EPR Piping Material Study: Basic Characterization and Low Cycle Fatigue at Room Temperature

Abstract

The 1963 ASME Section III design fatigue curve was generically applicable to a range of stainless steels in low cycle fatigue. In high cycle fatigue the behavior is sensitive to factors such as material strength, which raises questions about the applicability of the post-2009 ASME III stainless steel design fatigue curve as the generic and mandatory requirement up to 1011 cycles. In response, international codes and standards are investigating and incorporating opportunities for alternative design curves. Long-term Finnish research supports and application of risk-informed inspection and long-term operation strategies benefit from addressing material-specific behavior in fatigue management. In the ongoing study, stainless steel material batches representative of the EPR reactor in Olkiluoto have been selected for experimental fatigue research. This paper presents the first results on a 12″ schedule 140 Z2CND1812 N2 Class 1 pipe, including tensile properties and low cycle fatigue at room temperature.