Environment Assisted Fatigue – Rules, Assumptions and Challenges for Fatigue Management of Primary Piping

Abstract

This paper introduces and discusses the commonly used methods for calculating environmental penalty factors (Fen) to be used in fatigue assessment of stainless reactor components. Three alternative methods for determining Fen factors are introduced and instructed in the JSME S NF1-2009 Code in a language providing a designer the guidance needed for reliable and repeatable EAF assessment. Following these instructions together with the equations and parameters given in the NUREG/CR-6909 it is possible to obtain same Fen factors as by careful reading of the NUREG/CR-6909 alone. The NUREG/CR-6909, Rev. 1 contains notable amounts of valuable information, but instructions for application can be ambiguous or conflicting. An example related to the modified strain rate approach for determining Fen factors is provided.