ML112570095

Draft RAI Requesting Licensee to Reanalyze ECCS Performance for LOCA Under Extended Power Uprate Conditions

ML112570095
Person / Time
Site:	Monticello
Issue date:	09/12/2011
From:	Tam P Plant Licensing Branch III
To:	Eckholt G, Fields J Northern States Power Co
Tam P
References
TAC MD9990
Download: ML112570095 (1)

Text

Accession No. ML112570095 From: Tam, Peter Sent: Monday, September 12, 2011 3:15 PM To: 'Fields, John S.'; Eckholt, Gene F.

Cc: 'Loeffler, Richard A.'; Anderson, Paula K.; Parks, Benjamin; Pascarelli, Robert

Subject:

Monticello - Draft RAI re. ECCS analysis for the EPU application (TAC MD9990)

John:

By letter dated July 7, 2011, NSPM submitted a 30-day report in accordance with the requirements of 10 CFR 50.46. NSPM stated that the 30-day report is being made due to several recent General Electric (GE)/Hitachi Nuclear Energy 10 CFR 50.46 notifications received that have resulted in a cumulative increase in Peak Cladding Temperature (PCT) exceeding 50°F. The NRC staff reviewed this 7/7/2011 submittal and has developed the following comments. If you wish, the NRC staff will be glad to discuss these comments with your staff in a conference call. Alternatively, you may forgo a conference call and let the staff issue a formal RAI to convey these comments as a formal RAI.

NSPM reported that the sum of the absolute value changes of the peak cladding temperature (PCT) since the last analysis of record to be 110°F. NSPM stated that:

Considering all estimated effects of errors and changes, the adjusted PCT is 2040°F. This is 160°F below the 2200°F acceptance criterion of 10 CFR 50.46(b)(1). This is sufficient margin to justify taking no further action. No further reanalysis or other actions are planned.

10 CFR 50.46(a)(3)(ii) requires that the report include a proposed schedule for providing a reanalysis or taking other action as may be needed to show compliance with 10 CFR 50.46 requirements. Although NSPM stated that no further reanalysis or other actions are planned, the NRC staff is currently reviewing an ECCS evaluation in support of NSPMs extended power uprate application. The staff believes that the above errors, which generically affect the SAFER/GESTR-LOCA ECCS evaluation model on which the Monticello evaluation is based, may invalidate the EPU ECCS evaluation. The NRC staff does not, as a matter of general practice, approve ECCS evaluations that are known to contain errors.

Accordingly, the NRC staff is requesting that NSPM expeditiously supplement the EPU application to provide a revised ECCS evaluation that accounts for EPU operation and corrects for the errors discussed in NSPMs July 7, 2011, 30-day notification letter.

Peter S. Tam, Senior Project Manager (for D.C. Cook and Monticello)

Plant Licensing Branch III-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Tel. 301-415-1451