Document: NRC Regulatory Guide
Document ID: 7c9a00a8-375c-4641-bc1b-762a663a96d6
Document Type: regulatory_guide
Title: Guidelines for Evaluating Fatigue Analyses Incorporating the Life Reduction of Metal Components Due to the Effects of the Light-Water Reactor Environment for New Reactors (Rev. 1)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1417/ML14171A584.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.207
CFR Part: 
CFR Title: 

Content:
d Fen factors for use in evaluating the fatigue lives of reactor components exposed to LWR coolant environments. In Revision 0 of RG 1.207, the NRC staff identified a non-conservatism in the ASME Code fatigue design curve with respect to existing fatigue data for austenitic stainless steels and endorsed a separate stainless steel fatigue design curve, as documented in Revision 0 of NUREG/CR-6909. ASME modified the fatigue design curve in Section III for austenitic stainless steels in the 2009b Addenda to adopt the fatigue design curve developed in Revision 0 of NUREG/CR-6909. Section 3.2.11 of Revision 1 of NUREG/CR-6909 provides an updated and comprehensive review of, and technical basis for, continued use of the stainless steel fatigue design curve previously developed in Revision 0 of NUREG/CR-6909. The Fen defined for stainless steel in Revision 1 of NUREG/CR-6909 should be used in conjunction with this more recent stainless steel fatigue design curve when evaluating the CUF of ASME components that require a CUF calculation. Use of the austenitic stainless steel design curve also applies to the fatigue analyses for cast austenitic stainless steels, Ni-Cr-Fe alloys (e.g., Alloys 600, 690, 718, and 800) and their associated weld metals, as described in Section 4.3 of Revision 1 of NUREG/CR-6909. DG-1309, Page 5 Section 5 of Revision 1 of NUREG/CR-6909 evaluates margins in the ASME Code fatigue design curves. In conducting that evaluation, the ANL researchers reviewed data available in the literature to assess the subfactors (excluding environment) that are necessary to account for the effects of various uncertainties and differences between actual components and laboratory test specimens. The ANL researchers also performed statistical analyses using Monte Carlo simulations to develop fatigue design curves using the “95/95 criterion.” In other words, the curves should provide 95% confidence that the fatigue life of 95% of the population of laboratory test