a s o b s e r v e d . T h e r e a s o n f o r t h e d i s - c r epancy i n t h e w a l l - t h i c k n e s s measure- m e n t s f o r t h e s e c o n d lead-molybdenum t e s t i s n o t known.

The molybdenum s p e c i m e n s u s e d were n o t a c t u a l l y s e c t i o n s o f t u b i n g b u t were made o f molybdenum f o i l b e n t i n t o a c y l i n d e r . The f o i l had a s p e c i f i e d t h i c k n e s s o f 10 m i l s , which was checked by m i c r o m e t e r r e a d i n g s a t two p o i n t s on t h e f o i l . I t i s p o s s i b l e t h a t t h e r e was a v a r i a t i o n i n t h i c k n e s s i n t h e

128


TEST TEMPERATURE (OC) METAL No’ Hot Zone Cold Zone.

Columbium 1 800 57 5 2 800 56 5

Mo 1 ybd enum 1 800 450

2 8 00 595

Type 304, high carbon, s ta in le s s s t ee l (d ) 1 800 50 0

T A B L E 10.4. C O R R O S I O N OF S T R U C T U R A L M E T A L S BY L E A D I N QUARTZ THERMAL

SPECIMW WALL THICKNESS ( in . )

Original Hot Zone

0.035 0.032

0.035 0.033

0.010 0.006(‘)

0.010 0.011

(O)Stoppage c a u s e d by f a i l u r e o f h o t l e g h e a t e r ; no p l u g formed.

(

( ‘ )Di screpancy p r o b a b l y caused by v a r i a t i o n i n tube t h i c k n e s s .

Se hedu 1 e d t erai n a t i o n.

(d)Examinat ion i n c o m p l e t e .

f o i l and t h a t t h e o r i g i n a l f o i l u s e d i n t e s t No. 2 w a s s l i g h t l y g r e a t e r t h a n 10 m i l s t h i c k .

T h e r e s u l t s o f t h e t e s t w i t h t y p e 3 0 4 s t a i n l e s s s t ee l a r e incomple t e . On t h e b a s i s o f t h e t h e r m a l r e c o r d o f t h e e x p e r i m e n t , however , i t a p p e a r e d t h a t c i r c u l a t i o n i n t h i s l oop was a l s o s t o p p e d b y p l u g f o r m a t i o n . T h e t y p e 3 0 4 s t a i n l e s s s t e e l s p e c i m e n u s e d h a d a c a r b o n c o n c e n t r a t i o n o f 0.087%.

‘ I n s u m m a r y , b o t h c o l u m b i u m a n d molybdenum showed v e r y good r e s i s t a n c e t o m a s s t r a n s f e r a n d c o r r o s i o n i n l i q u i d L e a d . On t h e o t h e r h a n d , s e v e r e c o r r o s i o n a n d m a s s t r a n s f e r o c c u r r e d i n t h e l e a d - I n c o n e l s y s t e m s d e s p i t e t h e c a r e f u l d e o x i d a t i o n o f t h e l e a d w i t h h y d r o g e n . T h e t e s t s h a v e i n c l u d e d a n i c k e l - b a s e a l l o y ( I n c o n e l ) , columbium, molybdenum, and an i r o n - b a s e a l l o y ( t y p e 304 s t a i n l e s s s t e e l ) . ‘[t i s p l a n n e d t o e x t e n d t h e s t u d y t o o t h e r i r o n - b a s e a l l o y s , such a s t y p e 4 1 0 s t a i n l e s s s t e e l , t o a l o w - c a r b o n t y p e 304 s t a i n l e s s s t e e l , and t o Armco i r o n .

Cold Zone

0.034

0.033

0.006(

0.010

TIME OF OPERATION

( h r )

C O R R O S I O N O F C E R A M I C S BY F L U O R I D E S A N D L I Q U I D M E T A L S

D. C. Vree land L. R. T r o t t e r E. E. Hoffman J. E. Pope

Me t a 1 l u r gy D i v i s i on

E. E. Ketchen L. G. O v e r h o l s e r M a t e r i a l s Chemis t ry D i v i s i o n

L. A. Mann J. M. C’ i s a r D. R. Ward ANP D i v i s i o n

Cermets i n F l u o r i d e s and L i q u i d Metals. Two cermets were p r e p a r e d by t h e Ceramics L a b o r a t o r y ; one c o n s i s t e d o f T i c p l u s 20% N i and 15% CbC p l u s TaC, and t h e o t h e r c o n s i s t e d o f Z r C p l u s 20% i r o n . T h e s e cermets were t e s t e d i v v a r i o u s c o r r o s i v e mediums by s e a l i n g t h e m , t o g e t h e r w i t h t h e c o r r o d i n g a g e n t , u n d e r v a c u u m i n I n c o n e l t u b e s . A f t e r t h e t u b e s had b e e n h e a t e d f o r 1 0 0 h r a t 8 1 6 O C , s p e c i m e n s were r e m o v e d , c h e c k e d f o r w e i g h t and d i m e n s i o n a l c h a n g e s , and e x a m i n e d m e t a l l o g r a p h i c a l l y . I n t h e t e s t s w i t h sodium and l e a d , t h e r e was l i t t l e or n o a t t a c k ( F i g . 1 0 . 6 ) . The

129


Fig. 10.7. Titanium Carbide Cermet After Exposure to NaF-ZrF,-UF, (46-50-4 mole 5%) f o r 100 hr at 816OC.

TABLE 10.5. RESULTS OF STATIC TESTS OF Tic AND ZrC CERMETS IN SODIUM, LEAD, AND SOME FLUORIDE MIXTURES

CERMET

T i C

ZrC

CORRODANT

Na

Pb

NaF-KF-Li F-UF.1 (10 .9-43 .5-44 .5-1 .1 mole So)

NaF-ZrFq-UF4 (46-50-4 mole X)

Na

NaF-KF-Li F-UFI, (10 .9-43 .5-44 .5-1 .1 mole %)

WEIGHT CHANGE ( g / i n . 2 )

-0.0065

Pb a d h e r i n g

F l u o r i d e

t o spec imen

adheTing t o specimen

-0 .0119

-0.0037

-0 .0158


No a t t a c k a p p a r e n t



Bonding m a t e r i a l appea red t o be l e a c h e d from specimen t o a d e p t h o f 5 m i l s

Specimen showed t h a t some un i fo rm s o l u t i o n had t a k e n p l a c e , b u t no t h i c k n e s s change was i n v o l v e d

S u r f a c e appea red t o be s l i g h t l y rough en ed

13 0


m i x t u r e NaF-KF-LiF-UF4 ( 1 0 . 9 - 4 3 . 5 - 4 4 . 5 - 1 . 1 m o l e So) a p p e a r e d t o h a v e l i t t l e e f f ' e c t on t h e s e m a t e r i a l s , b u t i n t h e o n e t e s t w i t h N a F - Z r F 4 - U F , ( 4 6 - 5 0 - 4 m o l e % I , t h e s p e c i m e n w a s a t t a c k e d t o a d e p t h o f 5 m i l s ( F i g . 10 .7) . No s i g n i f i c a n t d i m e n s i o n a l c h a n g e s c o u l d b e n o t e d i n any o f t h e t e s t s . The w e i g h t l o s s d a t a and t h e r e s u l t s o f m e t a l l o g r a p h i c e x a m i n a t i o n a r e g i v e n i n T a b l e 10.5. -

S t f t h e A R E - B e 0 B l o c k s i n Na and NaK. Two t e s t s h a v e b e e n p e r f o r m e d w i t h ARE b e r y l l i u m o x i d e

o r b l o c k s h e q t e d for s e v e r a l h o u r s a t 8 1 0 ° C i n a t y p e 347

s t a i n l e s s s t e e l p o t c o n t a i n i n g Na or NaK. I n t h e f i r s t t e s t , t h e b e r y l l i u m o x i d e wa:; i m m e r s e d i n 255 i n . 3 o f

F i g . 1 0 . 6 . Zirconium Carbide Cermet After Exposure t o s o d i u m for 100 hr a t 816OC.

sodium f o r 213 h r a t 816°C. A l t h o u g h no c r a c k i n g o r s p a l l i n g o f t h e b e r y l l i u m o x i d e w a $ n o t i c e a b l e i m m e d i a t e l y a f t e r t h e t e s t , t h e s u r f a c e i m - p e r f e c t i o n s a p p a r e n t i n p a r t a o f F i g . 1 0 . 8 o c c u r r e d a f t e r t h e t e s t s p e c i m e n had b e s o a k e d i n a l c o h o l and wa te r .

I n t h e s e c o n d t e s t , t h e NaK w a s t r a n s f e r r e d t o t h e p o t w i t h t h e b e r y l l i u m o x i d e when b o t h t h e N a K and t h e b e r y l l i u m o x i d e were a t r o o m t e m p e r a t u r e . T h e t e s t w a s r u n f o r 5 0 0 h r a t 8 1 6 ° C w i t h t h e b e r y l l i u m o x i d e i m m e r s e d i n 2 5 5 i n . 3 o f NaK. A f t e r t h e t e s t , t h e b e r y l l i u m o x i d e w a s b a d l y c r a c k e d , a s c a n b e s e e n i n p a r t b' o f F i g . 10. 8. T h e w e i g h t a n d d i m e n s i o n a l c h a n g e s n o t e d f o r bo th t e s t s a re g iven i n T a b l e 10.6.

131


. .

F i g . 10 .8 . ARE Beryllium Oxide Blocks After S t a t i c Tests i n Na and NaK a t 816’C. . (a) I n Na f o r 213 h r ; ( b ) i n NaK f o r 500 h o u r s .

Seesaw T e s t s o f Be0 i n NaK. B e - r y l l i u m o x i d e spec imens 1 / 4 b y 1/4 by l i n , were t e s t e d i n NaK i n t h e r o c k e r f u r n a c e f o r 1 0 0 h r , w i t h a h o t - z o n e t e m p e r a t u r e o f a p p r o x i m a t e l y 8 3 0 ° C a n d a c o l d - z o n e t e m p e r a t u r e o f a p - p r o x i m a t e l y 4 5 0 ° C . S p e c i m e n s were c r i m p e d i n t o t h e h s t e n d o f t h e t u b e t o p r e v e n t t h e i r s l i d i n g f r o m t h e b o t e n d t o t h e c o l d e n d . S p e c i m e n s i n d i c a t e d i n T a b l e 10.7 as“1ow d e n s i t y ” h a d a d e n s i t y o f a p p r o x i m a t e l y 2 . 2 7 ; t h o s e i n d i c a t e d a s “ h i g h d e n s i t y ” had a d e n s i t y o f a p p r o x i m a t e l y 2 . 8 3 .

132

t

F

i S p e c i m e n s i n d i c a t e d a s “ d e h y d r a t e d ” were d r i e d f o r 2 4 h r a t 125°C b e f o r e t e s t . The i n f o r m a t i o n d e r i v e d f r o m t h e s e e x p e r i m e n t s i s t a b u l a t e d i n T a b l e 10 .7 . I t i s e v i d e n t from t h e s e d a t a t h a t a f t e r t h e s p e c i m e n s were s t r i p p e d i n a l c o h o l t h e r e w a s some s l i g h t e v i d e n c e o f c r a c k i n g i n t h e h i g h - d e n s i t y spec imens and some s l i g h t e v i d e n c e o f s p a l l i n g i n t h e l o w - d e n s i t y s pec i m e n s .

Convection Loop t e s t s o f Be0 i n NaK. E i g h t s p e c i m e n s o f Be0 1 / 4 by 1/4 by 1 / 2 i n . were p l a c e d i n a w i r e b a s k e t


BEFORE AFTER CHANGE AFTER CLEANING I N TEST TEST ( % I WATER AND DRYING

i n t h e s u r g e t a n k o f a t h e r m a l c o n - v e c t i o n l o o p , and NaK was p e r m i t t e d t o f l o w o v e r t h e s p e c i m e n s a t a v e l o c i t y o f abou t 8 fpm f o r 212 h o u r s . The t e m p e r a t u r e of t h e NaK was 1150'F i n t h e c o l d l e g a n d lOOO'F i n t h e h o t l e g , a n d t h e s a m p l e s w e r e i n c o n t a c t w i t h NaK a t 1500'F. The NaK s p e c i m e n s i n t h e s e c o n d t e s t were p r e t r e a t e d b e f o r e e x p o s u r e t o t h e h o t N a K :in t h e f o l l o w i n g m a n n e r : spec imens 1 and 2 r e c e i v e d no s p e c i a l p r e t r e a t m e n t ; s p e c i m e n s 3 and 4 were t r e a t e d wi th MgNO,; spec imens 5 and 6 were i m p r e g n a t e d w i t h AlF, and CaF,; s p e c i m e n s 7 and 8 w e r e t r e a t e d w i t h BeN03. The t e s t r e s u l t s a r e g i v e n i n T a b l e 10 .8 .

CHANGE ( % I

I t i s n o t e w o r t h y t h a t s p e c i m e n s 1, 3 , 5 , and 7 were l o c a t e d above s p e c i - mens 2. 4, 6 , and 8 , r e s p e c t i v e l y , i n t h e b a s k e t d u r i n g e x p o s u r e t o t h e NaK, and i n e a c h c a s e t h e u p p e r s p e c i m e n s u f f e r e d t h e g r e a t e r l o s s i n w e i g h t . S p e c i a l t r e a t m e n t o f Be0 t o i n c r e a s e i t s r e s i s t a n c e t o h o t N a K a p p e a r s t o o f f e r p o s s i b i l i t i e s , a n d f u r t h e r t e s t s a r e t o be conduc ted . The e f f e c t of t h e d e n s i t y o f t h e s p e c i m e n c o u l d n o t be c o r r e l a t e d t o t h e we igh t l o s s e s i n t h e s e t es t s .

Solubility o f B e 0 in N a K . V a r i o u s w o r k e r s h a v e i n i t i a t e d e x p e r i m e n t s t o d e t e r m i n e , i f p o s s i b l e , t h e e f f e c t o f NaK on B e 0 a t . t e m p e r a t u r e s o f a p p r o x i m a t e l y 800'C i n bo th s t a t i c and

Length, in . 5.9 14 5.917 +0.05

Width, i n . 3.706 3.708 +0.05

Weight, 1: 3.154 3,221 +2.1 3.205 +1.6

TABLE 10.7. RESULTS OF SEES

Length, i n . 5.909 5.899 -0.17 Width, i n . 3.714 3.7 12 -0.05

Weight, 1: 3. 160 3.205 +1.4 3.187

SPEXXNIEN

High d e n s i t y , d e h y d r a t e d

+0.85

WEIGHT LOSS

( g / i n .

0.0454

0.0286

0.0893

0.0104

I!

I TESTS O F B e 0 I N N a K AFTER 100 hr AT 816'C

WEIGHT LOSS

( 9 6 )

2.38

1.25

5. 15

0.52

TOTAL WEIGHT LOSS (mg)

30.7

18.9

47.0

6.1

TOTAL Be0 FOUND BY ANALYSIS OF NaK FILTER AND CONTAINERS

(mg)

14.26

4.97

9.91

6.02

'Th i s test tun f o r o n l y 16 hours .

133


d y n a m i c t e s t s y s t e m s . T h e w e i g h t l o s s e s o f t h e Be0 b l o c k s o b s e r v e d i n a n u m b e r o f i n s t a n c e s p r o m p t e d a s e a r c h f o r t h e b e r y l l i u m t h a t had been r e m o v e d f r o m t h e b l o c k . I n t h o s e t e s t s f o r which t h e NaK was f i l t e r e d a t room t e m p e r a t u r e , t h e b e r y l l i u m found i n t h e f i l t r a t e c o r r e s p o n d e d t o a p p r o x i m a t e l y 3 ppm o f BeO, which was a v e r y s m a l l p a r t o f t h e t o t a l b e r y l l i u m r e m o v e d f r o m t h e b l o c k s . F u r t h e r e x a m i n a t i o n r e v e a l e d t h a t t h e b e - r y l l i u m o r t h e B e O , o r b o t h , w a s l o c a t e d p r i m a r i l y on t h e w a l l s o f t h e c o n t a i n e r s t o which i t a d h e r e d t i g h t l y . The q u e s t i o n t h e n a r o s e a s t o ' w h e t h e r or n o t t h e b e r y l l i u m was removed from t h e b l o c k and d e p o s i t e d on t h e w a l l by some p r o c e s s i n v o l v i n g s o l u b i l i t y o f Be or Be0 i n t h e NaK a t 800OC.

Two t e s t s were p e r f o r m e d t o measu re t h e s o l u b i l i t y i n NaK a t 800°C. I n t h e f i r s t t e s t , Be0 was c o n t a c t e d wi th NaK a t 8OO0C f o r 6 h r i n t h e r e a c t i o n - f i l t r a t i o n r i g p r e v i o u s l y d e s c r i b e d . 1 6 ) The MaK was f i l t e r e d a t a p p r o x i m a t e l y 8OO0C, and t h e f i l t r a t e was c o l l e c t e d i n a n i c k e l r e c e i v i n g t u b e . Based on t h i s s i n g l e e x p e r i m e n t , t h e s o l u b i l i t y o f b e r y l l i u m i n NaKat 8OO0C c o r r e s p o n d s t o r o u g h l y 1 0 0 ppm, b u t i t i s n o t known w h e t h e r t h e m a t e r i a l d i s s o l v e d was Be or BeO.

(6)ANP Quar. P r o g . R e p . D e c . 1 0 , 1 9 5 2 , ORNL- 1439, F i g . 1 0 . 7 , p . 121.

I n t h e s e c o n d t e s t , a s t a i n l e s s s t e e 1 t h e r m a l c o n v e c t i o n l o o p w a s u s e d t o c i r c u l a t e NaK o v e r Be0 b l o c k s s u s p e n d e d i n t h e s u r g e t a n k . A f t e r 2 1 2 h r o f c i r c u l a t i o n a t a f l o w r a t e o f 6 t o 10 fpm, a w e i g h t loss of a b o u t 25% was m e a s u r e d f o r t h e B e 0 b l o c k s ( o r i g i n a l w e i g h t o f 4 g ) . A f t e r t h e NaK h a d b e e n d r a i n e d , t h e l o o p w a s s e c t i o n e d a s shown i n F i g . 10 .9 . T h e o p e r a t i n g t e m p e r a t u r e s o f t h e l o o p a r e g i v e n o n t h e f i g u r e , a l o n g w i t h t h e a n a l y t i c a l r e s u l t s f o r t h e B e 0 d e t e r m i n a t i o n s o n t h e r e s p e c t i v e 3 1 / 2 - i n . s e c t i o n s .

The a n a l y t i c a l r e s u l t s show t h a t t h e t h r e e c o l d e s t ( a n d l o w e s t ) s e c t i o n s o f t h e l o o p c o n t a i n e d t h e g r e a t e s t c o n c e n t r a t i o n s o f b e r y l l i u m . S i n c e t h e a n a l y t i c a l d a t a show no a c c u m u l a t i o n o f Be0 f r a g m e n t s i n t h e c o l d e s t p a r t o f t h e t a n k , i t i s s u g g e s t e d t h a t a d i s s o l u t i o n p r o c e s s , g o v e r n e d by t h e t e m p e r a t u r e g r a d i e n t , i s r e s p o n s i b l e f o r t h e t r a n s f e r o f t h e m a t e r i a l f r o m t h e B e 0 b l o c k t o t h e w a l l s . o f t h e c o l d r e g i o n .

Such a mechanism c o u l d be r e p r e s e n t e d by t h e f o l l o w i n g r e a c t i o n :

2NaK t 2Be0 e NazO t K,O -t 2Be , w h i c h , i f t h e r e a c t i o n p r o c e e d s s l i g h t l y t o t h e r i g h t a t 8 0 0 ° C a n d t h e b e r y l l i u m f o r m e d i s s o l u b l e i n NaK, w o u l d a c c o u n t f o r r e m o v a l o f

TABLE 10.8. RESULTS OF TESTS OF Be0 IN NaK

Average l o s s i n dimensions per s u r f a c e , i n .

Loss of weight , g

Loss of weight ( % I

Dens i ty o f specimen

1

0.006

0.152

1 1 . 5

2.60

2

0.004

0.120

9 . 6

2.50

0.002

0.091

6.8

2.54

SPECIMEN NUMBER

0.002

0.076

6.0

2.45

5

0 .000

0.069

4.9

2.82

6

0 . 0 0 1

0 . 0 6 2

4 . 7

2.65

7

0.005

0.162

11.1

2.66

8

0.004

0 .119

9.6

2.45

("'Much o r a l l o f t h e we ight l o s s may have been due t o t h e shedding o f a t h i n s u r f a c e f i l m i n t h e . a l c o h o l b a t h .

134



WEIGHT OF Be0 FOUND IN VARIOUS SECTIONS

AVERAGE SECTION NO. B e 0 (mg) TEMPERATURE ( O F )

i 3 5 6 7 9

10 11 13

i5 17 18* 19 20 21

22

14%

4.13 1.37 5.52

2.17 22.08

248.4 70.8

5.76

3.64 4.14

4.74

6.72 27.48

*14 and48 LOCATED UNDER HEATER

i 500 1360

1 250

4140

1860 1370

144 0 I800 1480

Fig. 10.9. Schematic Diagram o f Convection Loop for NaK-Be0 Tes t Showing Temperature and Be0 Recovered in Various Sections.

135


b e r y l l i u m from t h e Be0 b l o c k . I f t h e s o l u b i l i t y o f b e r y l l i u m i s l e s s a t 6 0 0 ° C t h a n a t 8OO0C, d e p o s i t i o n or a l l o y i n g i n t h e c o l d a r e a would o c c u r .

EFFECT OF ATMOSPHERE ON THE MASS TRANSFEROF NICKELIN HYDROXIDES

H . J. Buttram C. R. C r o f t F. K e r t e s z


The i n c l i n e d - t u b e t e c h n i q u e p r e v i - o u s l y d e s c r i b e d ( ' ) was u s e d f o r f u r t h e r s t u d y o f t h e e f f e c t o f v a r i o u s e x p e r i - m e n t a l f a c t o r s on t h e mass t r a n s f e r o f n i c k e l by h y d r o x i d e s . With a t empera - t u r e g r a d i e n t o f 150°C (800°C a t t h e b o t t o m a n d 6 5 0 ° C a t t h e t o p ) u n d e r h e l i u m a t m o s p h e r e , s o d i u m h y d r o x i d e t r a n s p o r t e d e n o u g h n i c k e l t o t h e l i q u i d l e v e l o f t h e i n c l i n e d n i c k e l t u b e t o p l u g i t c o m p l e t e l y i n 48 h o u r s . A s was p r e v i o u s l y m e n t i o n e d , hydrogen g a s s w e e p i n g o v e r t h e s u r f a c e o f t h e m o l t e n h y d r o x i d e r e d u c e d t h e m a s s t r a n s f e r c o n s i d e r a b l y ; o n l y p o l i s h i n g o f t h e h o t end and r o u g h e n i n g o f t h e c o l d e n d o f t h e t u b e c o u l d be obse rved . T h e t e m p e r a t u r e g r a d i e n t w a s t h e n i n c r e a s e d t o 300°C (500°C a t t h e t o p a n d 8 0 0 ° C a t t h e b o t t o m ) , a n d a hydrogen a tmosphe re was used . S i m i l a r s a t i s f a c t o r y " r e s u 1 t s were o b t a i n e d ; t h e h y d r o g e n l a r g e l y s u p p r e s s e d a n y c r y s t a l d e p o s i t a t t h e l i q u i d l e v e l .

A t t e m p t s were made t o d e t e r m i n e t h e minimum p r e s s u r e a t w h i c h m a s s t r a n s f e r is e f f e c t i v e l y i n h i b i t e d by hydrogen . A 50 v o l % hel ium-50 v o l % h y d r o g e n m i x t u r e o v e r t h e h y d r o x i d e g a v e s a t i s f a c t o r y r e s u l t s . On t h e o t h e r h a n d , w i t h an a b s o l u t e h y d r o g e n p r e s s u r e o f 38 c m Hg - e s t a b l i s h e d a s a m a n u a l l y a d j u s t e d v a c u u m - t h e hydrogen sys t em a f f o r d e d n o p r o t e c t i o n , p o s s i b l y b e c a u s e o f t h e t e c h n i q u e e mp l o y e d.

A number o f o t h e r a t m o s p h e r e s was a l s o a p p l i e d o v e r sodium h y d r o x i d e i n t h e i n c l i n e d t u b e t e s t . The u s e o f

( ? ) A N P Q u a r . P r o g . R e p . D e e . 1 0 , 1 9 5 2 , ORNL- 1439, p . 142 f f .

c a r b o n monoxide and f o r m i n g g a s ( 1 0 % H, i- 90% N2) d i d n o t have a b e n e f i c i a l e f f e c t . Water i n t h e h y d r o g e n , e v e n i n s m a l l q u a n t i t i e s , r e s u l t e d i n c o n s i d e r a b l e mass t r a n s f e r . B u b b l i n g t h e h y d r o g e n t h r o u g h w a t e r a t v a r i o u s t e m p e r a t u r e s r e s u l t e d i n n i c k e l c r y s t a l d e p o s i t s i n a m o u n t s s i m i l a r t o t h o s e o b t a i n e d u n d e r a h e l i u m a t m o s p h e r e . A c o n t i n u o u s vacuum o v e r t h e s y s t e m ( w h i c h w o u l d r e m o v e a n y h y d r o g e n f o r m e d d u r i n g t h e t e s t ) r e s u l t e d i n e x t r e m e l y h e a v y c o r r o s i o n a n d m a s s t r a n s f e r , a n d l e f t t h e h y d r o x i d e w i t h a n i c k e l c o n c e n t r a t i o n o f u p t o 3%. However , when t h e t u b e was e v a c u a t e d a n d s e a l e d , t h e m a s s t r a n s f e r was much l e s s s e v e r e . Dry a i r was d e f i n i t e l y l e s s h a r m f u l t h a n w e t h y d r o g e n . The u s e o f c o m m e r c i a l s o d i u m h y d r o x i d e , w h i c h c o n t a i n s u p t o 2 % w a t e r , r e s u l t e d i n g r e a t l y r e d u c e d m a s s t r a n s f e r u n d e r d r y h y d r o g e n . O n e e f f e c t o f t h e d r y h y d r o g e n may b e t o s t r i p t h e w a t e r from t h e h y d r o x i d e .

