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The Effect of an Aggressive Cool-Down Following A Refueling Outage Accident in which a Pressurizer Safety valve is Stuck Open  

Lim, Ho- Gon (Korea Atomic Energy Research Institute)
Park, Jin-Hee (Korea Atomic Energy Research Institute)
Jang, Seung-Cheol (Korea Atomic Energy Research Institute)
Publication Information
Nuclear Engineering and Technology / v.36, no.6, 2004 , pp. 497-511 More about this Journal
Abstract
A PSV (pressurizer safety valve) popping test carried out in the early phases of a refueling outage may trigger a test-induced LOCA(loss of coolant accident) if a PSV fails to fully close and is stuck in a partially open position. According to a KSNP (Korea standard nuclear power plant) low power and shutdown PSA (probabilistic safety assessment), the failure of a high pressure safety injection (HPSI) accompanied by the failure of a PSV to fully close was identified as a dominant accident sequence with a significant impact on low power and shutdown risks (LPSR). In this study, we aim to investigate and verify a new means for mitigating this type of accident using a thermal-hydraulic analysis. In particular, we explore the applicability of an aggressive cool-down combined with operator actions. The results of the various sensitivity studies performed there will help reduce LPSR and improve Refueling outage safety.
Keywords
PSV; low power and shutdown; PSA; aggressive cool-down;
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