Document: NRC Regulatory Guide
Document ID: 96ecfd93-e64a-4f35-93fe-d3b95daac61d
Document Type: regulatory_guide
Title: Monitoring the Effectiveness of Maintenance at Nuclear Power Plants + HISTORY –HISTORY 06/2018 – DG-1336 , Proposed Revision 4 09/2011 – DG-1278 , Proposed Revision 3 08/1996 – DG-1051 , Proposed Revision 2 06/1994 – DG-1031, Proposed Revision 1 11/1992 – DG-1020, Proposed Revision 0 (Rev. 4)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1812/ML18129A080.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.160
CFR Part: 
CFR Title: 

Content:
d be considered for inclusion as defined in 10 CFR 50.65(b). 4. Nonsafety related SSCs Section 8.2.1.2 “Nonsafety-Related SSCs that Mitigate Accidents or Transients” is endorsed with the following clarification. The NRC endorses Section 8.2.1.2 of NUMARC 93-01, Rev. 4F, without any limitations or conditions. In its 1991 Final Rule, 56 FR 31,306, the Commission discussed "defense-in-depth" at various locations. Minimizing challenges to safety systems is consistent with the Commission's defense-in-depth philosophy. 56 FR at 31,307. The maintenance rule provides for continued emphasis on the defense-in- depth principle by including selected BOP (i.e., nonsafety-related) SSCs, integrates risk consideration into the maintenance process, provides an enhanced regulatory basis for inspection and enforcement of BOP maintenance-related issues. 56 FR 31,308. To ensure that licensees operate safely, NRC's regulatory program is intended to ensure both a low frequency of transients that challenge safety systems and a high reliability of safety systems to respond to these challenges. 56 FR at 31,314. This approach to regulation is part of the fundamental principle of defense-in-depth that underlies all NRC regulation. 56 FR at 31,314-315. Defense-in-depth provides for both accident prevention and accident mitigation with principal emphasis on prevention. 56 FR at 31,315. The scope of SSCs subject to the maintenance rule includes safety-related SSCs, and certain nonsafety-related SSCs that meet one or more of four specific criteria in 50.65(b)(2). 56 Fed. Reg. 31,310. The intention of 50.65(a)(1) is that the licensee establish a monitoring regime which is sufficient in scope to provide reasonable assurance that (1) intended safety, accident mitigation and transient mitigation functions (“intended functions”) of the structures, systems, and components (SSCs) described in paragraphs (b)(1) and (b)(2)(i) can be performed; and (2) for the SSCs described in paragraphs (b)(2)(ii)