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LOS ALAMOS SCIENTIFIC LABORATORYOF THEUNIVERSITYOF CALIFORNIAo LOSALAMOS NEW MEXICO
F.. ..-
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LOS ALAMOS CRITICAL-MASS DATA
{. “.
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Eca ––ClC-l4 REPORT COLLECTION
$% _:_ - -~m - -,:-.~m . REPRODUCTION ..-.
COPY,.
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LEGAL NOTICE
4,
\
This report was prepared as an account of Govern-ment sponsored work, Neither the United States, nor theCommission, nor any person acting on behalf of the Com-mission:
A. Makes any warranty or representation, expressedor implied, with respect to the accuracy, completeness, orusefulness of the information contained in this report, orthat the use of any information, apparatus, method, or pro-cess disclosed in this report may not infringe privatelyowned rights; or
B. Assumes any liabilities with respect to the useof, or for damages resulting from the use of any informa-tion, apparatus, method, or process disclosed in this re-port.
As used in the above, “person acting on behalf of theCommission” includes any employee or contractor of theCommission, or employee of such contractor, to the extentthat such employee or contractor of the Commission, oremployee of such contractor prepares, disseminates, orprovides access to, any information pursuant to his em-ployment or contract with the Commission, or his employ-ment with such contractor.
Printed in USA. Price $1.50. Available from the
office of Technical ServicesU. S. Department of CommerceWashington 25, D. C.
LAMS-3067UC-46, CRITICALITY STUDIESTID-4500 (28th Ed.)
.
LOS ALAMOS SCIENTIFIC LABORATORYOF THE UNIVERSITY OF CALIFORNIA LOS ALAMOS NEW MEXICO
REPORT WRITTEN. April 1964
REPORT DISTRIBUTED: May 6, 1964
LOS ALAMOS CRITICAL-MASS DATA
by
H. C. Paxton
Contract W-7405-E NG. 36 with the U. S. Atomic Energy Commission
All LA?& reporte are informal doeumente, usually prepared fora speoialpur-peee and primarily prepared for uee withinthe Leboretory retherthen forgeneml dietrlbutfon.l’hierepertbee not been edited,rwdewed, or verifiedforeooureoy. AU LAM9 reperteexpress the vlewe of the authors 8.9 of thetime they wexw wrlttm auf do nti Mcemm.rfly reflecttheepinioneof the LosAlamos SolentIffo L8beratory or the final npinion of the euthors on the eubjeot.
1
s-
b
.
.U
u
.“
ABSTRACI’
Tabulated are critical masses of simple systems, which
have been measured at Los Alamos through the year 1963.
.
“-
3
...
4
.“
u.,
,.
TABLE OF ~NTENTS
Page
ABSTRACT . . . . . . . . . . . . . . . . . . . . . . . 3
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . 9
IA1
IA2
IA3
IB1
IB2
IB3
ICl
IC2
IC3
IC4a
TABLES
Highly Enriched U Metal, Unreflected . . . . . . 11
U(93.4) - U(N) Metal Cylinders,Unreflected . . . . . . . . . . . . . . . . . .12
U(93.3) - U(N) Metal Cylinders,15.00” Diameter, Unreflected . . . . . . . . . . 13
Enriched U Metal Sphere or Pseudosphere,U(N) Reflector. . . . . . . . . . . . . . . . .14
Enriched U Metal Cylinder, Pseudocylinderor Parallelepi.ped, U(N) Reflector . . . . . . . 15
Miscellaneous Enriched U Metal,U(N) Reflector. . . . . . . . . . . . . . . . .16
Highly Enriched U Metal, Reflector ofTh, W, WC, MoorMo2C . . . . . . . . . . . . .17
Highly Enriched U Metal, Reflector ofZn, Cu, Ni, Co,orFe . . . . . . . . . . . . .18
Highly Enriched U Metal, Reflector ofTi, Al, A1203, Mg, Be, or BeO . . . . . . . . . 19
Highly Enriched U Metal, CompleteGraphite Reflector.. . . . . . . . . . . . . .2o
TABLES (Continued)
Page
Highly Enriched U Metal, PartialGraphite Reflector.. . . . . . . . . . . . . .21
IC4b
IC5 Highly Enriched U Metal, Reflector ofD20 (99.8%) . . . . . . . . . . . . . . . ...22
Highly Enriched U Metal, CompleteReflector of H20 or Polyethylene . . . . . . . . 23
IC6a
IC6b Highly Enriched U Metal, CompleteReflector of Paraffin . . . . . . . . . . . . . 24
IC6C Highly Enriched U Metal, Partial Reflector
‘f ‘2°’Polyethylene, Lucite, or Paraffin . . . 25
..
IC7
IIA1
Highly Enriched U, Mixed Reflector . . . . . . . 26
U(93.3) Metal Cylinders Diluted withFe, Ni, cu. or Zn, 15” Diameter, Unreflected . . 27 I
U(93.3) Metal Cylinders Diluted withMo, Ta, or W, 15” Diameter, Unreflected . . . . 28
IIA2
IIIA3 U(93.3) Metal Cylinders Diluted withAl, Zr, or Hf, 15” Diameter, Unreflected . . . . 29 IU(93.3) - Graphite Cylinders, Unreflected . . . 30IIB1
IIB2a Graphite-Moderated Highly-Enriched U,Reflector of Graphite . . . . . . . . . . . . . 31
IIB2b Graphite-Moderated Highly-Enriched U,Reflector of Be (Plus some Graphite) . . . . . . 32
Lucite Moderated U(93.16), Unreflected . . . . . 33IIC1
IIC2a Lucite Moderated U(93.16), > 6“ ThickLucite Reflector . . . . . ~ . . . . . . . . . . 34
IIC2b Lucite Moderated U(93.16) Slabs, 6“ ThickLucite Reflectors on Two Large Surfaces Only . . 35
Lucite-Graphite Moderated U(93.16),Unreflected . . . . . . . . . . . . . . . . . . 36
IID1
-’.
