Missile Risk Assessment for Nuclear Power Plant Under Super Typhoon

Structures, systems and components (SSCs) of nuclear power plants are susceptible to wind-generated missiles under super typhoon, especially for water tanks and electrical equipment arranged in the open air. The tank of the conventional island demineralized water distribution (SER) system is the largest open-air tank of CPR1000 nuclear power plant, which has a high probability of being affected by missiles. To evaluate the missile risk for nuclear power plant under super typhoon, taking SER tank for example, an analysis using probabilistic safety assessment (PSA) method focused on typical accident sequences is carried out. Based on qualitative analysis of initiating events and mitigation functions required, the missile PSA model is established considered the failure probabilities of SER tank under different typhoon conditions. The quantitative evaluation is carried out from the aspect of accident mitigation and overall risk of the unit. The results show that the SER tank is one of the main weaknesses in accident mitigation and has a certain contribution to the overall risk of the unit. Therefore, the risk of missile for nuclear power plant under super typhoon should be concerned.