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:
ent (e.g., a pump failure results in loss of flow that causes a trip). Standby SSCs are those whose failure would not become apparent until the next demand, actuation, or surveillance. Only those SSCs of low safety significance whose failure would be readily apparent (because they are normally operating) should be monitored by plant-level criteria. SSCs may have both normally operating and standby functions. To adequately monitor the effectiveness of maintenance for the SSCs associated with standby functions, licensees should develop SSC-specific performance criteria or goals, or condition monitoring. Safety Significance Safety Significance Categories The Maintenance Rule requires that goals be established commensurate with safety. To implement this requirement, NUMARC 93-01 establishes two safety significance categories, “risk significant” and “non-risk significant.” Within Section 9.0 “Establishing Risk and Performance Criteria/Goal Setting and Monitoring” of NUMARC 93-01 the process for placing SSCs in either of these two categories is described. The Statements of Consideration for the rule use the terms “more risk- significant” and “less risk-significant.” NRC Inspection Procedure 71111.12, “Maintenance Effectiveness” (Ref. 16), uses several terms discussing safety significance. The NRC staff determined that the preferred terminology is that described in the inspection procedure. Some licensees may elect to define other safety significance categories or may elect to define more than two categories, which would be acceptable if these alternative categories are defined in the licensee’s procedures and used consistently. DG-1336, Page 14 Safety-Significance Ranking Methodology The NRC’s endorsement of the safety significance ranking methodology in NUMARC 93-01 for purposes of the Maintenance Rule should not be construed as an endorsement of that methodology for other applications. Normally Operating SSCs of Low Safety Significance