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Research Papers

Analysis of Loss of Heat Sink for ITER Divertor Cooling System Using Modified RELAP/SCDAPSIM/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

D. Ray

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

P. Munshi

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

C. Allison

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

1Corresponding author.

Manuscript received April 25, 2018; final manuscript received January 17, 2019; published online July 19, 2019. Assoc. Editor: Eugene Shwageraus.

ASME J of Nuclear Rad Sci 5(4), 042202 (Jul 19, 2019) (8 pages) Paper No: NERS-18-1030; doi: 10.1115/1.4042707 History: Received April 25, 2018; Revised January 17, 2019

The present work includes thermal hydraulic modeling and analysis of loss of heat sink (LOHS) accident for the ITER divertor cooling system. The analysis is done for the new design of full tungsten divertor. The new design is also analyzed for different local heat loads ranging from 10 MW/m2 to 20 MW/m2 (while maintaining the total heat load 200 MW) under the steady-state fluid conditions. The LOHS event is selected since divertor is the most sensitive component to loss or reduction in coolability of divertor primary heat transport system (DV-PHTS) loop as it receives large heat flux from plasma. The main objective of this analysis is to find margins to unwanted conditions like overstress temperatures of structure and elevated water level in the pressurizer. The analysis is done by modified thermal hydraulic code RELAP/SCDAPSIM/MOD 4.0. The results obtained are compared with the results of old divertor design which uses carbon fiber composite (CFC) layer to show that how the new design of divertor behaves compared to the older design under the accident scenario. A detailed model of DV-PHTS loop and its ancillary system is presented. The model includes promotional integral differential (PID) controller for controlling the pressurizer heater and spray system. A detailed pump model is also included in the present analysis which was previously used as a time-dependent junction. The analysis shows that under the accident scenario, (a) the divertor structure temperature at the critical sites (inner vertical target (IVT) and outer vertical target (OVT)) is always within the design limit and does not affect the structural integrity of the divertor. (b) The water level in the pressurizer increases moderately and finely controlled by the PID controller, and pressurizer safety valve does not open.

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References

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Figures

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Fig. 1

Full tungsten divertor: (a) divertor heat structures, (b) vertical target monoblock structure, (c) geometric of vertical target monoblock, and (d) thermal hydraulic model of tungsten monoblocks with single channel, seven control volumes, and seven heat structures

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Fig. 2

Schematic of ITER DV-PHTS loop and modeling of LOHS

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Fig. 3

Thermal hydraulic nodalization of ITER divertor cooling system

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Fig. 4

Proportional integral differential controller modeling

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Fig. 5

Loss of heat sink analysis of ITER divertor cooling system for new full tungsten divertor: (a) local temperature profile of plasma facing IVT surface, (b) hot leg coolant temperature profile, (c) level of coolant in pressurizer, and (d) pressure profile in the coolant loop

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Fig. 6

Comparison of plasma facing surface temperature profile with RELAP/SCDAPSIM (new full tungsten divertor design) and (old divertor design) under LOHS accident

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Fig. 7

Comparison of coolant temperature profile with RELAP/SCDAPSIM (new full tungsten divertor design) and (old divertor design) under LOHS accident

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Fig. 8

Comparison of coolant level in pressurizer with RELAP/SCDAPSIM (new full tungsten divertor design) and (old divertor design) under LOHS accident

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Fig. 9

Comparison of coolant pressurizer pressure profile with RELAP/SCDAPSIM (new full tungsten divertor design) and (old divertor design) under LOHS accident

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Fig. 10

Comparison of coolant pressurizer pressure profile with RELAP/SCDAPSIM (new full tungsten divertor design) with and without spray and heater

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Fig. 11

Local lower IVT surface temperature with different heat flux under steady-state fluid conditions and maintenance of the total heat load of 200 MW that is removed by DV-PHTS HRS

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