International Conference on Fast Reactors and Related Fuel Cycles: Safe

Technologies and Sustainable Scenarios

Gagan Gupta, S. Jalaldheen, P. Chellapandi, S.C. Chetal

March 6, 2013 FR13. Paris 1

REACTOR DESIGN GROUP

INDIRA GANDHI CENTRE FOR ATOMIC RESEARCH, KALPAKKAM, INDIA

Outline

• Status of FBR Program in India

• Modification from PFBR Reactor Assembly to Fast Breeder Reactor (FBR) -I &II Reactor Assembly

• Structural Analysis for FBR-I & II components

• Detailed structural analysis of other components

• Summary

March 6, 2013 FR13. Paris 2

FBR Program in India

• In India, Prototype Fast Breeder Reactor (PFBR) is under advance stage of construction at Kalpakkam. All the major components are erected. Commissioning of the Reactor will be soon.

• Further, It is planned to Build one more twin unit 500 MWe FBR – I & II.

• Towards standardization of FBR, Conceptual design of FBR-I & II is finalized based on the feedback from PFBR and detail design is under progress.

• In FBR-I & II, Innovative design features have been incorporated in the reactor assembly components, to achieve improved economy and enhanced safety.

March 6, 2013 FR13. Paris 3

Reactor Assembly - PFBR to FBR-I & II in a Nutshell

LRP

SRP

Advanced design of major components: Material inventory reduction~ 25% ,

Simplified fuel handling scheme, Reduced manufacture time, Increased safety

Box type –> Dome shape

Conical–> Single torus

GP- bolted -> welded

Primary pipes : 4 to 8

Embedded SV

4

Fast Breeder Reactor Reactor Assembly

Inner vessel with

single toroidal shell

(redan) directly

connecting grid plate

with the upper

cylindrical shell

Optimization of main

vessel thickness

Integrated liner and

safety vessel with

thermal insulation

arrangement Conical

shell for

reactor

assembly

support

Dome

shaped

roof slab

Welded grid plate

with reduced height

Eight primary pipes

Thick

plate

Rotatable

plugs

No change in

Reactor Vault Concept

1 2

3

4

5 6

7

8

March 6, 2013 FR13. Paris 5

15 14 11 13

10

07 09

05

03 01

16

08

06

12

02

13

72

5 Ø1210

0

Schematic of FBR Reactor Assembly

Focus on Reactor Assembly as it has long delivery components influencing the erection time

Roof Slab

Roof Slab (Box Type) in PFBR Roof Slab (Dome Shape) in CFBR

Deflection of Dome Shaped Roof

Slab von Mises stress in Dome

Shaped Roof Slab March 6, 2013 FR13. Paris 7

Large Rotatable Plug and Small Rotatable Plug

• In PFBR large rotatable plug (LRP) and small rotatable plug (SRP) are box type structure

• In FBR-I & II thick plate concept is conceived for SRP and LRP

Thick Plate SRP & LRP of

CFBR

Deflection contour of LRP Deflection contour of SRP

March 6, 2013 FR13. Paris 8

Grid Plate

Deflection in FBR Grid Plate Von Mises Stress distribution in FBR

Grid Plate

PFBR

BOLTED CONSTRUCTION

4 PRIMARY PIPES

Wt. 76 T

HARDFACING BETWEEN GP

and CSS

FBR

WELDED CONSTRUCTION

8 PRIMARY PIPES

Wt. 33 T

NO HARDFACING

PFBR Grid Plate

March 6, 2013 FR13. Paris 9

Inner Vessel

• The shape of inner vessel is optimised with reduced upper shell

diameter and double curvature single toroidal redan, which

results in higher buckling strength and reduced thickness and

hence reduced weight.

