### U.S. NUCLEAR REGULATORY COMMISSION 

# REGULATORY GUIDE

44C• OFFICE OF NUCLEAR REGULATORY RESEARCH



## REGULATORY GUIDE 1.182 (Draft was issued as DG-1 082) 

### ASSESSING AND MANAGING RISK 

### BEFORE MAINTENANCE ACTIVITIES AT NUCLEAR POWER PLANTS

A. INTRODUCTION The U.S. Nuclear Regulatory Commission (NRC) has amended the Maintenance Rule, 10 CFR 50.65, by adding anew paragraph (a)(4): Beforeperforming maintenance activities (including but not limited to surveillances, post-maintenance testing, and corrective and preventive maintenance), the licensee shall assess andmanage the increase inrisk that mayresult from the proposed maintenance activities. The scope ofthe assessment may be limited to structures, systems, and components that arisk-informed evaluation process has shown to be significant to public health and safety. [64FR 38551, July 19, 1999, "Monitoring theEffectiveness ofMaintenance atNuclear Power Plants"]
As ofJuly 1998, Maintenance Rule Baseline Inspections at allU.S. nuclear power plant sites were complete. NRC staffexperience during the baseline inspections indicated that all licensees have developed programs to implement the recommended pre-maintenance assessment provision ofthe original paragraph (a)(3). However, the baseline inspections identified a number ofinstances in which these assessments were not performed (including somethat caused a significant increase in risk) and identified weaknesses in licensees' programs that could result infailures to perform adequate assessments prior to maintenance activities. Partly because ofthese inspection findings, the Commission approved the

Regulatory guides areissued to describe and make available to the public such information as methods acceptable tothe NRC staff forimplementing specific parts ofthe NRC's regulations, techniques used by the staff in evaluating specific problems or postulated accidents, and data needed bythe NRC staff in itsreview ofapplications for permits and licenses. Regulatory guides are not substitutes for regulations, and compliance with them is not required. Methods and solutions different from those set out in the guides will be acceptable ifthey provide a basis for the findings requisite to the issuance or continuance of a permit or license by the Commission.
This guide was issued after consideration of comments received from the public. Comments and suggestions for improvements in these guides are encouraged at all times, and guides will be revised, as appropriate, to accommodate comments and to reflect new information or experience. Written comments may be submitted tothe Rules and Directives Branch, ADM, U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001. Regulatory guides are issued in ten broad divisions: 1, Power Reactors; 2, Research and Test Reactors; 3, Fuels and Materials Facilities; 4, Environmental and Siting; 5, Materials and Plant Protection; 6, Products; 7, Transportation; 8, Occupational Health; 9, Antitrust and Financial Review; and 10, General. Single copies of regulatory guides (which may be reproduced) may be obtained free of charge by writing the Distribution Services Section, U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, orby faxto (301)415-2289, or by email to DISTRIBUTION@NRC.GOV. Many regulatory guides are also available on the internet atNRC's home page at <WWW.NRC.GOV> orthrough NRC's Electronic Reading Room at the same web site. This Regulatory Guide 1.182 is ADAMS Accession Number ML003699426. 

### May 2000amendment to ensure that licensees assess and manage increases in risk associated with maintenance activities. In a series ofpublic meetings, theNRC staffmet withindustry representatives to discuss the change in the rule inrelation to proposed revisions to Revision 2 ofNUMARC 93-01, "Industry Guideline for Monitoring the Effectiveness ofMaintenance at Nuclear Power Plants"1 (May 1993). Revision 2 ofNUMARC 93-01 was prepared by theNuclear Energy Institute (NEI) and is endorsed byRevision 2 ofRegulatory Guide 1.160, "Monitoring theEffectiveness ofMaintenance at Nuclear Power Plants."2 Based in part on these discussions with industry representatives, this Regulatory Guide 1.182 provides guidance on implementing the provisions of 10 CFR 50.65(a)(4) by endorsing arevised Section 11 toNUMARC 93-01. Regulatory Guide 1.182 will be used as a companion guide toRegulatory Guide 1.160 as guidance on methods acceptable to the NRC stafffor assessing and managing the increase inrisk thatmay result from maintenance activities and for implementing the optional reduction in scope of SSCs considered in the assessments. The information collections contained inthis regulatory guide are covered by the requirements of10 CFR Part 50, which were approved by the Office ofManagement and Budget, approval number 3150-0011. Ifa meansused to impose an information collection does notdisplay a currently valid OMB control number, theNRC may not conduct or sponsor, and a person isnot required to respond to, the information collection.