./
IID2a
IID2b
IIE1
IIE2
IIFla
IIFlb
IIF2
IIF3
IIIA1
IIIA2
IIIB1
IIIB2
IIIB3
IIIB4
IIIB5
IIIB6
TABLES (Continued)
Page
Lucite-Graphite Moderated U(93.16),Lucite Reflected . . . . . . . . . . . . . . . 37
Lucite-Graphite Moderated U(93.16) Slabs,6“ Thick Lucite Reflectors on TwoLarge Surfaces Only . . . . . . . . . . . . . . 38
Diffuse U(93.1) Reflected by Thick D20or Be (Cavity Assemblies) . . . . . . . . . . . 39
U(93.65)0 F -D O Solutions, Bare,D20 orGraphite ?e?le?ted . . . . . . . . . . . . . . AO
U(14.67)02S04-H20 Solution, Sphere . . . . . . 41
U(93.5)-Phosphate Aqueous Solution,Cylinders, 3.o” Thick Fe Reflector . . . . . . 42
Enriched-Uranium Hydride Composition . . . . . 43
Lattices of U(94) Metal Units, H20Moderated, H20 Reflected . . . . . . . . . . . 44
Plutonium-Metal Spheres . . . . . . . . . . . . 45
Plutonium-Metal Cylinders . . . . . . . . . . . 46
Diluted Pu Cylinders, 6.0” Diameter,Unreflected. . . . . . . . . . . . . . . . . . 47
Diluted Pu2.0” Thick
Diluted Pu4.5” Thick
Diluted Pu7.5” Thick
Diluted Pu2.0” Thick
Diluted Pu4.5” Thick
Cylinders, 6.0” Diameter,U(NO.3) Reflector . . . . . . . . . 48
Cylinders, 6.0” Diameter,U(*O.3) Reflector . . . . . . . . . 49
Cylinders, 6.0” Diameter,U(*O.3) Reflector . . . . . . . . . 50
Cylinders, 6.0” Diameter,ThReflector . . . . . . . . . . . . 51
Cylinders, 6.0” Diameter,ThReflector . . . . . . . . . . . . 52
7
IIIB7
IV
VA
VB
TABLES (Continued)
7.5” Thick Th Reflector .
U-233 Metal Spheres . . .
Pu or U-233 Metal SpheresU(~93) Metal Spheres . .
Diluted Pu Cvlinders. 6.0” Diameter,.*..* ●
✎✎☛✎☛ ●
Within● **** .
.
.
●
Pu Metal Cylinder Within U(93.2) MetalCylinder, Thick U(N) Reflector . . . .
REFERENCES. . ● . . . . . ● . . . . . . . ● ●
.
●
●
✎
✎
.
.
.
.
.
.
.
.
.
.
Page
. 53
. 54
. 55
. 56
. 57
.
..
8
I
I.
.’
-,
-.
INTRODUCTION
Numerous Los Alamos critical mass data have beenpublished only as points on curves, frequently after adjust-ment to “standard” conditions (e.g., to uniform values ofU235 enrichment and density), and usually without indicationof reliability. Under these conditions, original data tendto become lost. It is the purpose of this compilation toretrieve original critical masses and to give some means ofjudging the quality of measurements.
Indexes of accuracy are probable error, if it has beenestimated, the maximum mass of fissile material used in themeasurement, or the maximum central-source neutron multi-plication attained. For nonhydrogenous systems a multipli-cation of 10 usually corresponds to a core mass that is 70%to 80% of critical, 20 corresponds to 85% to 90% of thecritical mass, 50 corresponds to 93% to 97%, and 100 corre-sponds to 96-1/2% to 98-1/2%. Generally, the probableerror in critical mass is about one-quarter of the differencebetween the critical mass value and the maximum massemployed. This estimate may be valid down to an indicatedprobable error of 1% to 2%, beyond which the probable erroris usually controlled by the precision with which the com-position and geometry of the system can be described.Maximum multiplication is not a reliable index of accuracyfor hydrogen-moderated assemblies because of the severeinfluence of neutron-spectral distortion.
Not included in this compilation are several criticalassemblies that cannot be described adequately by simpleentries in tables (e.g., assemblies with nonuniform cores).Also omitted are a few critical mass estimates for which themaximum mass used was less than three-quarters of thecritical value.
The following symbolism appears in the tables ofcritical masses:
.9
#-
m-C critical mass of core
mmax - maximum mass used, in same units as mc
.Mmax -
maximum central source neutron multiplicationattained
hc - critical height of cylindric core
d- diameter of core
LxHxW- length times height times width ofparallelepipeds
P - density Iw/o - weight percent
v/0 - volume percent
U(93) - enriched uranium containing 93 w/o U235
U(N) - uranium with natural isotopic composition
.-
,L
.10
-../.
zl-l
Miii
=4E+
t-.
w0)
v.
zN.
ww(nP.
l-l
!-4.
0-H
u).
m
l-l
In
Cd.a
.11
+
du.55?
..0In
oIn
.0F1
.0+
9-I
o
q+o
a)Ln
2+J(u
IQco.l-l
dCQco
o“0°
mo“co.0
Iin.smii
c)
12
-!
?-.
