Document: NRC Regulatory Guide
Document ID: 7d480029-59df-44fe-9db8-c1c86566dac9
Document Type: regulatory_guide
Title: Operation and Maintenance Code Case Acceptability, ASME OM Code (Rev. 5)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML2219/ML22196A063.pdf
Revision Date: 2023-05
Chapter: 
Section ID: RG-1.192
CFR Part: 
CFR Title: 

Content:
he 1995 Edition up to and including the 2000 Addenda of the OM Code when applied in conjunction with the provisions for leakage rate testing in, as applicable, ISTC 4.3 (1995 Edition with the 1996 and 1997 Addenda) and ISTC 3600 (1998 Edition through the 2004 Addenda). In addition, licensees who continue to implement Section XI of the ASME BPV Code as their Code of Record may use OMN-1 in lieu of the provisions for stroke-time testing specified in Paragraph 4.2.1 of ASME/ANSI OM Part 10 as required by 10 CFR 50.55a(b)(2)(vii) subject to the conditions in this RG. Licensees who choose to apply OMN-1 must apply all its provisions. (1) The adequacy of the diagnostic test interval for each MOV must be evaluated and adjusted as necessary, but not later than 5 years or three refueling outages (whichever is longer) from initial implementation of OMN-1. (2) When extending exercise test intervals for high-risk MOVs beyond a quarterly frequency, licensees must ensure that the potential increase in CDF and risk associated with the extension is small and consistent with the intent of the Commission’s Safety Goal Policy Statement. (3) When applying risk insights as part of the implementation of OMN-1, licensees must categorize MOVs according to their safety significance using the methodology described in OM Code Case OMN-3, with the conditions discussed in this RG, or using other MOV risk-ranking methodologies accepted by the NRC on a plant-specific or industrywide basis with the conditions in the applicable safety evaluations. NOTE: As indicated at 64 FR 51370–51386, licensees are cautioned that, when implementing OMN- 1, the benefits of performing a particular test should be balanced against the potential adverse effects placed on the valves or systems caused by this testing. OMN-2 (1998 Addenda) (2001 Edition) (2004 Edition) (2009 Edition) (2012 Edition) Thermal Relief Valve Code Case, OM Code-1995, Appendix I (Note: This OM Code Case was annulled in the 2017 Edition of