B. DISCUSSION The objective ofthe Maintenance Rule, 10 CFR 50.65, is to require monitoring ofthe overall continuing effectiveness oflicensee maintenance programs to ensure that (1) safety-related and certain nonsafety-related structures, systems, and components (SSCs) are capable of performing their intended functions, (2) for nonsafety-related equipment, failures will not occur that prevent the fulfillment ofsafety-related functions, and (3) failures resulting in scrams and unnecessary actuations ofsafety-related systems are minimized. (Note that, for Maintenance Rule purposes, the term "SSC" may denote a structure, system, ortrain. Although components maybe monitored individually at the licensee's discretion, the Rule and its guidance generally do not require monitoring to that level ofdetail.) Thebenefits ofperforming maintenance activities during power operations include increased system and plant reliability, reduction ofplant equipment and system material condition

'Copies are available for inspection or copying for a fee from the NRC Public Document Room at 2120 LStreet NW., Washington, DC; the PDR's mailing address is Mail Stop LL-6, Washington, DC 20555; telephone (202)634-3273; fax (202)634-3343.
2Single copies of regulatory guides, both active and draft, and draft NUREG documents may be obtained free of charge by writing the Reproduction and Distribution Services Section, OCIO, USNRC, Washington, DC 20555-0001, or by fax to (301)415-2289, or by email to <DISTRIBUTION@NRC.GOV>. Copies of active and draft guides are available for inspection or copying for a fee from the NRC Public Document Room.

1.182-2deficiencies that could adversely impact plant operations, and reduction ofwork scope during plant refueling outages. However, relevant margins ofsafety couldbe inadvertently reduced under certain conditions, for example, ifmaintenance isperformed at power without proper controls and careful consideration ofrisk. Theintent of10CFR 50.65(a)(4) isto require that licensees perform assessments before maintenance activities are performed on SSCs covered bythe Maintenance Rule and manage the increase in riskthat may result from the proposed activities. The results ofthese assessments areto be used in conjunction with otherregulatory requirements and, therefore, cannot be used asjustification to perform activities which may not comply with other regulations. Performing the assessment ofSection 11 does not relieve the licensee from compliance with its license (including technical specifications) and applicable regulations. The intent ofcertain phrases in this guide isto eliminate overlapping requirements for assessments that could be considered to exist under 10 CFR 50.65(a)(4) and 10 CFR 50.59. This clarification applies to temporary alterations directly related to and required in support ofthe specific maintenance activity being assessed. (Note that when amaintenance activity to restore adegraded condition is planned, acompensatory measure already in place addressing that condition would have to be considered in the assessment under 10 CFR 50.65(a)(4) ifthe measure isto remain in place during the maintenance activity.)

C. REGULATORY POSITION Section 11, "Assessment ofRiskResulting from Performance ofMaintenance Activities," dated February 11, 2000, ofNUMARC 93-01, "Industry Guideline forMonitoring the Effectiveness ofMaintenance atNuclear Power Plants," provides methods that are acceptable to the NRC stafffor complying with the provisions of 10 CFR 50.65(a)(4). Section 11 references other documents, but NRC's endorsement ofSection 11 should not be considered as endorsement ofthe referenced documents. Note that, in paragraph 1.ofSection 11.3.7.2, the value "10"3/year" is suggested bythe authors as a ceiling for configuration-specific core damage frequency. The subject ofsuch a ceiling value is currently being studied bytheNRC. At somelater date, a similar ordifferent value maybe promulgated bythe agency. At this time,the NRC neither endorses nor disapproves ofthe 10" 3/year value.

D. IMPLEMENTATION The purpose ofthis section is to provide information to licensees and applicants regarding theNRC staff's plans for using this regulatory guide. Except in those cases in which a licensee or applicant proposes an acceptable alternative method for complying with specified portions ofthe NRC's regulations, the method described in this guide willbe used withRegulatory Guide 1.160in the evaluation ofassessment processes before maintenance activities, management ofthe increases in riskfrom maintenance activities, and implementation ofthe option to reduce the scope ofSSCs considered for the assessments.

1.182-3REGULATORY ANALYSIS The regulatory analysis that waspublished withthe July 19, 1999, revisionto the Maintenance Rule, 10 CFR 50.65, is also applicable for this Regulatory Guide 1.182. Acopy of the regulatory analysis is available for inspection or copying for afee inthe Commission's Public Document Room at 2120 L Street NW., Washington, DC, under task DG-1082.

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001



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