TABLE 1A3
U(93.3) - U(N) MSTAL CYLINDSRS, 15.00” DIAMSTER, UNRSFLECIWD
Indicated layers, combinations of 0.3 cm thick U(93.3) and U(N), 0.6 cm U(N) or 1.5 cm U(N), start
with U(N) at bottom and end with portion of sandwich at top
Average composition is that of final stack
Corrected for influence of supports of split stack
Communicated by G. A. Jarvis
averagecomposition
u (93.3)
U (86.4)
u (83.4)
U (80.5)
u (77.7)
u (75.1)
u (70.5)
U (65.5)
U (64.4)
U (56.6)
u (57.l)C
u (50.5)
u (50.7)C
u (47.0)
u (47.1)
U (44.2)
U (38.0)
U (31.6)
U (28.9)
U (23.9)
U (21.3)
u (19.3)
repeated layers,thickness (cm)
3) ufX)-~ —
0.3
3.6
2.4
1.8
1.5
1.2
0.9
3.6
0.6
2.4
2.1
1.8
1.5
0.6
0.3
1.2
0.9
0.3
0.6
)
[1
0.30.3
0.30.3
0.30.3
0
0.3
0.3
0.3
0.3
0.3
0.3
1.5
0.3
1.5
1.5
1.5
1.5
0.6
0.3
1.5
1.5
0.6
1.5
()
1.5 b0.3
1
)
1.5 b0.6
)
1.5 b0.9
F(total U)
(g/cm3)
18.06
18.08
17.95
17.98
17.98
16.19
18.16
16.33
18.21
16.37
18.34
18.35
16.44
18.42
18.25
18.49
18.49
18.51
18.32
18.65
18.62
18.66
h=
(in.)
3.18
3.36
3.50
3.60
3.70
3.77
4.00
4.05
4.34
4.60
4.66
5.25
5.25
5.53
5.61
5.92
7.02
8.23
9.63
11.73
14.15
17.85
he/d
0.212
0.224
0.233
0.240
0.247
0.252
0.266
0.270
0.289
0.306
0.311
0.350
0.350
0.369
0.374
0.394
0.468
0.548
0,642
0.782
0.943
1.190
a Corrections not as detailed as those for next-to-last item in Table IA1
mc
(kg U235)
155.2a
152.1
151.6
150.8
149.8
149.1
148.2
140.8
147.6
138.5
141.2
140.9
142.2
138.8
139.8
140.1
142.9
139.2
147.5
151.6
162.6
185.8
b The 1.5 cm U(N) plate was at base of stack; it alternates with the thinnerSuccessive sandwiches
c Extra U(93.3) plates at top of stack
U(N) in
(kgm?s)
151
146
146
146
146
146
146
136
142
136
137
137
141
134
134
137
140
135
144
149
155
175
.-
. 13
.-.mt-l
N0-H
Nm,-4
0.
m,+
N10.
.
u5-CI
u ‘>
E
Y
UY
00+Ina.
0.-l
m0
.-$
vc
oo.
.a4
WE
IIn
In.
m.-l
!3
mnv
-.-.J
Lo
‘2.n
0.
‘7sm“x
15
#-
TABLE IB3
MISCELLANEOUS ENRICRED U METAL, U(N) Reflector
reference core
a
b
c
(14) annulus, 12.25” o.d. x 6.00”
id. x 3.01” high, stack of
1/2” and 1/4” thick rings
U(93.4), 5(U) - 18.7 g/cm3
(14) annulus, 12.25” o.d. X 6.00”
id. x 2.03” high, stack of
1/2” and 1/4” thick rings
u(93.4), F(u) - 18.7 g/cm3
(15) pseudocylinder, 13.74” av
dia x 12.00” av compo-
sition:= 18.1 v/O U(93.6),
7 - 3.38 g/cm3; 13.6 v/O
U(N), T - 2.58 g/cm3; 11.8
v/o Fe, 7 - 0.92 g/cm3;
52.3 v/o Al, T - 1.40 g/cm3;
4.2 V/O void
refleotor
1.00” thick, F - 19.0 g/cm3,
completely envelops core
3.00” thick, ~ - 19.0 g/cm3,
completely envelops core
kg :35
77.2 ~ 0.3
(mmax > mc)b
52.2 k 0.3
“’’ma.- 51.6)
pseudocylinder 5.0” av 93.0
thickness, T - 18.9 g/cm3 (Mmax - 225)
Unlisted, is a nonuniform assembly of mixed plates and rings of U(93.4) and U(N) thatenclose a near-central cylindrical cavity, 15.0” dia x 11.8”; outside dimensions ofthe assembly are 21.0” dia x -.21” high (S. J. Balestrini, G. A. Jarvis, J. D. Orndoff,December 1961). Average composition bounding cavity is U(27), -.4-1/2” thick U(N) ringsform tOD and bottom of cylinder. At critical, the total mass is -1400 kg U(N) and 339kg U(93_.4). Uncorrected-for l/4° thick steel-plate
Corrected for small gap between assembly halves
Average thickness of core discs, blocks, and shaped-“0.3”, Fe -0.25”, Al -0.9”
supporting portion a~ove cavity.
Al fillers: U(93.6) *0.4”, U(N)
16
.
-....
.
8-A“
g-0“N-
m.
00m“
m0“
‘1
17
a
1(
,....-.
18
-.
..
TASLE ICI
HIGSLY 624RIC3!ED U M22AL, RsFLEmOR OF Ti, Al, A1203, MC, 9s , OR 6e0
,.
-.
r. f shape(11) cylinder
(11) cylinder
(19) sphere
(11) cylinder
(11) c~linder
(11) cylinder
(11) cylinder
(11) cylinder
(11) cylind=r
(11) sphere
(11) sphere
(11) sPhere
(11) cylinder
(11) cylinder
(12) cylinder
(12) cylinder
(12) cylinder
(12) cylind=r
(12) cylinder
(11) pse.dosphere
(11) Pswdoephera
(10) psoudospbere
dimensions(1..)
