Document: NRC Regulatory Guide
Document ID: aa450282-f5b0-4dd2-b41a-917a7491deb2
Document Type: regulatory_guide
Title: Preparing Probabilistic Fracture Mechanics (Rev. 0)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML2133/ML21334A158.pdf
Revision Date: 2023-05
Chapter: 
Section ID: RG-1.245
CFR Part: 
CFR Title: 

Content:
f Rupture (xLPR) (Ref. 13), and others. Furthermore, the NRC has used probabilistic fracture mechanics methods in developing regulatory positions, such as the alternate pressurized thermal shock (PTS) rule at 10 CFR 50.61a, “Alternate fracture toughness requirements for protection against pressurized thermal shock events,” and the 2020 assessment (Ref. 14) of RG 1.99, “Radiation Embrittlement of Reactor Vessel Materials,” (Ref. 15) Revision 2, issued May 1988. In 2018, the NRC published the technical letter report, “Important Aspects of Probabilistic Fracture Mechanics Analyses” (Ref. 16), to outline the important concepts for using PFM in support of regulatory applications and held a public meeting to discuss this technical letter report. Following the October 23, 2018, public meeting on “Discussion of a graded approach for probabilistic fracture mechanics codes and analyses for regulatory applications,” (Ref. 17) the Electric Power Research Institute (EPRI) developed a proposal on the minimum contents of a submittal that uses PFM as part of its technical basis. Some licensees have submitted licensing applications claiming to have followed the EPRI minimum requirements. However, in reviewing these submittals, the NRC has found that the minimum requirements in the EPRI proposal are not always clear and concise. Further, the EPRI document does not precisely define its guidance when the minimum requirements specified in the EPRI guidance are not sufficient, leading to ambiguity, inefficient reviews, and uncertainty in regulatory outcomes. Importantly, the NRC staff accounted for EPRI’s proposal when developing this RG. In 2021, the NRC will publish, concurrently with this RG, NUREG/CR-7278, “Technical Basis for the use of Probabilistic Fracture Mechanics in Regulatory Applications” (Ref. 6), which constitutes the detailed technical basis for this RG. The NRC has an approved methodology for risk-informed decision making for design-basis changes