Design review of SPWR with PSA methodology

This paper presents the procedures and results of a PSA (Probabilistic Safety Assessment) of the SPWR (System-Integrated PWR), which is being developed at the Japan Atomic Energy Research Institute (JAERI) as a medium sized innovative passive safe reactor, to assist in the design improvement of the SPWR by reviewing the design and identifying the design weaknesses. This PSA was performed in four steps: (1) identification of initiating events by the failure mode effect analysis and other methods, (2) delineation of accident sequences for three selected initiating events using accident progression flow charts and event trees, (3) quantification of event trees based on the review of past PSAs for LWRs, and (4) sensitivity analysis and interpretation of results. Qualitative and quantitative results of PSA provided very useful information for decision makings of design improvement and recommendations for further consideration in the process of detailed design