1. Dynamic Simulation of Relief Line during Loss of Insulation Vacuum of the ITER Cryoline
S. Badgujar1, J. Kosek2, D. Grillot2, A. Forgeas2, B. Sarkar2, N. Shah1, K. Choukekar1, and H-S Chang2
1ITER-India, Institute for Plasma Research, Near Indira Bridge, Bhat, Gandhinagar – , India
2ITER Organization, Route de Vinon-sur-Verdon, CS , St. Paul Lez Durance Cedex, France

2. OUTLINE INTRODUCTION EVENT DESCRIPTION
ITER CRYOGENIC SYSTEM
ITER CRYOLINES (CLs)
RELIEF LINE (RL) AND Torus and Cryostat CRYOLINE (TCC)
EVENT DESCRIPTION
PURPOSE OF STUDY, INPUTS AND MODEL SETUP
CASES AND SCENARIO STUDIED
RESULTS AND DISUCSSION
SUMMARY

3. CRYOGENIC SYSTEM AT ITER
LN2 Plant (×2) K
Cryoplants
LHe 1
LHe 2
LHe 3
80 K GHe Loops (×2)
3 Plants
Avg K
4/50 K SHe/GHe distribution
80 K GHe distribution
Cryodistribution
7 boxes
Magnets: PF&CC
Magnets: CS
Magnets: TF
Magnets: ST
Cryo Pumps
Thermal Shields
CryoLines
~5 km
Introduce quickly the ITER cryogenic system
EU-DA IO
IN-DA
4K USERS
IN-DA
80K USERS

4. layout OF cryogenic system
Explain the relevant area of ITER cryogenic components

5. CRYOLINES IN TOKAMAK BUILDING
Say a few words about ITER cryolines system from ACB to the clients, emphasis the complexity

6. Relief Line Network
RL recovers helium discharged from process PSVs of the different cryogenic users and sent it to storage via heater and recovery system
“A”: PSV assembly on process pipe of RL (DN200) RD
Tokamak Building (B11)
Area 53
Gas Storage
Atm Heater
Plant bridge
11-L3
“A”
SW shaft
NW shaft
B51
B52
11-B1
Rec.
compressor
Gas Bags
Overview of relief network and function of relief line
PSV form HCB/CTCB/ CL –clients/nodes
11-B2 RD RD
PSV form CTB/CVB/CL –clients/nodes
Cryoplant Buildings
B50s
Annex building B52
Cold relief line (vacuum insulated)
Warm relief lines

7. Torus and Cryostat Cryoline (TCC) with RL
RL towards Cryoplant area via plant bridge
North West Shaft
B1 Level
B2M Level
L3 Level L2 L1 B1
ACB CP X Y Z
TCC South
342CHS RL
CVBs
Relief line B2
B2M
TCC North
342CHN
TCC c/s
Vacuum Barrier
Introduce briefly TCC – its function and show the layout
Animation will show how the flow from RL in case of LIV
CVB18

8. Event description POSSIBLE EVENTS
Site Power Failure or Loss of Cooling Power (LOCP) (RL sizing case)
Loss of Vacuum in the Tokamak Cryostat (Cr LIV) (indirect)
Loss of Vacuum in the Tokamak Vacuum Vessel (VV LIV) (indirect)
Loss of Insulation Vacuum (LIV) for CL or Auxiliary Cold Boxes (ACBs)
LIV of the CLs is one of the worst scenarios apart from LIV in ACBs.
As per the loads specification of CL
He LIV: break of internal piping
Air LIV (without fire): leak in OVJ
Air LIV (with fire): external fire and consequent leak in OVJ (loss of sealing)
LIV of CL/ACB is category III (unlikely) event with the occurrence of
5×10-3/year (once in lifetime of system)
Cases when RL will have flow in it

