Document: NRC Regulatory Guide
Document ID: 2704425a-c58a-45c4-93ab-8761721c3e7a
Document Type: regulatory_guide
Title: Evaluation of Reactor Pressure Vessels with Charpy Upper-Shelf Energy Less Than 50 Ft-Lb
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0037/ML003740038.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.161
CFR Part: 
CFR Title: 

Content:
ted resolution ofUSI A-l I by issuing NUREG-0744, "Resolution of the Task A-1l Reactor "Vessel Materials Toughness Safety Issue (Ref. 5), which provided methods for evaluating the fracture behavior of these materials. Further, Generic Letter 82-26 (Ref. 6) was issued to advise licensees of the USI resolution. No new require ments were implemented as part of the USI resolution. However, neither NUREG-0744 nor Generic Letter 82-26 contained criteria for demonstrating equivalence of margins with Appendix 0 of the ASME Code. Rather, the NRC staff asked Section X) of the ASME Boiler Pressure Vessel Code Committee to develop and suggest to the staff appropriate criteria. In February 1991, the Chairman of the ASME Section XI Subgroup on Evaluation and Standards provided to the NRC staffcriteria that had been developed by members of the Working Group on Flaw Evaluation (WGFE) and the Working Group on Operating Plant Criteria (WGOPC) (Ref 7). Although these criteria did not represent ASME Code criteria, they did represent the best opinion of knowledgeable persons familiar with the problem and with the ASME Code. Upon review, the NRC staff found these criteria to be acceptable for denstrating margins of safety equivalent to those in Appendix 0 of the ASME Code (Ref. 3). However. specific methods for evaluating the criteria still were being developedby the ognizant ASME Code committees. Further, those efforts were not expected to provide specific guidance on determining event sequences and transients to be consid ered, nor were they exected to provide specific guidance on approprit material properties. This guide has been developed to provide comprehen sive guidance acceptable to the NRC staff for evaluating reactorpressure vesses when the Charpy upper-shelf energy falls below the 50 ft-lb limit of Appendix G to 10 CFR Part 50. The analysis methods in the Regulatory Position are based on methods developed for the ASME Code, Section XI, Appendix K ( 8). The staff has reviewed