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Research Papers

Ex-Vessel Loss of Coolant Accident Analysis of ITER Divertor Cooling System Using Modified RELAP/SCADAPSIM/Mod 4.0

[+] Author and Article Information
S. P. Saraswat

Nuclear Engineering and
Technology Programme,
Indian Institute of Technology Kanpur,
Kanpur 208016, India
e-mails: satyasar@iitk.ac.in;
satyasivam@gmail.com

P. Munshi

Nuclear Engineering and
Technology Programme,
Indian Institute of Technology Kanpur,
Kanpur 208016, India
e-mail: pmunshi@iitk.ac.in

A. Khanna

Nuclear Engineering and Technology
Programme,
Indian Institute of Technology Kanpur,
Kanpur 208016, India
e-mail: akhanna@iitk.ac.in

C. Allison

Innovative Systems Software,
Idaho Falls, ID 83406
e-mail: iss@cableone.net

Manuscript received March 27, 2017; final manuscript received June 14, 2017; published online July 31, 2017. Assoc. Editor: Xu Cheng.

ASME J of Nuclear Rad Sci 3(4), 041009 (Jul 31, 2017) (13 pages) Paper No: NERS-17-1021; doi: 10.1115/1.4037188 History: Received March 27, 2017; Revised June 14, 2017

The initial design of ITER incorporated the use of carbon fiber composites in high heat flux regions and tungsten was used for low heat flux regions. The current design includes tungsten for both these regions. The present work includes thermal hydraulic modeling and analysis of ex-vessel loss of coolant accident (LOCA) for the divertor (DIV) cooling system. The purpose of this study is to show that the new concept of full tungsten divertor is able to withstand in the accident scenarios. The code used in this study is RELAP/SCADAPSIM/MOD 4.0. A parametric study is also carried out with different in-vessel break sizes and ex-vessel break locations. The analysis discusses a number of safety concerns that may result from the accident scenarios. These concerns include vacuum vessel (VV) pressurization, divertor temperature profile, passive decay heat removal capability of structure, and pressurization of tokamak cooling water system. The results show that the pressures and temperatures are kept below design limits prescribed by ITER organization.

