Optimization of Environmental Fatigue Evaluation: Step 1

In order to introduce environmental effects into fatigue evaluation of design and construction codes, the environmental fatigue evaluation method should not only be established, but the conservativeness of the codes, such as safety factors of design fatigue curve and simplified elastic-plastic analysis method (Ke factor), etc. should also be reviewed. Then plant designers should optimize total system of fatigue evaluation according to the objective of the codes by properly selecting design transient conditions and stress analysis methods used in fatigue evaluations as necessary. In addition, investigation of measures for reducing fatigue should be performed to mitigate possible fatigue initiators and alternative evaluation methods in case that the evaluation result should exceed the criteria specified in the design and construction codes. This paper discusses the present status in the review of these items for the Japanese PWR plants and future prospects to tackle on the application of environmental fatigue evaluation in design stage of plant construction.© 2007 ASME