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 a new paragraph (a)(4): 

Before performing maintenance activities (including but not limited to surveillances, 

post-maintenance testing, and corrective and preventive maintenance), the licensee 

shall assess and manage the increase in risk that may result from the proposed 

maintenance activities. The scope of the assessment may be limited to structures, 

systems, and components that a risk-informed evaluation process has shown to be 

significant to public health and safety. [64 FR 38551, July 19, 1999, "Monitoring 

the Effectiveness of Maintenance at Nuclear Power Plants"] 

As of July 1998, Maintenance Rule Baseline Inspections at all U.S. nuclear power plant sites were 

complete. NRC staff experience during the baseline inspections indicated that all licensees have 

developed programs to implement the recommended pre-maintenance assessment provision of the original 

paragraph (a)(3). However, the baseline inspections identified a number of instances in which these 

assessments were not performed (including some that caused a significant increase in risk) and identified 

weaknesses in licensees' programs that could result in failures to perform adequate assessments prior to 

maintenance activities. Partly because of these inspection findings, the Commission approved the 

Regulatory guides are issued to describe and make available to the public such information as methods acceptable to the NRC staff for implementing specific 

parts of the NRC's regulations, techniques used by the staff in evaluating specific problems or postulated accidents, and data needed by the NRC staff in 

its review of applications 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 if they 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 to the 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, or by fax to (301)415-2289, or by email to DISTRIBUTION@NRC.GOV. Many regulatory guides are 

also available on the internet at NRC's home page at <WWW.NRC.GOV> or through NRC's Electronic Reading Room at the same web site. This Regulatory 

Guide 1.182 is ADAMS Accession Number ML003699426.

May 2000
amendment to ensure that licensees assess and manage increases in risk associated with 

maintenance activities. 

In a series of public meetings, the NRC staff met with industry representatives to discuss the 

change in the rule in relation to proposed revisions to Revision 2 of NUMARC 93-01, "Industry 

Guideline for Monitoring the Effectiveness of Maintenance at Nuclear Power Plants"1 (May 1993). 

Revision 2 of NUMARC 93-01 was prepared by the Nuclear Energy Institute (NEI) and is 

endorsed by Revision 2 of Regulatory Guide 1.160, "Monitoring the Effectiveness of Maintenance 

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 a revised Section 11 to NUMARC 93-01. 

Regulatory Guide 1.182 will be used as a companion guide to Regulatory Guide 1.160 as 

guidance on methods acceptable to the NRC staff for assessing and managing the increase in risk 

that may result from maintenance activities and for implementing the optional reduction in scope of 

SSCs considered in the assessments. 

The information collections contained in this regulatory guide are covered by the 

requirements of 10 CFR Part 50, which were approved by the Office of Management and Budget, 

approval number 3150-0011. If a means used to impose an information collection does not display 

a currently valid OMB control number, the NRC may not conduct or sponsor, and a person is not 

required to respond to, the information collection. 

B. DISCUSSION 

The objective of the Maintenance Rule, 10 CFR 50.65, is to require monitoring of the 

overall continuing effectiveness of licensee 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 of safety-related functions, and (3) failures resulting in scrams and 

unnecessary actuations of safety-related systems are minimized. (Note that, for Maintenance Rule 

purposes, the term "SSC" may denote a structure, system, or train. Although components may be 

monitored individually at the licensee's discretion, the Rule and its guidance generally do not 

require monitoring to that level of detail.) 

The benefits of performing maintenance activities during power operations include 

increased system and plant reliability, reduction of plant equipment and system material condition 

'Copies are available for inspection or copying for a fee from the NRC Public Document Room at 2120 L Street 

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.

1.182-2
deficiencies that could adversely impact plant operations, and reduction of work scope during plant 

refueling outages. However, relevant margins of safety could be inadvertently reduced under 

certain conditions, for example, if maintenance is performed at power without proper controls and 

careful consideration of risk. The intent of 10 CFR 50.65(a)(4) is to require that licensees perform 

assessments before maintenance activities are performed on SSCs covered by the Maintenance Rule 

and manage the increase in risk that may result from the proposed activities. The results of these 

assessments are to be used in conjunction with other regulatory requirements and, therefore, cannot 

be used as justification to perform activities which may not comply with other regulations. 

Performing the assessment of Section 11 does not relieve the licensee from compliance with 

its license (including technical specifications) and applicable regulations. The intent of certain 

phrases in this guide is to 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 of the specific maintenance activity 

being assessed. (Note that when a maintenance activity to restore a degraded condition is planned, 

a compensatory measure already in place addressing that condition would have to be considered in 

the assessment under 10 CFR 50.65(a)(4) if the measure is to remain in place during the 

maintenance activity.) 

C. REGULATORY POSITION 

Section 11, "Assessment of Risk Resulting from Performance of Maintenance Activities," 

dated February 11, 2000, of NUMARC 93-01, "Industry Guideline for Monitoring the 

Effectiveness of Maintenance at Nuclear Power Plants," provides methods that are acceptable to 

the NRC staff for complying with the provisions of 10 CFR 50.65(a)(4). Section 11 references 

other documents, but NRC's endorsement of Section 11 should not be considered as endorsement 

of the referenced documents. Note that, in paragraph 1. of Section 11.3.7.2, the value "10"3/year" 

is suggested by the authors as a ceiling for configuration-specific core damage frequency. The 

subject of such a ceiling value is currently being studied by the NRC. At some later date, a similar 

or different value may be promulgated by the agency. At this time, the NRC neither endorses nor 

disapproves of the 10"3/year value. 

D. IMPLEMENTATION 

The purpose of this section is to provide information to licensees and applicants regarding 

the NRC 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 of the NRC's regulations, the method described in 

this guide will be used with Regulatory Guide 1.160 in the evaluation of assessment processes 

before maintenance activities, management of the increases in risk from maintenance activities, and 

implementation of the option to reduce the scope of SSCs considered for the assessments.

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REGULATORY ANALYSIS

The regulatory analysis that was published with the July 19, 1999, revision to the 

Maintenance Rule, 10 CFR 50.65, is also applicable for this Regulatory Guide 1.182. A copy of 

the regulatory analysis is available for inspection or copying for a fee in the 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

years