United States Nuclear Regulatory Commission - Protecting People and the Environment

Modified Proposed Final Revision to 10 CFR 50.65, "Requirements for Monitoring the Effectiveness of Maintenance at Nuclear Power Plants"

May 11, 1999

The Honorable Shirley Ann Jackson
Chairman
U.S. Nuclear Regulatory Commission
Washington, D.C. 20555-0001

Dear Chairman Jackson:

SUBJECT: MODIFIED PROPOSED FINAL REVISION TO 10 CFR 50.65, "REQUIREMENTS FOR MONITORING THE EFFECTIVENESS OF MAINTENANCE AT NUCLEAR POWER PLANTS"

During the 462nd meeting of the Advisory Committee on Reactor Safeguards, May 5-8, 1999, we reviewed the modified proposed final revision to 10 CFR 50.65 and proposed revisions to Regulatory Guide 1.160, "Assessing and Managing Risk Before Maintenance Activities at Nuclear Power Plants." During our review, we had the benefit of discussions with representatives of the NRC staff and Nuclear Energy Institute (NEI). We also had the benefit of the documents referenced.

We reviewed a previous version of 10 CFR 50.65 during our 461ST meeting and issued a report dated April 14, 1999. In that report, we stated that both high safety significant structures, systems, and components (SSCs) and low safety significant SSCs need to be addressed by the Maintenance Rule. We note that the usual classification of SSCs as high or low safety significant is based on probabilistic risk assessments (PRAs) of typical configurations at power. A different configuration or a different mode of operation may change the relative rankings of the SSCs.

Since our April 14, 1999 report, the staff has proposed to add the following language to paragraph(a)(4) of 10 CFR 50.65: "Scope of the assessment may be limited to structures, systems, or components that a risk-informed evaluation process has shown to be significant to public health and safety." We recommend the following modification to the staff's proposed language:

"Scope of the assessment may be limited to structures, systems, or components that a risk- informed evaluation process has shown to be significant to public health and safety for the proposed configuration."

The staff also stated that it is considering revising Regulatory Guide (RG) 1.160 to adopt the configuration risk management program (CRMP) in RG 1.177, "An Approach for Plant-Specific, Risk-Informed Decisionmaking: Technical Specifications." The program described under Key Component 1 of Section 2.3.7.2 of RG 1.177 requires an assessment of all SSCs modeled in the licensee's PRA in addition to all SSCs considered high safety significant that are not modeled in the PRA. This program, however, does not include a discussion of other SSCs. The CRMP was designed for extending outage time as allowed in the technical specifications and may not be appropriate for managing the risk of maintenance activities. Since the number of low safety significant SSCs modeled in licensees' PRAs may vary widely, we are concerned that there may be configurations of SSCs out of service for maintenance that would not have received an assessment. We recommend that the CRMP in RG 1.177 not be adopted.

We believe that licensees need to take responsibility for evaluating and managing the risk associated with taking multiple SSCs out of service. Plant operators should not be confronted with inadequately evaluated plant configurations. This can be avoided by appropriately evaluating the actual configuration. We note that currently operating plants have not been designed with the intent of performing on-line maintenance, but recognize that technology is now available to manage appropriately the risk associated with on-line maintenance. Therefore, we support the industry practice of performing on-line maintenance, as long as this is done safely.

Sincerely,

/s/

Dana A. Powers
Chairman

References:

  1. Modified proposed Final Revision to 10 CFR 50.65, "Requirements for Monitoring the Effectiveness of Maintenance at Nuclear Power Plants," received May 5, 1999.

  2. U. S. Nuclear Regulatory Commission, Revision 3 to Regulatory Guide 1.160 (DG-1082), "Assessing and Managing Risk Before Maintenance Activities at Nuclear Power Plants," April 1999.

  3. Report dated April 14, 1999, from Dana A. Powers, Chairman, ACRS, to Shirley Ann Jackson, Chairman, NRC, Subject: Proposed Final Revision to 10 CFR 50.65, "Requirements for Monitoring the Effectiveness of Maintenance at Nuclear Power Plants."

  4. U. S. Nuclear Regulatory Commission, Regulatory Guide 1.177, "An Approach for Plant- Specific, Risk-Informed Decisionmaking: Technical Specifications," August 1998.

  5. Letter dated December 14, 1998, from Anthony R. Pietrangelo, Nuclear Energy Institute, to John C. Hoyle, Secretary of the Commission, Subject: Industry Comments on Proposed Rulemaking to 10 CFR 50.65(a)(3), Requirements for Monitoring the Effectiveness of Maintenance at Nuclear Power Plants.

  6. Letter dated January 22, 1999, from Ralph E. Beedle, Nuclear Energy Institute, to Shirley Ann Jackson, Chairman, NRC, regarding proposed revision to the maintenance rule and 10 CFR 50.59.

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