5.25 dia,held - 1.61’
S.2S dia,he/d - 1.3!3m
(llemtingshells)
5.25 dia.h=/d - 1.59’
5.25 dia,he/d - 1.35’
5.35 dia,h=/d - 1.40’
5.35 dim,he/d - 1.14a
5.2S dia,held - 1.66s
5.25 dia.h=ld - 1.46%
(nestingshells)
(nemti.gshells)
(nestingshells)
5.2S dia,h=/d - l.lOa
5.2S dis,he/d - 0.90’
15.00 dim,he/d - 0.131
15.00 dia.h=/d - 0.090
15.00 di.,he/d - 0.068
1s.00 dia,h=/d - 0.053
15.00 dia.he/d - 0.042
(1/2,,m nblocks)i
(1/2- . “blocks)A
(1/2,!❑ l”blocks)
material
U(93.3)
U(93.3)
Ll(93.lS)
U(93.3)
U(93 .3)
U(93 .3)
U(93 .3)
U(93.3)
U(93 .3)
U(9S.9)
U(93.9)
U(93.6)
U(63 .3)
U(93 .3)
U(93.4)
U(93 .4)
U(93 .4)
U(93 .4)
U(93.4)
U(94)
U(94)
U(S2 .7)
5 (total u)
(CA?)18 .7S
18.75
18.40
16.75
18.75
18.7$
18.75
18.75
18 .7s
18.s
18.75
18.6
18.75
18.75
17.7
17.7
17.7
17.7
17.7
18.7
18.7
17.8
reflector
n.t=rialTib
Ti b
Al (2014)
Al (2S)
Al (22)
‘1203
A1203
Mu (FS-1)
w (rS-l)
9.
64
Za
se (qw)
w (qw)
90
E.0
9a
&
94
Seo
B@
S.30
shspe
cylinder
cylinder
sphere
cylinder
cylinder
cylinder
cylinder
cylinder
cylinder
sphere
sphere
sphere
cylinder
cyltnder
cylinder
cylinder
cylinder
cylinder
cylinder
P.eudOsPh.re
Ps.udosphere
(24” cube)
thickness(i”.)
0.Soo
1.000
2.610i 0.03
0.500
1.000
0.500
1.000
0.500
1.000
1.6s
1.69
4.64
0.500
1.000
1.00
2.00
3.00
4.00
S.oo
2.35 .“
3.5 .“
3 (tot.1)4@3-
4.50
4.50
2.82
2.70
2.70
2.76
2.76
1.77
1.77
1.64
1.64
1.64
1.84
1.64
1.60
1.60
1.60
1.80
1.80
2.69
2.69
-2.69
me(IQZ
U235,
52.4 i 0.6
45.0 t 0.1
34.71 i 0.1
52.0 f 0.6
44.1 50.1
45.5
37.2
54.2 + 0.7
47.7 i 0.3
22.2 * 0.2
21.6
13.1 i 0.2C
38.69 i 0.1
29.26 i 0.1
93.9 i 0.9
84.9 i 1.0
49.0 * 1.0
37.6 i 0.S
30.4 k 0.S
19.7
1s..5
10.3
mm..—
16
125
170
17
200
-.100
.150
13
34
100
24
143
4s0
210
25
23
35
13
15
8s
105
critical
● Cor= of dl.ws 1.30’,to 0.075°, thick; ❑= corrected empirically for incidental reflection,and 0.05 i“.3 central c.. ity
diaphragm supporting p.rt of sssemhly,
b Composition 98.5 w/o T;, 2.5 ./0 Cr, 1 w/o Fe
c With 0 .010,,Cd between core a“d reflector, m - 14.0 kc U335 (Mmax - 21)c
d Uncorrected for 0.06 in.3 ce”trnl source cavity
-------TAHLK 1C4a
HIGHLY 6NRIC212D U METAL, CT3UPL2T’6 GRAPHITE R3YLEC1’13R
Graphito is trade C3-212 except as noted
core
dimensionsr (total u)
(in. ) material (g/cm3)m f shape—
(20) sphere
(20) ●phera
(20) sphara
(20) =Phera
(20) sphere
(20) cylinder
(20) pseudoc ylinder
(20) cylinder
(20) cylinder
(20) cylinder
(20) cylinder
(20) cylinder
(20) pseudocyllnder
(20) pseudocylinder
(11) cylinder
(11) cylinder
(12) cylinder
(12) cylinder
(12) cylinder
(12) cylinder
(21) cylinder
(14) annulus
a Uncorrectedfar O.0S
(nestingahells)a
(nestinKSh.lls) ~
(nestingshells) *
(nestinshahs) f
(nestinshahs) s
3.25 dia,held - 2.9S=
9.62 ~V diahe/d - 1.85~
3.98 dia,he/d - 1.30=
4.7S dia,he/d - 0.S15=
5.50 dia,he/d - 0.49S=
6.375 dia,h=/d - 0.345=
7.50 dia,he/d - 0.235=
h - 1.50,he/d - 0.177d
h - 1.00,h=/d - 0.081d
S.2S dia,he/d - 1.42°
S.25 dia,he/d - 1.16°
3.24 dia,he/d - 6.79
3.24 din,he/d - 4.97
S.24 dia.he/d - 4.41
15.00 dim,he/d - 0.073f
&?-dA~i92g
12.25 o.d. X6.00 id. X2.66
U(93.9)
U(63.9)
U(93.9)
U(93.9)
U(93.9)
U(93 .7)
U(94)
U(93.7)
U(93 .7)
u(93 .6)
U(94.0)
U(94.0)
U(94.0)
U(64.0)
U(93.3)
U(93 .3)
U(93.2)
U(93.2)
u(63.2)
U(93.4)
U(93.4)
U(93.4)
h.3 central scarcecavity
16.7
1s.7
18.4S
16.7S
16.5
16.5
18.7
16.5
16. S
16.5
18.5
18. s
16.7
18.7
16 .7S
18.75
16.7
18.7
16.7
17.7
16.7
16.7
reflector
sphere
sphere
sphere
sphere
pseudosphereb
pseudosphereb
pseudosphereb
pseudosphereb
pseudosphereb
pseudosphermb