I n a d d i t i o n t o t h e t e s t s w i t h s o d i u m h y d r o x i d e , e x p e r i m e n t s were made w i t h sodium h y d r o x i d e - p o t a s s i u m h y d r o x i d e e u t e c t i c , w i t h p u r e p o t a s s i u m h y d r o x i d e , and w i t h l i t h i u m h y d r o x i d e . W i t h n o n e o f t h e s e m a t e r i a l s c o u l d t h e i n h i b i t i n g e f f e c t o f h y d r o g e n on t h e m a s s t r a n s f e r o f n i c k e l b e o b - t a i n e d ; t h e r e a s o n f o r t h i s i s n o t y e t c l e a r . More c l o s e l y c o n t r o l l e d e x p e r i m e n t s a r e p l a n n e d .

FUNDAMENTAL CORROSION RESEARCH

I d e n t i f i c a t i o n o f Corrosion Products from Convection Loops (D. C. Hoffman, M a t e r i a l s C h e m i s t r y D i v i s i o n ) . C o o l i n g j e t s t h a t i m p i n g e d o n t h e c o l d l e g o f an I n c o n e l t h e r m a l c o n v e c t i o n l o o p i n w h i c h t h e L i F - N a F - K F e u t e c t i c c o n t a i n i n g 1 . 8 m o l e % o f UF, w a s c i r c u 1 a t i n g , p r o d u c e d p a r t i a 1 p 1 u g s which p e r s i s t e d a f t e r t h e c o o l i n g j e t s were removed and c o u l d n o t b e l i q u e f i e d a t t e m p e r a t u r e s o f up t o 650°C. X-ray a n a l y s i s o f t h e p l u g s s h o w e d t h e p r e s e n c e of KF and some m a t e r i a l t h a t

4

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g a v e a s l i g h t l y s h i f t e d s p e c t r u m o f K,NaCrF, . P e t r o g r a p h i c i n v e s t i g a t i o n s u b s t a n t i a t e d t h e p r e s e n c e o f t h i s compound and a l s o r e v e a l e d some b r i g h t m e t a l t h a t was shown t o be nonmagnet ic . I n s p e c t i o n u n d e r b i n o c u l a r s (45X) .$:showed a ne twork of c r y s t a l s , presumed t o b e t h e K 2 N a C r F 6 , g r o w i n g i n w a r d from t h e t u b e w a l l s .

The coinpound K2NaCrF6 h a s a s o l u - b i l i t y i n t h e NaF-KF-LiF e u t e c t i c o f 450 ppm C r ( I I 1 ) and 2000 ppm C r ( I I 1 ) a t 500 a n d 65OoC, r e s p e c t i v e l y . I t t h e r e f o r e a p p e a r s p r o b a b l e t h a t K 2 N a C r F 6 h a s b e e n r e s p o n s i b l e f o r p l u g g i n g i n t h i s l o o p , a s w e l l a s i n o t h e r s , i n w h i c h t h e a m o u n t o f m e t a l t r a n s f e r r e d was i n s u f f i c i e n t t o a c c o u n t f o r t h e phenomenon. Of t h e t e n s t a i n l e s s s t e e l h a r p s t h a t were p lugged w h i l e c i r c u l a t i n g t h i s m i x t u r e , s i x showed h i g h e r chromium c o n t e n t i n t h e c o l d l e g , o n e s h o w e d h i g h e r chromium c o n t e n t i n t h e h o t l e g , and t h e o t h e r t h r e e showed n o s y s t e m a t i c v a r i a t i o n .

The K,NaCrF, c r y s t a l s a p p a r e n t l y f o r m an o p e n n e t w o r k t h a t g r a d u a l l y s t o p s t h e f l o w w i t h o u t d e v e l o p i n g , u n d e r u s u a l o p e r a t i n g c o n d i t i o n s , e a s i 1 y d e t e c t a b l e l o c a 1 c oncen t r a t ion s . The obse rv 21 t i on t h a t i n c r e a s ed ope r a t i n g t e m p e r a t u r e s p o s t p o n e t h e o n s e t o f p l u g g i n g in s t a i n l e s s s t e e l l o o p s i s c o n s i s t e n t w i t h t h i s e x p l a n a t i o n o f t h e p l u g g i n g phenomenon.

P r e p a r a t i o n o f S p e c i a l C o m p l e x F l u o r i d e s (B. J. S tu rm, L. G. Overholser , M a t e r i a l s Chemis t ry D i v i s i o n ) . P r e p a - r a t i o n s o f K 2 L i C r F , , K N a L i C r F s , L i2NaCrF6, Na2LiCrF, , and NaCrF, h a v e b e e n made t o f u r n i s h s p e c i m e n s f o r x - r a y a n d o p t i c a l c r y s t a l l o g r a p h i c d a t a . C o n t i n u e d s t u d y o f t h e complex f l u o r i d e s o f n i c k e l h a s n o t y e t e s t a b l i s h e d whether d e f i n i t e compounds o r s o l i d s o l u t i o n s e x i s t i n t h e c o m p o s i t i o n r a n g e b e t w e e n K,NiF, and Na2Ni F, . A l s o , s e v e r a 1 s imp l e f l u o r i d e s o f t h e s t r u c t u r a l m e t a l s , i n c l u d i n g chromof l u o r i d e , f e r r o f l u o r i d e , n i c k e l f l u o r i d e , and f e r r o u s o x i d e , have been

p r e p a r e d f o r s t u d i e s o f t h e i r e f f e c t on c o r r o s i o n by f u e l m i x t u r e s .

C h r o m i c f l u o r i d e c a n be p r e p a r e d by t h e r m a l decompos i t ion o f (NH, ),CrF, a t t e m p e r a t u r e s n o t e x c e e d i n g 900°C; some CrF, i s formed a t h i g h e r t empera - t u re s . Chromous f l u o r i d e i s p r e p a r e d by h e a t i n g (NH,),CrF, or a m i x t u r e o f h y d r a t e d CrF, and NH,KF, t o 1200°C i n g r a p h i t e c r u c i b l e s . The p r o d u c t from e i t h e r of t h e s e p r o c e d u r e s i s i d e n t i c a l w i th t h a t o b t a i n e d by hydrof l u o r i n a t i o n o f m e t a l l i c chromium a t 800°C. F e r r i c f l u o r i d e i s p r e p a r e d by h y d r o f l u o r i - n a t i o n o f uanhydrous" FeC1, a t 200 t o 3 0 0 ° C . F e r r o u s f l u o r i d e m a y b e p r e p a r e d by h e a t i n g ( N H 4 1 3 F e F 6 a t 750°C or, p r e f e r a b l y , by h y d r o f l u o r i - n a t i o n o f FeC1, a t a maximum t e m p e r a - t u r e o f 500°C. N i c k e l f l u o r i d e i s b e s t p r e p a r e d by t h e r m a l decompos i t ion o f ( N H , ) , N i F , . F e r r o u s o x i d e i s p r e p a r e d by d e c o m p o s i t i o n , u n d e r an a tmosphe re o f CO,, o f f e r r o u s o x a l a t e p r e c i p i t a t e d from an aqueous s o l u t i o n o f f e r r o u s ammonium s u l f a t e by ammonium o x a l a t e . The f e r r o u s o x i d e p r o d u c e d i s v e r y f i n e l y d i v i d e d and i s e a s i l y o x i d i z e d by room t e m p e r a t u r e a i r ; a l l h a n d l i n g o f t h i s compound r e q u i r e s a d r y , i n e r t a tmosphere .

Air O x i d a t i o n o f F u e l M i x t u r e s ( R . P . M e t c a l f , M a t e r i a l s C h e m i s t r y D i v i s i o n ) . S o l i d UF, i s known t o y i e l d UO,F, and UF, a s p r e d o m i n a n t r e a c t i o n p r o d u c t s when t r e a t e d w i t h o x y g e n a t h i g h t e m p e r a t u r e s . ( * * ' ) However, when mol ten NaUF5 i n a n i c k e l b o a t was t r e a t e d w i t h 40 t o 60 cc /min o f d r y a i r f o r 2 t o 6 h r a t 7 5 O o C , n o g a s e o u s u r a n i u m c o m p o u n d s w e r e obse rved .

X - r a y - d i f f r a c t i o n t e c h n i q u e s r e v e a l t h e p r e s e n c e o f N i O , U,O,, and Na,NiF, a m o n g t h e s o l i d p r o d u c t s o f t h e r e a c t i o n . I n a d d i t i o n , s e v e r a l u n - i d e n t i f i e d p r o d u c t s t h a t may b e

F r i e d and N. R . D a v i d s o n , T h e R e a c t i o n of UF v i t h D r y 0,; A Ner S y n t h e s i s of U F 6 , AECD- 2981 ?May 1 9 4 5 ) .

(9)S. S. K i r s l i s . T. S. M c l i l l a n and H . A. B e r n h a r d t , T h e R e a c t i o n of U r a n i u m Te t r a f l u o r r d e w l t h D r y O x y g e n , K-567 (March 1 5 , 1 9 5 0 ) .

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d o u b l e f l u o r i d e s o f n i c k e l a r e obse rved . The a b s e n c e o f UO,F, and UO, a n d t h e l a c k o f e v i d e n c e f o r v o l a t i l i z a t i o n

2 N i + 0, - 2Ni0

2NiO + UF, d UO, + PNiF ,

o f UF, a r e n o t e w o r t h y . 3U0, + 0, - U,O, 2NaF + NiF, - Na,NiF,

T h e s e r e s u l t s , a s w e l l a s t h e r a p i d c o r r o s i o n r a t e o f n i c k e l i n I t a p p e a r s t h a t t h e c o n t a i n e r p l a y s c o n t a c t w i t h m o l t e n f l u o r i d e s i n a i r , a n i m p o r t a n t p a r t i n t h e m e c h a n i s m a r e c o n s i s t e n t w i t h t h e f o l l o w i n g o f a i r o x i d a t i o n o f u r a n i u m i n t h e r e a c t i o n mechanism : m o 1 t en f l u or i d es .

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11. METALLURGY AND CERAMICS

P

W. D. Manly J . M. Warde Met a1 l u r gy D i v i s i o n

C o n e - a r c w e l d i n g i s now b e i n g a p p l i e d t o t h e p r o d u c t i o n o f t h e many t u b e - ' t o - h e a d e r j o i n t s n e e d e d i n t h e c o n s t r u c t i o n o f t h e c o m p l i c a t e d h e a t e x c h a n g e r s f o r a i r c r a f t r e a c t o r s . S i n c e t h e h e a t e x c h a n g e r s a r e t o be o p e r a t e d a t a m o d e r a t e l y h i g h p r e s s u r e f o r t h e t e m p e r a t u r e i n v o l v e d , d i s h e d h e a d e r s h e e t s a r e d e s i r e d . The d i s h e d h e a d e r s h e e t s impose a new problem o f u n e q u a l a r c d i s t a n c e s i n c o n e - a r c w e l d i n g . S t u d i e s a r e u n d e r way t o s e l e c t t h e p r o p e r c o n d i t i o n s t o min imize t h i s e f f e c t so t h a t c o n s i s t e n t l y sound w e l d s c a n be p roduced . I n t h e f a b r i - c a t i o n o f l a r g e h e a t e x c h a n g e r t e s t u n i t s by N i c r o b r a z i n g , d i f f i c u l t i e s d u e t o d i l u t i o n and e m b r i t t l e m e n t by t h e b r a z i n g a l l o y were e n c o u n t e r e d .

I t i s p o s s i b l e t o s u b s t i t u t e o t h e r a l l o y s f o r t h i s b r a z i n g c y c l e t h a t w i l l n o t c a u s e s e v e r e d i l u t i o n a n d e m b r i t t l e r n e n t , a n d t h e e v a l u a t i o n o f h i g h - t e m p e r a t u r e b r a z i n g a l l o y s i s c o n t i n u i n g . The m e l t i n g p o i n t o f t h e p a l l a d i u m - n i c k e l b r a z i n g a l l o y was l o w e r e d by a d d i t i o n s o f g e r m a n i u m , T h e e f f e c t s o f t i m e a t t h e b r a z i n g t e m p e r a t u r e a n d o f j o i n t s p a c i n g on t h e s t r e n g t h p r o p e r t i e s o f N i c r o b r a z e d j o i n t s have been d e t e r m i n e d , A summary o f t h e b u t t - b r a z e t e n s i l e s t r e n g t h d a t a o b t a i n e d on t h e v a r i o u s b r a z i n g a l l o y s i s p r e s e n t e d .

A s e a r c h f o r a s a t i s f a c t o r y b r a z i n g a l l o y f o r t h e j o i n i n g o f s t a i n l e s s - s t e e l - o r I n c o n e l - c l a d c o p p e r f i n s t o I n c o n e l and s t a i n l e s s s t e e l t u b e s h a s p r o v e d f r u i t f u l , a n d t h e o x i d a t i o n c h a r a c t e r i s t i c s o f t h e a l l o y s t h a t show good f l o w a b i l i t y on I n c o n e l a r e now b e i n g s t u d i e d . H o w e v e r , i t h a s been d e m o n s t r a t e d t h a t a ch rome-p la t ed , h i g h - c o n d u c t i v i t y , c o p p e r f i n d o e s n o t h a v e s u f f i c i e n t o x i d a t i o n r e s i s t a n c e f o r t h i s a p p l i c a t i o n ,

The e f f e c t s o f e n v i r o n m e n t a n d o f s u r f a c e t r e a t m e n t on t h e c r e e p a n d s t r e s s - r u p t u r e p r o p e r t i e s o f I n c o n e l a r e s t i l l b e i n g s t u d i e d , P r e o x i d i z e d specimens were t e s t e d i n a r g o n , and i t was f o u n d t h a t t h e c r e e p p r o p e r t i e s were q u i t e s i m i l a r t o t h o s e d e t e r m i n e d i n a r g o n ; t h e r e f o r e s u r f a c e o x i d a t i o n i s n o t t h e c o n t r o l l i n g f a c t o r i n t h e l o n g e r r u p t u r e t imes o b s e r v e d i n t h e a i r t e s t s

C o n t r o l r o d i n s e r t s o f a m i x t u r e o f b o r o n c a r b i d e a n d i r o n a r e b e i n g p r e p a r e d by powder m e t a l l u r g y t e c h - n i q u e s f o r t h e GE-ANP p r o g r a m . T h e c o n t r o l r o d i n s e r t s m u s t b e m e t a l - l u r g i c a l l y b o n d e d t o t h e o u t s i d e s t a i n l e s s s t e e l t u b e , a n d v a r i o u s b r a z i n g a l l o y s a r e b e i n g s t u d i e d f o r t h i s a p p l i c a t i o n . B o r o n c a r b i d e s a f e t y r o d s f o r t h e Tower S h i e l d i n g F a c i l i t y were a l s o p roduced .

S p e c i a l h e a t s o f a h i g h - p u r i t y I n c o n e l a r e b e i n g p r e p a r e d f o r c o r - r o s i o n t e s t s , I n t h e s u b s e q u e n t e x t r u s i o n o f I n c o n e l t u b e s , one o f t h e b i g g e s t d i f f i c u l t i e s t o o v e r c o m e i s t h e s e l e c t i o n o f a p r o p e r e x t r u s i o n l u b r i c a n t . A s a t i s f a c t o r y t u b e h a s been produced by t h e u s e o f g l a s s a s a l u b r i c a n t . I n o t h e r s t u d i e s , t h e o x i d a t i o n c h a r a c t e r i s t i c s o f columbium a r e b e i n g i n v e s t i g a t e d , a n d s o m e e x p l o r a t o r y r u n s have been made on t h e p r o d u c t i o n o f m a t e r i a l s f o r u s e a s pump s e a l s o f t h e f a c e - s e a l t y p e b e i n g s t u d i e d by t h e E x p e r i m e n t a l E n g i n e e r i n g Group.

An enamel w i t h h i g h b o r o n c o n t e n t was a p p l i e d on a s h i e l d t e s t p l a t e , b u t a p a r t o f t h e s u r f a c e was n o t w e l l c o v e r e d a n d a s e c o n d a t t e m p t w a s n e c e s s a r y . Two cermet f u e l e l e m e n t s a r e d e s c r i b e d , I m p r e g n a t i o n o f h e x a g o n a l b e r y l l i u m o x i d e b l o c k s w i t h b e r y l l i u m and magnesium n i t r a t e s and

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c a l c i u m a n d a l u m i n u m f l u o r i d e s was a t t e m p t e d . The f l u o r i d e s f i l l e d t h e p o r e s , and t h e magnesium i m p r e g n a t i o n shows promise.

WELDING AND BRAZING RESEARCH

P. P a t r i a r c a V . G. Lane G. M. S l a u g h t e r C. E , S c h u b e r t


Cone-Arc W e l d i n g . T h e d e s i g n o f r e c e n t fue l - to -NaK h e a t e x c h a n g e r s , f o r r e a c t o r r e s e a r c h h a s n e c e s s i t a t e d t h e f a b r i c a t i o n o f s m a l l , I n c o n e l , t u b e - t o - h e a d e r s u b a s s e m b l i e s t h a t c a n b e b u i l t i n d i v i d u a l l y and t h e n be welded i n t o o n e , l a r g e r , t e s t a s s e m b l y . I t i s o b v i o u s f r o m t h e l a r g e number o f t u b e - t o - h e a d e r j o i n t s t o be h e l i a r c w e l d e d t h a t a s e m i a u t o m a t i c m e t h o d would be e x t r e m e l y d e s i r a b l e . A s a r e s u l t , t h e c o n e - a r c w e l d i n g t e c h n i q u e was a p p l i e d t o p r e l i m i n a r y e x p e r i m e n t s i n t h i s subassembly f a b r i c a t i o n . S i n c e t h e h e a t e x c h a n g e r i s t o be o p e r a t e d a t a m o d e r a t e l y h i g h p r e s s u r e for t h e t e m p e r a t u r e i n v o l v e d , d i s h e d h e a d e r s h e e t s a r e d e s i r a b l e . I f t h e p l a n e o f t h e bottom o f t h e h e a d e r i s k e p t l e v e l d u r i n g w e l d i n g , i t i s o b v i o u s t h a t u n e q u a l a r c d i s t a n c e s w i l l p r e v a i l a r o u n d t h e p e r i p h e r y o f many o f t h e t u b e s . Thus t h e a b i l i t y t o make c o n - s i s t e n t l y s o u n d w e l d s on t h e d i s h e d h e a d e r d e p e n d s , t o a l a r g e d e g r e e , upon t h e s e l e c t i o n o f c o n d i t i o n s t h a t w i l l m i n i m i z e t h e s e v a r i a t i o n s i n a r c d i s t a n c e . O f f s e t t i n g t h e t u n g s t e n e l e c t r o d e from t h e c e n t e r o f t h e t u b e p r i o r t o w e l d i n g and u s i n g a b a l l - a n d - s o c k e t j o i n t a r r a n g e m e n t f r o m w h i c h t h e h e a d e r c a n be p i v o t e d a r e o b v i o u s means o f e q u a l i z i n g t h e a r c d i s t a n c e a round t h e t u b e p e r i p h e r y .

P r e l i m i n a r y e x p e r i m e n t s o n t h i s problem have c o n s i s t e d o f i n v e s t i g a t i n g t h e v a r i a b l e s o f a r c c u r r e n t , a r c t i m e , and e l e c t r o d e d i s t a n c e r e q u i r e d t o p r o d u c e c o n s i s t e n t l y l e a k - t i g h t w e l d s . An e x p e r i m e n t a l , c o n e - a r c w e l d e d , t e s t s p e c i m e n i s s h o w n i n F i g . 11.1, w h i c h i l l u s t r a t e s t h e

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c

F i g . 1 1 . 1 . An E x p e r i m e n t a l Heat Exchanger S u b a s s e m b l y A f t e r Cone-Arc Weld ing .

t e n d e n c y f o r u n e v e n m e l t i n g a r o u n d some o f t h e t u b e p e r i p h e r i e s when t h e t u n g s t e n e l e c t r o d e was c e n t e r e d o v e r t h e t u b e w i t h t h e h e a d e r p l a t e a x i s p e r p e n d i c u l a r t o t h e e l e c t r o d e a x i s . T h e d i a m e t e r o f t h e h e a d e r p l a t e i s t

2 1 / 4 i n , and t h e p l a t e t h i c k n e s s i s 0.125 i n c h . The t u b i n g h a s a n o u t s i d e d i a m e t e r o f 0 .148 i n . w i t h a 0 . 0 2 5 - i n . w a l l , a n d t h e h o l e c e n t e r - t o - c e n t e r d i s t a n c e i s a p p r o x i m a t e l y 0 . 3 7 8 i n c h .

Some d i f f i c u l t i e s h a v e b e e n e n - c o u n t e r e d w i t h j o i n t s t h a t a r e n o t p r e s s u r e - t i g h t , b u t i t i s e x p e c t e d t h a t f u r t h e r e x p e r i m e n t s w i l l e n a b l e t h e p r o d u c t i o n o f s u b a s s e m b l i e s t h a t w i l l b e c o m p l e t e l y s o u n d , I n e a c h t e s t a s sembly t h a t h a s been f a b r i c a t e d t h u s f a r , o n l y o n e or two j o i n t s were u n s a t i s f a c t o r y ; t h e o t h e r j o i n t s were p r e s s u r e - t i g h t t o a i r a t a p p r o x i m a t e l y , 6 0 p s i g . T h i s i n d i c a t e s t h a t a n improvement i n t e c h n i q u e or a s l i g h t v a r i a t i o n i n w e l d i n g c o n d i t i o n s s h o u l d h e l p t o i m p r o v e t h e q u a l i t y o f t h e s e c o n e - a r c welded j o i n t s .

F a b r i c a t i o n o f Heat Exchanger U n i t s . A s e c o n d l a r g e s o d i u m - t o - a i r h e a t e x c h a n g e r a s s e m b l y was f a b r i c a t e d by

(l)ANP Q u a r . P r o g . R e p . D e c . 10, 1 9 5 2 , ORNL- 1439, p . 1 6 4 .

5

N i c r o b r a z i n g and t h e o v e r - a l l a p p e a r - a n c e , a s :shown i n F i g . 1 1 . 2 , was much b e t t e r t h a n t h a t o f t h e f i r s t a s - s e m b l y . ( ' ) C h a n g e s i n c o r p o r a t e d i n t h e b r a z i n g p r o c e d u r e f o r t h i s s e c o n d u n i t were t h e u s e o f l e s s e r q u a n t i t i e s o f N i c r o b r a z , t h e u s e o f s e v e r a l a s p i r a t o ~ s t o p r o m o t e more e v e n h y - d r o g e n f l o w b e t w e e n t h e f i n s , t h e b u i l d u p o f t h e whole a s s e m b l y o f f t h e c a n b o t t o m t o o v e r c o m e t h e d r a s t i c i n i t i a l h e a t i n g r a t e , and t h e u s e o f a s l i g h t l y l o w e r b r a z i n g t e m p e r a t u r e . P r e s s u r e t e s t i n g w i t h h e l i u m , however , r e v e a l e d t h e p r e s e n c e o f a l e a k i n t h e t u b e - t o - f i n m a t r i x . A t e c h n i q u e was deve loped t o s e a l o f f t h i s t u b e on e a c h s i d e o f t h e l e a k by r e b r a z i n g ,

F i g . 1 1 . 2 . S o d i u m - t o - A i r R a d i a t o r After N i c r o b r a z i n g .


b u t u p o n p e r f o r m i n g t h i s o p e r a t i o n , s e v e r a l o t h e r l e a k s a p p e a r e d i n o t h e r t u b e s .

I t i s h o p e d t h a t t h e d a m a g i n g e f f e c t s c a u s e d by s u b s e q u e n t N i c r o - b r a z i n g o p e r a t i o n s c a n be e l i m i n a t e d by a d o p t i n g a m o d i f i e d d e s i g n t h a t w o u l d p e r m i t t h e h e l i a r c w e l d i n g o f t h e t u b e - t o - h e a d e r j o i n t s a n d t h e j o i n t s i n t h e h e a v i e r m a n i f o l d s e c t i o n s . By t h e u s e o f t h e s i n g l e - b r a z e method, a n y l e a k s i n t h e t u b e - t o - f i n m a t r i x a f t e r b r a z i n g c a n b e e l i m i n a t e d from t h e c o o l a n t c i r c u i t by p l u g w e l d i n g t h e p r o p e r t u b e s , The t u b e - t o - h e a d e r w e l d s c o u l d t h e n b e made by m a n u a l h e l i a r c w e l d i n g , a s c o u l d t h e o t h e r j o i n t s i n t h e m a n i f o l d c i r c u i t . Wi th some minor changes i n r a d i a t o r d e s i g n , i t seems p r o b a b l e t h a t c o m p l e t e d u n i t s c o u l d be f a b r i c a t e d w i t h l e s s c h a n c e o f o b t a i n i n g l e a k y j o i n t s , By e l i m i - n a t i n g s e v e r a l h i g h - t e m p e r a t u r e b r a z i n g o p e r a t i o n s , g r a i n growth i n t h e s t a i n - l e s s s t e e l t u b e s c o u l d be m i n i m i z e d , a s c o u l d e m b r i t t l i n g o f t h e b a s e m e t a l by b r a z i n g a l l o y d i f f u s i o n .

I t i s w e l l k n o w n t h a t c e r t a i n N i c r o b r a z e d s t a i n l e s s s t e e l j o i n t s e x h i b i t b r i t t l e n e s s t o a h i g h d e g r e e . T h i s f a c t o r , c o u p l e d w i t h t h e a l l o y i n g away o f t h e t u b e w a l l by b r a z i n g a l l o y d i l u t i o n and d i f f u s i o n , i s t h o u g h t t o be r e s p o n s i b l e f o r a m a j o r p o r t i o n o f t h e l e a k s e n c o u n t e r e d i n h e a t e x c h a n g e r f a b r i c a t i o n . S i n c e i t seems p r o b a b l e t h a t j o i n t b r i t t l e n e s s may a l s o b e a s s o c i a t e d w i t h d i l u t i o n and d i f f u s i o n phenomena, a s y s t e m a t i c s t u d y o f t h i s problem h a s been i n i t i a t e d .

