Nuclear Engineering and Technology

Korean Nuclear Society (한국원자력학회)
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Effect analysis of ISLOCA pathways on fission product release at Westinghouse 2-loop PWR using MELCOR

  • Kim, Seungwoo (Department of Nuclear Engineering, Hanyang University) ;
  • Park, Yerim (Department of Nuclear Engineering, Hanyang University) ;
  • Jin, Youngho (Department of Nuclear Engineering, Hanyang University) ;
  • Kim, Dong Ha (Department of Nuclear Engineering, Hanyang University) ;
  • Jae, Moosung (Department of Nuclear Engineering, Hanyang University)
  • Received : 2020.10.05
  • Accepted : 2021.03.20
  • Published : 2021.09.25
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Abstract

As the amount of fission product released from ISLOCA was overestimated because of conservative assumptions in the past, several studies have been recently conducted to evaluate the actual release amount. Among several pathways for the ISLOCA, most studies were focused on the pathway with the highest possibility. However, different ISLOCA pathways may have different fission product release characteristics. In this study, fission product behavior was analyzed for various pathways at the Westinghouse two-loop plant using MELCOR. Four pathways are considered: the pipes from a cold leg, from a downcomer, from a hot leg to the outlet of RHR heat exchanger, and the pipe from the hot leg to the inlet of RHR pump (Pathway 1-4). According to the analysis results, cladding fails at around 2.5 h in Pathways 1 and 2, and on the other hand, about 3.3 h in Pathways 3 and 4 because the ISLOCA pathways affect the safety injection flow path. While the release amount of cesium and iodine ranges between 20 and 26% in Pathways 1 to 3, Pathway 4 allows only 5% to the environment because the break location is submerged. Also, as more than 90% of cesium released to the environment passes through the personnel door, reinforcing the pressure capacity of the doors would be a significant factor in the accident management of the ISLOCA.

Keywords

Acknowledgement

This work was supported by the Nuclear Safety Research Program through the Korea Foundation Of Nuclear Safety (KOFONS), granted financial resource from the Multi-Unit Risk Research Group (MURRG), Republic of Korea (No. 1705001).

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