pseudosphereb
pseudosphereb
pseudosphereb
pseudosphereb
cylinder
cylinder
cylinder
cylinder
cylinder
cylinder
cylinder
(envelOPscore)
tbicknesa(in. )
2.00
4.00
6.00
8.00
17 av
17 av
17 av
17 av
17 av
17 *V
17 ● v
17 av
17 av
17 ,V
0.s00
1.000
4.65
5 .7s
6.25
7.00
2.00
2.00
1.67
1.67
1.67
1.67
1.66
1.66
1.66
1.66
1.66
1.66
1.66
1.66
1.66
1.66
1.67
1.67
1.60
1.60
1.60
1.60
1.66
-..1.67
‘ck “235,
29.6 * 0.3
24.3 i 0.2
21.5 * 0.2
19.s * 0.3
17.0
22. s
20.1
18.3
17.5
ls. s
20.0
22.7
24.6
34.6
46.35 i 0.2
37.71 * 0.1
51.7 * 0.9
37.9 i 0.7
33.6 i 0.7
52.1 * 1.0
50.0
73.3 i 0.3
b Pil.-grade graphite surrounds ..5’0thick c2-312
= Interlocking rings; uncorrected for O .06 in.3
central source cavity
d Poraed of 1/2” min blocks
9 Cure of disc= 1.20” to 0.075” thick: m corrected empirically for incidental reflection, diaphragm supporting pariof assembly, and O .0s in. g central cavfty
f Core of O.3 cm thick plates; empirical correction for diaphragm supp-arting part of assembly
g ~re of 0.315,. thick plates: empiric.1 correction for diaPhragm suPPOrthC Part Of ~ms~bly
Mmax
58
150
150
42
46
17
40
109
62
7s
107
1s0
90
200
51
>500
233
13s0
460
20
16
..
.
. .
..
.
-’
;.x
a:c
0
Inmm0.
+4
a0.
CT
J
wt-
ti.
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*UY
ID.+mm
..
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Dm
w
21
0In
0.0’)
r-lUI
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In
In.
mf+
lan0).
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+!-4U2+
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a)
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dn
.
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mm
mw
:
::
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=Ul
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-.
TA6LE IC6m
HIGHLY ENR1CH2L2U k15TAL, CC41PLETE lfEf’LEC7UR OF lf,.0 OR POLY&HfYLW6
“.
.see also first lccm of Table 11F3
CO,.
dimensions T (total U)
(in.) (g/”~)re f shape—
(25) sphere
(25) spheresurroundedby O.O1OssCd
(20) sphere
(24) sphere
(24) hollow sphere,filled with H20
( 24) h.allow sphere,filled with If20
(24) hollow sphere,filled with X20
(20) cylinder
(20) cylinder
(20) cylinder
(20) cyll”der
(20) cyl i“der
(20) cylinder
(21) a“nulu.
(26) bomisbell,S.gmented
(12) cylinder
(12) cylinder
(11) cylinder
(11) cylinder
(12) cylittd.ar
(12) cylinder
(14) . . ..1.s
(shells)0.83 id.
(shell=)0.63 id.
(nostinshells)s
(nestingshells)e
3.60 id.
4.00 id.
4.68 id.
3.98 dia,he/d - 1.90”
4.75 di. ,b=/d - 0.98”
5.S0 dia.held - 0.66=
6.375 dia,h /d - 0.46”c
7.00 dia,he/d - 0.365”
7.S0 dia.he/d - 0.300”
6.14 o.d. x3.05 id. x5 .75~
12.0 o.d. ,10.0 id.
3.24 die,Ll=/d- 12.2
15.00 alla,he/d - 0.082C
5.25 din,he/d - 1.34d
5.25 dia,be/d - 1.OOd
3.24 din,he/d - 6.0
15.00 die,he/d - 0.095”
12.25 o.d. x6.00 id. x2.20
.ater$al
U(93 .9)
U(93.9)
U(93 .9)
U(63.9)
U(93.9)
U(93 .9)
U(93.8)
U(93 .7)
U(93.6)
U(93 .6)
u(94.0)
U(94 .0)
U(94.0)
U(93.15)
U(93.5)
U(93 .2)
U(93 .4)
U(93 .3)
U(93 .3)
U(93 .2)
U(93.4)
U(93.4)
18.5
18.4
18.5
18.5
18.5
18.5
18.5
18..5
18.5
18.5
16.5
18.5
16.5
18.75
18.7S
18.7
17.7
18.75
18.75
18.7
17.7
18.7
reflector.
material shaPe
H20 cylinder
H20 cylinder
f120 cylinder
H20 sphere
H20 sphere
H20 sphere
QO sphere
H20 cyll”der
Ifzo cylinder
H20 cylinder
H20 cylinder
H20 Cylinder
H20 c,li”der
H20 Cylinder
H*O cylinder
IfZo cylinder
U20 cylinder
pc.lyethyle”e cylinder
Polyethylene cyli”dm’
POIYethyle”e cyll.der
polyethylene cylinder
polyethylene (envelopscore)
thickness(in.)
