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:
ions (“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) and (b)(2)(iii), failures will not occur which prevent the fulfillment of safety-related functions, and failures resulting in scrams and unnecessary actuations of safety related systems are minimized. 56 FR at 31,308. 10 CFR 50.65(b)(2)(i) requires in part that the scope of the monitoring program includes nonsafety related SSCs “[t]hat are relied upon to mitigate accidents or transients.” Where the initial licensing of the plant was complete prior to the Commission’s order requiring FLEX equipment, EA 12-049, the FLEX equipment presumably has no “intended function” (intended safety, accident mitigation and transient mitigation functions as described in paragraphs Sections 50.62(b)(1) and 50.65 DG-1336, Page 20 (b)(2)(i)) for that plant. However, it is possible that, through license amendments under 50.90-50.92, or through changes made to the FSAR or facility without license amendments under 50.59, a licensee might have commenced “rely[ing] upon” flex equipment under 50.65(b)(2)(i). Planning to use FLEX equipment as part of defense-in-depth, i.e., as an additional beyond-the-FSAR way to prevent or mitigate an accident, is not the same as “rely[ing] upon” the equipment under 50.65(b)(2)(i); the FLEX equipment does not automatically gain an “intended function” when a plan is made to use FLEX equipment as part of defense in depth. Last, where a licensee does formulate a beyond-the-FSAR defense in depth plan to use equipment, the equipment might still scope into the maintenance rule under 50.65(b)(2)(ii) or (b)(2)(iii) if failure of the defense in depth (e.g. FLEX) equipment could prevent safety-related structures, systems, and components from fulfilling their safety-related function; or could cause a reactor scram or actuation of a safety-related