N i c r o b r a z e d t u b e - t o - f i n j o i n t s a r e b e i n g p r e p a r e d by u s i n g 0 . 0 1 0 - i n . - t h i c k , t y p e 302 s t a i n l e s s s t e e l f i n m a t e r i a l and 0 .150- in . -ODJ 0 , 0 1 6 - i n . - w a l l , t y p e 304 s t a i n l e s s s t e e l t u b i n g f o r s t u d y i n g , by m e t a l l o g r a p h i c e x - a m i n a t i o n , t h e e f f e c t s o f ( 1 ) t h e q u a n t i t y o f b r a z i n g a l l o y u s e d , ( 2 ) t h e b r a z i n g t e m p e r a t h r e f o r a g i v e n t i m e , and ( 3 ) t h e b r a z i n g t i m e f o r a g i v e n t e m p e r a t u r e , S m a l l , m e d i u m , and l a r g e amounts o f b r a z i n g a l l o y and

141


t h e t i m e a t t e m p e r a t u r e , w h i c h may v a r y f r o m 1 0 m i n t o 1 8 h r ( f o r a n o v e r n i g h t b r a z i n g c y c l e ) , a r e b e i n g i n v e s t i g a t e d . The c h o i c e of b r a z i n g t e m p e r a t u r e i s b e i n g v a r i e d from 20°C a b o v e t h e m e l t i n g p o i n t t o a maximum of 120°C above t h e m e l t i n g p o i n t .

S i n c e i t may be a d v i s a b l e t o f i n d a s u b s t i t u t e f o r N i c r o b r a z i n t h e c o n - s t r u c t i o n o f s o d i u m - t o - a i r h e a t e x - c h a n g e r , two o t h e r b r a z i n g a l l o y s a r e b e i n g s u b j e c t e d t o s i m i l a r d i f f u s i o n and d i l u t i o n i n v e s t i g a t i o n s . An 82% Au-18% N i a l l o y i s t y p i c a l o f t h e l o w e r - m e 1 t i n g , d u c t i l e , o x i d a t i o n - r e s i s t a n t b r a z i n g a l l o y s t h a t , u n - f o r t u n a t e l y , a r e i n c o m p a t i b l e w i t h sodium b u t may be used f o r t u b e - t o - f i n c o n s t r u c t i o n i f d i l u t i o n and d i f f u s i o n c a n be c o n t r o l l e d . A 60% Mn-40% N i a l l o y h a s been shown t o be c o m p a t i b l e w i t h sodium, b u t i t i s s l i g h t l y a t t a c k e d i n h i g h - t e m p e r a t u r e o x i d a t i o n t e s t s . I t i s a l s o somewhat b r i t t l e i n t h e a s - b razed c o n d i t i o n .

Brazing of Copper to Inconel. The need f o r a s a t i s f a c t o r y b r a z i n g a l l o y f o r j o i n i n g c o p p e r f i n s t o I n c o n e l t u b i n g and f o r e d g e - s e a l i n g s h e a r e d , I n c o n e l - c l a d , c o p p e r f i n s h a s b e e n emphasized. The r e s u l t a n t b r a z e s h o u l d

be r e s i s t a n t t o o x i d a t i o n a t 1500"F , s h o u l d p r e f e r a b l y s e r v e a s a d i f f u s i o n b a r r i e r a g a i n s t c o p p e r p e n e t r a t i o n i n t o t h e I n c o n e l d u r i n g s e r v i c e , a n d s h o u l d have a r e l a t i v e l y h i g h s t r e n g t h a t 1 5 0 0 ° F . I t i s l i k e l y t h a t some a l l o y o t h e r t h a n a c o p p e r - b a s e a l l o y w o u l d b e s t f i l l t h e s e r e q u i r e m e n t s .

An e x p e r i m e n t a l , m o d i f i e d , N i c r o b r a z a l l o y , w h i c h m e l t s a t a p p r o x i m a t e l y 1850"F, a p p e a r s t o be v e r y p r o m i s i n g , a s do a l l o y s o f 82% Au-18% N i and 90% Au-10% Co. O x i d a t i o n t e s t s a t 1500°F on b r a z e d I n c o n e l j o i n t s i n d i c a t e n o a p p r e c i a b l e a t t a c k . A l i s t o f s e v e r a l a l l o y s , c u r r e n t l y b e i n g i n v e s t i g a t e d , t h a t m e l t i n t h i s medium t e m p e r a t u r e r a n g e i s g i v e n i n T a b l e 11.1. F low- a b i l i t y t e s t s on I n c o n e l h a v e b e e n made, and t h e r e s u l t s o f t h e s e t e s t s a r e a l s o l i s t e d i n T a b l e 11.1.

E d g e - s e a l i n g e x p e r i m e n t s on chromium- p l a t e d c o p p e r d i s k s a r e b e i n g c o n - d u c t e d , a n d t e c h n i q u e s a r e b e i n g s t u d i e d f o r o b t a i n i n g a s a t i s f a c t o r y e d g e s e a l o n t h e s e d i s k s . A t t h e p r e s e n t , t h e f i n e d g e s a r e b e i n g suspended i n a s l u r r y o f t h e m o d i f i e d , l o w - m e l t i n g - p o i n t , N i c r o b r a z a l l o y and s l o w l y r o t a t e d u n t i l an e v e n c o a t i n g o f b r a z i n g a l l o y i s d e p o s i t e d . T h e

TABLE 11.1. PROPERTIES OF THE MEDIUM-TEMPERATURE BRAZING ALLOYS CURRENTLY BEING INVESTIGATED

BRAZING ALLOY

95.5% Cu-4.5% Be

92% Cu-8% S i

1 5 % Cu-25% Sn

Low-me1 t i n g - p o i n t N ic robraz

82% Au-18% N i

90% Ag-10% CU

90% Au-10% Co

95% Ag-5% Ge

90% Cu-10% Ge

142

MELTING POINT (OF)

1590

1530

1470

1800

1800

1600

1830

1650

1800

BRAZING TEMPERATURE

(OF)

1750

17 00

1600

1850

1850

1800

187 0

1700

1870

FLOWABI LI TY ON INCONEL

Poor

Poor

Good

Good

Excel 1 e n t

Poor

Good

Poor

Good

METHOD OF APPLICATION

Powder

Powder

Powder

Powder

S h e e t

S h e e t

S h e e t

S h e e t

S h e e t

f i n i s t h e n e d g e b r a z e d i n a h y d r o g e n a t m o s p h e r e . A n o t h e r m e t h o d t o b e i n v e s t i g a t e d f o r c o v e r i n g t h e s e exposed c o p p e r e d g e s i s t h e p r e p l a c i n g o f a f i n e w i r e o f b r a z i n g a l l o y i n t h e c r e v i c e fo rmed by c h e m i c a l l y e t c h i n g away a s m a l l amount o f c o p p e r i n n i t r i c a c i d . It is e x p e c t e d t h a t t h i s l a t t e r t e c h n i q u e , i f s u c c e s s f u l , w i l l p r e v e n t f i n d i s t o r t i o n , w h i c h i s b e l i e v e d t o b e d u e t o u n a v o i d a b l e n o n u n i f o r m w e t t i n g o f t h e f i n p e r i p h e r y b y b r a z i

EVALUATION TESTS OF BRAZING ALLOYS

P. P a t r i a r c a V. G. Lane G. M . S l a u g h t e r C. E. S c h u b e r t

Met a 1 l u r g y D i v i s i o n


l ower t h e m e l t i n g p o i n t o f t h e 60% Pd- 40% N i b r a z i n g a l l o y , 5% germanium was added. T h i s a l l o y can be c o n s i s t e n t l y b r a z e d a t 2 1 5 0 " F , w h i c h i s i n t h e b r a z i n g r a n g e o f t h e m o r e common N i c r o b r a z a l l o y . S t a t i c c o r r o s i o n t e s t s on b r a z e d j o i n t s i n t h e m o l t e n f l u o r i d e s a l t s i n d i c a t e t h a t t h e r e i s o n l y s l i g h t a t t a c k by m o l t e n NaF-KF- LiF-UF, ( 1 0 . 9 - 4 3 . 5 - 4 4 . 5 - 1 . 1 mole % I , a s shown i n F i g . 11.3, w h e r e a s s e v e r e a t t a c k i s p r e s e n t o n t h e s a m p l e i m m e r s e d i n N a F - Z r F 4 - U F , ( 4 6 - 5 0 - 4 m o l e % ) , F i g . 1 1 . 4 .

E f f e c t o f Brazing Time on J o i n t S t r e n g t h . A r e v i e w o f r e s u l t s o f r e c e n t and p r e v i o u s e x p e r i m e n t s c o n - d u c t e d t o e v a l u a t e t h e e f f e c t o f t i m e a t t h e b r a z i n g t e m p e r a t u r e o n t h e j o i n t s t r e n g t h o f N i c r o b r a z e d I n c o n e l j o i n t s shows t h a t t h e e f f e c t o f t i m e

Fig. 1.1.3. Inconel Joint Brazed w i t h a 60% Pd-35% Ni-5% Ge Alloy After 100 hr a t 1500'F in NaF-KF-LiF-UF, (10 .9 -43 .5 -44 .9 -1 .1 mole %). E t c h e d w i t h a q u a r e g i a , 10W.

1 4 3


Y-8701

. b

* *

r a t 1500'F i n NaF-ZrF,-UF4 ( 4 6 - 5 0 - 4 mole %). E t c h e

n o t s o i m p o r t a n t a s t h e p r e v i o u s l y t o t h a t o f N i c r o b r a z , w l t o r t e d l i m i t e d d a t a i n d i c a t e d . The n i c k e l , chromium, a n

room t e m p e r a t u r e s t r e n g t h s o f t h e s e a n d t h e r e f o r e d i f f u s j o i n t s a r e g e n e r a l l y much l e s s t h a n w h a t h i t h e s t r e n g t h o f t h e b a s e I n c o n e l and c o n c e n t r do n o t v a r y a p p r e c i a b l y w i t h t i m e a t s t r e n g t h s t e m p e r a t u r e . Only o c c a s i o n a l l y does a a t 1500" j o i n t e x h i b i t h i g h t e n s i l e s t r e n g t h a t h i g h , a s room t e m p e r a t u r e , a n d t h e p r e v i o u s f r a c t u r e s o f t e n o c c u r i n t h e b a s e r e s u l t s w e r e a p p a r e n t l y d i s t o r t e d by t h e s e i n f r e q u e n t h i g h v a l u e s . A summary of t h e d a t a i s g i v e n i n T a b l e 1 1 . 2 ; f o u r t e n s i l e b a r s were t e s t e d f o r each b r a z i n g t ime,

I t i s e x p e c t e d t h a t t h e b r a z i n g t ime w i l l h a v e a g r e a t e r e f f e c t w i t h s t a i n l e s s s t e e l , b e c a u s e t h e w i d t h o f t h e d i f f u s i o n zone i s g e n e r a l l y l a r g e r . The c o m p o s i t i o n o f I n c o n e l i s s i m i l a r

m e t a l . E f f e c t o f S p a c i n g on Brazed J o i n t

S t r e n g t h . An i n v e s t i g a t i o n was con- d u c t e d t o d e t e r m i n e t h e e f f e c t o f j o i n t s p a c i n g o n t h e s h o r t - t i m e , r o o m - t e m p e r a t u r e , t e n s i l e s t r e n g t h o f N i c r o b r a z e d I n c o n e l j o i n t s . F o u r b u t t - b r a z e d t e n s i l e b a r s were p r e p a r e d f o r each j o i n t s p a c i n g of 0.005, 0.010, 0 .015 , and 0.020 i n c h . The r e s u l t s o f

t

144


TIME AT 2150°F (min)

5

10

2 0

3 0

t

AVERAGE ROOM-'IEMF'ERATURE TENSILE STRENGTH OF JOINT EFFICIENCY BRAZED JOINTS ( p s i ) ( 0 . 2 5 2 - i n . specimen) ( % I

34 ,900 40

40 ,100* 46

32 ,900 38

31 ,400 36

t h i s i n v e s t i g a t i o n i n d i c a t e t h a t j o i n t s p a c i n g i s n o t a c r i t i c a l f a c t o r i n t h e r o o m - t e m p e r a t u r e t e n s i l e s t r e n g t h o f N i c r o E r a z e d I n c o n e l j o i n t s , a t l e a s t w i t h i n t h e r a n g e s i n v e s t i g a t e d . T h i s r a n g e s h o u l d c o v e r n e a r l y a l l a p p l i c a t i o n s , s i n c e t h e e f f e c t o f a s h r i n k f i t would t e n d t o b e l o s t d u r i n g t h e f u r n a c e b r a z i n g o p e r a t i o n , and a s p a c i n g o f o v e r 0.020 i n . would r e s u l t i n e x t r e m e l y poor f i t u p .

S t r e n g t h o f B r a z e d J o i n t s w i t h V a r i o u s IBase M e t a l s . B u t t - b r a z e t e n s i l e d a t a on t h e 73.5% Ni-16.5% Cr- 10.0% S i a l l o y i n d i c a t e t h a t t h e b a s e - m e t a l c o m p o s i t i o n may b e a v e r y i m p o r t a n t f a c t o r i n d e t e r m i n i n g t h e s u b s e q u e n t t e n s i l e s t r e n g t h s o f b r a z e d j o i n t s . T h e a v e r a g e o f t h e r o o m - t e m p e r a t u r e t e n s i l e s t r e n g t h s o f t h e I n c o n e l j o i n t s w a s 3 3 , 7 0 0 p s i . S i m i l a r t e s t s o n b r a z e d t y p e 3 1 6 s t a i n l e s s s t e e l s h o w e d a n a v e r a g e t e n s i l e s t r e n g t h o f 6 4 , 4 0 0 p s i , which i s n e a r l y d o u b l e t h e v a l u e r e c o r d e d f o r I n c o n e l . The e l e v a t e d - t e m p e r a t u r e t e s t s f o r b o t h b a s e m e t a l s g a v e e x c e l l e n t r e s u l t s . J o i n t e f f i c i e n c i e s o f 99% were o b t a i n e d € o r I n c o n e l , and e f f i c i e n c i e s o f 98% w e r e o b t a i n e d f o r t y p e '316 s t a i n l e s s s t e e l .

N i c r o b r a z e d j o i n t s on s t a i n l e s s s t e e l a l s o had h i g h e r t e n s i l e s t r e n g t h s t h a n N i c r o b r a z e d j o i n t s o n I n c o n e l . The a v e r a g e , r o o m - t e m p e r a t u r e , t e n s i l e s t r e n g t h f o r s t a i n l e s s s t e e l j o i n t s

was 6 8 , 8 0 0 p s i , w h e r e a s t h e c o r r e s - p o n d i n g v a l u e f o r I n c o n e l was 3 4 , 9 0 0 p s i . The 1500°F t e n s i l e t e s t s a g a i n g a v e e v i d e n c e o f j o i n t e f f i c i e n c i e s a p p r o a c h i n g 100% €or b o t h b a s e m e t a l s .

A summary of' a major p o r t i o n o f t h e b u t t - b r a z e t e n s i l e d a t a o b t a i n e d t h u s f a r i s p r e s e n t e d i n T a b l e 11.3. T h e v a l u e l i s t e d f o r t h e r o o m - t e m p e r a t u r e s t r e n g t h o f N i c r o b r a z e d I n c o n e l j o i n t s i s t h a t r e s u l t i n g f r o m a s e r i e s o f t e s t s i n which some s p e c i m e n s f r a c t u r e d a t v a l u e s n e a r l y e q u a l t o t h e t e n s i l e s t r e n g t h o f I n c o n e l . H e n c e , t h i s a v e r a g e v a l u e i s somewhat h i g h e r t h a n t h e v a l u e s shown i n T a b l e 1 1 . 2 , i n which no d a t a were r e c o r d e d t h a t i n d i - c a t e d s u c h h i g h t r e n d s . A l s o t h e v a l u e s o f j o i n t e f f i c i e n c y f o r s t a i n - l e s s s t e e l j o i n t s a r e o n l y a p p r o x i m a t e b e c a u s e t h e 0 . 2 5 2 - i n . - d i a s t a i n l e s s s t e e l t e n s i l e b a r s h a v e n o t y e t b e e n t e s t e d a f t e r t h e y were s u b j e c t e d t o t h e b r a z i n g c y c l e .

CREEP-RUPTURE TESTS OF STRUCTURAL METALS

R . B. O l i v e r J . W. Woods D. A. Doug las C. W . Weaver


P r e o x i d i z e d I n c o n e l i n Argon. I t was p r e v i o u s l y r e p o r t e d ( 2 ) t h a t t h e e n v i r o n m e n t s u r r o u n d i n g t h e s p e c i m e n

(2)R. B . O l i v e r , D . A . D o u g l a s , K . W . R e b e r , J . W . Woods, and C . W . Weaver , ANP Q u a r . P r o g . R e p . D e c . IO, 1 9 5 2 , ORNL-1439, p. 159.

1 4 5


TABLE 11.3. BUTT-BRAZE TENSILE DATA FOR SEVERAL HIGH-TEMPERATURE BRAZING ALLOYS

BRAZING ALLOY

N i c r o b r a z

60% Pd-40% N i

73.5% Ni-16.5% Cr-10.0% S i

75% Ag-20% Pd-5% Mn

BASE METAL

I n c one 1

I n c o n e l

Type 316 s t a i n l e s s s tee l

I n c o n e l

Type 316 s t a i n l e s s s tee l

I n c o n e l

d u r i n g t e s t would h a v e a s i g n i f i c a n t e f f e c t on t h e c r e e p r a t e and r u p t u r e l i f e . R e s u l t s o b t a i n e d d u r i n g t h e p a s t q u a r t e r c o n t i n u e t o i n d i c a t e t h a t t h e p r o p e r t i e s a r e b e s t w h e n t h e I n c o n e l is t e s t e d i n a i r , p o o r e s t when t e s t e d i n a h y d r o g e n a t m o s p h e r e , and i n t e r m e d i a t e when t e s t e d i n a r g o n . The r u p t u r e l i f e o b s e r v e d i n t e s t s i n a h y d r o g e n a t m o s p h e r e was o f t h e o r d e r o f o n e - t e n t h t h e l i f e o b s e r v e d when t e s t e d i n a i r ; t h i s o b s e r v a t i o n h o l d s f o r s t resses o f 4000 p s i or l e s s . One h y p o t h e s i s r e g a r d i n g t h e l o n g r u p t u r e l i f e i n a i r i n v o l v e d a s t r e n g t h e n i n g a c t i o n by t h e o x i d e f i l m formed d u r i n g t h e e a r l y p a r t o f t h e t e s t . To t e s t t h i s p o s s i b i l i t y , a s e r i e s o f spec imens was h e a t e d i n a i r f o r 200 h r a t 815°C t o form such a f i l m .

The p r e o x i d i z e d spec imens were t h e n t e s t e d a t 815°C i n a r g o n , s t r e s s e d t o 2 5 0 0 , 3 5 0 0 , a n d 4 5 0 0 p s i . I n t h e t h r e e t e s t s , t h e r u p t u r e t i m e s were f a r s h o r t o f t h e r u p t u r e t imes i n a i r , a n d were v e r y c l o s e t o t h e l i f e when t e s t e d i n a r g o n . I t i s t o be n o t e d

TEMPERATURE ( O F )

Room

1500

Room

1500

Room

1500

Room

1500

Room

1500

Room

1500

TENSILE STRENGTH

( p s i 1

47 , 000

24 , 500

87 ,600

21 ,000

7 5 ,400

22 ,400

3 3 , 7 0 0

23 ,100

64 ,400

25,000

55,900

1 9 , 7 0 0

JOINT EFFICIENCY

(%)

5 4

100

100

93

92

88

39

99

79

98

64

8 5

t h a t t h e e l o n g a t i o n d u r i n g t e s t was much g r e a t e r t h a n t h a t o b s e r v e d i n o t h e r e n v i r o n m e n t s , a n d t h e r e was n o e v i d e n c e o f c r a c k i n g i n t h e f i l m . F i g u r e 11.5 shows t h e s t r a i n vs. t ime r e l a t i o n s h i p s o f t h e b r i g h t a n d t h e p r e o x i d i z e d s p e c i m e n s t e s t e d i n a r g o n . T h e s e r e s u l t s c o u l d mean e i t h e r t h a t n i t r o g e n r a t h e r t h a n o x y g e n was t h e c o n t r o l l i n g f a c t o r or, a s i s m o r e p r o b a b l e , t h a t t h e o x i d e f i l m formed s t r e s s r i s e s when i t c r a c k e d and t h a t t h i s a c t i o n , i n t u r n , p r o m o t e d t h e i n t e g r a n u l a r c r a c k i n g t h a t u l t i m a t e l y 1 ed t o f a i l u r e .

Peened Inconel in Argon. Specimens o f I n c o n e l h a v e b e e n h e a v i l y p e e n e d w i t h f i n e s t e e l s h o t and a r e now b e i n g t e s t e d i n a r g o n . T h i s m e c h a n i c a l w o r k i n g o f t h e s p e c i m e n s u r f a c e h a s i n c r e a s e d t h e r u p t u r e l i f e i n com- p a r i s o n w i t h t h e l i f e o f s p e c i m e n s t h a t d i d n o t r e c e i v e t h i s t r e a t m e n t .

c

t

i

1 * t

A l s o , t h e c r e e p r a t e f o r t h e p e e n e d s p e c i m e n i s much l o w e r t h a n t h a t o b s e r v e d f o r o t h e r s p e c i m e n s a t t h e same s t r e s s i n a n y a t m o s p h e r e . I t i s

146


UNCLASSIFIED

0 100 200 300 400 500 600 700 600 900 1000 1100 1200 1300 1400 1500 TIME (hr)

F i g . 1 1 . 5 . S t r a i n v s . T i m e c u r v e s f o r Control and P r e o x i d i z e d I n c o n e l S p e c i - mens a t 1500°F i n Argon.

i m p r o b a b l e t h a t t h i s e f f e c t i s t h e r e s u l t o f r e s i d u a l c o m p r e s s i v e s t r e s s i n d u c e d hy t h e p e e n i n g a c t i o n , s i n c e s u c h s t r e s s e s w o u l d r e c o v e r a t a t e m p e r a t u r e lower t h a n t h e t e s t t emper - a t u r e . I t i s hoped t h a t m e t a l l o g r a p h i c e x a m i n a t i . o n w i l l f u r n i s h a c l u e f o r e x p l a i n i n g t h e i m p r o v e d p r o p e r t i e s r e s u l t i n g from t h e p e e n i n g .

E f f e c t o f I n c o n e l G r a i n S i z e on T i m e t o Rupture. As a ge m e n t , f i n e - g r a i n e d I n c o n e l ( 0 . 1 0 5 m m i n d i a m e t e r ) i s more s e n s i t i v e t h a n c o a r s e - g r a i n e d I n c o n e l ( 0 . 2 5 0 m m i n d i a m e t e r ) t o t h e s e v e r a l t e s t e n v i r o n - m e n t s . T a b l e 1 1 . 4 t a b u l a t e s t h e c o m p a r a t i v e r e s p o n s e s t o t h e s e e n v i r o n - m e n t s a t a r e p r e s e n t a t i v e s t r e s s l e v e l .

E f f e c t o f Environment on S t r a i n v s . T i m e C u r v e s f o r I n c o n e l . A f i n e - g r a i n e d spec imen i s b e i n g t e s t e d t h a t was r u n i n a r g o n f o r t h e f i r s t 160 h r a n d t h e n a l t e r n a t e l y i n h y d r o g e n a n d a r g o n a t m o s p h e r e s . E a c h a t m o s p h e r e w a s m a i n t a i n e d f o r a b o u t 1 0 0 h o u r s . When t h e h y d r o g e n was i n t r o d u c e d , t h e s t r a i n r a t e was a c c e l e r a t e d ; and w h e n t h e a r g o n was r e - i n t r o d u c e d , t h e c r e e p r a t e d u r i n g t h e a r g o n c y c l e r e m a i n e d a p p r o x i m a t e l y t h e same a s t h e l a s t c r e e p r a t e i n hydrogen . T h e s e r e s u l t s a p p e a r t o i n d i c a t e t h a t t h e e f f e c t o f t h e h y d r o g e n a t m o s p h e r e i s o n e o f a p e r m a n e n t n a t u r e . M e t a l l o g r a p h i c s t u d i e s do n o t c l e a r l y r e v e a l what t h e e f f e c t i s ; however, t h e m i c r o s t r u c t u r e i n d i c a t e s t h e p o s s i b l e r e m o v a l o r

147


F i n e - g r a i n e d I n c o n e l C o a r s e - g r a i n e d I n c o n e l

T e s t e d i n a i r

Peened and t e s t e d i n a rgon

T e s t e d i n a rgon

P r e o x i d i z e d and t e s t e d i n a rgon

T e s t e d i n mol t e n NaF-ZrF,-UF, (46-50-4 mole X)

T e s t e d i n hydrogen

"2500

73 0

730

415

2 50

s o l u t i o n o f c a r b i d e s and o x i d e s and a much m o r e f r e a u e n t i n c i d e n c e o f i n t e r g r a n u l a r c r a c k i n g when t h e t e s t s a r e conduc ted i n a hydrogen a tmosphe re .

The s t r a i n v s . t i m e r e l a t i o n s h i p s o f f i n e - g r a i n e d I n c o n e l t e s t e d i n t h e s e v e r a l e n v i r o n m e n t s a t 8 1 5 ° C a n d s t r e s s e d t o 3 5 0 0 p s i a r e s h o w n i n F i g . 11.6. The r e s u l t s a r e r e p r e s e n t a - t i v e o f s e v e r a l t e s t s i n e a c h e n v i r o n - ment. The absence o f a l i n e a r , s econd- s t a g e s e c t i o n i n t h e s t r a i n v s . t i m e c u r v e s m i g h t i n d i c a t e t h a t t h e i n t e r - g r a n u l a r c r a c k i n g c h a r a c t e r i s t i c o f h i g h - t e m p e r a t u r e f a i l u r e i s i n i t i a t e d v e r y e a r l y i n t h e t e s t l i f e . T h e v a r i o u s t e s t c o n d i t i o n s may e i t h e r h a s t e n o r r e t a r d t h e f o r m a t i o n a n d p r o p o g a t i on o f t h e s e i n t e r g r a n u l a r c r a c k s a n d , h e n c e , a l t e r t h e c r e e p - r u p t u r e p r o p e r t i e s .

