In this paper, fatigue assessment of Class 1 nuclear power piping according to ASME Boiler and Pressure Vessel Code, Section III, NB-3600, is discussed. Key parameters involved in the fatigue assessment, i.e. the alternating stress intensity Salt, the penalty factor Ke and the cumulative damage factor U, are addressed. In particular, a so-called simplified elastic-plastic discontinuity analysis for alternative verification when basic fatigue requirements found unsatisfactory, and the procedures for evaluating the alternating stress intensity Salt, is reviewed. Factors that can significantly affect the reliability and accuracy of the fatigue assessment are examined. It is illustrated that there is a great need of other alternatives to this simplified elastic-plastic analysis procedure. An alternative based on non-linear finite element analysis is suggested. This paper is a continuation of our work presented in ICONE16-21, which attempted to categorize design rules in the code into linear and non-linear rules and to clarify corresponding requirements that can be used in combination with non-linear finite element analysis.

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