Evaluation of Environmental Fatigue in PWR PLM Activities

It is important to evaluate environmental fatigue for establishing long-term maintenance plans as part of Plant Life Management (PLM) activities for nuclear power plants. In Japan, the former MITI requested the utilities in 2000 to use “The Guidelines for Evaluating Fatigue Initiation Life Reduction in LWR Environment (MITI guidelines)” for PLM evaluation. In 2002, Thermal and Nuclear Power Engineering Society (TENPES) issued the guidelines for applying the evaluation formulas of MITI guidelines to actual plants. At present, fatigue evaluations taking into account environmental effects as part of PLM activities are conducted in accordance with these guidelines. This paper describes how a typical PWR plant conducts such an evaluation. The Japan Society of Mechanical Engineers (JSME) is now drawing up a code for environmental fatigue evaluation, incorporating the latest data on fatigue experiments and know-how on fatigue evaluation. After being issued, this code will be used to evaluate environmental fatigue in PLM activities.