Examination on safety guidelines for ITER in Japan

Through the preparation during ITER site selection process, in Japan, examination of the policy for guidelines to implement safety design and safety assessment of the ITER facility was made among the authorities of nuclear safety and JAERI based on 'Basic Policy of ITER Safety Regulation' by the ITER Safety Regulation Working Group of Ministry of Education, Culture, Sports, Science and Technology (opened to the public, November 23rd 2003) and a report was summarized by Nuclear Safety Research Association. The policy was regarded to be a draft of the internal rules/standards for the users and the basis for establishment of practical guidelines of safety design and safety assessment for the structures, systems and components, of which the ITER facility consists. Taking account of that ITER is the first full-scale D-T fusion device and with recognition that clarification of the fundamental issues on safety of such a fusion device is important, much effort was paid to understand of the safety features of a fusion device. Then, policies on the approaches to secure safety of the ITER facility, i.e., selection of the design basis accidents, classification of aseismatic importance, etc., were examined with comparisons of those applied to the existing nuclear facilities. In the report, the policy for guidelines to implement safety design basically included the requirements, which the regulation on handling radioisotopes and devices to emit radiation specifies to implement practical designs, and the design requirements described in the 'Basic Policy of ITER Safety Regulation'. On the other hand, the policy for guidelines to implement safety evaluation aimed to confirm integrity of the design preventing radiation hazards to the public in conditions of the normal operation and the design basis accidents. Through the process of examination, some comments and proposals, related to structural integrity, risk assessment, conservativeness in the analysis of plasma behavior, etc., were given for the expected application for licensing ITER in Japan. In this paper, the details of policy for safety guidelines for ITER and those comments and proposals are described with their background. (author)