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:
e 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 The 12/20/10 DG-1408, Page 35 CODE CASE NUMBER TABLE 5 ANNULLED OR SUPERSEDED UNACCEPTABLE SECTION XI CODE CASES ANNULLMENT OR REVISION DATE NRC staff finds it is unacceptable to allow such a large flaw to remain in service in Class 1 piping. b. In paragraphs 2.(c)(1) and 2.(c)(2) of Code Case N-766, the postulated and as-left flaws need to be evaluated because the postulated flaws are supposed to represent the capabilities of the NDE techniques applied. For example, if a 15-degree circumferential flaw that is 11% through- wall is detected, this would be evaluated instead of a 360-degree, 10% through-wall flaw. A 360-degree, 10% through-wall flaw should be analyzed to determine the fatigue and stress-corrosion cracking degradation mechanisms. c. Paragraph 2.(f) of Code Case N-766 should be revised to include the following: “The flaw growth calculation due to stress corrosion cracking should include the welding residual stresses. The flaw growth calculation shall be performed in accordance with IWB-3640 and/or Appendix C to the Section XI” Note: The NRC conditionally approved Code Case N-766-3 in RG 1.147. N-770-3 N-770-4 N-770-5 N-770-6 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 is incorporated by reference in 10 CFR 50.55a. The staff expects to review the latest Code-approved version of Code Case N-770 for incorporation directly in 10 CFR 50.55a under 10 CFR 50.55a(g)(6)(ii)(F). 4/7/13 5/7/14 0/17E 4/18/19 N-780 Alternative Requirements for Upgrade, Substitution, or