DETERMINING SUCCESS CRITERIA FOR A SPENT FUEL POOL PRA

摘要

Spent fuel pools (SFPs) in nuclear power plants can be a source of public risk due to radiation release or economic loss for the plant owner. Previous risk analyses have generally shown that the frequency of a serious incident related to SFPs is low. The leading assessed potential causes of the risk contributing scenarios include seismic events affecting SFP integrity or other events that could cause structural damage to the SFP liner/structure (e.g., cask drop events). While the March 2011 earthquake near the Fukushima Dai-ichi plant in Japan provided confirmation of the robustness of the SFPs, it also heightened awareness that they could be subject to challenges that might ultimately lead to a radionuclide release. There is a need to understand more clearly the risks associated with SFPs, to understand the interactions with the reactor fuel, and to ensure that vulnerabilities are appropriately addressed. The various postulated challenges to fuel cooling in the SFP may lead to a wide variability in required response time. The SFP conditions can adversely impact the Reactor Building refuel floor conditions in a boiling water reactor (BWR) plant such that local access may be inhibited or precluded. However, other areas of the Reactor Building may remain accessible for some local actions until significant radionuclide release from the SFP or containment is initiated. This variability in success criteria timing translates directly into the degree of successful mitigation that can be assigned to the postulated accident scenarios. Using the MAAP 5.0.1 code, success criteria can be determined for a SFP PRA by determining values for the key functions of the success criteria.