The p r o g r a m o f t e s t i n g i n m o l t e n f l u o r i d e m i x t u r e s c o n t i n u e s , b u t t h e < - c u r a c y o f t h e r e s u l t s i s c l o u d e d by t e m p e r a t u r e c o n t r o l d i f f i c u l t i e s and by t h e e f f e c t s o f t h e d e s c a l i n g p r o c e d u r e . The f i r s t s e r i e s o f t e s t s w a s p r e c e d e d by a s o d i u m d e s c a l i n g o p e r a t i o n . T h e r u p t u r e t i m e s were v e r y s h o r t , a n d t h e m i c r o s t r u c t u r e s i n d i c a t e a s t r e s s - c o r r o s i o n t y p e o f f a i l u r e . S u b s e q u e n t t e s t s were p r e - ceded by a f l u o r i d e d e s c a l i n g p r o c e s s . The r u p t u r e t imes were c l o s e r t o t h o s e o b s e r v e d i n a r g o n , a n d t h e m i c r o - s t r u c t u r e s r e v e a l e d s u b s u r f a c e v o i d s

"2500

835

500

470

600

o r h o l e f o r m a t i o n a n d v e r y l i t t l e i n t e r g r a n u l a r c r a c k i n g . Only one t e s t o f c o a r s e - g r a i n e d I n c o n e l i n f l u o r i d e s showed a l o n g e r r u p t u - e l i f e t h a n t h e b e s t l i f e o b s e r v e d f o r t h e f i n e - g r a i n e d spec imens a t t h e same s t r e s s ,

Type 316 S t a i n l e s s S t e e l Tube Burst T e s t s i n Argon. The t u b e - b u r s t t e s t s r u n t o d a t e were f o r t y p e 316 s t a i n - l e s s s t e e l t u b e s l o a d e d i n t e r n a l l y w i t h a r g o n u n d e r p r e s s u r e and h e l d i n an a tmosphe re o f p u r e a r g o n . A s p e c i - men s o l o a d e d h a s a m u l t i a x i a l s t r e s s s y s t e m , and t h e r e s u l t s i n d i c a t e t h a t t h e t e s t l i f e u n d e r t h e s e c o n d i t i o n s w i l l be much l e s s t h a n t h a t found f o r t h e same m a t e r i a l s t r e s s e d i n t e n s i o n o n l y a t a s t r e s s e q u a l t o t h e maximum s t r e s s imposed on t h e t u b e .

FABRICATION OF CONTROL A N D SAFETY RODS

E . S. Bomar H . I n o u y e J . H. Coobs R . W . J o h n s o n

M e t a l l u r g y D i v i s i o n A . Levy

P r a t t and Whitney A i r c r a f t D i v i s i o n

Control Rods f o r the G - E R-1 Reactor. A s t u d y c o n c e r n i n g t h e a d a p t a t i o n o f t h e i ron -cemen ted boron c a r b i d e compo- s i t i o n u s e d f o r t h e ARE s a f e t y r o d s l u g s t o t h e c o n t r o l r o d s f o r t h e G-E R - 1 r e a c t o r w a s u n d e r t a k e n a t t h e r e q u e s t o f t h e G e n e r a l E l e c t r i c Co. I n b r i e f , t h e s p e c i f i c a t i o n s f o r t h e s e

148

.

p r e v i o u s p r o g r e s s r e p o r t ( 3 ) i n c l u d e d s o m e r e s u l t s o f t e s t s c o n d u c t e d i n a r g o n p u r i f i e d by t i t a n i u m s p o n g e . T h e w o r k d u r i n g t h i s p e r i o d h a s i n - c l u d e d 1 0 0 - h r t e s t s i n vacuum a t 800 a n d 1 0 0 0 ° C . T h i s w o r k w i l l a l s o i n d i c a t e t h e p r e s s u r e s t o l e r a b l e i n s u b s e q u e n t h e a t t r e a t m e n t s . The d a t a o b t a i n e d t h u s f a r a r e g i v e n i n T a b l e 11 .6 . F u t u r e work i s t o i n c l u d e t h e e f f e c t o f r e c i r c u l a t i n g t h e p u r i f i e d g a s o v e r t i t a n i u m s p o n g e a n d d r y i n g a g e n t s by u s i n g a pump i n a c l o s e d sys t em.

O x i d a t i o n . T e s t s h a v e b e e n com- p l e t e d on t h e o x i d a t i o n o f columbium i n a i r c o n t a i n i n g 18 .7 m m w a t e r vapor . T h i s i n v e s t i g a t i o n w a s u n d e r t a k e n a f t e r a r u n m a d e a t 4 0 0 ° C i n a i r t h a t i n a d v e r t e n t l y c o n t a i n e d w a t e r v a p o r r e s u l t e d i n a p a r t i c u l a r l y r a p i d r a t e o f o x i d a t i o n . A c o n s t a n t h u m i d i t y was o b t a i n e d hy p a s s i n g t h e a i r t h r o u g h a s a t u r a t e d s o l u t i o n o f NH,C1 a t 25°C; t h e m o i s t u r e c o n t e n t checked t o w i t h i n 0.5% o f t h e s a t u r a t i o n v a l u e when t h e w a t e r a b s o r b e d i n a n h y d r o n e w a s weighed.

T h e r e s u l t s a t 4 0 0 ° C h a v e b e e n checked , arid t h e y show t h a t t h e p r e s e n c e o f m o i s t u r e i n c r e a s e s t h e o x i d a t i o n r a t e by a f a c t o r o f a b o u t 400 a t t h e end o f 1 0 h o u r s . A t 600°C, a r e v e r s e e f f e c t was found i n t h a t t h e o x i d a t i o n

(3)E. S. Bomar and H. I n o u y e , ANP Q u a r . P r o g . R e p . D e c . 1 0 , 1952, ORNL-1439. p. 157.


r a t e d e c r e a s e d s i g n i f i c a n t l y ( b y a f a c t o r o f 2 ) . I t w a s a l s o a p p a r e n t t h a t t h e o x i d a t i o n r a t e was n o t l i n e a r . S e v e r a l b r e a k s i n t h e c u r v e of a p l o t o f w e i g h t g a i n v s . t i m e h a v e b e e n o b s e r v e d a n d d u p l i c a t e d . A t 8 0 0 , 1000 , and 12OO0C, t h e o x i d a t i o n r a t e s i n m o i s t a i r a r e n o d i f f e r e n t f r o m t h o s e i n d r y a i r .

X - r a y d a t a h a v e been o b t a i n e d f o r t h e s p e c i m e n s o x i d i z e d i n a i r ; a n d t h u s f a r t h e o x i d e s f o r m e d a r e a l l m o d i f i c a t i o n s of Cb,O,, o f which t h e r e a r e t h r e e . ( 4 ) I n c o n s i s t e n c i e s have been o b s e r v e d f o r t h e o x i d a t i o n r a t e s a t 800°C. I n t h e s e runs , f l a t s h e e t o x i d i z e d t o a w h i t e s c a l e o n t h e e d g e s , b u t t h e o t h e r a r e a s f o r m e d a r a t h e r d e n s e b l a c k o x i d e . A 0 . 0 4 0 - i n . wire became e n t i r e l y w h i t e w i t h o x i d e . Above 800"C, t h e o x i d a t i o n r a t e showed a s l i g h t d e v i a t i o n f r o m l i n e a r i t y . T h i s may h a v e b e e n t h e r e s u l t o f p a r t i a l p r o t e c t i o n o f t h e u n d e r l y i n g metal by t h e t h i c k o x i d e or a d e c r e a s e i n t h e s u r f a c e a r e a . The r e s u l t s a t 800 , 1000, and 1200°C a r e b e i n g checked by o x i d i z i n g c o l u m b i u m r o d t h a t i s c l a d o n t h e c i r c u m f e r e n c e w i t h I n c o n e l . I t i s hoped t h a t t h e i n c o n s i s t e n c i e s o b s e r v e d a t 800°C c a n be e l i m i n a t e d by t h i s m e t h o d , s i n c e i t i s b e l i e v e d t h a t t h e i n c o n s i s t e n c i e s were c a u s e d by t h e s u r f a c e a r e a s n o t b e i n g c o n s t a n t .

( 4 ) G . B r a u e r , 2. a n o r g . u . a l l g e n . chca, 248, 1-21 (1941).

TABLE 11 .6 . RESULTS OF 100-hr TESTS OF COLUMBIUM IN VACUUM I =

TEMPERATURE:

- ("C)

800

1000

-

1.0

0.1

0.01

0.1

0.05

0.01

+O. 0046

+O. 0006 -0.0002

+O. 00051

+O. 00037 0.00005

HARDNESS MANGE VPN (10-kg l o a d )

+27 1

+22

-1 6

+ 17

+9

-40

REMARKS

B r i t t l e , s l i g h t l y t a r n i s h e d

B r i g h t

B r i g h t

S1 i g h t l y t a r n i s h e d

S1 i g h t l y t a r n i s h e d

B r i g h t

151


F A B R I C A T I O N OF METALS

E . S . Bomar, Jr . H . Inouye J. H . Coobs R . W. J o h n s o n


P r a t t and Whitney A i r c r a f t D i v i s i o n A. Levy

H i g h - C o n d u c t i v i t y Me t a l s f o r R a d i a t o r F i n s . A p r o g r a m h a s b e e n o u t l i n e d f o r t h e e v a l u a t i o n o f c o a t e d m e t a l s s u i t a b l e f o r r a d i a t o r f i n ma- t e r i a l s , m e t h o d s o f a s s e m b l y , a n d e f f e c t s o f e x p o s u r e t o h i g h t e m p e r a - t u r e s . T h e c o a t e d m e t a l s m u s t h a v e good t h e r m a l c o n d u c t i v i t y , a s w e l l a s t h e r e q u i r e d h i g h - t e m p e r a t u r e c o r r o s i o n r e s i s t a n c e . The m a t e r i a l s r e q u i r e d f o r t h i s work h a v e been o r d e r e d , and t h e d e t a i l e d e x p e r i m e n t a l work m u s t a w a i t t h e i r a r r i v a l .

S m a l l q u a n t i t i e s o f m a t e r i a l s s i m i l a r t o t h o s e on o r d e r h a v e b e e n p r e p a r e d and s u b m i t t e d t o t h e W e l d i n g Group f o r e v a l u a t i o n o f b r a z i n g t e c h - n i q u e s . T h e s e m a t e r i a l s i n c l u d e c h r o m i u m - p l a t e d c o p p e r , I n c o n e l - and t y p e 310 s t a i n l e s s - s t e e l - c l a d c o p p e r , a n d I n c o n e l - a n d t y p e 310 s t a i n l e s s - s t e e l - c l a d s i l v e r .

h i g h - c o n du c t i v i t y c o p p e r c h r o m i u m - p l a t e d t o v a r i o u s t h i c k n e s s e s was t e s t e d i n f l o w i n g a i r a t 815°C f o r times up t o 30 h o u r s . I t w a s f o u n d t h a t t h e c h r o m i u m o x i d e formed on t h e s u r f a c e s p a l l e d and d i d n o t form a p r o t e c t i v e f i l m . Thus , t h e p o s s i b i l i t y o f u s i n g c h r o m i u m - p l a t e d c o p p e r f o r h i g h - c o n d u c t i v i t y f i n s i s n o t v e r y p r o m i s i n g .

S o l i d - P h a s e Bonding. Two s e r i e s o f s a m p l e s o f s o l i d - p h a s e bonded m e t a l s h a v e b e e n p r e p a r e d a n d a r e t o b e s t u d i e d . One s e r i e s o f s a m p l e s w i l l be u s e d f o r e v a l u a t i n g t h e e f f e c t o f t i m e on t h e e x t e n t o f b o n d i n g ; t h e o t h e r s e t w i l l be u s e d f o r m e a s u r i n g t h e e f f e c t i v e n e s s o f e l e c t r o d e p o s i t e d c h r o m i u m i n b o n d i n g m o l y b d e n u m t o o t h e r m e t a l s ,

Chromium was s e l e c t e d a s a t r i a l b o n d i n g medium b e c a u s e o f i t s u n - l i m i t e d s o l u b i l i t y w i t h molybdenum.

O x y g e n - f r e e ,

R u n s h a v e b e e n made w i t h c h r o m i u m - p l a t e d molybdenum v s . n i c k e l , i r o n , s t a i n l e s s s t e e l , and I n c o n e l a t 1150 and 125OOC. One r u n h a s been made t o c h e c k t h e s e l f - w e l d i n g o f molybdenum a t 1500°C.

E x t r u s i o n o f H i g h - P u r i t y T u b i n g . T h i s p h a s e o f d e v e l o p m e n t i s a r e s u l t o f t h e p r e s e n t n e e d f o r h i g h - p u r i t y I n c o n e l t u b i n g - and s u b s e q u e n t l y f o r o t h e r h i g h - t e m p e r a t u r e a l l o y s - f o r c o r r o s i o n t e s t i n g t o d e t e r m i n e t h e e f f e c t o f i m p u r i t i e s o n c o r r o s i o n r e s i s t a n c e . The p r i m a r y p r o b l e m t o d a t e i n t h e e x t r u s i o n p r o c e s s h a s been o n e o f l u b r i c a t i o n , a s e v i d e n c e d by s e v e r a l a t t e m p t s t o p roduce t h e I n c o n e l t u b i n g . None o f t h e e x t r u s i o n s h a s b e e n e n t i r e l y s u c c e s s f u l , b e c a u s e e i t h e r t h e m a n d r e l b r o k e or t h e t u b e r u p t u r e d .

M o l t e n g l a s s was s e l e c t e d a s t h e l u b r i c a n t f o r t h e e x t r u s i o n p r o c e s s , which i s a m o d i f i c a t i o n o f S e j o u r n e t - U g i n e p r o c e s s , b e c a u s e t h e u n i t e x t r u s i o n p r e s s u r e s r e q u i r e d a r e lower w i t h g l a s s t h a n w i t h g r a p h i t e or o i l . A n o t h e r f a c t o r f a v o r i n g m o l t e n g l a s s i s t h e r e d u c e d p o s s i b i l i t y o f p i c k u p o f c a r b o n a n d s u l f u r . A s a n i l l u s - t r a t i o n , a s o l i d r o d w a s e x t r u d e d s u c c e s s f u l l y by u s i n g N e c r o l i n e , which h a s a g r a p h i t e b a s e , and a n a l y s i s i n d i c a t e d an i n c r e a s e i n c a r b o n a n d s u l f u r from c a s e t o e x t r u d e d fo rm, a s f o l l o w s : 0.01% c a r b o n a s c a s t , 0.03% c a r b o n e x t r u d e d ; 0 . 0 0 7 % s u l f u r a s c a s t , 0.011% s u l f u r e x t r u d e d .

For t h e e x t r u s i o n s made t h u s f a r , t h e e x t r u s i o n b i l l e t w a s h e a t e d i n m o l t e n l e a d g l a s s . U n f o r t u n a t e l y , a p o r t i o n o f t h e l e a d compound p r e s e n t i n t h e g l a s s w a s r e d u c e d , a n d a s a r e s u l t m e t a l l i c l e a d p r e c i p i t a t e d i n t h e b a t h . T h e m e c h a n i s m o f t h e r e - d u c t i o n i s n o t y e t known; however , t h e g l a s s was h e l d i n a s t a i n l e s s s t e e l c o n t a i n e r t h a t w a s s e a t e d i n a n d e x t e n d e d above t h e t o p o f a g a s - f i r e d p o t f u r n a c e . The p r e s c r i b e d e x t r u s i o n t e m p e r a t u r e f o r I n c o n e l i s 2300"F, b u t w i t h t h e p r e s e n t h e a t i n g a r r a n g e m e n t ,

r

i

152

2 1 0 0 ° F i s ; t h e maximum t e m p e r a t u r e o b t a i n a b l e . T h e s e f a c t o r s , no d o u b t , c o n t r i b u t e d t o or c a u s e d t h e e x t r u s i o n f a i l u r e s .

One o f t h e u l t i m a t e o b j e c t i v e s i s t o o b t a i n t u b i n g t h a t h a s n o i n c l u s i o n s r e s u l t i n g f rom t h e a d d i t i o n of m a l - l e a b i l i z i n g e l e m e n t s such a s magnesium, t i t a n i u m , manganese, and aluminum. To d e t e r m i n e which ma 1 1 e a b i 1 i z i n g e l e m e n t s a r e n e c e s s a r y , i n g o t s were vacuum c a s t w i t h (1) no m a l l e a b i l i z i n g e l e m e n t s , ( 2 ) 0 .05% m a g n e s i u m ( n o m i n a l ) , a n d ( 3 ) 0 . 2 5 % t i t a n i u m , a s a T i - A l - M n m a s t e r a l l o y , a n d 0 . 0 5 % m a g n e s i u m . D i f f i c u l t y was e x p e r i e n c e d i n a t t e m p t i n g t o a d d m a g n e s i u m i n t h e f o r m o f a m a s t e r a l l o y t o I n c o n e l m e l t s u n d e r v a c u u m b e c a u s e o f t h e h i g h v a p o r p r e s s u r e o f magnesium.

T h e s e i n g o t s w e r e s u c c e s s f u l l y e x t r u d e d by u s i n g r o c k wool i n s u l a t i o n i n t h e p r e s s c o n t a i n e r and g l a s s wool ( b o t h p y r e x and s o f t g l a s s ) on t h e h o t e x t r u s i o n b i l l e t . T h i s p r o c e d u r e i s e s s e n t i a l l y t h e same a s t h a t employed by t h e I n t e r n a t i o n a l N i c k e l Co, T h e e x t r u s i o n c o n d i t i o n s were: Tempera tu re 2225°F D i e 45"V E x t r u s i o n time 1 t o 3 s e c E x t r u s i o n p r e s s u r e -50 t s i E x t r u s i o n r a t i o 13.7 S u r f a c e s 1 i gh tl y roughened

TEMPERATURE PRESSING ("C)

RUN NO. MATERIAL

1 FU ("C" g r a d e ) 7 60

2 Cu YCJ' g r a d e ) 910

3 Ag ( p r e c i p i t a t e d ) 65 5

4 95% Ag ( p p t . 1-596 Cu (,,CJJ g r a d e ) 830 5 Ag (-60 t 100 mesh) 9 30

6 18-8 s t a i n l e s s steel ' 1010


DENSITY ( A t h e o r e t i c a l )

92.8

95.3

95.7

95.2

94.0

78.0

A d d i t i o n a l work i s t o i n c l u d e t h e e x t r u s i o n o f I n c o n e l t u b i n g u n d e r s i m i l a r c o n d i t i o n s a n d t h e e x t r u s i o n o f t h e a u s t e n i t i c s t a i n l e s s s t e e l s , s u c h a s t y p e 3 1 0 s t a i n l e s s s t e e l . F u t u r e melts w i l l be made i n z i r c o n i a c r u c i b l e s t o e l i m i n a t e m a g n e s i u m p i c k u p .

HOT-PRESSED PUMP SEALS

E. S. Bomar, J r . J . H. Coobs R. W . J o h n s o n

M e t a l l u r g y D i v i s i o n A. Levy

P r a t t and Whitney A i r c r a f t D i v i s i o n

A s e r i e s o f e x p l o r a t o r y r u n s h a s been made o n m a t e r i a l s b e i n g c o n s i d e r e d f o r t e s t s e a l r i n g s . The r i n g s a r e t o b e composed o f Ag, Cu, 95% Ag-5% Cu a l l o y , o r 18 -8 s t a i n l e s s s t e e l w i t h 1 4 v o l % MoS,. T e s t spec imens 1 / 2 i n . i n d i a m e t e r a n d 3 / 8 i n . l o n g were p r e p a r e d by h o t p r e s s i n g a t 2 5 0 0 p s i i n a g r a p h i t e d i e , w i t h t h e r e s u l t s shown i n T a b l e 1 1 . 7 .

T h e f i r s t r u n s o n t h e c o p p e r , s i l v e r , and Ag-Cu a l l o y c o m p o s i t i o n s w i t h MoS, d e m o n s t r a t e d t h a t t h e s e m a t e r i a l s may be r e a d i l y f a b r i c a t e d by h o t p r e s s i n g . Run 5 shows t h e b e h a v i o r of a c o a r s e g r a d e of s i l v e r (-60 t 100 m e s h ) , w h i c h i s on hand i n q u a n t i t y . Run 6 shows t h a t t h i s c o a r s e p o w d e r

153


may be s a t i s f a c t o r y b u t t h a t i t i s somewhat more d i f f i c u l t t o c o n s o l i d a t e . An i n i t i a l run made w i t h t h e s t a i n l e s s s teel-MoS, c o m p o s i t i o n d i d n o t c o n - s o l i d a t e s u f f i c i e n t l y . F u r t h e r r u n s a r e p lanned a t somewhat h i g h tempera- t u r e s , w i t h molybdenum o r A 1 , 0 , u s e d a s d i e l i n e r s i f n e c e s s a r y .

CERAMICS L. M. Doney J . R. J o h n s o n S. D . F u l k e r s o n A. J . T a y l o r

G. D. White M e t a l l u r g y D i v i s i o n

Ceramic coatings for Shielding. A l e a d b o r a t e e n a m e l was a p p l i e d by f l a m e - s p r a y i n g t o a 5 - f t by 5 - f t by 7 / % - i n . s t e e l p l a t e , b u t t h e c o a t i n g was i m p e r f e c t on p a r t o f t h e s u r f a c e . The t h i c k n e s s o f t h e p l a t e p r e v e n t s t h e s p r a y i n g o f a smooth, g l a s s c o a t - i n g , even when t h e p l a t e is i n i t i a l l y p r e h e a t e d t o 1000°F. A l a r g e r f lame- s p r a y u n i t would p r o b a b l y w o r k , b u t w i t h t h e a v a i l a b l e u n i t , a maximum s t e e l t h i c k n e s s o f a b o u t 1/8 i n . i s i n d i c a t e d ,

T h e c o a t i n g c a n be s u c c e s s f u l l y a p p l i e d by t h e s t a n d a r d e n a m e l i n g t e c h n i q u e o f d u s t i n g t h e p o w d e r e d g l a s s o n t h e r e d h o t m e t a l . An i n i t i a l m e t a l t e m p e r a t u r e o f 1400’F is a d e q u a t e for t h i s c o a t i n g .

Development of Cermet Fuel Elements. A C r - A 1 2 0 3 s o l i d f u e l e l e m e n t o f p ~ s s i b l e u s e i n n u c l e a r - p o w e r e d a i r - c r a f t h a s b e e n f a b r i c a t e d . T h e s e c e r m e t e l e m e n t s would be f o r u s e i n a r e a c t o r s y s t e m t h a t r e s e m b l e d a d i s k h e a t e x c h a n g e r , D i s k s o f Cr -A12 .0 , c o n t a i n i n g an e n c l o s e d “ s a n d w i c h ” r i n g o f UO, a r e s t r u n g on 1 / 4 - i n . - d i a s t a i n l e s s s tee1 t u b e s t h r o u g h which a c o o l a n t p a s s e s , T h e s e d i s k s g i v e u p t h e i r h e a t t o a n a i r s t r e a m p a s s i n g o v e r t h e i r s u r f a c e s , T h e c o o l a n t k e e p s t h e s t e e l t u b e s c o o l enough t o m a i n t a i n a d e q u a t e s t r e n g t h , r e s i s t o x i d a t i o n , and p r o v i d e some m o d e r a t i o n i n t h e r e a c t o r c o r e .

The Cr-A1,0, cermet h a s e x c e l l e n t o x i d a t i o n r e s i s t a n c e u p t o 2200’F and a d e q u a t e h e a t - s h o c k r e s i s t a n c e i n t h e form p r o p o s e d . H o w e v e r , r a d i a t i o n damage and f i s s i o n p r o d u c t r e t e n t i o n a r e unknown. T h e d i s k s h a v e b e e n f a b r i c a t e d w i t h a 0 . 0 2 0 - i n . t h i c k n e s s a n d a 1 - i n . o u t s i d e d i a m e t e r . A p h o t o m i c r o g r a p h o f a C r - A 1 2 0 3 d i s k s e c t i o n c o n t a i n i n g 8 w t 76 UO, i s shown i n F ig . 11.7.

A s i l i c o n - s i l i c o n c a r b i d e m a t e r i a l h a s b e e n p r o p o s e d a s a p o t e n t i a l l y u s e f u l s o l i d a i r c r a f t r e a c t o r f u e l e l e m e n t , a n d e x p e r i m e n t s h a v e b e e n c a r r i e d o u t t o f a b r i c a t e such e l e m e n t s . A p r o c e s s s i m i l a r t o t h a t deve loped by t h e Carborundum Co. f o r i m p r e g n a t i n g carbon i s used. C r o s s - s h a p e d e l e m e n t s

Fig. 11.7. Section o f Cr-A1,0, Cermet Disk Containing 8 wt % UO,.

1 5 4


h a v e b e e n f a b r i c a t e d a n d a r e b e i n g t e s t e d t o o b t a i n p h y s i c a l p r o p e r t y measurements. R a d i a t i o n damage s t u d i e s a n d s i m u l a t e d r e a c t o r s e r v i c e t e s t s have been o u t l i n e d .

