Recent results of level 1 PSA for nuclear power plants in Japan

This paper summarizes the recent results of level 1 probabilistic safety assessment (PSA) for nuclear power plants (NPPs) in Japan, focusing on some results at the Japan Institute of Nuclear Safety (JINS) of the Nuclear Power Engineering Test Center (NUPEC). Both governmental organizations including JINS and industry groups are carrying out Level 1 and Level 2 PSA for NPPs. It can be said that the level 1 PSA results obtained by both JINS and industry groups are approximately the same. The core damage frequencies for typical Japanese NPPs, even applying upper 5% values, are small enough to meet the International Atomic Energy Agency's proposal of the value 10-5/reactor year for future plants. The above-mentioned level 1 PSAs do not represent final ones and in the near future, will be reevaluated based on the current methodology and the domestic data bases which are now under development in Japan