In the fatigue analysis for Class 1 components in MITI Notification No.501,the simplified elastic-plastic analysis with the fatigue penalty factor (Ke factor) is applied when the primary plus secondary stress intensity exceeds 3Sm. It is known that the Ke factor has a large conservatism. Therefore, to rationalize the present Ke factor, the elastic analyses and the elastic-plastic analyses were performed, and the analyzed Ke factors were evaluated. The analyses were performed with various loading conditions and geometric models so that the analyses results could be represented for the actual design of major LWR components. And the adequacy of the rationalized Ke factor was verified with the experimental data for piping and with the evaluation results for the severest actual components from the viewpoint of the fatigue evaluation.