Reduction of the Porosity of ARE Beryllium Oxide. A s e r i e s o f e x p e r i - m e n t s was i n i t i a t e d i n an a t t e m p t t o r e d u c e t h e p o r o s i t y a n d t o i n c r e a s e t h e c o r r o s i o n r e s i s t a n c e o f t h e h e x a g o n a l b e r y l l i u m o x i d e b l o c k s t h a t a r e t o b e used f o r t h e ARE. Impregnat ion o f porous b e r y l l i u m o x i d e t e s t p i e c e s w i t h v a r i o u s m a t e r i a l s was a t t e m p t e d , a n d p r e l i m i n a r y v a p o r d e p o s i t i o n s t u d i e s were begun. S a m p l e s o f t h e i m p r e g n a t e d b e r y l l i u m a n d t h e o t h e r s p e c i m e n s w i l l be s u b j e c t e d t o c o r - r o s i o n tes t s i n sodium,

I n t h e f i r s t i m p r e g n a t i o n , t h e b e r y l l i u m o x i d e t e s t p i e c e s ( 1 / 2 by 1/4 by 1 / 4 i n . ) were i m m e r s e d i n m o l t e n h y d r a t e d b e r y l l i u m n i t r a t e a t 135°C f o r 4 8 h o u r s , The t e s t p i e c e s were t h e n p l a c e d i n a s m a l l p o r c e l a i n c r u c i b l e , c o v e r e d w i t h t h e b e r y l l i u m n i t r a t e , and h e a t e d u n t i l e v o l u t i o n o f NO, was c o m p l e t e . T h e n , a f t e r t h e p o w d e r e d b e r y l l i u m o x i d e h a d b e e n s c r a p e d from t h e s u r f a c e s , t h e t e s t p i e c e s were h e a t e d t o 1550"C, h e l d for 1 5 min , and a l l o w e d t o c o o l t o room t e m p e r a t u r e . T h i s p r o c e d u r e c a u s e d a s l i g h t permanent i n c r e a s e i n t h e weight o f t h e t e s t p i e c e s b u t n o m e a s u r a b l e r e d u c t i o n i n p o r o s i t y .

The second i m p r e g n a t i o n e x p e r i m e n t was c a r r i e d o u t u n d e r s i m i l a r c o n - d i t i o n s , b u t magnes ium n i t r a t e was u s e d i n s t e a d o f b e r y l l i u m n i t r a t e . T h i s i m p r e g n a t i o n r e s u l t e d i n a n a p p r e c i a b l e permanent w e i g h t g a i n and i n a r e d u c t i o n o f t h e p o r o s i t y t o a b o u t 35% of i t s o r i g i n a l v a l u e ,

The t h i r d method t r i e d w a s s u c c e s s f u l i n r e d u c i n g t h e p o r o s i t y o f t h e t e s t p i e c e s t o an a l m o s t n e g l i g i b l e amount. I n t h i s m e t h o d , a m i x t u r e o f 3 7 . 5 % AlF, a n d 6 2 . 5 % CaF, was p r e f u s e d t o g i v e a g l a s s . T h e g l a s s w a s t h e n p u l v e r i z e d and s u s p e n d e d i n w a t e r t o g i v e a v e r y h e a v y s u s p e n s i o n . T h e

0

s m a l l ( 1 / 2 by 1/4 by 1 /4 i n . ) b e r y l l i u m o x i d e t e s t p i e c e s were d i p p e d i n t o t h i s s u s p e n s i o n and d r a i n e d , aind t h e a d h e r i n g c o a t i n g was d r i e d . T h e s e p i e c e s w e r e t h e n h e a t e d t o 1 5 5 0 " C , h e l d f o r 1 5 min a t t h i s t e m p e r a t u r e , and a l l o w e d t o c o o l i n t h e f u r n a c e . T h i s t r e a t m e n t r e s u l t e d i n t h e c o a t i n g s o a k i n g i n t o t h e p o r o u s p i e c e s a n d c o m p l e t e l y f i l l i n g t h e p o r e s .

A t e s t was p e r f o r m e d t o d e t e r m i n e whether t h e method o u t l i n e d above f o r t h e A1F,-CaF2 m i x t u r e would be f e a s i b l e w h e n u s e d on o n e o f t h e A R E - s i z e b l o c k s . One o f t h e h a l f - b l o c k s o f b e r y l l i u m o x i d e , which had been shown t o be p o r o u s by b o t h i m m e r s i o n i n a f u s c h i n - d y e - a l c o h o l s o l u t i o n a n d by t h e w a t e r a b s o r p t i o n m e t h o d , w a s c o a t e d w i t h t h e AlF , -CaF2 m i x t u r e . The c o a t e d b l o c k was t h e n h e a t e d a t 750°C p e r h o u r t o 1 5 5 0 ° C , h e l d a t 1550°C f o r a b o u t 4 5 m i n , and c o o l e d o v e r n i g h t i n t h e f u r n a c e . The r e s u l t w a s a n o n p o r o u s b l o c k , e x c e p t f o r c r a c k s t h a t , a l t h o u g h p r e s e n t i n t h e b l o c k b e f o r e t h e h e a t t r e a t m e n t , were now much e n l a r g e d ,

T o d e t e r m i n e t h e c a u s e f o r t h e e n l a r g e m e n t o f t h e c r a c k s , two , f u l l - s i z e , h e x a g o n a l b l o c k s o f b e r y l l i u m oxide were h e a t e d a t 750°C p e r hour t o 1550°C and h e l d f o r 1 h o u r . T h e s e b l o c k s h a d n o a p p l i e d c o a t i n g , a n d hence any e f f e c t s c o u l d be a t t r i b u t e d t o t h e h e a t t r e a t m e n t . T h e r e w e r e s e v e r a l m i n u t e c r a c k s a n d a 2.one o f w e a k n e s s p e r p e n d i c u l a r t o t h e a x i s a c r o s s t h e middle o f e a c h b l o c k b e f o r e t h e h e a t t r e a t m e n t was c a r r i e d o u t . However , t h e s e b l o c k s a r e t y p i c a l - n e a r l y a l l b l o c k s on h a n d h a v e t h i s z o n e o f w e a k n e s s . A f t e r t h e h e a t t r e a t m e n t , b o t h b l o c k s h a d b r o k e n a l o n g t h e z o n e o f w e a k n e s s , a n d o n e h a d a l s o s p l i t a x i a l l y from o n e s i d e i n t o t h e c o r e h o l e . I t i s t o b e c o n c l u d e d t h e r e f o r e t h a t t h e b l o c k can be broken by h e a t i n g a t 750°C p e r hour and t h a t t h e i m p r e g n a t i o n t r e a t - ment i s n o t t h e c a u s e o f t h e c r a c k i n g o f t h e p i e c e s .

155

1 2 . HEAT TRANSFER AND PHYSICAL PROPERTIES

H. F. Poppendiek Reac to r Exper imenta l

Some p r e l i m i n a r y t h e r m a l c o n d u c - t i v i t y measu remen t s on m o l t e n sod ium h y d r o x i d e w e r e m a d e , a n d r e s u l t s i n d i c a t e t h a t t h e c o n d u c t i v i t y i n - c r e a s e s f r o m a b o u t 0 . 4 t o a b o u t 0 . 8 B t u / h r . f t * " F o v e r t h e t e m p e r a t u r e range of 650 t o 1000°F. The e n t h a l p i e s a n d h e a t c a p a c i t i e s o f s t r o n t i u m h y d r o x i d e and NaF-ZrF,-UF, ( 5 0 - 4 6 - 4 mole %) have been o b t a i n e d . The h e a t c a p a c i t y o f s t r o n t i u m h y d r o x i d e was found t o be 0 .32 k 0 . 0 3 c a l / g o o C o v e r t h e t e m p e r a t u r e range o f 570 t o 900°C; t h e -+'&at c a p a c i t y o f N a F - Z r F 4 - U F , ( 5 0 - 4 6 - 4 m o l e % ) w a s f o u n d t o b e 0 .31 k 0 .03 c a l / g ' " C ove r t h e tempera- t u r e r a n g e o f 5 5 0 t o 850OC. Some p r e l i m i n a r y v i s c o s i t y measurements on mol ten sodium hydrox ide were made t h a t v a r i e d from 4 .6 c p a t 34OoC t o 2 . 5 cp a t 448°C. Vapor p r e s s u r e measurements made on t h e e n r i c h e d ARE f u e l were much lower t h a n t h e t h e o r e t i c a l v a l u e d e t e r m i n e d f o r t h e p u r e c o m p o n e n t s (NaF, ZrF , , and UF,), which i n d i c a t e s t h e e x i s t e n c e of complex compounding of i o n s a t h i g h t e m p e r a t u r e s . A graph of t h e t e m p e r a t u r e v a r i a t i o n of t h e P r a n d t l m o d u l i o f s e v e r a l f l u o r i d e m i x t u r e s , a s w e l l a s some l i q u i d m e t a l s , w a t e r , a i r , and sodium hydrox- i d e , h a s b e e n p r e p a r e d ; t h e P r a n d t l m o d u l i o f t h e f l u o r i d e m i x t u r e s a r e be tween a p p r o x i m a t e l y 1 and 10 i n t h e h i g h - t e m p e r a t u r e r a n g e i n which a i r - c r a f t r e a c t o r s a r e t o o p e r a t e .

An a n a l y s i s h a s b e e n c o m p l e t e d t h a t c a n b e u s e d t o m i n i m i z e t h e we igh t of a r a d i a t o r f o r a g i v e n power o u t p u t by o p t i m i z i n g t h e f i n s p a c i n g , f i n t h i c k n e s s tube d i a m e t e r , and t u b e

p l a t e - f i n r a d i a t o r s he l amina r f low r e g i o n .

An a p p a r a t u s h a s b e e n d e s i g n e d f o r d e t e r m i n i n g f l u i d v e l o c i t y p r o f i l e s i n t h e a n n u l a r s p a c e s found i n r e a c t o r s y s t e m s . T e m p e r a t u r e d i s t r i b u t i o n s

- - Enginee r ing D i v i s i o n

i n t h e r m a l e n t r a n c e r e g i o n s o f c i r - c u l a t i n g f u e l r e a c t o r s y s t e m s a r e b e i n g d e t e r m i n e d m a t h e m a t i c a l l y by t h e f i n i t e d i f f e r e n c e m e t h o d . An a p p a r a t u s f o r e x p e r i m e n t a l s t u d y o f t h e the rma l s t r u c t u r e i n a c i r c u l a t i n g - f u e l s y s t e m s i m i l a r t o t h e ARiE c o n - f i g u r a t i o n h a s been assembled.

THERMAL C O N D U C T I V I T Y OF L I Q I J I D S

W. D. Powers S. J . C l a i b o r n e R. M. B u r n e t t

R e a c t o r Exper imen ta l E n g i n e e r i n g D i v i s i o n

T h r e e d i f f e r e n t m e t h o d s a r e now b e i n g u s e d t o d e t e r m i n e t h e t h e r m a l c o n d u c t i v i t y o f l i q u i d s a t h i g h tempera- t u r e s . Two m e t h o d s a r e b a s e d o n s t e a d y - s t a t e f l o w of h e a t downward t h r o u g h a t h i n s e c t i o n of l i q u i d , and t h e t h i r d method i n v o l v e s t r a , n s i e n t h e a t f l ow from an e l e c t r i c a l l y h e a t e d t u b e t o t h e s u r r o u n d i n g t e s t l i q u i d . T h e s e methods have been d e s c r i t b e d i n p r e v i o u s q u a r t e r l y r e p o r t s . A t p r e s e n t , t h e t h e r m a l c o n d u c t i v i t y o f m o l t e n s o d i u m h y d r o x i d e i s b e i n g d e t e r m i n e d . P r e l i m i n a r y r e s u l t s i n d i c a t e t h a t t h e c o n d u c t i v i t y o f sodium h y d r o x i d e i n c r e a s e s f rom abou t 0 . 4 t o a b o u t 0 . 8 B t u / h r * f t * " F o v e r t h e t e m p e r a t u r e r a n g e o f 6 5 0 t o 1000 O F .

A f t e r a d d i t i o n a l t h e r m a l c o n d u c - t i v i t y measurementson sodium hydrox ide h a v e b e e n c o m p l e t e d , s o m e o f t h e o t h e r hydrox ides w i l l be i n v e s t i g a t e d .

HEAT C A P A C I T Y OF L I Q U I D S

W . D. Powers G. C. B l a l o c k R e a c t o r Exper imen ta l E n g i n e e r i n g

D i v i s i o n

The e n t h a l p y and t h e h e a t c i apac i ty o f s t r o n t i u m hydrox ideand NaF-ZrF,-UF, (50-46-4 mole %) have been d e t e r m i n e d

157


0 d -@a-

w i t h B u n s e n i c e c a l o r i m e t e r s : f o r s t r o n t i u m hydrox ide o v e r t h e t empera - t u r e range 570 t o 900"C, ( ' )

HT ( l i q u i d ) - HOoC ( s o l i d ) = 0.32 T - 19 , c = 0.32 f 0.03 ; P

f o r ARE f u e l m i x t u r e NaF-ZrF4-UF, (50 -46-4 mole X) o v e r t h e t e m p e r a t u r e range 550 t o 8 5 0 ° C , ( 2 )

HT ( l i q u i d ) - HOoC ( s o l i d ) = 0.31 T - 9 , c = 0.31 f 0.03,

P

( l ) W . D. Powers and G. C. B l a l o c k , B e a t C a p a c i t y of S t r o n t i u m H y d r o x i d e , O W L CF-53-2-84 (Feb. 9. 1953).

(2)W. D. Powers and G. C. B l a l o c k . H e a t C a p a c i t y o f F u s e d S a l t M i x t u r e N o . 3 0 , ORNL CF-53-2-56 (Feb. 6, 1953).

I8 I

I I I-MELTING POINT - 520OC

/J

200

240

200

c

\" 160 - 0 Y

> -J a a 5 120 z W

00

4 0

0

where H i s t h e e n t h a l p y i n c a l / g , T i s t h e t e m p e r a t u r e i n " C , and c i s r

t h e h e a t c a p a c i t y i n ca l /g*"C . Shown i n F i g . 1 2 . 1 a r e a few of

t h e many e n t h a l p y - t e m p e r a t u r e p o i n t s f o r t h e ARE f u e l m i x t u r e t h a t w e r e used t o e s t a b l i s h t h e above e n t h a l p y and h e a t c a p a c i t y r e l a t i o n s h i p s .

P

VISCOSITY AND DENSITY OF ALKALI HYDROXIDES

R. F. Redmond S. I . Cohen T. N. J o n e s

Reac to r Exper imen ta l E n g i n e e r i n g D i v i s i o n

A p r e l i m i n a r y s t u d y o f t h e v i s c o s i t y of sodium hydrox ide was made by u s i n g

8c96et- DWG. 48661

400 500 600 700 800 900 TEMPERATURE ("C)

Fig. 12.1. Enthalpy vs. Temperature for Fluoride Fuel, NaF-ZrF,-uF4 ( 5 0 - 4 6 - 4 mole %). LJ

158


a m o d i f i e d B r o o k f i e l d v i s c o m e t e r t o check v a l u e s r e p o r t e d i n t h e l i t e r a - t u r e . The r e s u l t s , wh ich a g r e e w i t h t h o s e i n t h e l i t e r a t u r e t o w i t h i n abou t lo%, a r e a s f o l l o w s :

TEMPERATURE (OC) VISCOSITY ( c p )

340.3 4.55 399.5 2.95 448.0 2.45

A d r y b o x t h a t w i l l c o n t a i n f a c i l i t i e s f o r measur ing d e n s i t i e s a n d v i s c o s i t i e s h a s been d e s i g n e d and i s b e i n g f a b r i - c a t e d . A new d e v i c e w i l l be employed t h a t r e l a t e s d e n s i t y t o t h e d i f f e r e n c e i n p r e s s u r e r e q u i r e d t o b u b b l e g a s t h r o u g h o u t l e t s p l a c e d a t two l e v e l s i n t h e m a t e r i a l . A h o r i z o n t a l c a p i l l a r y t u b e v i s c o m e t e r i s b e i n g d e s i g n e d and shou ld soon be r eady f o r c o n s t r u c t i o n . T h i s d e v i c e f o r o b t a i n i n g a b s o l u t e measu remen t s w i l l o p e r a t e u n d e r more n e a r l y i s o t h e r m a l c o n d i t i o n s t h a n some o f t h e p r e v i o u s v i s c o m e t e r s .

VAPOR PRESSURES OF FLUORIDES

R. E . Moore M a t e r i a l s Chemis t ry D i v i s i o n

1, V a p o r p r e s s u r e s t u d i e s o f t h e f l u o r i d e s a l t m i x t u r e s and t h e i r p u r e components o f i n t e r e s t i n c o n n e c t i o n w i t h t h e A i r c r a f t R e a c t o r E x p e r i m e n t were c o n t i n u e d d u r i n g t h e p a s t q u a r t e r . The me thod and a p p a r a t u s o r i g i n a l l y d e s c r i b e d by Rodebush and Dixon(3 ) and d i s c u s s e d i n p r e v i o u s r e p o r t s ( 4 " ) were used f o r t h e s e measurements.

The vapor p r e s s u r e of t h e e n r i c h e d f u e l m i x t u r e NaF-ZrF4-UF, ( 5 0 - 2 5 - 2 5 mole %) was f o u n d t o i n c r e a s e f rom 5 t o 63 mm Hg o v e r t h e t e m p e r a t u r e r ange o f 848 t o 1096°C and i s r e p r e s e n t e d by t h e e q u a t i o n

g ) = -6906/T ( O K ) -t 6.844 . a t i o n i s 32 kca l /mole

d A. L. D i x o n , P h y s . R e v .

(4)R. E . M o o r e and C. J . B a r t o n , ANP Q u a r .

("R. E. Moore, A N P Q u a r . P r o g . R e p . D e c . 1 0 ,

26, 851 (1925).

P r o g . R e p . S e p t . 1 0 , 1 9 5 1 , OWL-1154, p. 136.

1 9 5 1 , OWL-1170, p . 126.

and t h e c a l c u l a t e d b o i l i n g p o i n t i s 1470 "C.

I f t h e m i x t u r e i s r e g a r d e d a s b e i n g composed o f t h e compounds z i r c o n i u m t e t r a f l u o r i d e , u ran ium t e t r a f l u o r i d e , and sodium f l u o r i d e , t h e i d e a l v a p o r p r e s s u r e a t 9 7 0 ° C , a t e m p e r a t u r e a r b i t r a r i l y c h o s e n for c o m p a r i s o n p u r p o s e s , i s c a l c u l a t e d from R a o u l t ' s law t o be 518 mm Hg. The a c t u a l vapor p r e s s u r e o f 1 9 m m i s a v e r y l a r g e n e g a t i v e d e v i a t i o n from i d e a l i t y . T h i s r e s u l t i s i n a g r e e m e n t w i t h r e s u l t s o b t a i n e d f o r o t h e r z i r c o n i u m t e t r a - f l u o r i d e - b e a r i n g m i x t u r e s and h a s been i n t e r p r e t e d a s an i n d i c a t i o n t h a t z i r c o n i u m t e t r a f l u o r i d e a n d u r a n i u m t e t r a f l u o r i d e e x i s t i n thle f u s e d m i x t u r e i n t h e form of complex i o n s . However , i t i s i n t e r e s t i n g t o n o t e t h a t when t h e m i x t u r e i s c o n s i d e r e d t o b e composed of NaZrF' and NaUE:' ( t h e v a p o r p r e s s u r e o f NaUF' a t 97OoC i s n e g l i g i b l e ) , t h e i d e a l p r e s s u r e i s c a l c u l a t e d t o be 33 mm. The n e g a t i v e d e v i a t i o n i s s t i l l p r e s e n t , b u t t o a much less e x t e n t . I t i s p o s s i b l e t h a t f u r t h e r c o m p l e x i n g o f t h e z i r c o n i u m t e t r a f l u o r i d e i s a c c o m p l i s h e d b y a d d i n g NaUF5 t o NaZrF'. I o n s such a s NaZrFi may e x i s t i n t h e s e m e l t s , ,

P r e l i m i n a r y vapor p r e s s u r e d a t a f o r z i r c o n i u m t e t r a f l u o r i d e and NaF-ZrF4- UF, (50 -46-4 mole % ) , t h e c o m p o s i t i o n c h o s e n f o r t h e ARE f u e l , w e r e r e - p o r t e d p r e v i o u s l y . ( ' ) T h e v a p o r p r e s s u r e e q u a t i o n f o r z i r con ium t e t r a - f l u o r i d e , o b t a i n e d f r o m t h e l a t e s t d a t a by t h e method o f l e a s t s q u a r e s , i s l o g P (mm Hg) = -10935.6/T ( O K )

-k 12.113 , from which t h e h e a t of s u b l i m a t i o n , 50 k c a l / m o l e , a n d t h e s u b l i m a t i o n t e m p e r a t u r e , 912OC, were c a l c u l a t e d . S i m i l a r l y , t h e d a t a f o r NaF-ZrF,-UF, (50-46-4 mole %) a r e r e p r e s e n t e d by l o g P (mm Hg) = -7551/T ( O K ) -k 7.888 . The hea t o f v a p o r i z a t i o n , 35 kcal / rnole ,

(6)R. E. Moore, ANP Q u a r . P r o g . R e p . S e p t . I o , 1 9 5 2 , OWL-1375, p. 147.

159


and t h e b o i l i n g p o i n t , 1235"C, were c a l c u l a t e d from t h i s e q u a t i o n .

P R A N D T L M O D U L I O F V A R I O U S M A T E R I A L S

The P r a n d t l number i s one of t h e i m p o r t a n t m o d u l i t h a t c h a r a c t e r i z e c o n v e c t i v e h e a t t r a n s f e r . I n t h e c a s e o f t u r b u l e n t f l o w , c o n v e c t i v e h e a t t r a n s f e r may b e d i v i d e d i n t o t h r e e c l a s s e s , depend ing upon t h e n a t u r e of t h e f l u i d : t h e l i q u i d m e t a l s a r e i n t h e P r a n d t l m o d u l u s r a n g e of a b o u t 0 . 0 0 3 t o 0 . 0 6 ; t h e o r d i n a r y f l u i d s a r e i n t h e P r a n d t l modulus r a n g e of a b o u t 0 . 5 t o a h u n d r e d ; v e r y v i s c o u s f l u i d s have P r a n d t l numbers of s e v e r a l h u n d r e d a n d a b o v e . E a c h o f t h e s e d i f f e r e n t c l a s s e s o f f l u i d s i s d e f i n e d by a d i f f e r e n t t u r b u l e n t c o n v e c t i o n h e a t t r a n s f e r r e l a t i o n s h i p . It i s of i n t e r e s t t o n o t e t h e c l a s s i n wh ich t h e f l u o r i d e m i x t u r e s f a l l . F i g u r e 1 2 . 2 p r e s e n t s a g r a p h o f P r a n d t l modulus v s . t e m p e r a t u r e f o r t h e l i q u i d m e t a l s , w a t e r , a i r , and sodium hydrox- i d e , a s w e l l a s f o r t h r e e f l u o r i d e m i x t u r e s . I n t h e h i g h - t e m p e r a t u r e r a n g e i n which a i r c r a f t r e a c t o r s a r e t o o p e r a t e , t h e f l u o r i d e s have P r a n d t l moduli t h a t a r e i n t h e r ange o f a p p r o x i - m a t e l y 1 t o 10 and t h u s s h o u l d have t h e h e a t t r a n s f e r c h a r a c t e r i s t i c s of o r d i n a r y f l u i d s .

S P E C I F I C R E A C T O R H E A T T R A N S F E R PROBLEMS

W. S. Farmer R e a c t o r Exper imen ta l E n g i n e e r i n g

D i v i s i on

The problem of d e s i g n i n g a minimum- w e i g h t a i r r a d i a t o r f o r t h e t u r b o j e t e n g i n e s o f a nuc lea r -powered a i r c r a f t h a s b e e n g iven f u r t h e r s t u d y d u r i n g t h e p a s t q u a r t e r . An a n a l y s i s was made( ' ) which i n v o l v e d m i n i m i z i n g t h e w e i g h t o f a n a i r r a d i a t o r f o r a g i v e n power o u t p u t by o p t i m i z i n g t h e f i n s p a c i n g , f i n t h i c k n e s s , t u b e d i a m e t e r , a n d t u b e s p a c i n g f o r p l a t e - f i n r a d i a t o r s

(7)W. S. F a r m e r , M i n i m u m leight A n a l y s i s for an A i r Radiator, ORNL CF-53-1-111 ( t o b e i s s u e d ) .

160

o p e r a t i n g i n t h e l a m i n a r f l o w r e g i o n . D i f f i c u l t i e s due t o poor b r a z e c o n t a c t between t h e f i n s and t u b e s have r e c e n t l y b e e n e x p e r i e n c e d i n t h e f a b r i c a t i o n o f p l a t e - f i n r a d i a t o r s . T h e r e f o r e a t t e n t i o n i s now b e i n g g i v e n t o o t h e r t y p e s of f i n s , s u c h a s c i r c u l a r d i s k f i n s , t h a t c a n be f a b r i c a t e d s o t h a t t h e d i f f i c u l t i e s c a n be o b v i a t e d . A g e n e r a l a n a l y s i s i s b e i n g made of t h e p e r f o r m a n c e of r a d i a t o r s t h a t embody s e v e r a l d i f f e r e n t t y p e s of e x t e n d e d s u r f a c e s and shapes .

Because t h e a i r r a d i a t o r i s t o be o p e r a t e d a t h i g h t e m p e r a t u r e s w i t h l a r g e t e m p e r a t u r e d i f f e r e n c e s e x i s t i n g be tween t h e w a l l t e m p e r a t u r e and t h e a i r t e m p e r a t u r e , t h e p rob lem of non- i s o t h e r m a l h e a t t r a n s f e r assumes con- s i d e r a b l e i m p o r t a n c e . S i n c e e f f o r t s t o c o r r e l a t e t h e performance of s e v e r a l a i r r a d i a t o r s t e s t e d by t h e E x p e r i - menta l E n g i n e e r i n g Group w i t h e x i s t i n g t h e o r i e s f o r n o n i s o t h e r m a l h e a t t r a n s f e r have no t been t o o s u c c e s s f u l , t h e p o s s i b i l i t y o f d e v e l o p i n g new a n a l y t i c a l s o l u t i o n s i s b e i n g examined.

T U R B U L E N T C O N V E C T I O N I N A N N U L I

J. 0. B r a d f u t e J. I. Lang Reac to r Exper imenta l E n g i n e e r i n g

D i v i s i on

A c r i t i c a l r e v i e w o f a l l t h e i s o t h e r m a l v e l o c i t y d i s t r i b u t i o n d a t a known t o e x i ~ t ( * * ~ * ~ ~ ) f o r a n n u l u s s y s t e m s was c o m p l e t e d , and t h e d a t a a r e j u d g e d t o b e e i t h e r p a r t l y o r w h o l l y u n s a t i s f a c t o r y b e c a u s e s u f f i - c i e n t c a r e i n m a k i n g t h e d i f f e r e n t e x p e r i m e n t a l measu remen t s was a p p a r - e n t l y n o t e x e r c i s e d . The n e e d f o r good e x p e r i m e n t a l v e l o c i t y d a t a i n d e v e l o p i n g m a t h e m a t i c a l , t u r b u l e n t - f l o w , h e a t - t r a n s f e r r e 1 a t i o n s f o r

( * ) J . G. K n u d s e n a n d D. L. Katz, P r o c e e d i n g s of the M i d w e s t e r n C o n f e r e n c e o n F l u i d D y n a m i c s , First Conference, May 12-13 , 1950, p. 175.

