Document: NRC Regulatory Guide
Document ID: a4944d20-ef6e-480b-a45d-14425bedd2e5
Document Type: regulatory_guide
Title: ASME Code Cases Not Approved for Use (Rev. 8)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML2219/ML22196A065.pdf
Revision Date: 2023-05
Chapter: 
Section ID: RG-1.193
CFR Part: 
CFR Title: 

Content:
ugh RG 1.147. The NRC has dispositioned Code Case N-722-2 as unacceptable. 9/8/11 N-729-9 Alternative Examination Requirements for PWR Reactor Vessel Upper Heads With Nozzles Having Pressure-Retaining Partial-Penetration Welds, Section XI, Division 1 Code Case N-729 is mandated with conditions as specified in 10 CFR 50.55a for augmented examinations of PWR reactor vessel upper head penetrations. 2/21E N-740-2 Dissimilar Metal Weld Overlay for Repair of Class 1, 2, and 3 Items, Section XI, Division 1 The NRC staff identified many technical issues regarding the provisions of Revisions 0 and 1. The issues were communicated to the cognizant Section XI committees, and the staff continues to work with the committees to resolve the issues. Due to the total number of issues and the nature of some (e.g., lack of certain fundamental design details), the staff determined that it would be inappropriate to attempt to conditionally approve either version 0 or 1 in RG 1.147. 11/10/08 DG-1408, Page 17 CODE CASE NUMBER TABLE 2 UNACCEPTABLE SECTION XI CODE CASES SUMMARY DATE OR SUPPLEMENT/ EDITION The ASME has approved and published Code Case N-740-2. Although Revision 2 addresses some of the NRC staff’s concerns, significant issues remain. For example, the definition of nominal weld and base material appear to be inconsistent with the provisions of Section III. In addition, additional detail is required on how to perform the flaw growth or design analysis. Finally, additional detail is required on how the overlays are designed. N-770-7 Alternative Examination Requirements and Acceptance Standards for Class 1 PWR Piping and Vessel Nozzle Butt Welds Fabricated With UNS N06082 or UNS W86182 Weld Filler Material With or Without Application of Listed Mitigation Activities, Section XI, Division 1 The NRC requires the Code Case N-770 examinations to be performed as an augmented inspection program under 10 CFR 50.55a(g)(6)(ii)(F). The latest version of Code Case N-770 approved by the NRC