Evaluation of fuel damage frequency resulting from loss of spent fuel pool cooling

The spent fuel is kept and cooled in the Spent Fuel Pool (SFP). Therefore, there is some risk of the spent fuel damage in the SFP as well as that of the reactor core damage when abnormal events such as loss of cooling accident occur. It is thought that the risk of spent fuel damage in the SFP is lower than that of reactor core, because the decay heat level generated by the spent fuel in the SFP is lower than that of reactor core. However, there is a possibility that the fuel damage risk of the SFP cannot be ignored in comparison with the core damage during the refueling outage, because the fuel that has high decay heat level is transferred to the SFP during the exchange of fuel and the mitigation system for the SFP is limited in comparison with the reactor core. Therefore, in this study, risk monitor to evaluate the SFP fuel damage risk during the plant shutdown conditions was constructed for a BWR plant, and the SFP fuel damage frequency was evaluated. By utilizing the risk monitor, the useful risk information for the safety management activity can be supplied during the refueling outage. (author)