NRC RESEARCH ACTIVITIES ON ENVIRONMENTALLY-ASSISTED FATIGUE

摘要

Over the past ten years, evaluation for license renewal and new reactors has provided significant experience and insight on the use of the environmental fatigue multiplier (F_(en)) approach, and recognized the need for further refinement of this methodology, as well as its application to other areas. Hence, the NRC has initiated further research work on environmentally assisted fatigue (EAF). The objectives of these research activities are as follows:1. Develop a transient stress evaluation software tool for rapidly determining thermal transient stresses in reactor components.2. Develop an American Society of Mechanical Engineers (ASME) Boiler & Pressure Vessel Code (Code) fatigue calculation software tool for estimating fatigue usage factors in reactor components.3. Develop revised fatigue cumulative usage factor (CUF) limit criteria for postulated high energy line break (HELB) locations.4. Update existing EAF methodology, develop application techniques for applying the methodology, and revise U.S. Nuclear Regulatory Commission (NRC) Regulatory Guide (RG) 1.207 accordingly, if appropriate.5. Participate in a round-robin study, conducted by the Electric Power Research Institute (EPRI) Advisory Panel on Environmental Fatigue, to solve a fatigue sample problemEach of these activities is briefly described in this paper.