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:
, because of significant conservatism in quantifying other plant-related variables involved in CUF calculations (such as cyclic behavior, including stress and loading rates), the 40-year design of the current fleet of reactors was satisfactory. The NRC staff concluded that there was no basis for a cost/benefit backfit analysis to justify imposition of a new regulatory requirement on operating reactors. However, the calculations that supported the resolution of this issue indicated the potential for an increase in the frequency of pipe leaks as plants continue to operate. Thus, with the consideration of a risk-informed perspective, the staff concluded that applicants for renewed licenses should address the effects of LWR coolant environments on component fatigue lives as they develop aging-management programs for license renewal, in ways consistent with existing requirements in 10 CFR 54.21, “Contents of Application—Technical Information.” These findings were captured in the initial versions of the GALL Report and the SRP-LR as guidance applicable to plants pursuing license renewal. The NRC staff’s closeout of GSI 190 and the associated research also led to the development of Revision 0 of RG 1.207 (Ref. 8) to document guidance related to evaluation of environmental effects for new reactors. The guidance provided in Revision 1 of RG 1.207 is a consolidation and update of the staff’s previous guidance and is limited to new reactors, operating reactors pursuing license renewal, and plants where evaluation of LWR coolant environments already forms a part of the CLB. In the late 1960s and early 1970s, ASME developed design fatigue curves for Section III of the ASME Code based on tests conducted in laboratory air environments at room temperature. The original ASME Code developers applied a margin of two on strain (or stress) and a margin of twenty on cyclic life to develop design fatigue curves that accounted for variations in materials, size, surface finish,