Proceedings of the workshop on reactor safety research. Focusing on the integrity of aged components

The Workshop on Reactor Safety Research focusing on the integrity of aged components was held at the Tokai Research Establishment on March 17, 2003. The purpose of the Workshop was to obtain useful information to proceed with the reactor safety research in future and to resolve the issues on the integrity evaluation of aged components through the discussions followed by the presentations on the results of the research at JAERI on all the research subjects assigned to JAERI in the Five-Year Program of Safety Research for Nuclear Installations established by the Nuclear Safety Commission, and on those of studies at JAERI on the integrity of core shrouds of BWR plants. Thirty-eight people from outside JAERI including the press such as Nihon Television Network Corporation and Shin-Ibaraki Shinbun and fifty-seven people from JAERI attended the Workshop. In the general issue session, the research results on the LWR fuel safety, thermal-hydraulic safety, and risk assessment and management were presented. The research results themselves were evaluated highly valuable in general while it was suggested that further studies were needed on how to apply them to safety regulation and/or to further safety enhancement. In the topical issue session, first, the research results on the integrity evaluation of aged components were presented and then, a forum was held to discuss with the participants. The answers from the participants to the questionnaire on the Workshop showed that the presentations from JAERI and commentaries from the regulatory body and industry were helpful for clarification of the issues. It was pointed out during the discussion that probabilistic methods would be effective for integrity evaluation of aged components. It was also pointed out that it would be important to make the public feel safe by taking thorough measures even in the case where the issues were not safety significant. There remain some unresolved issues such as the mechanism of crack initiation on the core shrouds. It was expected by the participants that JAERI would play an important role to resolve such issues. This report compiles as the proceedings all the viewgraphs presented in the workshop, questions and answers, comments from the participants and summary of the responses from the participants to the questionnaire. (author)