>12
>12
>12
3.25
14.6
14.4
14.3
>12
>12
>12
>12
>12
>12
>12
>6
>12
>12
0.500
1.000
4.00
2.00
3.00
‘3(g/cm )
1.00
1.00
1.00
1.00
1.00
1.00
1,00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
0.921
0.921
0.92
0.92
0.92
(kKmc&)
23.4
32.9
23.2
23.5
2s.1
26.3
27.7
26.7
23.7
24.4
25.9
27.7
29.0
28.6 i 0.5
56
93.2 + 5
59.0 * 0.S.
43.7
32.7
61.3 ~ 0.9
68.4 * 0.8
56.6 * 0.3
a Uncorrected for O .0S i“ .3 central source cavity
b water fills .“””1”s
c Core of 0.3 cm plates; empirical correction for’ sm.11 source c.vity and diaphrngm s.ppc.rti”g part of assembly (not used withH20 reflector)
uMax—
49
32
154
35
40
80
19
101
200
1s0
108
53
35
20
43
170
140
140
161
79
@c
d Empirical cm-roctlo” for sm.11 c..tr.l cavity ●“d support effects
e Corrected for small gap 1“ fi”.1 c.anfigur.ticm
23
.-
.
TABLE IC6b
HIGHLY ENRICHED U METAL, COMPLETE REFLECTOR OF
Paraffin reflector cylindrical, >8” thick, 7 =
PARAFFIN
0.89 g/cm3
core
m
(kg U;35)dimensions
(in.)
(nestingshells)a
(shells),0.83 id.
3.25 dia,he/d = 4.4b
3.98 dia,he/d = 1.80b
4.75 dia,he/d = 0.915b
5.50 dia,he/d = 0.605b
6.375 dia,he/d = o.45b
7.50 dia,he/d = 0.280b
T (total U)
(g/cm3 )
18.5
Mmax
62
ref
(20)
(25)
(20)
(20)
(20)
(20)
(20)
(20)
shape
sphere
sphere
cylinder
cylinder
cylinder
cylinder
cylinder
cylinder
material
U(93.9) 22.2
U(93.9) 18.5 22.8
35
69
U(93 .7) 18.5 11
U(93.7) 18.5 25.0
22.2
77
U(93.8) 18.5 108
123U(93 .8) 18.5 22.4
U(94.0)
U(94.0)
18.5 24.5 200
18.5 26.9 86
Uncorrected for 0.05 in.3 central source cavity
0.05 in.3 central
a
bInterlocking rings *0.4° thick, uncorrected forsource cavity
24
. .
TABLE IC6C
HIGNLY ENRICN20 U METAL, PARTIAL R.8FLE~R oF H20,POLYETHYLENE,LUclTE,oR pARAFFIN(5)
Reflector same diameter as core
core of 0.3 cm plates and rings; n= cOrrected empirically fOr diaphra~ suPPOrtlng Part Ofassembly, for incidental reflection, and for small central source cavity
cylinder
dia (in. )
a
b
c
15.00
21.00
15.00
21.00
15.00
21.00
15.00
21.00
15.00
21.00
15.00
21.00
15.00
21.00
15.00
21.00
15.00
21.00
15.00
21.00
15.00
21.00
material
U(93.3)
u(93.2)
U(93.3)
U(93.2)
U(93.3)
U(93.2)
U(93.3)
U(93.2)
U(93.3)
U(93.2)
lJ(93.3)
U(93.2)
U(93.3)
U(93.2)
U(93.3)
u(93.2)
U(93.3)
U(93.2)
U(93.3)
U(93.2)
U(93.3)
U(93.2)
7 (total U)
(g/cm3)
17.9 * 0.2
18.2 * 0.2
17.9 * 0.2
16.2 k 0.2
17.9 * 0.2
18.2 k 0.2
17.9 * 0.2
16.2 i 0.2
17.9 * 0.2
18.2 k 0.2
17.9 * 0.2
18.2 * 0.2
17.9 * 0.2
18.2 f 0.2
17.9 * 0.2
18.2 f 0.2
17.9 * 0.2
16.2 t 0.2
17.9 * 0.2
18.2 * 0.2
17.9 * 0.2
18.2 k 0.2
reflector—
material
H20a
H20a
polyethylene
polyethylene
polyethylene
polyethylene
polyethylene
polyethylene
polyethylene
polyethylene
polyethylene
polyethylene
polyethylene
polyethylene
polyethylene
polyethylene
polyethylene
polyethylene
lucite
lucite
paraffin
paraffin
surfacesreflected
top plane
top plane
top plane
top plane
top plane
top plane
both planes
both planes
top plane
top plane
top plane
top plane
top plane
top plane
top plane
top plane
top plane
top plane
top plane
top plane
top plane
top plane
thickness(in. )
6.oO
6.00
1.00
1.00
2.00
2.00
2.00
2.00
3.00
3.00
4.00
4.00
6.00
6.00
8.00
8.00
10.00
10.00
6.00
6.00
6.00
6.00
P
.@@
1.00
1.00
0.925
0.925
0.925
0.925
0.925
0.925
0.925
0.925
0.925
0.925
0.925
0.925
0.925
0.925
0.925
0.925
1.18
1.18
0.87
0.87
(kgm;235)
109.6 * 0.4
188.5 i 0.7
126.2 ~ 0.5
228.4 + 0.6
113.6 * 0.4
196.5 + 0.6
73.1 * 0.3
117.4 * 0.3
109.3 * 0.4
190.3 f 0.6
106.5 i’0.4
168.5 ~ 0.6
106.7 * 0.4b
187.9 i 0.6C
108.5 + 0.4
187.8 k 0.6
108.5 f 0.4
187.6 + 0.6
106.4 f 0.4
182.1 * 0.6
109.2 t 0.4
188.5 k 0.6
Empirical correction for effecz of 1/16” Al tank containing water, via influence of the tankcontaining lucite
Critical mass 129.0 i 0.5 (Mmax - 170) when 0.015” Cd between core and reflector
Critical mass 228.4 * 0.6 (Mmax - 38) when 0.015” Cd between core and reflector
Mnax
250
99
167
125
57
35
73
90
77
280
75
160
99
195
110
245
120
102
52
74
130
49
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TABLE 11?,1
DIFFUSE u(93.1) RSFLSC7ECI BY TR1= D20 OR *
“235enrichment of all uranius is 93.15 W)O
(CAVITY AsssmwIEs)
cm-e cylindric reflectorcavity cylinaer tllickness Interior
ref dimensions (in. ) fuel material—
(in.)
