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:
ft-lb (68J). unless it is demonstrated in a manner approved by the Director, Office of Nuclear Reactor Regulation, that lower values of upper-shcfenergy will provide margins of safety against fracture equivalent to those required by Appendix ofothe ASME Code." This Regulatoxy Guide 1.161, 'Evaluation of Reactor Prcssure Vessels with Charpy Upper-Shelf Ener-y Less Than 50 ft-lb,' has been developed to provide acceptance criteria and analysis methods acceptable to the NRC staff for demonstrating margins equivalent to those in Appendix 0 to Section III of the ASME Code. Publication ofrgulatcry guidance was undertaken because no comprehensive guidance currently exists, and there are reactors, both pressurized water reactors and boiling water reactors, with upper-shelf energy that is projected to fall below the 50 ft-lb regulatory limit before the end of the current license period. Withut comprehensive regulatory guidance. each affected licensee will have to submit a plant-specific analysis, including acceptance criteria and evaluation methods, and the staffwill have to evaluate each submittal without the benefit of staed acceptance criteria and approved evaluation methods. 2. OBJECTIVES The objective of this guide is to provide acceptance criteria and evaluation methods acceptable to the NRC staff for demonstrating margins equivalent to those in Appendix 0 to Section MI of the ASME Code for those beltline materials whose Charpy upper-shelf energy falls below the regulatory limit provided in Appendix 0 to 10 CFR Part 50. 3. ALTERNATIVES Two alternatives to issuing evaluation procedures for pressure vessels with Charpy upper-shelf energy less than 50 ft-lb were considered: (1) endorse actions being implemented by Section X[ of the ASME Code and (2) take no action. 3.1 Endone ASME Code, Section XI, Appendix K The ASME, in Section X)M has published Appendix K' that provides acceptance criteria and evaluation procedures for pressure vessels with Charpy upper-shclf energy