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References

Pérez, M., Freixa, J., Mas de les Valls, E., Sandeep, T., and Chaudhari, V., 2015, “ RELAP/SCDAPSIM/MOD4.0 Modification for Transient Accident Scenario of Test Blanket Modules Involving Helium Flows Into Heavy Liquid Metal,” 41st Annual Meeting of the Spanish Nuclear Society, A Coruña, Spain, Sept. 23–25. https://www.researchgate.net/publication/281618708_RELAPSCDAPSIMMOD40_MODIFICATION_FOR_TRANSIENT_ACCIDENT_SCENARIO_OF_TEST_BLANKET_MODULES_INVOLVING_HELIUM_FLOWS_INTO_HEAVY_LIQUID_METAL
Perez, M. , and Allison, C. M. , 2015, “ The Development of RELAP/SCDAPSIM/ MOD4.0 for Advanced Fluid Systems Design Analysis,” 23th International Conference on Nuclear Engineering (ICONE-23), Chiba, Japan, May 17–21, Paper No. ICONE23-1623. https://www.researchgate.net/publication/277323629_The_Development_of_RELAP5SCDAPSIMMOD40_for_Advanced_Fluid_Systems_Design_and_Analysis
Trivedi, A. K. , Sandeep, K. T. , Allison, C. M. , and Munshi, P. , 2014, “ Incorporation of Lithium Lead Eutectic as a Working Fluid in RELAP5 and Preliminary Safety Assessment of LLCS,” Fusion Eng. Des., 89(12), pp. 2956–2963. [CrossRef]
Pitts, R. A. , Carpentier, S. , Escourbiac, F. , and Stangeby, P. C. , 2013, “ A Full Tungsten Divertor for ITER: Physics Issues and Design Status,” J. Nucl. Mater., 438(Supplement), pp. S48–S56. [CrossRef]
Sheng, C. H. , 2002, “ MELCOR Analyses of Divertor Ex-Vessel LOCA During Normal Operation,” STUDSVIK, Sweden, Report No. STUDSVIK-ES-02-36. https://inis.iaea.org/search/search.aspx?orig_q=RN:33055848
Sheng, C. H. , and Sjoberg, A. , 2003, “ MELCOR Model of Divertor Cooling Loop and Divertor Ex-Vessel LOCA Analysis for the ITER Plant,” Fusion Eng. Des., 69(1–4), pp. 577–583. [CrossRef]
ITER, 2010, “ Generic Site Safety Report (GSSR) Volume VII,” Analysis of Reference Events, ITER, Cadarache, France, Report No. G 84 RI 6 01-07-10 R 1.0. https://fusion.gat.com/iter/iter-fdr/final-report-sep-2001/Plant_Assembly_Documents_(PADs)/Generic_Site_Safety_Report_GSSR/GSSR_07_AnlysRefEvnts_text.pdf
ITER, 2010, “ Generic Site Safety Report Volume XI,” Safety Models and Codes, ITER, Cadarache, France, Report No. G 84 RI 10 00-12-14 W 0.3. https://fusion.gat.com/iter/iter-fdr/final-report-sep-2001/Plant_Assembly_Documents_(PADs)/Generic_Site_Safety_Report_GSSR/GSSR_11_SafetyModels+Codes.pdf
Sheng, C. H. , and Sponton, L. , 2005, “ ITER Divertor Ex-Vessel Pipe Break,” Fusion Eng. Des., 75–79, pp. 1217–1220. [CrossRef]
Popov, E. , Yoder, G. , and Seokho, H. , 2010, “ RELAP5 Model of the Divertor Primary Heat Transfer System,” U.S. Department of Energy, Washington, DC, Report No. US ITER 12102-TD0002-R00. https://info.ornl.gov/sites/publications/Files/Pub25481.pdf
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Figures

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Fig. 1

Schematic of ITER DV-PHTS loop

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Fig. 2

Thermal hydraulic nodalization of ITER divertor cooling system

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Fig. 3

RELAP/SCADAPSIM nodalization diagram VVPSS

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Fig. 4

Divertor cassette heat structures

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Fig. 5

(a) Steady-state lower IVT tungsten surface temperature, (b) steady-state divertor inlet outlet temperature, (c) steady-state DV-PHTS loop main pump mass flow rate, and (d) steady-state divertor inlet and outlet pressure

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Fig. 6

(a) Divertor lower IVT tungsten surface temperature profile during ex-vessel LOCA, (b) pressure profile of VV and TCWS during ex-vessel LOCA, (c) ex-vessel break mass flow rate, and (d) in-vessel break mass flow rate

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Fig. 7

Ex-vessel break mass flow rate

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Fig. 8

In-vessel break mass flow rate

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Fig. 9

Divertor lower IVT tungsten surface temperature profile during ex-vessel LOCA

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Fig. 10

Pressure profile of VV during ex-vessel LOCA

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Fig. 11

Pressure profile of TCWS vault during ex-vessel LOCA

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Fig. 12

VVPSS bleed line and rupture disk mass flow rates

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Fig. 13

Drain tank line mass flow rates

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Fig. 14

Pressure profile of VV with different in-vessel break sizes during ex-vessel LOCA

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Fig. 15

Pressure profile of TCWS vault with different in-vessel break sizes during ex-vessel LOCA

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Fig. 16

Temperature profile of lower DV-IVT tungsten surface with different in-vessel break sizes during ex-vessel LOCA

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Fig. 17

Pressurization trend of TCWS vault at different locations of ex-vessel break

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Fig. 18

Ex-vessel mass flow rate with different control volume size cases: (a) smaller volume case and (b) larger volume

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