(3s) 40 dia X 40 0.003” U foil covering D20 (99.2 w/0) 20cavity surf ace, on av0.05” Al support
(35) same except 4“ dia sxisl channel through bottrn reflector
(35) same except 6’” dia axial channel through bottom reflector
(35) same except 8“ dla axial channel through bottom reflect~
(35) 8ame except 9“ din axial channel through bott.m reflector
(35) same except 10,, dia axial channel through bottom reflectOr
(35) same except 23.9 kg D20 (12,,x 12’” CY1) mt cavity center (no channel)
(35) 40 dia X 40
(36) 15-1/2 dia X 31
(36) 15-1/2 dla x 31
(36) 15-1/2 dia x 31
(36) 1S-1/2 dia X 16
SIX 40” dieca Of0.035’? av o foil 8“apart along cmwity
axle, on 1/16’” Al plates
0.022” a“ u foilcovarinc cavity sur-face, on 1/16” Alsupper t
0.01s” ,“ u foilcovering cavity sur-face, on 1/16” Alsupport
0.6 o.d., 0.25 id.graphite - 22 w/o Urods, distributeduniformly withincavity, parallel toaxis
0.6 c..d.o 0.25 id.graphite - 22 v/o Urods, distributedullifOTDIY withincavity, parallel to
D20 (99.2 w/o) 20
se (F - 1.77 g/cm3) 14 wall, 18 top,15 bottc,
se (7- 1.79c/c.%16. S wall,18 top, 15 bottom
s.9(F-1.79 g/cm3) 16.5 wall,18 top, 15 bottom
se (75- 1.77 c/cm3) 14 wall, 18 toP,30 bottom
liner
1/8’” Al, ~V
1/8%1 Al, av
1/16” Al
1/16” Al
(,s :3’)6.00*
6.06
6.09
6.19
6.26
6.40
5.60b
7 .B7C
11. od
7.74
7 Se, f
g.9K
axis
a After correction for Al cavity liner and fuel support, m= - 5.33 kg; 6.93 kg of 0.003,, foil covers the. cav%tycompletely
bCorrected for effect of Al container for central D20
c After corractlon for Al cavity liner and fuel support, m= -7.0 kg
d &.rrected (-O ,04 kg) for Al fuel support
e Corracte.d (-0.03 kg) for Al cavity liner
M.,x
critical
critical
Critic.1
critical
critical
critic.1
critical
critical
56
100
130
138
f8 - 7.30 kg when fuel concentrated tc...rd Outmide of c.vity,m - 8.60 kg when fuel concentrated long axis; with 14,,r~flector wall, m= - 8.99 kg when fuel concentrated toward outc%de of c.vity
C Corrected (-O .02 kg) for Al cavity liner
.
39
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-.
REFERENCES
(1) G. E. Hansen, Status of Computational and ExperimentalCorrelations for Los Alamos Fast-Neutron Critical~ssemblies, Physics of Fast and Intermediate Reactors,AEA9 vi enna (1962).
(2) G. E. Hansen and D. P. Wood, Precision Critical-MassDeterminations for Oralloy and P1utonium in Spherical
ball Oy Tampers, LA-1356 Revised (to be issued).
(3) J. D. Orndoff and H. C. Paxton, Measurements onUntamped Oralloy Assembly, LA-1209 (February 1951) .
(4) V. Josephson, R. W. Paine, Jr. and L. L. Woodward,Oralloy Shape Factor Measurements, LA-1155 (August950) ●
(5) G. E. Hansen, D. P. Wood and B. Pe&a, Reflector Savingsof Moderating Materials on Large Diameter U(93.2%)S1abs, LAMS-2’(44 (June 1-!%?2).
(6) H. C. Paxton, Bare Critical Assemblies of Oralloy atIntermediate Concentrations of U-235, LA-16T1 (May954) ●
(7) private communication, D. M. Barton (September 1958).
(8) V. Josephson, Critical Mass Measurements on Oy in Tuand WC Tampers, LA-1114 deleted (May 1950) .
(9) J. D. Orndoff, H. C. Paxton and G. E. Hansen, CriticalMasses of Oralloy at Reduced Concentrations andDensities, LA-1251 (May 1951) .
(10) Private communication, C. P. Baker (December 1947).
(11) G. E. Hansen, H. C. Paxton and D. P. Wood, CriticalMasses of Oralloy in Thin Reflectors, LA-2203 (July
58) ●
57
REFERENCES (Continued)
(12) G. E. Hansen, H. C. Paxton and D. P. Wood, CriticalPlutonium and Enriched-Uranium-Metal Cylinders ofExtreme shape, Nuclear Scl. and Eng. ~, ~0-b’/~
(1960) ●
(13) J. J. Neuer Critical Assembly of Uranium Metal at anAverage U23~ Concentration of 16-1/4%, LA-2085(January 937 ).
