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:
ue curves to address potential parameter variations. Alternatively, a single bounding fatigue curve could be developed, but this approach might be overly conservative for most applications. The second method involved using an environmental factor (Fen) to adjust the CUF calculated with the design fatigue curves in Section III of the ASME Code to account for LWR coolant environments. The second method affords the designer greater flexibility to calculate the appropriate impacts for specific environmental parameters. Based on the results of the NRC’s efforts, the staff elected to develop guidance that used the Fen method. DG-1309, Page 4 In developing the underlying Fen models, researchers from Argonne National Laboratory (ANL) analyzed existing laboratory data to predict fatigue lives as a function of temperature, strain rate, dissolved oxygen level in water, and sulfur content of the steel. ANL defined an environmental factor, Fen, as the ratio of the component fatigue life in a room-temperature air environment to its fatigue life in an LWR coolant environment at operating temperature. The resultant Fen method also postulated a strain threshold below which environmental effects on fatigue lives did not occur. Calculating CUF using the provisions set forth in Section III of the ASME Code and multiplying the CUF by Fen provided a means of incorporating the environmental effects identified in Paragraph NB-3121 of Section III of the ASME Code when warranted. The NRC staff initially published the Fen method in NUREG/CR-6583 for carbon and low-alloy steel materials and NUREG/CR-5704 for austenitic stainless steel materials. In 2001, the NRC staff endorsed the Fen methods in NUREG/CR-6583 and NUREG/CR-5704 for use by licensees pursuing license renewal in the initial versions of the GALL Report and the SRP-LR. Additional data evaluation subsequent to the publication of these two documents resulted in a revised Fen method for new reactors that the staff documented in