Proposed Final Regulatory Guide 1.XXX, "Assessing and Managing Risk Before Maintenance Activities at Nuclear Power Plants"

March 10, 2000

The Honorable Richard A. Meserve
U.S. Nuclear Regulatory Commission
Washington, D.C. 20555-0001

Dear Chairman Meserve:


During the 470th meeting of the Advisory Committee on Reactor Safeguards, March 1-4, 2000, we reviewed the proposed final Regulatory Guide 1.XXX, "Assessing and Managing Risk Before Maintenance Activities at Nuclear Power Plants," which was developed to supplement Regulatory Guide 1.160, "Monitoring the Effectiveness of Maintenance at Nuclear Power Plants." Regulatory Guide 1.XXX endorses the revised Section 11, "Assessment of Risk Resulting from Performance of Maintenance Activities," of NUMARC 93-01. During our review, we had the benefit of discussions with representatives of the NRC staff and of the documents referenced.


1. The proposed final Regulatory Guide 1. XXX, which is a supplement to Regulatory Guide 1.160 should be approved for industry use.
2. We support the staff's endorsement of Section 11 of NUMARC 93-01 guidance document.


During our 467th meeting, November 4-6, 1999, we were briefed by the NRC staff and the Nuclear Energy Institute (NEI) on the proposed Revision 3 to Regulatory Guide 1.160 and were told that there were minor issues to be resolved, including the definition of unavailability. Subsequently, the NRC staff and NEI have resolved these issues and have agreed upon the definition of unavailability. We note that this definition reflects the contributions to unavailability of planned and unplanned down times only. This definition is acceptable for the purposes of Regulatory Guide 1.XXX.

During our discussion of Regulatory Guide 1.XXX, the staff identified additional changes proposed by NEI to Sections 11.3.2 and 11.3.8 of NUMARC 93-01. These changes are to address temporary alterations that are necessary for maintenance during power operations. For such temporary alterations, no review would be required under 10 CFR 50.59 unless the alterations are expected to be in effect for more than 90 days during power operation.

The staff states that temporary alterations, which are in effect less than 90 days, will be assessed under the requirements of 10 CFR 50.65(a)(4). To clarify the need for these assessments, the staff proposes to add the following paragraph to the implementation Section of Regulatory Guide 1.XXX:

The assessment does not relieve the licensee from obligations to its license or the regulations. The exemption requirements and 10 CFR 50.90 remain in effect. The intent is to eliminate overlapping requirements for assessments which 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 to support the specific maintenance activity being assessed.

We agree that licensees should not be required to perform duplicate assessments for temporary alterations during maintenance activities. We agree with the proposed additional paragraph. Regulatory Guide 1.XXX should be approved for industry use.

Dana A. Powers

References :

1. Memorandum dated February 16, 2000, from Theodore R. Quay, Office of Nuclear Reactor Regulation, NRC, to John T. Larkins, ACRS, Subject: Request for Review of Regulatory Guidance for 10 CFR 50.65, The Maintenance Rule.
2. Final Section 11 of NUMARC 93-01, "Assessment of Risk Resulting from Performance of Maintenance Activities," February 11, 2000.
3. NUMARC 93-01, Revision 2, Nuclear Energy Institute, "Industry Guideline for Monitoring the Effectiveness of Maintenance at Nuclear Power Plants," (line-in/line-out version), April 1996.
4. U. S. Nuclear Regulatory Commission, Regulatory Guide 1.160, Revision 2, "Monitoring the Effectiveness of Maintenance at Nuclear Power Plants," March 1997.

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