Technology assessment of aging management of nuclear power plants. Outline of technology assessment of 40 years aging plants

At present Japan has 54 reactors on line, with two under construction and 12 planned. In March 2010 the first of those now operating, Tsuruga-1 reactor, will reach the 40-year mark and Mihama-1 reactor will be the next. This article is the first of four serials, which will explain the past history of aging measures and technology assessment of 40 year aging plants based on new inspection system enforced in January 2009. An outline of technology assessment of aging plant management was described based on experiences of Tsuruga-1 reactor. A technology assessment of aging management of nuclear power plants, starting in 1996, was improved and enforced with maintenance plan incorporated. A periodical safety review is carried out to evaluate the implementation of quality assurance activity and reflection of latest technical knowledge, as well as periodical inspections once a year and every ten years. Furthermore, technology assessment (evaluation about aging plants) assuming 60 years operation in future, is obliged to perform about important components/structures in safety before 30 years passing after commissioning, and a long-term maintenance plan based on it also obliged to settle. And the contents are checked by NISA and then at periodical safety review of every ten years, a review and the check of the long-term maintenance plan are performed. (T. Tanaka)