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:
implements an OM Code Case, 10 CFR 50.55a requires implementation of the most recent version of that Code Case as listed in Tables 1 and 2. If an applicant or licensee implements an OM Code Case and a later version of the Code Case is incorporated by reference into 10 CFR 50.55a and listed in Tables 1 and 2 during the licensee’s present 120-month IST program interval, that licensee may use either the later version or the previous version. An exception to this provision would be the inclusion of a condition on the use of the OM Code Case that is necessary, for example, to enhance safety. Licensees who choose to continue use of the OM Code Case during the subsequent 120-month IST program interval will be required to implement the latest version incorporated by reference into 10 CFR 50.55a and listed in Tables 1 and 2. ASME may annul OM Code Cases because the provisions have been incorporated into the OM Code, the application for which it was specifically developed no longer exists, or experience has shown that an examination or testing method is no longer adequate. After ASME has annulled an OM Code Case, and the NRC has amended 10 CFR 50.55a and this guide, applicants or licensees may not implement that OM Code Case for the first time. However, an applicant or licensee who implemented the OM Code Case prior to annulment may continue to use that Code Case through the end of the present IST interval. An annulled OM Code Case cannot be used in the subsequent IST interval unless implemented as an approved alternative under 10 CFR 50.55a(z). If an OM Code Case is incorporated by reference into 10 CFR 50.55a and ASME later annuls it because experience has shown that an examination or testing method is inadequate, the NRC will amend 10 CFR 50.55a and this guide to remove the approval of the annulled Code Case. Applicants or licensees should not begin to implement such annulled OM Code Cases before the rulemaking. Notwithstanding these requirements, the Commission may