Abstract
Probability Safety Assessment (PSA) is a systematic approach to estimate the risk of nuclear power plants (NPPs). PSA has been widely utilized by nuclear utilities, nuclear industry, and nuclear regulators to enhance the safety of NPPs. Over the past few years, Severe Accident Guidelines (SAGs), which delineate the mitigation actions of core meltdown accidents of NPP, are developed to support operators and staffs in the Technical Support Center (TSC) during the emergency responses of core melt accidents. The proper executions of SAGs could decrease the failure probability of containment and reduce the amount of radionuclide released to the environment during the accident. It can be expected that the implementation of SAGs will reduce the risk of the operation of NPPs. However, SAGs are not available when the conventional Level-2 PSA analyses are performed. In this study the mitigation actions of SAGs are incorporated into the Level-2 PSA of a General Electric designed Boiling Water Reactor (BWR) with Mark III containment. The plant analyzed is Kuosheng Nuclear Power Plant of Taiwan Power Company (TPC). The purposes of the study are to assess the impact of SAGs on the risk of NPP and to identify the importance measure of these mitigation actions. MAAP code calculations are performed to verify and validate the mitigation actions specified in SAGs. In the conclusion of this thesis, we find that the percentage of intact containment is increased, and the percentage of other contentment failure modes are decreased. We could say SAGs bring positive effect and reduce the damage when the severe accident occurs.