In the last several years, the Pressure Vessel Research Council (PVRC) has been engaged in a continuing effort to define the effect of light-water reactor (LWR) coolant water environments on the fatigue properties of pressure boundary materials used in these reactor systems. This paper describes and summarizes the present status of this activity and discusses the direction of remaining activities. The paper focuses on the effect of the water environment on the S-N fatigue properties of carbon steels and austenitic stainless with some consideration of low alloy steels which are the main-pressure boundary materials. the results of activities that have proceeded outside of PVRC are also summarized since they have influenced the direction fo the PVRC effort. The concept of threshold values of the environmental and mechanical parameters that define conditions of moderate environmental effects is discussed and the need to revise some of these previously proposed values is noted. An external activity coordinated with the PVRC has developed a proposal for hte implementation of environmental considerations in the ASME Code, which has focused the need fro proper threshold values. The paper also discusses the S-N behavior of austenitic stainless steels in LWR environments where recent results indicate some differences compared to the behavior of carbon and low alloy steels. These differences will need to be considered in ASME Code implementations.
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