( 9 ) V . M i k r j u k o v , J . T e c h . P h y s . (U.S.S.R.) 4, 9 6 1 ( 1 9 3 7 ) .

('"R. R. R o t h f u s , C. C. M o n r a d , a n d B. E. S e n e c a l , Ind. Eng. Chen. 42, 2511 (1950) .

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a n n u l i ( v i a t h e heat-momentum t r a n s f e r ana logy) h a s prompted a modest program f o r d e t e r m i n i n g such d a t a .

An a p p a r a t u s h a s b e e n d e s i g n e d ( F i g . 1 2 . 3 ) t h a t w i l l c o n s i s t o f a 4 - i n . , v e r t i c a l , b r a s s p i p e a b o u t 2 0 f t l o n g which w i l l be t h e o u t e r a n n u l u s w a l l ; s m a l l e r d i a m e t e r t u b e s w h i c h w i l l b e t h e i n n e r a n n u l u s w a l l s ; a 6 - i n . , l u c i t e , t e s t s e c t i o n i n s e r t e d i n t h e o u t e r p i p e ; a h i g h - i n t e n s i t y l i g h t s o u r c e o f s h o r t d u r a t i o n ; a camera; and an a i r b lower . As a i r i s pumped th rough t h e a n n u l u s , pho tographs w i l l b e t a k e n o f t h e c o l l o i d a l d u s t p a r t i c l e s i n t h e a i r i l l u m i n a t e d by t h e v e r t i c a l p l a n e of l i g h t coming t h r o u g h t h e l u c i t e . The p o s i t i o n s o f t h e p a r t i c l e s s c a t t e r i n g t h e l i g h t c a n b e d e t e r m i n e d by s u p e r i m p o s i n g a p r e v i o u s l y d e t e r m i n e d p h o t o g r a p h o f

UNCLASSIFIED DWG 18663

n

FLOWMETER I I f /SURGE CHAMBER

Fig. 12.3. Schematic Diagram of the .-nnulus A p p a r a t u s f o r M e a s u r i n g Veloci ty Distributions.

a g r i d s y s t e m . By s t r o b o s c o p i c f l a s h i n g o f t h e l i g h t , s u c c e s s i v e p o s i t i o n s o f s e v e r a l p a r t i c l e s can b e o b t a i n e d ; f rom known t i m e i n t e r v a l s be tween f l a s h e s and t h e p o s i t i o n s o f t h e p a r t i c l e s , t h e v e l o c i t y o f t h e a i r c a n be measu red a s a f u n c t i o n of r a d i a l p o s i t i o n . A m o d i f i e d v e r s i o n o f t h i s a n n u l u s sys t em c a n be used t o s t u d y t h e h y d r o d y n a m i c b e h a v i o r o f c i r c u l a t i n g - f u e l r e a c t o r s .

* ;

CIRCULATING-FUEL HEAT TRANSFER H. F. Poppendiek G. Winn

Reac to r Exper imen ta l E n g i n e e r i n g D i v i s i o n

Thermal and hydrodynamic b o u n d a r y l a y e r s a r e u s u a l l y n o t e s t a b l i s h e d i n s h o r t - duc t c i r c u l a t i n g - f u e l s y s t e m s , s u c h a s t h e F i r e b a l l , f o r e x a m p l e . T h e s e s y s t e m s a r e b e i n g s t u d i e d m a t h e m a t i c a l l y . F o r some s p e c i f i c s y s t e m s , t h e d i f f e r e n t i a l e q u a t i o n s d e s c r i b i n g t h e boundary -va lue prob lem h a v e b e e n t r a n s f o r m e d t o f i n i t e d i f f e r e n c e e q u a t i o n s a n d e v a l u a t e d n u m e r i c a l l y . Recen t e v a l u a t i o n s have been made w i t h t h e a i d of h i g h - s p e e d computing machines .

An a p p a r a t u s t h a t w i l l y i e l d e x p e r i - m e n t a l i n f o r m a t i o n o n t h e t h e r m a l s t r u c t u r e i n c i r c u l a t i n g - f u e l s y s t e m s , i n b o t h t h e e n t r a n c e r e g i o n and t h e e s t a b l i s h e d f l o w r e g i o n , was b r i e f l y d e s c r i b e d p r e v i o u s l y . ( ' ' T h i s a p p a r a t u s , which h a s been f a b r i c a t e d and a s s e m b l e d (shown s c h e m a t i c a l l y i n F i g . 1 2 . 4 1 , c o n s i s t s o f a c l o s e d l o o p t h a t c i r c u l a t e s a s u l f u r i c a c i d s o l u t i o n ; a v o l u m e h e a t s o u r c e i s g e n e r a t e d w i t h i n t h e c i r c u l a t i n g a c i d by means o f a n a l t e r n a t i n g c u r r e n t . S e v e r a l o r i f i c e m e t e r s h a v e b e e n c a l i b r a t e d , and t h e power s u p p l y t h a t i s t o g e n e r a t e t h e volume h e a t s o u r c e a n d t h e t h e r m o c o u p l e s a r e t o b e i n s t a l l e d n e x t .

,

('"H. F. P o p p e n d i e k and G. Winn, ANP Quar P r o g . R e p . D e c . 1 0 , 1 9 5 2 , OF"-1439, p . 1 8 5 .

162


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URE REACTOR d i f f e r e n c e s , p r e s s u r e d r o p s , a n d pumping p o w e r s r e q u i r e d t o a c : h i e v e a s e r i e s o f d i f f e r e n t c o o l i n g t a s k s a r e b e i n g made. Because o f t h e l a r g e d i f f e r e n c e s i n p h y s i c a l p r o p e r t i e s o f t h e v a r i o u s c o o l a n t s b e i n g s t u d i e d , b o t h l a m i n a r and t u r b u l e n t f l o w a re

r t i n e n t h i g h - t e m p e r a t u r e c o o l a n t s , e n c o u n t e r e d . A t t imes , a s i g n i f i c a n t p a r t i c u l a r l y f l i n a k , sodium h y d r o x i d e , f r a c t i o n o f t h e c o o l a n t d u c t may l i e b i s m u t h , s o d i u m , a n d a i r , i s b e i n g i n a thermal and hydrodynamic e n t r a n c e i n v e s t i g a t e d . C o m p a r i s o n s o f t h e r e g i o n ; h e n c e , e n t r a n c e r e g i o n h e a t c i r c u l a t i o n v e l o c i t i e s , r a d i a l tempera- t r a n s f e r i s a l s o i n v o l v e d i n t h e s e t u r e d i f f e r e n c e s , a x i a l t e m p e r a t u r e s t u d i e s .

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D. S. B i l l i n g t o n , S o l i d S t a t e D i v i s i o n A. J. M i l l e r , ANP D i v i s i o n

Rad ia t ion -damage s t u d i e s of s t r u c - t u r a l m a t e r i a l s , f u e l s , a n d o t h e r c o o l a n t s exposed i n t h e ORNL g r a p h i t e r e a c t o r and t h e LITR have c o n t i n u e d . Two I n c o n e l c a p s u l e s c o n t a i n i n g t h e ARE z i r c o n i u m - b e a r i n g f u e l w e r e i r r a d i a t e d i n t h e MTR and e x a m i n e d . I n b o t h cases , v a r i o u s p o r t i o n s of t h e c a p s u l e w a l l s a t t a i n e d t e m p e r a t u r e s w e l l above 1500°F. T h e r e were i n d i - c a t i o n s o f c h a n g e s i n t h e f u e l com- p o s i t i o n , and c o r r o s i o n o c c u r r e d i n e x c e s s o f t h a t i n o u t - o f - r e a c t o r t e s t s a t 1 5 0 0 ° F . A t h i r d i r r a d i a t i o n i s now i n p r o g r e s s i n t h e MTR, and , w i t h a more e l a b o r a t e c o n t r o l s y s t e m , a n a t t e m p t i s b e i n g made t o h o l d t h e maximum w a l l t e m p e r a t u r e a t 1500°F. A d d i t i o n a l i n - r e a c t o r c a n t i l e v e r c r e e p m e a s u r e m e n t s on I n c o n e l i n an a i r a t m o s p h e r e were made i n b o t h t h e g r a p h i t e r e a c t o r a n d t h e LITR. I n c o n f i r m a t i o n of p r e v i o u s o b s e r v a t i o n s , i t a p p e a r e d t h a t t h e i r r a d i a t i o n had l i t t l e e f f e c t on t h e c r e e p s t r e n g t h .

T h e s e and o t h e r r a d i a t i o n - d a m a g e s t u d i e s a r e d e s c r i b e d . A d d i t i o n a l i n f o r m a t i o n i s c o n t a i n e d i n t h e So lid S t a t e Division Q u a r t e r l y P r o g r e s s R e p o r t f o r t h e Period Ending F e b r u a r y 10, 1953, ORNL-1506.

IRRADIATION OF FUSED MATERIALS M. T. Robinson D. D. Davies

H. E. Rober t son A. R i c h t C. C. Webster W. J. Sturm

n W. R. Willis M. J . Feldman i d S t a t e D i v i s i o n

R. J. Jones R. L. Knight E l e c t r o m a g n e t i c R e s e a r c h D i v i s i o n

Therma l - f lux measurements were made w i t h c o b a l t i n t h e fused s a l t t e s t i n g f a c i l i t y i n t h e M T R . The power d e n s i t y

i n t h e ARE t y p e o f f u e l was found t o be 2 7 0 0 w a t t s / c m 3 , r a t h e r t h a n t h e 1900 wat ts /cm3 p r e d i c t e d .

The w a l l t e m p e r a t u r e o f t h e f i r s t c a p s u l e o f t h e A R E t y p e o f f u e l i r r a d i a t e d i n t h e MTR was d e t e c t e d and c o n t r o l l e d by a s i n g l e t h e r m o c o u p l e . Examina t ion of t h e s u r f a c e i n c o n t a c t w i t h t h e f u e l d i s c l o s e d t h a t i 3 t l e a s t some p o r t i o n s o f t h e w a l l h a d b e e n h e a t e d t o t e m p e r a t u r e s f a r above 1500°F d u r i n g t h e 116 h r o f i r r a d i a t i o n . I n some s e c t i o n s , t h e I n c o n e l g r a i n s i z e hadbeen g r e a t l y i n c r e a s e d a n d c o r r o s i o n p e n e t r a t i o n o f up t o 1 0 t o 1 2 m i l s o c c a s i o n a l l y o c c u r r e d . I n t h e r e g i o n s o f normal g r a i n s i z e , t h e w a l l showed uniform, d e n s e , i n t e r g r a n u l a r c o r r o s i o n t h a t a v e r a g e d a b o u t 2 m i l s i n d e p t h , and t h e r e were s u b s u r f a c e v o i d s 2 t o 4 m i l s deep.

The s e c o n d MTR f u e l c a p s u l e was i r r a d i a t e d f o r 325 h r a n d t h e w a l l t empera tu re was d e t e c t e d a t t w o p o i n t s . T h e c o n t r o l t h e r m o c o u p l e h e l d t h e c a p s u l e w a l l l o c a l l y a t 1 5 0 0 " F , b u t t h e s e c o n d t h e r m o c o u p l e , s e v e r a l m i l l i m e t e r s away, r eco rded t e m p e r a t u r e s a s h i g h a s 1740°F. Examinat ion of t h e I n c o n e l i n t h i s c a s e s h o w e d o n l y d e n s e , i n t e r g r a n u l a r c o r r o s i o n t h a t averaged about 2 m i l s i n d e p t h .

S e a l e d I n c o n e l c a p s u l e s t h a t h a d been p r e p a r e d f o r i r r a d i a t i o n i n t h e MTR were x r a y e d , and t h e pho ' tog raph showed t h a t t h e f u e l was n o t s o l i d l y p a c k e d i n t o t h e 1 0 0 - m i l - I D f u e l chamber . R a t h e r t h a n o c c u p y i n g t h e b o t t o m o f t h e c h a m b e r , t h e f u e l was s c a t t e r e d o v e r t h e l e n g t h , and t h u s t h e r e were numerous v o i d s i n what had been assumed t o be a s o l i d f u e l column. C o n s i d e r a b l e s t u d y was g i v e n t o t h e f i l l i n g a n d t e m p e r a t u r e c o n t r o l t e c h n i q u e s . A t h i r d c a p s u l e , which i s c u r r e n t l y b e i n g i r r a d i a t e d i n t h e MTR,

16 5


was f i l l e d by an improved method, and i t was o b s e r v e d w i t h x r a y s t h a t t h e f u e l f o r m e d a n e a r l y c o n t i n u o u s 100-mi l -d i a co lumnin t h e lower 1/2 i n . o f t h e f u e l chamber . A r o d a t t a c h e d t o t h e c a p o f t h e c a p s u l e was f i t t e d t i g h t l y i n t o t h e f u e l c h a m b e r t o p r e s s on t h e t o p o f t h e f u e l t o h e l p ho ld i t i n p l a c e . Three thermocouples were s p o t t e d on t h e o u t s i d e chamber w a l l s t o r e c o r d t h e t e m p e r a t u r e s i n v a r i o u s l o c a t i o n s , a n d t h e y w e r e i n s t r u m e n t e d s o t h a t t h e t e m p e r a t u r e c o u l d be r e g u l a t e d by means o f t h e h o t t e s t t h e r m o c o u p l e . D u r i n g t h e c o u r s e o f t h e e x p e r i m e n t t h e m i d d l e t h e r m o c o u p l e h a s b e e n d a m a g e d , and t h e t e m p e r a t u r e i s now c o n t r o l l e d by t h e t o p and bot tom thermocouples .

Chemical a n a l y s e s and a n a l y s e s f o r t h e f i s s i o n p roduc t C S ' ~ ~ w e r e c a r r i e d o u t on t h e two f u e l samples i r r a d i a t e d i n t h e MTR. S i n c e t h e r e i s some doubt a s t o how t h o r o u g h l y t h e f u e l was d i s s o l v e d d u r i n g t h e c o u r s e o f t h e a n a l y t i c a l work, t h e r e i s some doub t a s t o t h e v a l i d i t y of t h e a n a l y t i c a l r e s u l t s . Work i s under way t o improve t h e methodsof d i s s o l u t i o n of t h e f u e l . However, a t r e n d t h a t w a r r a n t s ment ion was i n d i c a t e d by t h e a n a l y t i c a l r e - s u l t s . The re was i n d i c a t i o n t h a t t h e f u e l w h i c h c o u l d b e r e a d i l y m e l t e d o u t of t h e c a p s u l e was more d e f i c i e n t i n u r a n i u m t h a n c o u l d b e a c c o u n t e d f o r by b u r n u p . T h i s d e f i c i e n c y i n uranium d i d n o t occur i n t h e c o n t r o l s h e a t e d on t h e b e n c h a t 1500°F f o r an e q u i v a l e n t number o f hour s . I n a d d i - t i o n , when t h e C S ' ~ ' was c o u n t e d i n t h e f u e l t h a t had b e e n m e l t e d o u t , t h e r e was l e s s d e t e c t e d t h a n wou ld b e e x p e c t e d f r om t h e t h e rma I - f 1 ux m e a s u r e m e n t s . I n o n e c a s e , t h e d i s c r e p a n c y i n C S ' ~ ~ c o r r e s p o n d e d f a i r l y c l o s e l y w i t h t h e d i s c r e p a n c y i n u ran ium c o n t e n t , 33% and 28%, and l e d t o t h e s u p p o s i t i o n t h a t t h e uranium had been s e g r e g a t e d d u r i n g t h e e a r l y p o r t i o n o f t h e i r r a d i a t i o n p e r i o d . H o w e v e r , t h e s h o r t a g e i n ces ium migh t h a v e been d u e t o e s c a p e

166

o f xenon i n t o t h e c a p s u l e f r e e s p a c e and s u b s e q u e n t d e p o s i t i o n o f c e s i u m on t h e w a l l s .

I f i t i s assumed t h e r e a r e no con- v e c t i o n c u r r e n t s i n t h e c a p s u l e t o r e l i e v e t h e t e m p e r a t u r e g r a d i e n t s , t h e c e n t r a l p o r t i o n o f t h e f u e l i s c a l c u l a t e d t o b e 1200°F h o t t e r t h a n t h e f u e l a t t h e w a l l , w h i c h t h e t h e r m o c o u p l e s t r y t o h o l d a t 1500°F. Whether t h e a p p a r e n t u r a n i u m s e g r e - g a t i o n was due t o whatever t e m p e r a t u r e g r a d i e n t s may have e x i s t e d , t h e g e n e r a l o v e r h e a t i n g o f t h e c a p s u l e , f a u l t y a n a l y s e s , or t o r a d i a t i o n - d a m a g e i s a q u e s t i o n t h a t r e q u i r e s f u r t h e r i n v e s t i g a t i o n . I n i r r a d i a t i o n s c a r r i e d o u t s e v e r a l mon ths a g o w i t h t h e Y - 1 2 C y c l o t r o n a n d b y N o r t h American A v i a t i o n ( ) on t h e B e r k e l e y C y c l o t r o n , some e v i d e n c e s o f u r a n i u m s e g r e g a t i o n i n t h e v a r i o u s f u e l s were a l s o n o t e d , b u t t h e q u e s t i o n o f un - c e r t a i n t h e r m a l h i s t o r y e x i s t s f o r t h e s e c a s e s t o o .

B e f o r e o p e n i n g , t h e f i r s t c a p s u l e i r r a d i a t e d i n t h e MTR was h e a t e d t o w e l l above t h e n o r m a l m e l t i n g p o i n t o f t h e f u e l a n d i t s f r e e z i n g p o i n t was compared w i t h t h a t of u n i r r a d i a t e d f u e l i n a s i m i l a r c a p s u l e by means of a d i f f e r e n t i a l t h e r m o c o u p l e a r r a n g e - m e n t . T h e m e l t i n g p o i n t o f t h e i r r a d i a t e d f u e l a p p e a r e d t o be 23OF h i g h e r , b u t t h e d i f f e r e n c e was w i t h i n t h e r a n g e o f e x p e r i m e n t a l e r r o r . In a s i m i l a r e x p e r i m e n t , a s a m p l e o f f u e l i r r a d i a t e d f o r 1 4 0 h r i n t h e LITR a t 140 wat ts /cm3 appeared t o have a n l l ° F lower m e l t i n g p o i n t t h a n i t s c o r r e s p o n d i n g u n i r r a d i a t e d b e n c h t e s t s .

O n l y a s m a l l a m o u n t o f work i s now b e i n g d o n e on r a d i a t i o n damage w i t h t h e Y - 1 2 C y c l o t r o n . T h i s work i n c l u d e d an i n v e s t i g a t i o n o f methods f o r h e l i u m - c o o l i n g t a r g e t s c o n t a i n i n g f u s e d f l u o r i d e s ; t h e s t u d y h a s b e e n d i s c o n t i n u e d . A l s o , some w o r k i s

i

(l)W. V . Goddell e t a l . , C y c l o t r o n I r r a d i a t i o n of Fused F l u o r i d e s cn I n c o n e l a t E l e v a t e d T e a p e r a - t u r e s , NAA-SR-208 (Jan. 2 6 , 1953).

c


b e i n g c a r r i e d o u t t o d e t e r m i n e t h e u s e f u l n e s s of p r o t o n bombardment a s a m e t h o d f o r s t u d y i n g h y d r o g e n em- b r i t t l e m e n t i n m e t a l s .

IN-REACTOR CIRCULATING LOOPS 0. S‘ 1 sman R. M. C a r r o l l W. W. P a r k i n s o n C. D. Bauman J . B. T r i c e C. E l l i s A. S. Olson W. E. Brundage M. T. Morgan F. M. B lackshe r

S o l i d S t a t e D i v i s i o n

The l o o p p r e v i o u s l y r e p o r t e d ( 2 ) a s h a v i n g c i r c u l a t e d sodium i n t h e LITR f o r a week was examined t o d e t e r m i n e t h e c a u s e o f s t o p p a g e o f f l o w . I t was found t h a t t h e d i f f i c u l t y was due t o a l e a k i n t h e I n c o n e l t u b i n g t h a t caused a l o w e r i n g of t h e sodium l e v e l i n t h e s u r g e t a n k . A d d i t i o n a l e x p e r i - m e n t s w e r e c a r r i e d o u t w i t h s o d i u m l o o p s i n t h e g r a p h i t e r e a c t o r w h i l e i m p r o v e m e n t s w e r e b e i n g made i n t h e d e s i g n o f t h e LITR loop . Development c o n t i n u e d on a pump f o r u s e w i t h a n i n - r e a c t o r f l u o r i d e - f u e l - c i r c u l a t i n g system.

CREEP UNDER IRRADIATION W. W. Davis J. C. Wilson

J. C. Zukas S o l i d S t a t e D i v i s i o n

S e v e r a l new t e s t s h a v e b e e n com- p l e t e d on a n n e a l e d I n c o n e l a t 1500’F w i t h s t r e s s e s o f 3000 and 4000 p s i i n a i r i n b o t h t h e LITR and t h e g r a p h i t e r e a c t o r . The s p r e a d i n t h e d a t a and some v a r i a t i o n s i n e x p e r i m e n t a l c o n d i - t i o n s a l l o w no q u a n t i t a t i v e e s t i m a t e s t o be made o f t h e e f f e c t o f n e u t r o n b o m b a r d m e n t on r e e p , b u t i t c a n s a f e l y be s a i d t h a t t h e e f f e c t i s n o t g r e a t enough t o c a u s e m a t e r i a l change i n t h e d e s i g n s t r e s s v a l u e s f o r t h e s e m a t e r i a l s u n d e r t h e s e e x p e r i m e n t a l c o n d i t i o n s . T h e n e x t w o r k t o b e

( 2 ) A N P Quar. P r o g . R e p . D e c . 1 0 , 1 9 5 2 , ORNL- 1439, p . 187 .

performed w i l l be t o a s s e s s t h e e f f e c t o f t h e atmosphere i n which t h e specimen i s t e s t e d , s i n c e t h i s i s known t o be an i m p o r t a n t f a c t o r i n t h e c r e e p s t r e n g t h of I n c o n e l . ( ’ )

I n F i g . 1 3 . 1 , t h e 4 0 0 0 - p s i d a t a show t h a t l e s s c r e e p was e x p e r i e n c e d unde r i r r a d i a t i o n t h a n i n t h e s i n g l e bench t e s t . The odd s h a p e o f c u r v e X - 1 i s b e l i e v e d t o have b e e n c a u s e d by t h e l o a d i n g we igh t r e s t i n g a g a i n s t t h e m i c r o f o r m e r d u r i n g t h e e a r l y p a r t o f t h e t e s t . The d i f f e r e n c e b e t w e e n t h e LITR c u r v e s may h a v e r e s u l t e d b e c a u s e t h e t e s t shown by cu rve L-2 r e c e i v e d 24 h r o f i r r a d i a t i o n b e f o r e t h e f u r n a c e was t u r n e d on and t h e specimen was s t r e s s e d .

The t o t a l s t r a i n s i n e a c h o f two, 3OOO-psi, g r a p h i t e r e a c t o r t e s t s , and o n e LITR t e s t , shown i n F i g . 1 3 . 2 , a r e i n good agreement w i t h t h e v a l u e s f o r s i m i l a r t e s t s r e p o r t e d e a r l i e r . C 4 ) On t h e b a s i s of t h e s i n g l e bench t e s t t o w h i c h a l l t h e i n - r e a c t o r c u r v e s a r e c o m p a r e d , i t i s n o t p o s s i b l e t o say whether moreor l e s s c r e e p r e s u l t e d from i r r a d i a t i o n . A t t h e end of t h e q u a r t e r , two t e s t s were o p e r a t i n g i n t h e LITR i n a h e l i u m a t m o s p h e r e and d u p l i c a t e b e n c h t e s t s were a b o u t t o be s t a r t e d .

A n n e a l e d I n c o n e l a n d t y p e 3 4 7 s t a i n l e s s s t e e l b a r s were exposed f o r a one-week p e r i o d i n h o l e HB-3 o f t h e LITR i n a g r a d i e n t f u r n a c e t o d e t e r m i n e t h e h i g h e s t t e m p e r a t u r e a t w h i c h n e u t r o n bombardmen t w o u l d c a u s e a n i n c r e a s e i n h a r d n e s s o f t h e m e t a l s . The t e m p e r a t u r e g r a d i e n t w a s f r o m 1700 t o 1150°F over 4 . 5 - i n . spec imens . Rockwell B h a r d n e s s measurements were made a f t e r i r r a d i a t i o n and compared t o t h e i n i t i a l h a r d n e s s and t o t h e h a r d n e s s o f c o n t r o l b a r s s u b j e c t e d t o t h e same t i m e and t e m p e r a t u r e h i s t o r y a s t h e i n - r e a c t o r s p e c i m e n s . The I n c o n e l w a s h a r d e n e d s l i g h t l y b y

(3)ANP Qua, . P r o g . R e p . D e c . 10, 1 9 5 2 , ORNL-

( 4 ’ S o l z d S t a t e Q u a r . Prog. R e p . N o v . 1 0 , 1 9 5 2 , 1439, Fig. 1 4 . 1 , p. 188.

ORNL-1429, F i g . 2, p. 7. 6.

