Estimation of component failure rates for PSA in sodium-cooled fast reactor

高速炉PSAのための機器故障率評価

鳴戸 健一*; 栗坂 健一 

Naruto, Kenichi*; Kurisaka, Kenichi

In the Probabilistic Safety Assessment (PSA), it is important to evaluate failure rates correctly based on component operational and failure experiences accumulated in nuclear plants or other similar facilities. In order to evaluate the components failure rate for the fast reactor's PSA, Japan Atomic Energy Agency has developed a component reliability database system for sodium-cooled fast reactor (SFR) systems, named CORDS, and has collected the component reliability data from the four sodium fast reactor plants in Japan and the United States. In this study, we have developed a new definition of component boundary in the database, which differ from the original one to harmonize with basic events in PSA, and the new definition was applied for electric pumps and diesel generators, which consist of main parts and other many parts in the support system. We also have developed a new practical failure rate evaluation method based on Bayesian method, which considers cases corresponding to the various degrees in the accumulated component operating experience. Further, by using the method, the failure rate in PSA for the target fast reactor plant has been evaluated.