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:
NRC unconditionally approved Code Case N-716-2 in RG 1.147. 4/10/06 N-729-3 N-729-4 N-729-5 N-729-6 N-729-7 N-729-8 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. 4/4/12 6/22/12 3/15E 5/15E 6/17E 3/27/19 N-740 N-740-1 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. 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. 10/12/06 12/25/09 N-766 Nickel Alloy Reactor Coolant Inlay and Onlay for Mitigation of PWR Full Penetration Circumferential Nickel Alloy Dissimilar Metal Welds of Class 1 Items, Section XI, Division 1 a. Paragraph 1.(c)(1) of Code Case N-766 would potentially allow a 75% through-wall flaw to remain in service in the original Alloy 82/182 dissimilar metal weld, in accordance with Section XI, IWB-3600. The 12/20/10 DG-1408, Page 35 CODE CASE NUMBER TABLE 5 ANNULLED OR SUPERSEDED UNACCEPTABLE SECTION XI CODE CASES