ML16245A898

NRC Staffs Proposed Resolution of Issues Identified in Its Evaluation of Shutdown and Low-Power Operations

ML16245A898
Person / Time
Issue date:	09/15/1992
From:	Ward D Advisory Committee on Reactor Safeguards
To:	Taylor J NRC/EDO
References
D920915
Download: ML16245A898 (3)

Text

D920915 Mr. James M. Taylor Executive Director for Operations U.S. Nuclear Regulatory Commission Washington, D.C. 20555

SUBJECT:

NRC STAFF'S PROPOSED RESOLUTION OF ISSUES IDENTIFIED IN ITS EVALUATION OF SHUTDOWN AND LOW-POWER OPERATIONS During the 389th meeting of the Advisory Committee on Reactor Safeguards, September 10-12, 1992, we reviewed the staff's proposed Generic Letter (GL) 92-XX concerning resolution of the issues identified in its evaluation of shutdown and low-power operational risk (Draft NUREG-1449). The staff plans to issue this GL for public comment. Our Plant Operations Subcommittee considered this matter during its September 9, 1992 meeting. During these meetings, we had the benefit of discussions with representatives of the NRC staff and NUMARC. We also had the benefit of the documents referenced. We previously provided comments to you on the staff's program to resolve these issues in our letters of August 13, 1991 and April 9, 1992.

The proposed GL describes those actions that the staff believes are needed by holders of OLs and CPs to resolve shutdown and low-power operational risk issues. It also includes a regulatory analysis in support of the need for these actions. We note that NUMARC had not seen the proposed GL prior to our meetings and was therefore limited in its ability to comment at this time.

The proposed GL represents a generally appropriate means of dealing with these issues. We have several comments, noted below, that we believe the staff should consider before releasing this GL for public comment.

The staff proposes a technical specification (TS) for PWRs that would require that containment integrity (at least a single barrier in all penetrations) be maintained for the first seven days after shutdown. We agree that containment integrity should be maintained during any reduced inventory operation that takes place when decay heat is at a high level.

We found many problems with the staff's proposed implementa-tion of this requirement during this review. The staff has told us that it will make appropriate revisions to this TS requirement and expects to interface with industry groups on this issue during the public comment period.

The staff proposes that a fire hazards analysis be performed for decay heat removal (DHR) equipment used during cold shutdown and refueling. Licensees would be required to document the results and develop a DHR restoration contingency plan. On the basis of our discussion with the staff and NUMARC, we believe that the guidance provided in the proposed

GL could lead to fire-analysis requirements far beyond those that have been justified by the staff. We believe that more dialogue between the staff and industry is needed on this issue.

The staff has prepared a regulatory analysis in support of the proposed GL. If taken at face value, the quantitative aspects of this analysis support the conclusions reached by the staff.

However, the needed PRA input is not yet available and many questionable assumptions were made. The staff is in the process of completing two shutdown risk PRAs (Surry Power Station and Grand Gulf Nuclear Station). These will not be finished until the spring of 1993. While we agree that the staff's regulatory analysis provided some insights and should be issued for information, it does not justify the imposition of the GL requirements. The staff told us that it believes that the GL could be issued on the basis of a qualitative substantial additional protection argument. (The word "substantial" remains undefined.) A qualitative argument is already the basis for the fire-protection requirement of the GL.

In the past we have raised five related issues. The staff indicated that it would provide a response to these issues in the near future. In addition, we would like to be kept informed on the status of the follow-up study that the staff intends to perform on the issue of the control of switchyard and grid activities with the plant operating at power.

We expect to comment on the proposed final version of this GL after public comments have been reconciled.

Sincerely, David A. Ward Chairman

1. Memorandum (Undated) to Holders of Operating Licenses or Construction Permits for Light-Water Power Reactors,

Subject:

Resolution of Issues Identified in the NRC Staff's Evaluation of Shutdown and Low-Power Operations Pursuant to 10 CFR 50.54(f) (Generic Letter 92-XX), transmitted by memorandum dated August 6, 1992 from Gary M. Holahan, Office of Nuclear Reactor Regulation, NRC, for Raymond F. Fraley, ACRS

2. U. S. Nuclear Regulatory Commission, NUREG-1449, "Shutdown and Low-Power Operation at Commercial Nuclear Power Plants in the United States," Draft Report, February 1992

3. Letter dated April 9, 1992, from David A. Ward, Chairman, ACRS, to James M. Taylor, Executive Director for Operations, NRC,

Subject:

Evaluation of the Risks During Shutdown and Low-Power Operations for U.S. Nuclear Power Plants

4. Letter dated August 13, 1991, from David A. Ward, Chairman, ACRS, to James. M. Taylor, Executive Director for Operations, NRC,

Subject:

Evaluation of Risks During Low Power and

Shutdown Operations of Nuclear Power Plants