Document: 10 CFR Part 50
Document ID: cfc9c7b0-bbcd-4774-97ce-900cbc760408
Document Type: cfr
Title: Codes and standards.
Source: 10 CFR Part 50
Source URL: https://www.ecfr.gov/current/title-10/part-50/section-50.55a
Revision Date: 
Chapter: 
Section ID: 50.55a
CFR Part: 50
CFR Title: 10

Content:
1 ) Implementation. Holders of operating licenses or combined licenses for pressurized water reactors as of or after September 30, 2024, shall implement the requirements of ASME BPV Code Case N-770-7 instead of ASME BPV Code Case N-770-5, subject to the conditions specified in paragraphs (g)(6)(ii)(F)( 2 ) through ( 16 ) of this section, by no later than one year after September 30, 2024. All NRC authorized alternatives from previous versions of paragraph (g)(6)(ii)(F) of this section remain applicable. ( 2 ) Categorization. ( i ) Welds that have been mitigated by the Mechanical Stress Improvement Process (MSIP TM ) may be categorized as Inspection Items D or E, as appropriate, provided the criteria in Appendix I of the code case have been met. ( ii ) In order to be categorized as peened welds, in lieu of inspection category L requirements and examinations, welds must meet the performance criteria, qualification and examination requirements as stated by MRP-335, Revision 3-A, with the exception that no plant-specific alternative is required. ( iii ) Other mitigated welds shall be identified as the appropriate inspection item of the NRC authorized alternative or NRC-approved code case for the mitigation type in the appropriate NRC regulatory guides, as incorporated by reference in paragraph (a)(3) of this section. ( iv ) All other butt welds that rely on Alloy 82/182 for structural integrity shall be categorized as Inspection Items A-1, A-2, B-1 or B-2, as appropriate. ( v ) Paragraph -1100(e) of ASME BPV Code Case N-770-5 shall not be used to exempt welds that rely on Alloy 82/182 for structural integrity from any requirement of this section. ( 3 ) [Reserved] ( 4 ) Examination coverage. When implementing Paragraph -2500(a) of ASME BPV Code Case N-770-5, essentially 100 percent of the required volumetric examination coverage shall be obtained, including greater than 90 percent of the volumetric examination coverage for circumferential flaws. Licensees are prohibited