9. Purpose of the study
Operating condition of RL depends on particular event (one PSV or multiple PSV opening during LIV) and the combinations of failures
Several studies done for TCC under LIV during the detailed design of industry  RL was not part of that study
In order to analyze integrated behaviour of the RL under these events dynamic study with EcosimPro® to confirm the definition of RL e.g. maximum pressure, minimum temperature as well as PSV “A” of the RL itself A
Gas Bag
Atm Heater
Relief line
Why this study was done
TCC LIV was studied but not with RL, RL was designed before completion of LIV study of TCC or any other line CL
e.g. TCC
Heat flux in case of LIV (with or without fire)

10. Inputs for the simulations
Geometry of the line under LIV – TCC 342CHN (88+66=156 m)
Heat transferred during the LIV (w/ or w/o fire) (ISO )
Thermal conductivity of He, Air
Heat transfer coefficient during fire and unfired condition
Equation W3, W5, W3a, W5a
PSV/RD geometry (ISO 4126)
Estimation of the flow rate to be evacuated
Diameter of the PSV or RD needed to evacuate the flow rate
Riser line dimensions
All the necessary estimations done before simulating event in EcoSimpro mostly using 4126 and code, 3% of set pressure

11. Heat transferred in He LIV (kW) Heat transferred in Air LIV (kW)
Estimated Heat Flux
LIV  heat will be exchanged between  OVJ and the thermal shield, shield and the 4 K process pipes
Assuming all pipes are at their nominal temperatures the heat load to each pipes is estimated by considering this heat exchange
In case of fire, it is assumed that the MLI will stay in place considering the thermal inertia of the CL (OVJ, thermal shield, process pipes, fixed point etc.)
Process pipes
Heat transferred in He LIV (kW)
Heat transferred in Air LIV (kW)
L3-B2 / B2M (entire length)
Only B2M (vacuum barrier)
Only B2M (VB, building seg.)
w/ fire
w/o fire
CC/CD
287
162
652
170
407
C/CR
139 79
361 94
225 E
366
206
588 48
368 F
273
153
589 47
Heat flux summary which is output from the code calcualtion

12. Case 1 Configuration Case 1(a,b) To/from cryoplant Relief line
Gas Bag
Atm Heater
Burst at PS 21 bar
L3,B2
B2M
To/from cryoplant VB CC CD C CR E F
Description case 1- valves on both sides of line – at ACB and at CVB
ACB CP
342CHN
CVB18 CP
6 PSVs on last CVB18
6 PSVs on ACB CP

13. Case 2 Configuration Case 2 (a,b,c,d) To/from cryoplant Relief line
Gas Bag
Atm Heater
Burst into building, burst pressure (>PS) by try and error
L3,B2
B2M
To/from cryoplant VB CC CD C CR E F
Description case 2- SRV on CVB side and RD on ACB side
ACB CP
342CHN
CVB18 CP
6 PSVs on last CVB18
6 RDs on ACB CP

14. Case 3 Configuration Case 3 To/from cryoplant Relief line L3,B2 B2M
Gas Bag
Atm Heater
L3,B2
B2M VB
To/from cryoplant CC CD C CR
Description case 2- SRV on CVB side and RD on ACB side E F
ACB CP
342CHN
CVB18 CP
2 PSVs on last CVB18
6 RDs and 4 PSVs on ACB CP
Most preferable for maintenance and project management

15. Description of the Case Configuration
EcoSimpro Model Cases
3 cases and 7 scenarios have been analysed
Case Sr. No.
Description of the Case Configuration
LIV scenarios
He LIV
Air LIV
entire length (156 m)
only B2M (88 m)
only B2M (88 m)
w/ fire
w/o fire 1
6 PSVs on CVB PSVs on ACB
X [1a]
X [1b] 2
6 PSVs on CVB RDs on ACB
X [2a]
X [2b]
X [2c]
X [2d] 3
2 PSV on CVB PSVs and 6 RDs on ACB X
3 cases based on valve arrangement on ACB/CVBs – see next slides for the 3 cases
In all 6 inputs for LIVs are analysed
Case no3 is optimized one where most of the components on ACBs which is what project has asked

