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:
one 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 less than 50 ft-lb. However, the Appendix K evaluation procedures curently address only Service Levels A and B, and no guidance on specific materials properties is provided. It is important that all four service levels be considered in the evaluations, and it is important that specific guidance on estimating material properties be provided. Given the ASME codification process, and the process whereby the NRC endorses ASME appendices and code cases, the time delay in obtaining suitable guidance would be excessive. At present, the ASME's Appendix K does not provide complete guidance. As discussed above, Appendix K does not provide information on the selection of transients, and it gives very little detail on the selection of material properties. As such, a request for revision of Appendix K to Section XM of the ASME Code will have to be made. 3.2 Take No Action As discussed in SECY-93-048,2 'Status of Reactor Pressure Vessel Issues Including Compliance With 10 CFR Part 50, Appendices 0 and IV, using the NRC staffs generic criteria for estimating Charpy upper-shelf energy, there are currently 15 plants that would have calculated upper-shelf energy less than 50 ft-lb and 3 others that would haveuppcr-shelf energy below 50 ft-lb before the end of their operating licenses. Appendix 0 to 10 CFR Part 50 requires that licensees submit ,A.npdxK emously, Code Caw N-•S 12), "Asesment cef tor Vessels with low Upper ShelfCmpy kmpact Er"y ls,' Amrica Society of Mechanical Engineers, Section Xn 1993. 2Jcmes MK Taylor, Executive Director for Opcrat, SECY-93-04, Policy Issue (Infamtloo) for the Connissionae, USNRC Fchuay 25, 199. ics am~ ava'lable fr"or m eorpying f a fee =fr9= NRC Public Document Room at 2120 L Sret NW., Washington, DC; 1he PDR's maiing address is Mail Stop LL.6,