An Investigation Into the Feasibility of Environmental Fatigue Design for APR 1400 Primary Components and Piping With a 60 Year Design Life

This paper investigates the feasibility of environmental fatigue design for the APR1400 with the 60 year design life, which is based on sample evaluations of fatigue lives for the component and piping designed to the ASME Code Section III, Division 1. The materials sampled from the reactor coolant system (RCS) components are the low alloy steel for reactor pressure vessel outlet nozzles and the austenitic stainless steel for pressurizer surge line piping. Environmental fatigue evaluations of the component materials are performed employing the environment factor approach. Based on the evaluation results it is concluded the environmental fatigue design of the RCS components and piping for the APR1400 is not feasible as the Code requirement, and alternative approaches need be developed removing various conservatisms in the fatigue design methodology.