Overall von Mises Stress Distribution Critical bucking for Pressure and

Thermal Load

March 6, 2013 FR13. Paris 10

Main Vessel

• The Shape of Bottom dished head is optimized with

respect to buckling and plastic failure modes

Critical buckling mode

shape of Main Vessel Innovative Main vessel Bottom

dished head

March 6, 2013 FR13. Paris 11

Primary Pipe Assembly

Primary Pipe configuration for FBR

Four No. of Branch Pipe from each

Spherical Header

Large Size Seamless Pipe

Primary Pipe Configuration in PFBR

Two No. of Branch Pipe from each

Spherical header

Each Bend pipe made of three

segment joined via welding

Displacement in Radial direction Von Mises Stress in Primary pipe

March 6, 2013 FR13. Paris 12

Core Support Structure

Displacement in CSS Von Mises stress in CSS Buckling Analysis of CSS

3-D Model for CSS

March 6, 2013 FR13. Paris 13

Structural Analysis for Other Components

March 6, 2013 FR13. Paris 14

Intermediate Heat Exchanger Tubesheet Analysis :Thickness

Optimizaion

Net Internal Reaction force distribution in IHX for Level A

Locations Analyzed in detail for Top and

Bottom Tube Sheet are Inner Rim, Outer

Rim and Weld junction

Tube Sheet

Inner Rim

Perforated Region

Outer Rim

TUBE SHEET (HALF)

TOP VIEW OF BOTTOM-

(SECTIONAL VIEW)

BOTTOM TUBE SHEET

0°, 360°

90°

180°

DETAIL-A

DETAIL-B

150

BA

3600 HOLES Ø19.3

0D.1900

OD.491

OD.579

OD.497

TUBE SHEET (HALF)

TOP VIEW OF BOTTOM-

(SECTIONAL VIEW)

BOTTOM TUBE SHEET

0°, 360°

90°

180°

DETAIL-A

DETAIL-B

150

BA

3600 HOLES Ø19.3

0D.1900

OD.491

OD.579

OD.497

Nodal stresses behaviour at the Rim junction are not uniform, Hence Elemental stresses are

calculated by linear interpolation at the Rim junctions to check the thickness of tubesheet.

15

Thickness Optimizaion – Contd…

Effect of the Groove on Outer Rim junction of the Tubesheets are analyzed and it

was found that Stress at the surface is relaxed.

Radial and Hoop stress distribution at Outer rim junction with groove on Top Tube sheet

Total Radial stress σR Vs Thickness

-80

-60

-40

-20

0

20

40

60

80

100

-10 -5 0 5 10 15

σR (MPa)

Th

ick

ne

ss

(m

m)

Total Hoop stress σH Vs Thickness

-80

-60

-40

-20

0

20

40

60

80

100

-15 -10 -5 0 5 10 15

σH (MPa)

Th

ick

ne

ss

(m

m)

Total radial stress σR Vs Thickness

-80

-60

-40

-20

0

20

40

60

80

100

-10 0 10 20 30

σR (MPa)

Th

ick

ne

ss

(m

m)

Total Hoop stress σH Vs Thickness

-80

-60

-40

-20

0

20

40

60

80

100

-5 0 5 10 15

σH (MPa)

Th

ick

ne

ss

(m

m)

Radial and Hoop stress distribution at Outer rim junction without groove on Top Tube sheet

16

Three Dimensional Tube Sheet Analyses for Steam Generator

Equivalent solid plate methodology is general procedure used to analyze

the perforated plates

It fails to give stress distribution in non uniform diameter holes, realistic

stresses at interface of perforated and solid region, pressure effect inside

the holes of perforated plate, realistic thermal stress analysis of tube

sheet, effect of temperature dependent properties in perforated region

Radial stress distribution at critical ligament

along the SCP

3-D model of tube sheet

Deflection vs. radius for all cases (Without pressure inside

holes)

Deflection vs. radius for all cases (With pressure inside

holes)

Analysis of tube sheet is carried out with 1) equivalent solid plate

method as per RCC-MR considering isotropic & anisotropic material

model and 2) Three dimensional model

Parameters used for comparing the results

1) Membrane stress intensity 2) Membrane plus bending stress

intensity 3) Deflection of perforated plate at centre

Equivalent solid plate model

17

Stress Type Isotropic analysis Anisotropic analysis 3-D analysis

Pm 37.9 32.1 32.4

Pm + Pb RCC-MR, A-17 185.4 184

194.3 Modified procedure 200.7 193.2

Stress Type Isotropic analysis Anisotropic analysis 3-D analysis

Pm 59.1 54.4 47.2

Pm + Pb RCC-MR, A-17 185.42 184

212.2 Modified procedure 222.9 215.4

RCC-MR (A-17) procedure to calculate primary membrane plus bending stress

RCC-MR (A-17) uses maximum value

of radial or circumferential stress.

