Outline of Seismic PSA Implementation Standards on the Atomic Energy Society of Japan

In September 2004, the Atomic Energy Society of Japan has established 3 working groups (Seismic Hazard Evaluation, Building and Component Fragility Evaluation, Accident Sequence Evaluation) under the Seismic PSA working group in Technical Group on Nuclear Power Plant in Standards Committee with the purpose to develop its Seismic PSA implementation standards. The standards were approved by the Seismic PSA working group in December 2005 and by Technical Group on Nuclear Power Plant in June 2006. A plan is currently going on to pend upon a resolution by Standards Committee scheduled in October and to enter the public review phase. Meanwhile, the Nuclear Safety Commission of Japan established a working group for reviewing seismic design guidelines under the Technical Group on Nuclear Safety Standards and Guidelines in July 2001 so that the project to revise Examination Guideline for Seismic Design could be started. After the deliberation of almost five years, the final draft of the Examination Guideline for Seismic Design (Draft Seismic Guideline) was compiled in the working group meeting in April 2006. After a period of public comment submission for two months, the Guideline was decided in September. In the Guidelines, the risk by the extension of the effect of the seismic ground motion that exceeds the design basis seismic ground motion Ss is defined as 'residual risk', and the efforts to minimize the 'residual risk' as low as practically achievable should be made. Also, the Commission published the Draft Interim Report for Safety Goals in December 2003 and the performance goal in May 2006 as a part of the projects related to 'the residual risk'. In this report, the process of the formulation activities as well as the formulation policies / composition related to the above-mentioned Seismic PSA implementation standards are shown. In addition, the main characteristics of specific items consisting the implementation standards are described. (authors)