ML20065Q453

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Forwards Westinghouse North Anna Unit 1 Steam Generator Impacted Tube Ends Recovery Evaluation, Photographs of Steam Generator a & C Damaged Tube Sheets & Summaries of End Damage Repairs & Reactor Coolant Pump Failure
ML20065Q453
Person / Time
Site: North Anna Dominion icon.png
Issue date: 10/26/1982
From: Leasburg R
VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To: Harold Denton
Office of Nuclear Reactor Regulation
Shared Package
ML20065Q456 List:
References
601, NUDOCS 8210270204
Download: ML20065Q453 (2)


Text

r VINGINIA ELECTRIC AND Powna COMPANY HicnwoMn, VIRGINIA 20261

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Pumassant October 26 8 1982 Nottaam Uramassume Mr. Harold R. Denton, Director Serial No. 601 Office of Nuclear Reactor Regulation N0/RCC/jmj /SP4 Attn: Mr. Robert A. Clark, Chief Docket No. 50-338 Operating Reactors Branch No. 3 License No. NPF-4 Division of Licensing U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Gentlemen:

VIRGINIA ELECTRIC AND POWER COMPANY NORTH ANNA POWER STATION UNIT NO. 1 STEAM GENERATOR IMPACTED TUBE ENDS RECOVERY EVALUATION REACTOR COOLANT PUMP DIFFUSER ADAPTER BOLT FAILURE The purpose of this letter is to provide the details of the examinations and evaluations performed by Vepco and Westinghouse Electric Corporation on the steam generator impacted tube ends and the reactor coolant pump diffuser adapter bolt failure experienced at North Anna Unit No. 1.

Attachment I provides a detailed evaluation of the damaged tube ends, tubesheet, divider plate, and channel head bowl found in steam generators "A" and "C". In Attachment II you will find photographs and enlargements of the condition prevalent in both of the damaged steam generators. Attachment III is a description of the repair process Vepco is using to correct the damage to the tube ends.

Attachment IV is the evaluation of the reactor coolant pump diffuser adapter bolt failure. Vepco, Westinghouse, and Babcock & Wilcox are still evaluating the cause of the failure. All reactor coolant pumps in North Anna Unit I have had the diffuser adapter bolts replaced with the bolts recommended in the Westinghouse report. As indicated in the attachment, failure of the bolts would not present a safety concern for the reactor coolant system. Vepco concurred with the Westinghouse evaluation and decided to replace the bolts for Unit I based on economic considerations, col y \

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VauoNIA Etretu C AMD POWEN COMPANY TO We will continue to keep you informed on the progress of our evaluations of the problems at North Anna. We will be providing you by separate letter the flow splitter stub analysis and the report on Vepco's efforts to search for and retrieve loose parts in the Reactor Coolant System (RCS). If you have any questions regarding the details of the evaluations provided by this letter, please contact us at your earliest convenience.

Very truly yours, (L .L. %

R. H. Leasburg Attachments: I. North Anna Unit 1 Steam Generator Impacted Tube Ends Recovery Evaluation II. Photographs of Damaged Tube Sheets (Steam Generators "A" and "C")

III. Summary of Steam Generator Tube bnd Damge Repairs IV. RCp Diffuser Adapter Bolt Failure - North Anna Unit No. I cc: Mr. Richard C. DeYoung, Director Office of Inspection and Enforcement Washing ton , i,. C. 20555 Mr. James P. O'Reilly, Regional Administrator Region II Atlanta, Georgia 30303

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