CURRENT STATUS OF SAFETY REGULATION FOR OPERATING NUCLEAR POWER PLANTS IN JAPAN

摘要

Thirty years have passed since the first commercial nuclear power plant (NPP) in Japan commenced operation in 1966. In view of the increase in the number of plants that have been operated for many years, it is necessary to enhance the safety regulation for these operating NPPs in terms of comprehensive preventive maintenance and measures against plant ageing. In order to improve the situation, the Ministry of International Trade and Industry (MITI) launched a safety assurance activity of reviewing and evaluating periodic safety reviews (PSRs) performed by utilities as one of their self-imposed activities. Together with the PSR evaluation, MITI initiated a study on ageing issues for selected NPPs and released a policy on safety regulation for ageing plants. In 1992, MITI notified the LWR utilities to conduct PSRs of their plants and to report their results to it. The evaluation of PSRs by MITI was completed for three NPPs in 1994 and for four NPPs in 1995. In future, PSRs of four to five plants will be reviewed annually and individual NPPs will be examined at approximately ten-year intervals. The evaluation of PSRs is conducted from the viewpoints of 'comprehensive evaluation of operational experience' and 'reflecting the latest technical expertise'. With regard to the comprehensive evaluation of operational experience, the evaluation focused on the adequacy of the frameworks and the involved mechanisms to maintain and enhance plant safety and reliability, and of various improvements so far implemented in all operation related areas, such as operation management, maintenance management, radiation control and radioactive waste management. In evaluating the reflection of the latest technical expertise, examination focused specifically on whether the important technical information related to LWR safety was properly taken into account so as to enhance plant safety in the light of the latest information and knowledge in the areas of research and technological development for modern NPPs. The study on the measures for ageing issues was made on LWRs which are to play a main role in nuclear power generation in Japan. MITI identified the following items as representing the basic policy on safety regulation for ageing: sophistication of the periodic inspection, etc., technical standards of structures, self-imposed maintenance and technology development for plant ageing.