ML20107G342
| ML20107G342 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 09/27/1984 |
| From: | Mangan C NIAGARA MOHAWK POWER CORP. |
| To: | Starostecki R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| (55(E)-84-26), (NMP2L-0170), (NMP2L-170), NUDOCS 8411070334 | |
| Download: ML20107G342 (2) | |
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NUMOHAWK Y NIAGARA NIAGARA MOHAWK POWER CORPORATION /300 ERIE BOULEVARD WEST, SYRACUSE, N.Y.13202/ TELEPHONE (315) 474-1511 September 27, 1984 (NMP2L 0170)
Mr. R. W. Starostecki, Director U. S. Nucl ear Regulatory Comission Region I Division of Project and Resident Pvtgrams 631 Park Avenue King of Prussia, PA 19406 Re: Nine Mile Point - Unit 2 Docket No. 50-410
Dear Mr. Starostecki:
Enclosed is a final report in accordance with 10CFR50.55(e ) for the problem concerning internal corrosion of the main steam isolation valves.
This problem was reported via tel-con to your staff on July 20, 1984 An interim report was submitted via our letter dated August 20, 1984.
Very truly yours, dL%
C. V. Mangan Vice President Nuclear Engineering and Licensing CW1/GG/pbd xc: Director of Inspection and Enforcement U.S. Nuclear Regulatory Commission Washington, DC 20555 R. A. Gramm, NRC Resident Inspector Project File (2) 0411070334 840927 DR ADOCK 05000 ir 2 4
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n NIAGARA M0 HAWK POWER CORPORATION NINE MILE POINT - UNIT 2 DOCKET NO. 50-410 Final Report for the Problem Concerning Internal Corrosion of the Main steam Isolation Valves (55(e)-84-26)
Description of the Problem Niagara Mohawk Power Corporation has become aware of a problem involving valve leakage in excess of the design allowable.
The problem with the Crosby-supplied main steam isolation valves occurred during preoperative testing at Liebstadt, Switzerland, and at Midland Station of Consumers Power.
Inspection of the valves revealed that corrosion between the inside surfaces of the valve body and the spool seat had developed.
The corrosion is believed to be the cause of the leakage.
Communication with the vendor confirmed that a similar condition could occur with the Nine Mile Point Unit 2 main steam isolation valves.
Analysis of Safety Implications Excessive leakage of the subject valves could have resulted in a loss of primary containment isolation capability and Reactor Pressure Vessel pressure boundary.
If this problem were to have remained uncorrected, it could have adversely affected the safety of operations of the plant.
However, excessive leakage of these isolation valves would have been determined during the Type C testing for containment integrity.
Corrective Action The subject condition has been documented on Non-Conformance and Disposition Report (N&D) No. 8258.
The potential problem will be avoided by cladding tne pertinent interior surfaces of the valve bodies with a corrosion-resistant alloy,ightness in accordance with applicable Technical Specifications.The valves will Inconel 625.
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