Abstract
Probability Safety Assessment (PSA) is a holistic approach to estimate the reliability and safety of a nuclear power plant.PSA has been widely utilized by many nuclear utilities and its impact on the nuclear power plant (NPP) safety is very notable.After Fukushima Daiichi NPP accident, Ultra Response Guidelines (URG) was proposed by Taiwan power company in order to deal with Station Blackout (SBO) and other Beyond Design Basis Accidents (BDBA). The application of URG will prolong available AC power recovery time and reduce the amount of core damage frequency. These mitigation operations and facilities in URG are not considered in the conventional Level-1 PSA analysis.In this study,these mitigation actions of URG are incorporated into the Level PSA of a Westinghouse three loops Pressurized Water Reactor (PWR). The plant analyzed is Maanshan Nuclear Power Plant of Taiwan Power Company. The purpose of the study is to assess the impact of URG on the risk of NPP and to identify the importance measure of these mitigation actions. The result of this study shows that the Level-1 PSA overall SBO Core Damage Frequency (CDF) reduced from 2.49E-07(reactor year-1) to 9.41E-08(reactor year-1) after the application of URG. This thesis summarizes the results of the study in detail.