(14) Private communication, J. J. Neuer, G. A. Newby,H. C. Paxton and T. F. Wimett (March 1954).
(15) Private communication, H. C. Paxton and C. B. Stewart(May 1953).
(16) Private communication, D. P. Wood, L. C. Osborn andB. Pe%a (April 1960).
(17) Private communication, V. Josephson and R. W. paine,Jr. (March 1951).
(18) Private communication, J. C. Hoogterp and D. P. Wood(September 1955).
(19) D. P. Wood and B. Pe%a, Critical Mass Measurements ofOy and Pu Cores in Spherical Aluminum Reflectors,AMS-2579 (June 1961) .
(20) E. C. Mallary, Oralloy Cylindrical Shape Factor andCritical Mass Measurements in Graphite, Paraff in, andWater Tampers, LA-1305 (0ctober 1951) .
(21) J. C. Hoogterp, Critical Masses of Graphite-TampedHeterogeneous Oy-Graphite Systems, LA-1732 May 954) .
(22) Private communication, G. A. Jarvis (November 1961).
(23) private communication, D. p. Wood (October 1961).
(24) Private communication, F. F. Hart and C. B. Stewart(December 1953).
.,
.4
.-
(25) Private communication, R. W. Paine, Jr., D. P. Woodand R. S. Dike (April 1951).
58
u
. .
.
1.
.-. . . .
.
-.
. .
(26)
(27)
(28)
(29)
(30)
(31)
(32)
(33)
(34)
(35)
(36)
(37)
(38)
REFERENCES {Continued
F. F. Hart, Safety Tests for Melting and Casting
Oralloy, LA-1623 (December 1953).
Private communication, K. Gallup, G. E. Hansen(July 1951).
Private communication, R. E.1951) .
Private communication, E. C.
Private communication, J. J.R. H. White and T. F. Wimett
Private communication, G. A.
Schreiber (September
Mallary (March 1952).
Neuer, H. C. Paxton,(March 1954).
Jarvis (June 1963).
H. Iskenderian and C. C. Byers, Physics Calculationson Four Los Alamos Graphite Moderated CriticalAssembl ies, Trans. ANS l_, No. 1, p. 149 (June 1958);also private communication, C. C. Byers (September1957) .
G. E. Hansen, J. C. Hoogterp, J. D. Orndoff andH. C. Paxton, Beryllium-Reflected, Graphite-ModeratedCritical Assemblies, LA-2141 (0ctober ●
Private communication, S. J. Balestrini (November1963) .
Private communication, C. C. Byers (March 1962).
Private communication, G. A. Jarvis and C. C. Byers(October 1961).
R. N. Olcott, Homogeneous Heavy Water ModeratedCritical Assemblies, Part 1, Experimental, NuclearSci. and Eng. ~, 32’i-341 .
G. E. Hansen and W. H. Roach, Interpretation ofNeutron Resonance Detector Activities in CriticalUranyl Fluoride - Heavy Water Solutions, Proc.Brook haven Conf. on Resonance Absorption of Neutronsin Nuclear Reactors, Upton, New York, BNL 433 (C-24),pp. 13-25 (September 1956); also private communication,C. C. BYers (January 1956).
J-
59
.
.1
REFERENCES (Continued)
(39)
(40)
(41)
(42)
(43)
(44)
(45)
(46)
(47)
(48)
(49)
(50)
(51)
Los Alamos Scientific Laboratory of the University ofCalifornia, An Enriched Homogeneous Nuclear Reactor,RSI 22, 489-499 (July 1951) ; also L. D. P. King,Wate~Boilers. LA-1034 (December 1947).
R. E. Carter and J. C. Hinton, Water Tamper Measure-ments, LA-241 (March 1945).
J. C. Allred, P. J. Bendt and R. E. Peterson, criticalMeasurements on U03-H3P04 Solutions, Nuclear Sci. and%ng. ~, 498-500 (1958) .
Private communication, J. C. Allred, P. J. Bendt,H. C. Paxton and R. E. Peterson (April 1953).
G. A. Linenberger, J. D. Orndoff and H. C. Paxton,Enriched-Uranium Hydride Critical Assemblies, NuclearSci . and Eng. ~, 44= (1960) .
private communication, M. G. Holloway and C. P. Baker(December 1947).
H. C. Paxton and G. A. Linenberger, Polythene-25Critical Assembly and Neutron Distribution Studies,LA-749 (September 1949).
J. C. Hoogterp, Critical Masses of Oralloy LatticesImmersed in Water. LA-2026 (November 19553 .
G. A. Jarvis, G. A. Linenberger, J. D. Orndoff andH. C. Paxton, Two Plutonium-Metal Critical Assemblies,Nuclear Sci. and Eng. ~, 525-531 (1960) .
E. A. Plassmann and D. P. Wood, Critical ReflectorThicknesses for Spherical u233 and PuZaY Systems,Nuclear Sci. and Eng. ~, 615-620 (1960) .
private communication, D. P. Wood and C. C. Byers(December 1960).
Private communication, H. C. Paxton (October 1951).
D. P. Wood, C. C. Byers and L. C. Osborn, CriticalMasses of Plutonium Diluted with Other Metals,Nuclear Sci. and Eng. _~ .
● I
4
I
I
. .. I
I. .
60
REFERENCES (Continued)
(52) Private communication, G. E. Hansen (October 1963).
(53) Private communication, H. C. Paxton, G. E. Hansen,D. P. Wood and E. A. Plassmann (May 1960).
(54) D. M. Barton, W. Bernard and G. E. Hansen, CriticalMasses of Composites of Oy and Pu-239-240 in FlattopGeometry, LAMS-2489 (~ecember 1960 ) .
61
-.
