ML20084U440
| ML20084U440 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 03/06/1975 |
| From: | Kalivianakis N COMMONWEALTH EDISON CO. |
| To: | Oleary J Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20084U443 | List: |
| References | |
| NJK-75-125, NUDOCS 8306290044 | |
| Download: ML20084U440 (2) | |
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n-Mr. John F. O' Leary, Director Directorate of Licensing Regulation U. S. NUCLEAR REGULATORY C0mlSS10N Washington, D. C.
20545
REFERENCE:
Qu'ad-Cities Nuclear Power Station, Unit Two Docket No. 50-265, DPR-30 Section 6.6.B.2.b.
Dear Mr. O ' Leary:
The purpose of this letter is to inform you of an unusual event which was discovered at Quad-Cities Nuclear Power Station on February 7,1975. This letter is being submitted to you in accordance with Technical Specification 6.6.B.2.b.
With Unit 2 in the cold shutdowrt condition for scheduled refueling and all fuel removed from the reactor vessel for recirc piping repairs, feedwater check valve 2-220-62A was being disassembled to perform a modification to the seal ring. Upon disassembly, an indication of a flaw was discovered on the interior portion of the valve body about S/d inch long.
Prior to repair of the flaw, a quality assurance representative from Crane Company, the valve manufacturer, was dispatched to the station for consul-tation. He provided information indicating that the original valve body casting had a flaw, which was repaired before delivery. Radiographs of that repair showed a slag inclusion; however, according to the Crane representa-tive, this inclusion was acceptable by the standards of the code which governs the valve installation.
b Repair consisted of grinding out a 'six inch long portion of the valve body in the area of the flaw ar.d refilling to the originnt dimension. Heat treatment and final radiographic examination are scheduled to be complete by March 12th.
Grinding reduced the wall thickness of the valve to 1-1/2 inches, which is greater than the minimum allowable wall thickness of 1-5/16 inches. This, combined with the facts that code acceptance criteria classify the inclusion as an acceptable flaw, and that the valve wall was rebuilt to original thick-ness, minimizes the safety implications of this event. Even in the unlikely event that the valve body had sheared, the cmergency core cooling systems would have been able to provide adequate water to keep the reactor core covered and cooled; thus, the health and safety of the public were not adversely af-fected by this event.
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Mr. John F. O 'Lctry, Dire r M h 6,'1975' One other feedwater valve, the minimum flow feed regulating valve actually did fail in June 1974, it failed, however, as a result of a tranufacturing defect which had reduced a portion of the valve wall to less than the mini-mum allowable thickness. The details of this event were transmitted to you in quad-Cities' abnormal occurrence report of June 18, 1974. No other flaws of the type herein reported have been discovered at Quad-Cities; therefore, there are no safety implications of this event based on cumulative experience.
Very truly yours, COMM0tMEALTH EDISON COMPANY QUAD-CITIES NUCLEAR POWER STATION
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N. J. Kallvianakis Station Superintendent NJK:SRH/dkp cc: Region t il, Directorate of Regulatory Operations J. S. Abel
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