Comparison of Environmental Fatigue Evaluation Methods in LWR Water

Abstract

Many studies on the environmental fatigue of structural materials in LWR (Light Water Reactor) water have been carried out over the past 30 years. Early environmental fatigue tests were mainly carried out in Japan in the 1980s, and these results were reported to the ASME in 1988. After that, O. Chopra and W. Shack of ANL (Argonne National Laboratory) also carried out similar fatigue tests and reported that their data corresponded well to Japanese data. In the US, the PVRC (Pressure Vessel Research Council) started the CLEE Committee (Cyclic Life and Environmental Effect, Chair: Sumio Yukawa) for developing the environmental fatigue evaluation method in LWR water under the request from the ASME in 1991. This committee continued for 13 years and closed in 2004 after publishing the final report as WRC (Welding Research Council) Bulletin 487. After 1990 in Japan, the EFD Project (1993–1995) and the EFT Project (1994–2006) were carried out under the collaboration of electric utilities, plant vendors and government. A large number of environmental fatigue data have been generated in these projects, and these were offered to the US through the CLEE Committee. Based on Japanese and US fatigue data, environmental fatigue evaluation methods have been established in both countries that assess the effects of some parameters on fatigue life reduction in LWR water environments. This paper introduces the history of studies on the environmental fatigue in LWR water and the contributions of Sumio Yukawa to these activities. After that, the comparison of three major methods of environmental fatigue evaluation such as PVRC, JSME and MJREG/CR-6909 are reported.