167


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Fig. 13.1. In-Reactor Cantilever Creep Tests on Inconel in Air at 1500'F and 4000 psi.

bombardment a t t e m p e r a t u r e s a s h i g h a s 1550'F. The s t a i n l e s s s t e e l showed a n i n c r e a s e i n h a r d n e s s o n l y a t t e m p e r a t u r e s b e l o w 1400°F . E a r l i e r work on t y p e 3 4 1 s t a i n l e s s s t e e l ( ' ) i n d i c a t e d t h a t below 1400°F t h e c r e e p r a t e o f t h e m a t e r i a l was r e d u c e d by n e u t r o n b o m b a r d m e n t , w h e r e a s d a t a t a k e n a t 1 5 0 0 ° F i n d i c a t e d t h a t i n - c r e a s e d c r e e p r e s u l t e d d u r i n g i r r a d i -

("Solid S t a t e Q u a r . P r o g . R e p . May IO. 1 9 5 2 , OWL-1301, F i g . 2 . p. 6 .

f

a t i o n . A q u a l i t a t i v e c o r r e s p o n d e n c e c o u l d b e e x p e c t e d i n I n c o n e l , a n d t h e h a r d n e s s d a t a may h e l p t o e x p l a i n why no s u b s t a n t i a l e f f e c t s o f i r r a d i - a t i o n have y e t been observed . Because t h e s t e e p g r a d i e n t s i n t h e e x p e r i m e n t r e p o r t e d h e r e do n o t p e r m i t a c c u r a t e d e t e r m i n a t i o n of t e m p e r a t u r e , h a r d n e s s b l o c k s w i l l b e p l a c e d a l o n g s i d e t h e c r e e p s p e c i m e n s i n f u t u r e t e s t s t o e n a b l e more p r e c i s e d e t e r m i n a t i o n of i r r a d i a t i o n h a r d e n i n g c o n d i t i o n s a t s eve r a 1 temper a t u r e s .

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169

14. ANALYTICAL STUDIES OF REACTOR MATERIALS

a

C. D. S u s a n o , A n a l y t i c a l C h e m i s t r y D i v i s i o n J . M . Warde, M e t a l l u r g y D i v i s i o n

The work on r e a c t o r f u e l components d u r i n g t h e p a s t q u a r t e r h a s produced a s a t i s f a c t o r y method f o r t h e d e t e r m i - n a t i o n o f z i r c o n i u m i n t h e p r e s e n c e o f u ran ium. A method was a l s o d e v e l o p e d by w h i c h t h e r e d u c t i o n p r o d u c t s , u r a n i u m t r i f l u o r i d e a n d z i r c o n i u m m e t a l , may be d e t e r m i n e d i n t h e p r e s e n c e o f one a n o t h e r . These r educed s p e c i e s may be formed upon e x c e s s i v e a d d i t i o n o f a c o r r o s i o n i n h i b i t o r s u c h a s a h y d r i d e o r NaK t o t h e ARE f u e l m i x t u r e .

S t u d y h a s a l s o been c o n c e n t r a t e d on d e v e l o p i n g m e t h o d s f o r t h e d e t e r m i - n a t i o n o f c o n t a m i n a n t s i n t h e f l u o r i d e f u e l m i x t u r e s . An a p p a r a t u s h a s been d e v e l o p e d a n d t e s t e d i n w h i c h t r a c e s o f m e t a l l i c o x i d e s i n f l u o r i d e m i x t u r e s may be d e t e r m i n e d . The d e t e r m i n a t i o n o f t r a c e q u a n t i t i e s of hydrogen f l u o r i d e i n h e l i u m i i s e x p e d i e n t d u r i n g t h e f i n a l s t a g e s of t h e f u e l p r e p a r a t i o n p r o c e s s , and a method f o r r a p i d l y a c c o m p l i s h i n g t h i s a t t h e s i t e o f t h e f u e l p r e p a r a t i o n h a s been d e v e l o p e d .

A s t u d y iLs b e i n g made o f t h e compounds f o r m e d b e t w e e n f l u o r i d e m e l t s a n d t h e i r c o n t a i n e r s . R e s i d u e s o f t h e s e c o r r o s i o n p r o d u c t s a r e b e i n g examined a n a l y t i c a l l y and s p e c t r o g r a p h i c a l l y .

The s y s t e m s UC14-NaC1 and UCl,-KCl have been examined p e t r o g r a p h i c a l l y t o d e t e r m i n e compound and e u t e c t i c compo- s i t i o n s . O p t i c a l d a t a a r e i n c l u d e d f o r t h e compounds i n t h e s e s y s t e m s . P h a s e s p r e s e n t i n t h e NaF-ZrF, -UF, s y s t e m h a v e b e e n s t u d i e d p e t r o - g r a p h i c a l l y and by x - r a y d i f f r a c t i o n i n an e f f o r t t o d e f i n e t h e t e r n a r y and p s e u d o b i n a r y p h a s e r e g i o n s a n d t o i d e n t i f y t h e compounds t h e r e i n . D a t a f o r t h e c o m p o s i t i o n s s t u d i e d t o d a t e a r e i n c l u d e d .

The b u l k o f work p e r f o r m e d by t h e s e r v i c e g roups d u r i n g t h e p a s t q u a r t e r i n v o l v e d c h e m i c a l a n a l y s e s and p e t r o -

g r a p h i c e x a m i n a t i o n o f f l u o r i d e m i x t u r e s . I n a d d i t i o n , c h e m i c a l a n a l y s e s were p e r f o r m e d on a g r o u p o f t e s t s e c t i o n s from t h e b e r y l l i u m o x i d e v s . NaK t e s t s , and o x i d e d e t e r m i n a t i o n s were made on a number o f c h l o r i d e and f l u o r i d e s a m p l e s .

C H E M I C A L A N A L Y S I S OF R E A C T O R F U E L S A N D C O N T A M I N A N T S

J . C. W h i t e A n a l y t i c a l C h e m i s t r y D i v i s i o n

A new v o l u m e t r i c m e t h o d f o r t h e d e t e r m i n a t i o n o f z i r c o n i u m was d e - v e l o p e d . T h i s m e t h o d c o n s i s t s o f d i s s o l v i n g t h e z i r c o n i u m s a l t o f p - c h l o r o m a n d e l i c a c i d i n a n o n a q u e o u s medium w i t h e x c e s s s o d i u m m e t h y l a t e a n d back t i t r a t i n g w i t h a c e t i c a c i d . The r e a c t i o n i n v o l v e d i s s t o i c h i o m e t r i c ; h e n c e , n o e m p i r i c a l f a c t o r s a r e i n - v o l v e d .

A method f o r t h e d e t e r m i n a t i o n o f u r a n i u m t r i f l u o r i d e a n d z i r c o n i u m m e t a l , w h i c h a r e f o r m e d u p o n t h e a d d i t i o n o f z i r c o n i u m h y d r i d e o r o t h e r s i m i l a r c o r r o s i o n i n h i b i t o r s , w a s d e v e l o p e d . T h e s e d e t e r m i n a t i o n s c a n be made i n t h e p r e s e n c e o f e a c h o t h e r b e c a u s e o f t h e g r e a t d i f f e r e n t i a l r e a c t i o n r a t e s o f t h e s e two m a t e r i a l s w i t h d i l u t e h y d r o f l u o r i c a c i d r e a g e n t .

The r e a c t i o n s o f bromine t r i f l u o r i d e w i t h m e t a l l i c o x i d e s a r e b e i n g s t u d i e d i n an e f f o r t t o m e a s u r e t r a c e amounts o f o x i d e i n f l u o r i d e m i x t u r e s and a l s o t o d e t e r m i n e t h e c o m p l e t e n e s s o f f l u o r i n a t i o n o f z i r c o n i u m o x i d e d u r i n g t h e p r e p a r a t i o n o f t h e f l u o r i d e .

A method f o r t h e d e t e r m i n a t i o n o f t r a c e s o f hydrogen f l u o r i d e i n h e l i u m s w e e p i n g s o f f u e l p r e p a r a t i o n s was d e v e l o p e d i n which t h e g a s i s t r a p p e d i n b o r i c a c i d s o l u t i o n . The i n c r e a s e i n c o n d u c t i v i t y o f t h e s o l u t i o n c a u s e d

17 1


by f l u o b o r i c a c i d f o r m e d by t h e d e t e r m i n i n g z i r c o n i u m h a s b e e n d e - r e a c t i o n between HF and b o r i c a c i d is v e l o p e d i n w h i c h t h e p - h a l o m a n d e l a t e measured and r e l a t e d a s a f u n c t i o n o f s a l t i s d i s s o l v e d i n e x c e s s s t a n d a r d t h e c o n c e n t r a t i o n o f hydrogen f l u o r i d e . sodium m e t h o x i d e s o l u t i o n c o n t a i n i n g C o n c e n t r a t i o n s of t h e o r d e r o f 1 x l o - ' 3 p a r t s b e n z e n e a n d 1 p a r t m e t h a n o l , M HF can be d e t e r m i n e d i n t h i s manner. and t h e e x c e s s b a s e i s t i t r a t e d w i t h

The d i s s o l u t i o n o f I n c o n e l c o n - s t a n d a r d a c e t i c a c i d i n a s i m i l a r t a i n e r s , which h a v e been c o r r o d e d by b e n z e n e - m e t h a n o l s o l u t i o n w i t h thymol f l u o r i d e r e a c t o r f u e l s , was a t t e m p t e d b l u e u s e d a s t h e i n d i c a t o r . T h e e l e c t r o l y t i c a l l y i n s u c h a manner a s e q u a t i o n f o r t h e r e a c t i o n t h a t t a k e s t o s e p a r a t e m e t a l s from compounds. The p l a c e i s :

Z r (p-C1C,H4CHOHC00), + 4NaOCH, 4 4Na p-C1C,H4CHOHC00 -I- Z r (OCH, I4 . a m o u n t o f t h e d a t a c o l l e c t e d i s i n - s u f f i c i e n t t o p e r m i t d r a w i n g a n y d e f i n i t e c o n c l u s i o n s .

Z i r c o n i u m (C. K. T a l b o t t , J . M . McCown, A n a l y t i c a l C h e m i s t r y D i v i s i o n ) . O f t h e s e v e r a l p r o c e d u r e s e x p l o r e d for t h e d e t e r m i n a t i o n o f z i r c o n i u m , ( ' ) t h e s i m p l e s t and mos t a c c u r a t e i s a v o l u - m e t r i c method e m p l o y i n g m a n d e l i c a c i d , T h i s r e a g e n t i s e s p e c i a l l y good f o r d e t e r m i n i n g z i r c o n i u m i n t h e p r e s e n c e o f uranium. I t was d e c i d e d t o f u r t h e r i n v e s t i g a t e r e a g e n t s o f t h e m a n d e l i c a c i d t y p e , and a v o l u m e t r i c p r o c e d u r e was developed employing p-bromomandel ic a n d p - c h l o r o m a n d e l i c a c i d s . T h e s e a c i d s p r e c i p i t a t e z i r c o n i u m i n a c i d i c s o l u t i o n i n t h e f o r m o f z i r c o n i u m t e t r a p-bromo(chloro)mandelate, which i s more e a s i l y f i l t e r e d t h a n t h e z i r - conium m a n d e l a t e . ( I t i s p o s s i b l e t o t h e n d r y t h i s s a l t and d e t e r m i n e z i r - conium g r a v i m e t r i c a l l y , 3 , b u t t h e v o l u m e t r i c m e t h o d i s s i m p l e r t o e x e c u t e . 1

The s a l t d i s s o l v e s i n a l k a l i w i t h s u b s e q u e n t h y d r o l y s i s o f z i r c o n i u m . However , when an a l k a l i i s u s e d i n a n o n a q u e o u s medium t o d i s s o l v e t h e s a l t , h y d r o l y s i s d o e s n o t o c c u r . On t h i s b a s i s , a v o l u m e t r i c m e t h o d f o r

("ANP Quar. P r o g . R e p . D e c . 1 0 , 1 9 5 2 , ORNL-

("R. B. Hahn, Ana l . C h e r . 2 3 , 1259 ( 1 9 5 1 ) .

1439, p. 191 .

,., , "'R. E. Oesper and J . L. K l i n g e n b e r g , A n a l .

C h e a . 2 1 , 1509 ( 1 9 4 9 ) .

T h e r e a c t i o n , w h i c h a p p e a r s t o b e s t o i c h i o m e t r i c , e l i m i n a t e s t h e n e e d f o r t h e u s e o f e m p i r i c a l f a c t o r s . The l i m i t e d a v a i l a b i l i t y o f t h e r e a g e n t h a s made n e c e s s a r y t h e s y n t h e s i s o f p - c h l o r o m a n d e l i c a c i d . A m e t h o d p r o p o s e d by J e n k i n s ( 4 ) h a s been u s e d f o r t h i s p r e p a r a t i o n ; a y i e l d o f 50% i s o b t a i n e d .

R e d u c t i o n P r o d u c t s (W. J . R O S S , A n a l y t i c a l C h e m i s t r y D i v i s i o n ) . The a d d i t i o n o f z i r c o n i u m h y d r i d e t o i n h i b i t c o r r o s i o n i n f l u o r i d e r e a c t o r f u e l s h a s l e d t o a s t u d y o f t h e r e - d u c t i o n p r o d u c t s t h a t a p p e a r a s a r e s u l t o f t h i s a d d i t i o n , I t i s p o s t u l a t e d t h a t some u r a n i u m t e t r a - f l u o r i d e w i l l be r e d u c e d t o t h e t r i - f l u o r i d e and t h a t z i r c o n i u m m e t a l w i l l be formed. A p r o c e d u r e i n which i t i s p o s s i b l e t o d e t e r m i n e b o t h t h e s e s p e c i e s , u r a n i u m t r i f l u o r i d e and z i r - conium m e t a l , i n t h e same s a m p l e o f r e a c t o r f u e l h a s been d e v e l o p e d . The p r o c e d u r e i s b a s e d on t h e v a s t d i f - f e r e n c e s i n t h e r a t e s o f t h e f o l l o w i n g r e a c t i o n s w i t h 0 .2 M HF:

Z r + 6HF H2ZrF, + 2H,, f a s t , (1)

2UF3 t 2HF + 2UF4 -t H,, slow. (2)

R e a c t i o n 1 p r o c e e d s q u a n t i t a t i v e l y a t room t e m p e r a t u r e , w h e r e a s r e a c t i o n 2

(4)S. S. J e n k i n s , J . A B . C h e a . S O C . 5 3 , 2 3 4 1 ( 1 9 3 1 ) .

17 2

c

e.

e x h i b i t s no t e n d e n c y t o r e a c t u n d e r t h i s c o n d i t i o n f o r some time. A s t u d y o f t h e r a t e o f r e a c t i o n 2 i s i n c o m p l e t e ; however , upon h e a t i n g f o r 1 h r a t 9 0 ° C , o n l y 5.2% o f t h e t h e o r e t i c a l amount o f h y d r o g e n i s e v o l v e d . T h e s e r e s u l t s i l l u s t r a t e t h e s t a b i l i t y o f u r a n i u m t r i f l u o r i c d e i n t h i s medium. When a m i x t u r e o f z i r c o n i u m a n d u r a n i u m t r i f l u o r i d e was t r e a t e d w i t h 0 . 2 M HF, t h e volume o f h y d r o g e n l i b e r a t e d was e q u i v a l e n t t o t h e amount o f z i r c o n i u m p r e s e n t :

Zr -t 4HCl---+ ZrC1, -t 2H2, , slow,

4uF3 + LWCl - 3w4 -t uc1, -t 2H,, fas t .

Z i r c o n i u m l i b e r a t e s 4 . 9 % o f t h e t h e o r e t i c a l v o l u m e o f h y d r o g e n u p o n h e a t i n g f o r 1 h r a t 90°C i n 9 . 6 M HC1. U r a n i u m t r i f l u o r i d e r e a c t s q u a n t i - t a t i v e l y , a s shown by M a n n i n g ( ' ) i n h i s m e t h o d f o r t h e d e t e r m i n a t i o n o f u r a n i u m t r i f l u o r i d e . When a m i x t u r e o f t h e t w o i s t r e a t e d w i t h 9 .6 M HC1, hydrogen e q u i v a l e n t t o t h e t o t a l z i r - conium and uranium t r i f l u o r i d e p r e s e n t i s l i b e r a t e d i n a p p r o x i m a t e l y 2 0 min a t 9 O O C . T h i s r e a c t i o n c a n b e e x - p l a i n e d on t h e b a s i s o f f o r m a t i o n o f a c o m p l e x i o n by z i r c o n i u m w i t h t h e f l u o r i d e i o n s t h a t a r e l i b e r a t e d by h y d r o c h l o r i c a c i d a t t a c k on t h e uran ium t r i f 1uori .de.

A t w o - s t e p o x i d a t i o n r e a c t i o n i s , i n e f f e c t , u s e d t o d e t e r m i n e z i r c o n i u m and uranium t r i f l u o r i d e i n t h e p r e s e n c e o f e a c h o t h e r . A s o l u t i o n o f 0 . 2 M HF i s a d d e d t o t h e m i x t u r e a n d t h e volume o f h y d r o g e n e v o l v e d from t h i s r e a c t i o n , c o n d u c t e d a t room t e m p e r a - t u r e , i s c a l c u l a t e d a s z i r c o n i u m . A s o l u t i o n o f 9 . 6 M HC1 i s t h e n a d d e d , w i t h b o r i c a c i d , t p c o m p l e x e x c e s s f l u o r i d e i o n s , a n d t h e v o l u m e o f h y d r o g e n e v o l v e d u p o n h e a t i n g i s c a l c u l a t e d a s u r a n i u m t r i f l u o r i d e .

("D. L. Manning, W. K . Mil ler , and R. Rowan, J r . , M e t h o d s o f D e t e r m i n a t i o n o f V r a n t u n T r t - f l u o r i d e , OWL-1279 (May 2 5 , 1 9 5 2 ) .


P r e l i m i n a r y r e s u l t s h a v e b e e n e x - t r e m e l y p r o m i s i n g , T h e e f f e c t o f l a r g e e x c e s s e s o f s o d i u m , z i r c o n i u m , a n d u r a n i u m t e t r a f l u o r i d e s on t h e s e r e a c t i o n s i s b e i n g s t u d i e d .

Oxides ( J . E . L e e , J r . , A n a l y t i c a l C h e m i s t r y D i v i s i o n ) . M e t a l l i c o x i d e s r e a c t w i t h b r o m i n e t r i f l u o r i d e ( 6 ) a c c o r d i n g t o t h e r e a c t i o n

3 M 0 2 t 4BrF3 - 3MF, -t 2Br2 + 30, , w h e r e M r e p r e s e n t s a q u a d r i v a l e n t c a t i o n . The m e t a l l i c o x i d e c o n t e n t c a n be d e t e r m i n e d by m e a s u r i n g t h e amount o f oxygen e v o l v e d ; h e n c e , t h i s r e a c t i o n i s o f p o t e n t i a l i n t e r e s t i n d e t e r m i n i n g t h e o x i d e c o n t e n t o f f l u o r i d e m i x t u r e s .

A s c h e m a t i c d i a g r a m o f t h e a p p a r a t u s c o n s t r u c t e d f o r u s e i n s t u d y i n g t h i s t y p e o f r e a c t i o n i s shown i n F i g . 14.1. The r e a c t o r p o r t i o n is d e s i g n e d s o t h a t r e a c t i o n p r e s s u r e s o f up t o t h e o r d e r o f 1 t s i c a n b e p e r m i t t e d . T h e r e m a i n d e r o f t h e s y s t e m c o n s i s t s o f a r e a g e n t t r a n s f e r a r r a n g e m e n t , i n which t r a n s f e r may be made u n d e r vacuum, and a high-vacuum s y s t e m w i t h t h e necessa ry i n s t r u m e n t a t i o n f o r m e a s u r i n g t h e oxygen l i b e r a t e d d u r i n g t h e r e a c t i o n .

S e v e r a l s a m p l e s o f z i r c o n i u m o x i d e h a v e b e e n f l u o r i n a t e d w i t h chromium t r i f l u o r i d e i n t h i s e q u i p m e n t a t t e m p e r a t u r e s r a n g i n g from 200 t o 300°C. A n a l y s e s o f t h e r e a c t i o n r e s i d u e s i n d i c a t e t h a t t h e e x p e r i m e n t a l c o n - d i t i o n s employed t h u s f a r h a v e r e s u l t e d i n f l u o r i n a t i o n s t h a t a r e a t l e a s t 80% c o m p l e t e . E f f o r t s a r e b e i n g made t o o b t a i n q u a n t i t a t i v e f l u o r i n a t i o n by m e a n s o f s u c h p r o m o t e r s a s u r a n i u m d i o x i d e ,

Hydrogen Fluoride (D. L. Manning , A n a l y t i c a l C h e m i s t r y D i v i s i o n ) . A p o s s i b l e e x p l a n a t i o n o f t h e c o r r o s i v e - n e s s o f r e a c t o r f u e l s t h a t h a v e been t r e a t e d w i t h h y d r o g e n f l u o r i d e i s t h e p r e s e n c e o f t h e g a s e n t r a p p e d i n t h e s o l i d i f i e d m e l t . I n o r d e r t o remove t h i s g a s f r o m t h e m o l t e n f u e l , a n

( 6 ) H . J . Emeleus and A. A. Woolf, J . Chem. S O C . , p . 164-168 ( 1 9 5 0 ) .

17 3

http://1uori.de



T I

c- REACTOR

F i g . 14 .1 . Apparatus f o r S tudy ing R e a c t i o n s w i t h Bromine T r i f l u o r i d e .

o u t g a s s i n g - w i t h - h e l i u m s t e p h a s been s c r u b b i n g s o l u t i o n s t h r o u g h which t h e i n c l u d e d i n t h e f u e l p r e p a r a t i o n p r o - g a s e s a r e p a s s e d . T h i s t y p e o f c e d u r e . I t i s d e s i r e d t o t e s t t h e a n a l y s i s is r a p i d a n d h a s t h e a d d e d h e l i u m o f f - g a s f o r h y d r o g e n f l u o r i d e a d v a n t a g e t h a t i t may be made a t t h e a n d t o m o n i t o r t h e g a s s t r e a m . The s i t e o f t h e e x p e r i m e n t . S e v e r a l m o s t a t t r a c t i v e m e a n s o f a t t a c k i n g s c r u b b i n g s o l u t i o n s were s t u d i e d , and t h i s problem a p p e a r s t o be t h e measu re - t h e m o s t p r o m i s i n g were c a l c i u m h y - m e n t o f t h e c o n d u c t i v i t y o f t h e d r o x i d e and b o r i c a c i d .

17 4


C a l c i u m h y d r o x i d e r e a c t s w i t h h y - d rogen f l u o r i d e i n t h e f o l l o w i n g manner:

C a t + + 2011- + 2HF + CaF2 + 2H20

a n d r e d u c e s t h e c o n d u c t i v i t y o f t h e s o l u t i o n 13y r e m o v i n g h y d r o x y , l i o n s . A p p r o x i m a t e l y 1 0 0 p g o f h y d r o g e n f l u o r i d e r e d u c e d t h e c o n d u c t i v i t y o f 100 m l o f 7 X N c a l c i u m h y d r o x i d e s o l u t i o n by 7 X mho. A m o r e s e n s i t i v e d e t e r m i n a t i o n is p o s s i b l e i f b o r i c a c i d i s u s e d a s t h e s c r u b b i n g s o l u t i o n . T h e r e a c t i o n t h a t o c c u r s b e t w e e n h y d r o g e n f l u o r i d e a n d b o r i c a c i d is

H,BO, + 4HF - H+ + BF; + 3H,O , i n which a s t r o n g a c i d ( f l u o b o r i c ) i s f o r m e d ; t h e r e f o r e t h e h i g h l y m o b i l e h y d r o g e n i o n i s i n t r o d u c e d i n t o t h e s y s t e m a n d t h e c o n d u c t i v i t y i s ip - c r e a s e d . T h e c o n c e n t r a t i o n o f t h e b o r i c a c i d s o l u t i o n s h o u l d b e v e r y d i l u t e , 0 . 1 w t 76 or l e s s , s o t h a t t h e c o n d u c t i v i t y o f t h e s c r u b b i n g s o l u t i o n w i l l be e x t r e m e l y low, o f t h e o r d e r o f 2 x mho. T h e c o n d u c t i v i t y o f 1 0 0 m l o f 3 X l o ' , M b o r i c a c i d i s i n c r e a s e d 1 3 . 5 X mho b y t h e a d d i t i o n o f 100 p g o f hydrogen f l u o r i d e - a c h a n g e n e a r l y twice t h a t p r o d u c e d by t h e same amount o f hydrogen f l u o r i d e i n c a l c i u m h y d r o x i d e s o l u t i o n . T h e s e r e s u l t s show t h a t c o n d u c t i v i t y measu re - ments a r e ' ex t r eme ly s e n s i t i v e and w e l l

T A B L E 1 4 . 1 . S P E C T R O G R A P H I C A N A L Y S E S

s u i t e d f o r t h e p u r p o s e o f d e t e r m i n i n g hydrogen f l u o r i de .

C o r r o s i o n Products (D. L. Manning, A n a l y t i c a l C h e m i s t r y D i v i s i o n ) . Ex- p e r i m e n t s h a v e b e e n c o n d u c t e d t o a s c e r t a i n t h e e f f e c t s o f m o l t e n f l u o r i d e s a l t m i x t u r e s on I n c o n e l and o t h e r m e t a l l i c c o n t a i n e r s . I n t h e s e e x p e r i m e n t s , t h e m e t a l c o n t a i n e r t h a t h a s been exposed t o f l u o r i d e s i s made t h e a n o d e i n a s u l f u r i c a c i d - c i t r i c a c i d b a t h . S i n c e t h e m e t a l s e x i s t a s e l e m e n t s , t h e y a r e e l e c t r o l y t i c a l l y d i s s o l v e d and t h e r e b y s e p a r a t e d from t h e compounds p r e s e n t . A s i m i l a r m e t a l t u b e i s d i s s o l v e d f o r c o m p a r a t i v e p u r p o s e s . The r e s i d u e s from t h e a n o d i c d i s s o l u t i o n h a v e been a n a l y z e d chemi- c a l l y a n d s p e c t r o g r a p h i c a l l y . T h e a n a l y t i c a l m e t h o d s u s e d t o d a t e h a v e been u n r e l i a b l e b e c a u s e o f f l a k i n g o f m e t a l p a r t i c l e s d u r i n g d i s s o l u t i o n . R e f i n e m e n t s i n t h e e l e c t r o d e s y s t e m a r e b e i n g m a d e t o e l i m i n a t e t h i s d i f f i c u l t y . S p e c t r o g r a p h i c d a t a h a v e been c o l l e c t e d f o r I n c o n e l s p e c i m e n s t h a t were s u b j e c t e d t o t h e s t a n d a r d 1 0 0 - h r s t a t i c c o r r o s i o n t e s t w i t h NaF-ZrF4-UF,, w i t h and w i t h o u t a d d i t i o n of z i r c o n i u m h y d r i d e . The r e s u l t s a r e g i v e n i n T a b l e 14 .1 .

