ML20197H654

Forwards Nonproprietary WCAP-12764 & Proprietary WCAP-12763, Steam Generator Tube Collapse Considerations Presentation Matls. WCAP-12763 Withheld

ML20197H654
Person / Time
Site:	Farley
Issue date:	11/18/1990
From:	Hairston W ALABAMA POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML19310C887	List: ML20197H654 ML20197H660 ML20197H665
References
NUDOCS 9011200033
Download: ML20197H654 (4)

Text

A Alabams Powir Company

< 40 inverness Center Parkway cost Office Box 1295 Dirmingham, Alabama 35201 Telephone 205 868-5581 W o. Hairston,111 S%7&*O%**

AlabamaPower t

November 18, 1990

' Docket No. 50-364

.U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 Gentlemen:

- l Joseph M. Farley Nuclear Plant - Unit 2 Steam Generator Tube Plugging Technical Specification Amendment In order to provide margin for future operation of Joseph M. Farley Nuclear Plant Unit 2, Alabama Power Company has requested a technical specification amendment to-increase the allowable steam generator tube plugging limit _from 10% to 15% average with a 20% peak in any steam generator. This technical

. specification amendment, supported by WCAP-12659, Alabama Power Joseoh M.

Farlev Unit 2 Increased Steam Generator Tube Pluacina and Reduced Thermal Jesian Flow Licensino Report, was submitted to the NRC on July 31, 1990.

During the course of the NRC review, additional information was requested-from Alabama Power Company concerning steam generator flow area reduction as discussed in WCAP 12659.- At-a meeting on November 7, 1990, Westinghouse presented a discussion of the issue as it related to Farley Unit 2.

As requested,- the slides used for that presentation are forwarded in Attachment I as.WCAP-12763 (Proprietary) and WCAP-12764 (Non-Proprietary), Steam l Generator Tube Collapse Considerations. These slides represent Alabama Power Company _'s understanding of the issue as of the November 7,1990 meeting.

. Subsequent to this presentation, Alabama Power Company learned that significant loading on the tube support plate may result from a design basis LOCA event,' and thus any possible mis-impression that only seismic loads need be evaluated.for the pump outlet break should 'be-corrected.

We understand that Westinghouse will respond to the NRC's request for more information on this generic issue. Although of potential generic concern, the consequences of the above are no longer relevant to this licensing request due to the evaluation described below.

At the November 7,1990 presentation, the NilC Staff requested Alabama Power Company document that, based on engineering judgment, steam generator tube collapse would not occur for the combination of the loads from an SSE with LOCA loads.

Preliminary evaluations based on engineering judgment could LQ&$ Y f

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U. S. Nuclear Regulatory Commission November 18, 1990 Page 2 not provide reasonable assurance that no tubes would collapse under combined SSE' and LOCA loads. Therefore, in order to demonstrate that tube collapse will not occur, Alabama Power Company has assessed the' inherent integrity of the reactor coolant system (RCS) piping using Leak-Before-Break methodology.

This assessment has determined that the probability of breaks in the primary.

RCS loop piping is sufficiently low such that they need not be considered in the structural design basis. Although all required evaluations have not yet been completed, an evaluation has been completed to identify the most limiting break locations. An-assessment at these locations demonstrates that the Leak-Before4reak principle applies to the RCS primary loop piping at Farley Nuclear Plant.

Based on the exclusion of breaks in the RCS primary loops, the LOCA loads from the large branch line breaks were used to assess the potential for steam generator tube deformation. The combination of loads from the SSE with the loads from a break in the pressurizer surge line or from the accumulator lines proved to be the most limiting conditions.

Based on size and location,. the surge-line and the accumulator line bound all. other hot and cold leg branch line break loads. Using these combined loads, the evaluation showed that no steam generator tube collapse would occur. The results of these assessments are contained in Attachment 2.

Based on-use~ of' the Leak-Before-Break methodology, the 500F PCT penalty assessed in WCAP-12659 is no longer required. As a result, the large break LOCA PCT for Farley Unit 2 is 20730F. The licensing report, WCAP-12659, will be updated on completion of the Leak-Before-Break analysis.

Alabama Power Company has reviewed the significant hazards evaluation provided with the license amendment submitted on July 31, 1990. The conclusions of the significant hazards evaluation remain valid and no changes

- are considered necessary as a result of the application of the

. Leak-Before-Break principle to Farley Unit 2.

Alabama Power Company is taking interim measures to reduce the level of steam generator tube plugging below the current technical specification limit of 10%; however, these measures represent significant radiation exposure, cost and schedule delay in returning Unit 2 to service.

The NRC is therefore requested to approve the 15% tube plugging technical specification amendment as soon as possible.

Alabama Power Company will complete Leak-Before-Break anal / sis of the primary

. loop and currently expects to submit the completed analysis by January 31, 1991 if 15% tube plugging is approved. The enclosed evaluation to

-demonstrate applicability of Leak-Before-Break to Farley Units 1 and 2

. primary loops is intended to support only the resolution of the 15% tube plugging issue.

A U. S. Nuclear Regulatory Commission November 18, 1990 Page 3 Attachment I contains:

1.

WCAP-12763, " Steam Generator Tube Collapse Considerations" (Proprietary).

2.

WCAP-12764, " Steam. Generator Tube Collapse Considerations" (Non-Proprietary).

Also enclosed are a Westinghouse authorization letter, CAW-90-090, accompanying affidavit, Proprietary Information Notice, and Copyright Notice.

As WCAP-12763 contains information proprietary to Westinghouse Electric Corporation, it is supported by an affidavit signed by Westinghouse, the

owner of the information.- The affidavit sets forth the basis on which the information may be withheld from public disclosure by the Commission and addresses with specificity the considerations listed in paragraph (b)(4) of Section'2.790 of the Commission's regulations.

Accordingly, it is respectfully requested that the information which is proprietary to Westinghouse be withheld from public disclosure in accordance with 10 CFR Section 2.790 of the Commission's regulations.

Correspondence with respect to the copyright or proprietary aspects of the items listed above or the supporting Westinghouse Affidavit should reference CAW-90-090 and should be addressed to R. A. Wiesemann, Manager of Regulatory & Legislative Affairs, Westinghouse Electric Corporation, P.O.

Box 355,-Pittsburgh, Pennsylvania 15230-03N.

If there are any questions, please advise.

Respectfully submitted, ALABAMA POWER COMPANY

. G. Hairston, III WGH,III/ REM: dst Attachments SWORN TO AND SUBSCRIBED ~BEFORE ME cc: Mr. S. D. Ebnetter THIS/

DAY OF M O b l990

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