JSME Codes on Environmental Fatigue Evaluation

The “Guidelines for Evaluating Fatigue Initiation Life Reduction in the LWR Environment” (the MITI Guidelines) including equations to evaluate environmental fatigue were issued and notified the electric utilities in September 2000 by the former Agency for Natural Resources and Energy in Japan. The MITI Guidelines require the Japanese utilities to take into account environmental effects when conducting fatigue evaluation associated with Plant Life Management (PLM) activities for operating nuclear power plants. However, the MITI guidelines do not specify how to conduct the environmental fatigue evaluation under actual plant conditions. To provide a concrete and practical method to deal with environmental effects on fatigue evaluation of plant equipment, Thermal and Nuclear Power Engineering Society established the “Guidelines on Environmental Fatigue Evaluation for LWR Component” (the TENPES Guidelines) in 2002. Since then, the Japan Society of Mechanical Engineers (JSME) has reviewed the equations to calculate the environmental fatigue life correction factor, Fen in the MITI guidelines and the methods to evaluate the environmental fatigue in the TENPES guidelines considering the latest environmental fatigue data. Based on the result of the review, JSME intends to establish new environmental fatigue evaluation method. This paper explains the scheme and the technical basis of the evaluation methods in JSME codes, and the positioning of the codes to apply them to actual plant conditions. Another paper is released separately that shows the background of the equation to evaluate the fatigue life under the reactor cooling water environment.[19]