The amount o f t h e d a t a c o l l e c t e d i s i n s u f f i c i e n t t o p e r m i t d r a w i n g d e f i n i t e c o n c l u s i o n s . S e v e r a l p o i n t s o f i n t e r e s t a r e e v i d e n t , h o w e v e r . T h e

OF R E S I D U E S FROM A N O D I C D I S S O L U T I O N OF I N C O N E L U S E D I N S T A T I C C O R R O S I O N T E S T S OF F L U O R I D E REACTOR F U E L S

REACTOR FUEL

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17 5

ANP PROJECT QUARTERLY P R O G R E S S REPORT

s i l i c o n c o n t e n t i n t h e r e s i d u e f r o m c o r r o d e d I n c o n e l i s h i g h and i n d i c a t e s t h a t p r a c t i c a l l y a l l t h e s i l i c o n i n t h e f u e l i s d e p o s i t e d on t h e w a l l s o f t h e c o n t a i n e r ; t h e a d d i t i o n o f z i r - conium h y d r i d e r e s u l t s i n t h e d e p o s i t i o n o f some z i r c o n i u m on t h e c o n t a i n e r w a l l s ; and d e p o s i t i o n o f uran ium d o e s n o t o c c u r i n e i t h e r c a s e .

P R E P A R A T I O N O F URANIUM T E T R A C H L O R I D E

U’. J . Ross A n a l y t i c a l C h e m i s t r y D i v i s i o n

The p r e p a r a t i o n o f s e v e r a l k i l o g r a m s o f uranium t e t r a c h l o r i d e t o be used i n p h a s e s t u d i e s by t h e A N P C h e m i s t r y G r o u p h a s b e e n u n d e r t a k e n . T h e t e t r a c h l o r i d e i s b e i n g p r e p a r e d by c h l o r i n a t i n g UO, w i t h h e x a c h l o r o - p r o p e n e , a c c o r d i n g t o t h e d i r e c t i o n s g i v e n by P i t t e t ai.(’)

P E T R O G R A P H I C E X A M I N A T I O N O F F L U O R I D E S

G. D. Whi t e , M e t a l l u r g y D i v i s i o n T. N . McVay, C o n s u l t a n t

R o u t i n e p e t r o g r a p h i c e x a m i n a t i o n s o f more t h a n 800 s a m p l e s o f f l u o r i d e m i x t u r e s were made i n c o n n e c t i o n w i t h f u e l i n v e s t i g a t i o n s . P e t r o g r a p h i c e x a m i n a t i o n s were made o f c o m p o s i t i o n s i n t h e UC14-NaC1 and U C l , - K C l s y s t e m s . T h e d a t a o b t a i n e d f rom t h e s e e x a m i - n a t i o n s w e r e c o r r e l a t e d w i t h t h e t h e r m a l d a t a t o l o c a t e compound a n d e u t e c t i c c o m p o s i t i o n s .

U C l , - N a C l System. I n t h e UCI4-NaC1 b i n a r y s y s t e m , t w o c o m p o u n d s w e r e found: 2NaC1-UC14, and a compound w i t h more t h a n 5 0 % UCI,, p o s s i b l y NaC1.2UC1,. The l a t t e r compound seemed t o h a v e an i n c o n g r u e n t m e l t i n g p o i n t , s i n c e c o m p o s i t i o n s on t h e h i g h UC1, s i d e o f t h e b i n a r y always c o n t a i n c o n s i d e r a b l e amounts of f r e e UC1,.

Na,UCI Optical Data.

P a l e green t o c o l o r l e s s

( 7 ) B . M. P i t t e t a l . , T h e P r e p a r a t i o n of T C 1 , w i t h H e x a c h l o r o p r o p y l e n e , C - 2 . 3 5 0 . 3 (July 2 7 , 1945).

Uniaxia l n e g a t i v e ( t e t r a g o n a l or hexagonal ) R e f r a c t i v e i n d i c e s

E , 1.652 0, 1 . 6 6 4

NaU,CI Ye 1 1 ow- green B i a x i a l n e g a t i v e ( p r o b a b l y o r t h o r h o m b i c )

R e f r a c t i v e i n d i c e s w i t h s m a l l o p t i c a n g l e

a, 1.790 y , 1.850

U C 1 , - K C 1 S y s t e m . T h e UC1, - K C l s y s t e m p r o d u c e d t h r e e c o m p o u n d s : 2KCl*UCl,, K C l . U C l , , and an i n c o n g r u - e n t l y m e l t i n g compound i n t h e 67% UCl, r e g i o n o f t h e b i n a r y . T h e r e were two forms t h a t c r y s t a l l i z e d i n t h e compo- s i t i o n r a n g e o f 30% t o 35% UCl , . They were d i s t i n g u i s h e d by t h e i r d i f f e r e n c e s i n b i r e f r i n g e n c e a n d i n t e r f e r e n c e f i g u r e s .

Optical Data. K,UCI

1. P a l e green t o c o l o r l e s s U n i a x i a l n e g a t i v e R e f r a c t i v e i n d i c e s

E , 1.644 0, 1.654

2 . P a l e green t o c o l o r l e s s B i a x i a l p o s i t i v e , small o p t i c a n g l e R e f r a c t i v e i n d i c e s a, 1.636 y , 1.640

KUCl PI eochroism X, grey 2, b l u e - g r e e n

B i a x i a l p o s i t i v e , small o p t i c a n g l e R e f r a c t i v e i n d i c e s a, 1.692 P , 1.705 y , 1.759

KU,CI Yel l ow-green B i a x i a l p o s i t i v e , w i t h very small o p t i c a n g l e R e f r a c t i v e i n d i c e s a, 1.740 P , 1.809 Y, 1.820

17 6


X-RAY DIFFRACTION STUDIES P. A . Agron


T h e d e t e r m i n a t i o n o f t h e p h a s e s p r e s e n t i n s o l i d i f i e d m e l t s o f v a r i o u s compos i t io i i s i n t h e NaF-ZrF, -UF, s y s t e m h a s b e e n h e l p f u l i n e l u c i d a t i n g t h e p a t h s o f c r y s t a l l i z a t i o n . The r e g i o n s o f t h i s t e r n a r y s y s t e m t h a t a r e r i c h i n NaF h a v e been examined d u r i n g t h e p a s t q u a r t e r . Some p r o g r e s s h a s been made h e r e i n d e f i n i t i o n o f t h e t e r n a r y and p s e u d o b i n a r y p h a s e r e g i o n s .

The p e t r o g r a p h i c a n d x - r a y d i f - f r a c t i o n i d e n t i f i c a t i o n o f t h e p h a s e s found i n t h e s o l i d , upon m e l t i n g g i v e n c o m p o s i t i o i i s , a r e l i s t e d i n T a b l e 14.2. The p h a s e s have been grouped a c c o r d i n g t o t h e s i m i l a r i t i e s p r e s e n t i n t h e r e s p e c t i v e s o l i d i f i e d m e l t s , t h u s A - 1 a n d A-2 r e p r e s e n t o n e t e r n a r y a r e a ; B-1 a n d B-2, t h e a d j a c e n t t e r n a r y a r e a , e t c . T h i s d i v i s i o n i n t o t e r n a r y a r e a s i s :in f a i r a g r e e m e n t w i t h t h e i s o t h e r m ( a 1 c o n t o u r p l o t s ( t o b e p u b l i s h e d ) , H o w e v e r , t h e a n o m a l o u s s i t u a t i o n o f f o u r p h a s e s i n s a m p l e s B-1 and D - 2 o b v i o u s l y r e q u i r e s f u r t h e r i n v e s t i g a t i o n . A d d i t i o n a l c o m p o s i t i o n s o f t h e s e t e r n a r y a r e a s s h o u l d a l s o be i n v e s t i g a t e d b e f o r e mapping t h e p h a s e b o u n d a r i e s .

T h e e x a m i n a t i o n o f a n u m b e r o f f u s e d s o l i d s a l o n g t h e c o m p o s i t i o n l i n e j o i n i n g NaUF, and Na3ZrF, a p p e a r s t o i n d i c a t e a p s e u d o b i n a r y b e h a v i o r . A p p r o x i m a t e l y 90% o f t h e x - r a y d i f - f r a c t i o n ‘ p a t t e r n c a n be a s s i g n e d t o t h e s e two p h a s e s . The c o o l i n g c u r v e s o f a s e r i e s o f t h e s e c o m p o s i t i o n s ( t o b e p u b l i s h e d ) i n d i c a t e a b i n a r y e u t e c t i c a t a b o u t 22.5 m o l e % UF,.

T h e b e h a v i o r o f s a l t s a l o n g t h e c o m p o s i t i o n l i n e b e t w e e n NaUFS a n d N a Z r F s i s r a t h e r c o m p l e x b e y o n d 6 mole % UF, c o n t e n t ’ . ( 8 ) F u r t h e r s t u d y a l o n g t h i s c o m p o s i t i o n l i n e , w i t h t h e

( 6 ) p . A. Agron, X - r a y S t u d i e s o f P h a s e S e g r e - g a t i o n i n Pseudo NaZrFs-NaUF5 B i n a r y as a F u n c t i o n o f H e a t T r e t r t m e n t ~n R a d l a t c o n S t u d i e s , ORNL CF-53-1-332 ( J a n . 20, 1953).

u s e o f l i q u i d s a m p l i n g and q u e n c h i n g t e c h n i q u e s , w i l l be r e q u i r e d t o e x - p l a i n t h i s a r e a o f t h e p h a s e d i a g r a m .

SERVICE CHEMICAL ANALYSES H. P. House S. A. Reed

A. F. Roemer, J r . A n a l y t i c a l C h e m i s t r y D i v i s i o n

Work i n t h e ANP A n a l y t i c a l C h e m i s t r y L a b o r a t o r y d u r i n g t h e p e r i o d c o n s i s t e d p r i m a r i l y o f t h e a n a l y s i s o f a l k a l i - f l u o r i d e e u t e c t i c m i x t u r e s a n d z i r - conium f u e l s . A l t h o u g h t h e r e was a s l i g h t d e c r e a s e i n t h e t o t a l number o f s a m p l e s r e c e i v e d d u r i n g t h e q u a r t e r , t h e r e was a s i g n i f i c a n t i n c r e a s e i n t h e number o f m i s c e l l a n e o u s m a t e r i a l s r e c e i v e d . I m p o r t a n t among t h e s e was a g r o u p o f s a m p l e s t h a t were t e s t e d f o r b e r y l l i u m c o n t e n t . I n c l u d e d i n t h e g r o u p w e r e l a r g e s t e e l s e c t i o n s o f t e s t r i g s u s e d t o s t u d y t h e c o m p a t i - b i l i t y o f NaK a n d b e r y l l i u m o x i d e . The s p e c i m e n s were f i r s t t r e a t e d w i t h methanol t o remove e x c e s s NaK and t h e n l e a c h e d w i t h h o t , 50% sodium h y d r o x i d e s o l u t i o n s t o d i s s o l v e t h e b e r y l l i u m o x i d e a d h e r i n g t o t h e s u r f a c e s o f t h e s p e c i m e n s . The b e r y l l i u m c o n t e n t o f t h e a l c o h o l i c a n d c a u s t i c s o l u t i o n s was d e t e r m i n e d c o l o r i m e t r i c a l l y , w i t h p - n i t r o b e n z e n e a z o - o r c i n o l a s t h e chromogenic r e a g e n t .

A number o f u r a n i u m t e t r a c h l o r i d e s a m p l e s w e r e a n a l y z e d f o r UO, a n d UOC1,. S e p a r a t i o n o f UO, f r o m t h e s a l t was e f f e c t e d by r e f l u x i n g p o r t i o n s o f t h e m a t e r i a l w i t h d i l u t e ammonium o x a l a t e s o l u t i o n . The i n s o l u b l e UO, was removed by f i l t r a t i o n , d i s s o l v e d i n a c i d , and e s t i m a t e d q u a n t i t a t i v e l y by p o t e n t i o m e t r i c t i t r a t i o n w i t h f e r r i c s u l f a t e . The U O C l , , a l o n g w i t h a n y U O , , was s e p a r a t e d f rom t h e UCl, by r e f l u x i n g w i t h a n h y d r o u s m e t h y l a c e t a t e . The i n s o l u b l e r e s i d u e was d i s s o l v e d i n d i l u t e n i t r i c a c i d , and t h e UOC1, w a s c a l c u l a t e d f r o m a v o l u m e t r i c d e t e r m i n a t i o n o f t h e c h l o r i d e con t e n t .

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TABLE 14.3. SUMMARY OF SERVICE ANALYSES

ANP Reactor Chemistry Group

ANP Experimental Engineer ing Group

ADP P r o c e s s Improvement Group

Heat Transfer and Phys ica l P r o p e r t i e s Group

Electromagnet ic Research D i v i s i o n

NUMBER OF SAMPLES REPORTED

50 8

216

41

6

2

General E l e c t r i c Company 11

Total 784 I -

C o m p a r a t i v e t e s t s o f p h e n y l a r s o n i c a c i d and m a n d e l i c a c i d a s p r e c i p i t a n t s f o r z i r c o n i u m were c o m p l e t e d d u r i n g t h i s p e r i o d . S p e c t r o g r a p h i c e x a m i - n a t i o n o f z i r c o n i u m o x i d e r e s i d u e s r e s u l t i n g f r o m t h e i g n i t i o n o f p r e - c i p i t a t e s o f p h e n y l a r s o n i c a c i d r e v e a l e d t h e p r e s e n c e o f s i g n i f i c a n t a m o u n t s o f a r s e n i c , a n t i m o n y , a n d i r o n , Z i r con ium o x i d e from m a n d e l i c a c i d p r e c i p i t a t i o n s was found t o c o n - t a i n o n l y t r a c e s o f s i l i c o n . The u s e o f m a n d e l i c a c i d a s t h e p r e c i p i t a n t r e s u l t e d i n much b e t t e r s e p a r a t i o n s from i n t e r f e r i n g i o n s and , i n a d d i t i o n , a c o n s i d e r a b l e s a v i n g i n t i m e , By t h e u s e o f t h i s r e a g e n t d u r i n g t h e l a t t e r p a r t o f t h e q u a r t e r , a m a r k e d r e d u c t i o n i n t h e number o f d u p l i c a t e d e t e r m i - n a t i o n s weis e f f e c t e d , and a c o n s i d e r - a b l e i n c r e a s e i n t h e a c c u r a c y o f t h i s d e t e r m i n a t i o n was a t t a i n e d .

NUMBER OF DETERMINATIONS

REPORTED

4477

2424

97

86

15

114

7213

Of t h e 7 8 4 s a m p l e s r e p o r t e d d u r i n g t h e p e r i o d , 65% were s u b m i t t e d by t h e ANP R e a c t o r C h e m i s t r y Group and 27% by t h e E x p e r i m e n t a l E n g i n e e r i n g G r o u p . O v e r 7 0 0 0 d e t e r m i n a t i o n s were made d u r i n g t h e q u a r t e r , a f o u r t h o f w h i c h were m a d e o n n o n r o u t i n e s a m p l e s . S u m m a r i e s o f t h e A N P a n a l y t i c a l c h e m i s t r y w o r k f o r t h e q u a r t e r a r e g i v e n i n T a b l e s 1 4 . 3 and 14 .4 .

TABLE 14.4. BACKLOG SUMMARY

S a m p l e s on h a n d , 11-10-52 108

Number of s a m p l e s r e c e i v e d 808

T o t a l number o f s a m p l e s 9 1 6

Number o f s a m p l e s r e p o r t e d 784 B a c k l o g , 2-10-53 132

17 9

REPORT NO.

CF- 53- 1- 11 1 CF- 53- 1- 148

CF-53-2-159

CF- 52- 12- 153 CF-53-1-84

CF- 53- 1-260 CF- 5 3- 1- 276 ORNL- 1461

CF-53-1-64

CF- 53- 1-267

CF-53-1-317 Y-881 CF- 53- 2- 50

CF- 53-2- 99

O m - 1493

CF- 52- 12- 109 ( n o number)

MM- 54*

CF-53-1-83 CF- 53-2-79 ORNL-1463

1 5 . LIST OF REPORTS I S S U E D DURING THE QUARTER

TITLE OF REPORT AUTHOR (S )

I. General Design Minimum Weigh t A n a l y s i s f o r a n A i r R a d i a t o r W. S. Farmer

Component T e s t s Recommended t o P r o v i d e Sound A. P . F r a a s B a s i s f o r D e s i g n o f F l u o r i d e F u e l R e a c t o r s f o r T a c t i c a l A i r c r a f t

ARE Des ign Da ta W. B. C o t t r e l l

11. Experimental Engineering

An I m p r o v e d AC E l e c t r o m a g n e t i c Pump C e l l M. E. LaVerne

ARE R e g u l a t i n g Rod E. R. Mann S. H. Hanauer

M o o r e P r e s s u r e T r a n s m i t t e r T e s t Summary P. W. T a y l o r

Components o f F l u o r i d e Sys tems W. B. C o t t r e l l

A S i m p l e E I e c t r o m a g n e t i c F lowmeter for L i q u i d R. M. C a r r o l l Metals

111. Reactor Physics D e l a y e d N e u t r o n Damping of Non-Linear R e a c t o r W . K. E rgen

D e l a y e d N e u t r o n A c t i v i t y i n a C i r c u l a t i n g H . L. F. E n l u n d

Delayed Neu t ron A c t i v i t y i n t h e ARE Fuel Element H. L. F. Enlund

A G r a p h i t e Moderated C r i t i c a l Assembly E. L. Zimmerman

The A t t e n u a t i o n o f C a p t u r e Gammas i n a P l a n e F. Aberna thy

H e a t i n g by F a s t N e u t r o n s i n a B a r y t e s C o n c r e t e F. Aberna thy

Genera l Method o f R e a c t o r A n a l y s i s Used by ANP C. B. Mills

O s c i l l a t i o n s

F u e l R e a c t o r

L imi t ed Medium of F i n i t e T h i c k n e s s H. L. F. Enlund

S h i e 1 d H. L. F. Enlund

P h y s i c s Group

IV. Metallurgy and Ceramics

S p o t W e l d i n g of S t a i n l e s s C l a d F u e l E l e m e n t s G. M. S l a u g h t e r

F o r m a b i l i t y and Weldabi l i t y o f Vapor-Deposi t e d M a s s a c h u s e t t s Molybdenum. F i n a I n s t i t u t e o f

Techno 1 ogy

P r o g r e s s R e p o r t : The F1 as h We l d i n g o f Molybdenum. P a r t I - T e m p e r a t u r e D i s t r i b u t i o n D u r i n g t h e P o l y t e c h n i c F l a s h i n g Cyc le

A High-Tempera ture Cermet Fuel Element J. E. Johnson

Ceramic Fu ement R a d i a t i o n T e s t s J. R. Johnson

Methods o f F a b r i c a t i o n o f C o n t r o l a n d S a f e t y J. H. Coobs E lemen t s f o r t h e ARE and HRE R e a c t o r s E. S. Bomar

R e n s s e l a e r

I n s ti t u t e

* Number assigned by ANP R e p o r t s O f f i c e .

DATE ISSUED

1- 31- 53 1- 16- 53

2- 18-5 3

12-7-52 1- 9- 53

1-22-53 1-27-53 t o be i s s u e d

1-7-53

1-27-53

1-27- 53 12-7- 52 2-6-53

2- 11- 53

t o be i s s u e d

12-9- 52 10-31-52

12- 5- 52

1-9-53 2-9-53 t o be i s s u e d

18 3


R E P O R T N O .

ORNL- 149 1

CF- 52- 11-20 5

CF- 52- 12- 124

Y-B4-59

CF-53-1-233

CF- 53- 1-248

CF- 53- 2- 56

CF- 53- 2- 84

ORNL- 9 1 5

CF-52-11-129

CF-52-12-209

CF- 53- 1-279

ORNL- 1438

OWL- 1471

ORNL- 1479

ORNL- 1430

Y- B3 1- 3 90

ORNL- 1453

Y-B32-104

184

T I T L E OF R E P O R T AUTHOR (SI

C o r r o s i o n by Mol t e n F l u o r i d e s L. S. R icha rdson D. C. V r e e l a n d W . D. Manly

V. Heat Transfer and P h y s i c a l P r o p e r t i e s

E s t i m a t e s o f H e a t a n d Momentum T r a n s f e r H. F. Poppendiek C h a r a c t e r i s t i c s o f t h e Two F l u o r i d e C o o l a n t s : (L iF -48 M%, BeF-52 M%) and (NaF-10 M%, KF-46 M%, ZrF,-44 M%)

G e n e r a l i z e d V e l o c i t y D i s t r i b u t i o n f o r T u r b u l e n t W. B. H a r r i s o n Flow i n Annu l i J. 0. B r a d f u t e

R. V. B a i l e y

S e l e c t e d P h y s i c a l P r o p e r t i e s o f P o t a s s i u m and R . L. C u r t i s P o t a s s i u m Hydrox ide i n t h e T e m p e r a t u r e Range 100 t o 1000°C. A L i t e r a t u r e S e a r c h

M e a s u r e m e n t o f t h e T h e r m a l C o n d u c t i v i t y o f S. J. C l a i b o r n e F l u o r i d e M i x t u r e s No. 1 4 and No. 30

Remarks on t h e Fa1 I ing-Bal I V i scomete r R. F. Redmond S. I . Kaplan

Heat C a p a c i t y of Fused S a l t Mix tu re No. 30 W. D. Powers G. C. B l a l o c k

Heat C a p a c i t y of W. D. Powers G. C. B l a l o c k

F o r c e d C o n v e c t i o n H e a t T r a n s f e r i n T h e r m a l W. B. H a r r i s o n E n t r a n c e Regions

V i . S h i e l d i n g

Mate r i a l s Resea rch f o r Mobi le R e a c t o r S h i e l d i n g E. P . B l i z a r d

Thermal N e u t r o n Dose a t t h e Crew Compar tment J . L. M e e m

The Tower S h i e l d i n g F a c i l i t y E. P. B l i z a r d

D e t e r m i n a t i o n of t h e Power of t h e Bulk S h i e l d i n g E. B. Johnson

S h i e l d O p t i m i z a t i o n E. P. B l i z a r d Reac tor . P a r t 2 J. L. M e e m

A P ro ton Recoi l Type F a s t Neu t ron S p e c t r o m e t e r R. G. Cochran K . M . Henry

VII. Chemistry

M o d i f i c a t i o n s o f t h e D i m e t h y l g l y o x i m e Method M. L. Druschel for t h e C o l o r i m e t r i c D e t e r m i n a t i o n o f N i c k e l 0. Menis Based on t h e Use o f P o t a s s i u m P e r s u l f a t e a s R. Rowan, Jr. t h e Ox idan t

A n a l y t i c a l Chemistry-ANP P r o g r a m Q u a r t e r l y A n a l y t i c a l P r o g r e s s R e p o r t f o r P e r i o d E n d i n g November C h e m i s t r y 25, 1952 D i v i s i on

D i s s o l u t i o n o f NaK J. C. White C. K. T a l b o t t L. J . Brady

Minu tes of Committee M e e t i n g f o r t h e Coord ina t ion F. Kertesz o f H y d r o x i d e R e s e a r c h , F o u r t h M e e t i n g , December 10 and 11, 1952

DATE I S S U E D

t o be i s s u e d

11- 29- 52

12-19- 52

9-23-52

1 -8 -53

1- 14- 53

2 -6 -53

2-9-53

t o be i s s u e d

11-18- 52

1 -27-53

t o be i s s u e d

t o be i s s u e d

t o be i s s u e d

11- 3- 52

11-20- 52

12-2- 52

1 -7 -53

1)

I -

k

R E P O R T N O .

ORNL- 1376

ORNL- 1490

ORNL- 1495

Y-B32- 103

CF- 52- 12- 178

CF- 53- 1-129

O W - 1476

ORNL- 1500

Y- B3 1 - 40 3

ORNL- 1439

CF- 53-2- 126

CF- 53- 2-246


T I T L E OF R E P O R T AUTHOR (SI

Mass S p e c t r o m e t e r I n v e s t i g a t i o n o f UF, L. 0. G i l p a t r i c k R u s s e l l Baldock J. R. S i tes

G e n e r a l I n f o r m a t i o n C o n c e r n i n g F l u o r i d e s , A M. E. Lee

G e n e r a l I n f o r m a t i o n C o n c e r n i n g H y d r o x i d e s , A M. E. Lee

L i t e r a t u r e S e a r c h , Suppl . t o ORNL-1252

L i t e r a t u r e S e a r c h , Supp l . t o ORNL-1291

P o s s i b l e C o o l a n t s f o r S o l i d Fuel R e a c t o r s W . R. G r i m e s

Hydroxide Sys tems M. D. Banus

Fused S a l t Compos i t ions C. J . B a r t o n

An I n d i r e c t C o l o r i m e t r i c Method f o r t h e Deter- J. C. Whi te m i n a t i o n of Uranium D. L. Manning

R e c o v e r y o f Uranium as a S i n g l e P r o d u c t f rom C. F. Coleman F l u o r i d e s

VIII. Miscellaneous

A Guide f o r t h e S a f e H a n d l i n g of Mol t e n F l u o r i d e s R e a c t o r Components and Hydrox ides S a f e t y Committee

Ending December 10 , 1952 ANP P r o j e c t Q u a r t e r l y P r o g r e s s R e p o r t f o r P e r i o d W. B. C o t t r e l I

O b j e c t i v e a n d s t a t u s of ORNL-ANP R e a c t o r Program R. C. B r i a n t

ANP I n f o r m a t i o n Mee t ing o f F e b r u a r y 18, 1953 W. B. C o t t r e l l

D A T E I S S U E D

8- 29- 52

t o be i s s u e d

t o be i s s u e d

11-25-52

12-23-52

1- 15-53

1- 13- 53

t o be i s s u e d

1- 12- 53

1- 15- 53

2- 13- 53

3-2-53

185

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