Contribution of axial stress value is

neglected

Pressure inside the holes of the tube

sheet is not contributing in the final

value. RCC-MR (A-17) takes

maximum value of radial or

circumferential stress which would be similar as in case of two dimensional case

zz

rr

00

00

00

000

00

00

rr

Modification in RCC-MR (A-17) rules to calculate primary membrane plus bending

stress in perforated plate

Primary membrane plus bending stress should be calculated using component wise stress which would

include effect of axial stress & pressure inside holes

Without pressure inside holes

With pressure inside holes

18

Welding Simulation : Fabrication Mismatch

Thermo-mechanical simulation of austenitic steel welding process with respect to

Main Vessel - Roof Slab shell joint was carried out.

Meshing of complete cross-section along with base metal & various idealized passes shown in different colors

March 6, 2013 FR13. Paris 19

Variation of residual stress after final cooling down along hoop direction

Distance from weld centerline (0 –

100 mm)

Ho

op

str

ess a

t in

ne

r su

rface

(-300 -

+400 M

Pa)

Axia

l str

ess a

t in

ne

r

su

rface

(-300 -

+400 M

Pa)

Distance from weld centerline (0 –

100 mm) Variation of residual stress after final cooling down along axial direction

Variation of temperature during first pass along hoop direction at t = 2 seconds

Distance from weld centerline (0 – 30

mm)

Tem

pe

ratu

re (

0 –

1600

C)

Tem

pe

ratu

re (

0 –

800

C)

Distance from weld centerline (0 – 30

mm) Variation of temperature during first pass along hoop direction at t = 12 seconds 20

Ratcheting on Enhanced Nitrogen Steel

Axial strains predicted by Enhanced Nitrogen (0.14 %)

steel (SS316EN) were much higher than the strains

predicted for SS316LN steel for the same set of

parameters.

Tensile Stress 100 Mpa

Torque +/- 1 degree

21

Sloshing Instability : Enhance Safety

Liquid free surface sloshing

under vertical excitation

Liquid filled shells under

excitation

Stability chart for dynamic stability of free

surface under vertical excitation

Numerical simulations of sodium free surface of PFBR, ensured that under

seismic excitation, response of sodium free surface is bounded

March 6, 2013 FR13. Paris 22

Sloshing Instability : Experimental Investigation

Unstable response of free surface: ωv = 1.4648

Hz, av = 0.2g

Snap shots of free surface displaying instability

Stable response of free surface: ωv = 0.5643

Hz, av = 0.02g

Snap shots of free surface displaying stability

March 6, 2013 FR13. Paris 23

Load vs. deflection (with 1 hour hold time) plot of ORNL plate at 873K

Crack appeared on both sides of ORNL Plate Axisymmetric model and stress distribution

Stress relaxation

Life RCC-MR: 2002 RCC-MR: 2007 Experimental

No: of cycles 45 51 86

Creep-fatigue damage evaluation for SS-316LN (ORNL

Plates): - RCC-MR vs. Experiments

24

Summary

• PFBR design, manufacture, construction and safety review have given rich experience.

• Comprehensive roadmap has been drawn to design and develop future FBRs with focus on economy and standardisation.

• Advance detailed Structural analysis for various structure were carried out to understand the behaviour of the components

March 6, 2013 FR13. Paris 25

M A R C H 6 , 2 0 1 3 26

F R 1 3 . P A R I S

Acknowledgement

To all my colleague in IGCAR , INDIA

Thank You for kind Attention !