16. EcoSimpro Configuration (Case 3)
Recovery System
CVB18
RELIEF LINE
Riser lines and 2 PSVs
PSV A of RL
342CHN CL
ACB CP
Riser lines PSVs, 6 RDs on ACB CP
B2M
VB, building seg.
Model showing physical layout converted in ecosimpro model
TCC CL devided in two parts B2/B2M
ACB CP and 4 PSV 6 RDs , CVB 18 and 2 PSV – sizes from the FDR design, kd factor (critical flow) etc, set pressure 21 for PSV and 25 for RD
Relief line with its PSV, on bridge bare line and atm heater etc, gas bag  recovery system
B2-NWS-L3

17. Summary of Simulation Result
Cases
Max pressure in process pipes (first 25 sec)
Max pressure in RL
Minimum temp. of RL in B11 (PSV entry node at CVB/ACB)
Minimum temp. of RL in B11 except entry nodes at CVB/ACB
(bar)
(K)
CC/CD
C/CR
E/F 1a 28 23
8.2
10 / 50 10 1b
>30
>10
10 / 10 2a 26 22
6.2
10 / NA
120 2b
25.5 20
5.6
125 2c 18
6.7 2d
27.5
21.5
100 3
26.5
7.6
Similar result for similar heat flux even for different configuration cases
Summary of all the 6 simulations
Max pressure in TCC line within the test pressure
Max pressure in RL within the design pressure
Minimum temperature of RL process pipes confirms the min design temperature of 10K
Except Case 1b (whole line under Air LIV w/ fire)
Max. pressure in TCC stays within the test pressure (30 bar)
(PED compliant) with RD burst at 24.5 bar
Max. pressure in RL stays within the design pressure (10 bar)
Min. temperature in RL stays within design temperature of (10 K)
Case 3 the most preferable for maintenance and project management is compliant

18. Results for Case 3 FLOW FROM PSVs FLOW TO RL THROUGH PSV – ENTRY IN B1
CC, CD in L3
C+CR in B1
C, CR in B1
M from PRVs – ACB + CVB side
M to relief line at B1
C and CR overlapping (PSVs only in B1)
CC and CD overlapping (PSVs only in L3)

19. Results for Case 3 FLOW THROUGH RDs (never closing) – ACB side
PRESSURE AT THE RDs (burst at 24.5 bar)
M from RDs– ACB side
Pressure at RD  one can inform that the conceptual RD set pressure was 28 bar and throught this siumaltion it was optimized to 25 in order to keep the pressure in TCC below test pressure
C and CR overlapping (RDs only in L3)
CC and CD overlapping (RDs only in L3)
RD burst pressure obtained by try and error for compliance with code

20. Results for Case 3 MAX pressure in TCC process pipes
MAX pressure in TCC near PSVs
Test pressure
PSV set pressure
P below test pressure of TCC pipes
Results are compliant with PED criteria (less than test pressure)

21. Results for Case 3 Flow and pressure near PSV “A” of RL on bridge
MAX pressure in DN 65 RL in B1
Flow and pressure near PSV “A” of RL on bridge
P below design pressure of RL
Behaviour of PSV of RL 
MAX Pressure <10 bar (design pressure of RL)

22. Results for Case 3 Pressure and flow along the RL 7.6 max at B1 level
3kg/s max at L3 level
B1 port cell
B1 gallery
L3 gallery
Plant bridge
NW shaft

23. Summary
Integrated simulation of LIV events in TCC (one of the ITER CL) and behaviour of the RL is studied
It was necessary to verify the RL behaviour before finalizing the optimized location of PSVs/RDs
Pressure in CL/RL to be within the defined test/design pressure
Optimum option (from maintenance and project management point of view) with only two PSVs on CVB and four remaining PSVs, six RDs on ACB satisfies all the design requirements defined for both TCC and RL for the credible worst case
This option is now being used for the manufacturing and installation of the respective interfaces, similar studies for remaining CLs planned

24. THANK YOU

25. Acknowledgement
Authors would like to thank the colleagues from ITER-India in Gandhinagar, India and ITER Organization in St. Paul Lez Durance - France as well as industrial partners namely Air Liquide Advanced Technologies, France and INOX India Limited as well as its consortium partner A S Scientific Products, UK for their contribution to ITER Cryolines project