ML20085L520
| ML20085L520 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 01/07/1972 |
| From: | Worden W COMMONWEALTH EDISON CO. |
| To: | Morris P US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20085L521 | List: |
| References | |
| NUDOCS 8311010483 | |
| Download: ML20085L520 (1) | |
Text
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< o~ o So.an Commonwealth Edison Company ONE FIRST MATIONAL PLAZA
- C H 4 C A 4 0. ILLINOIS Ashkens Seph so.
POST O FFIC E GOI F 4 7
- C M I C A C O. BLL4NOl8 60400 Dresden Nuclear Power Station
- R. R. #1 Morris, Illinois 60450 January 7, 1972 68
/
Dr. Peter A. Morris, Director Division of Reactor Licensing U. S. Atomic Energy Commission Washington, D. C. 20545
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SUBJECT:
' LICENSE DPR 25 DRESDEN NUCLEAR POWER STATION UNIT #3 k SECTI0r; 6.6.B.3 0F THE TECHNICAL SPECIFICATIONS m .Co .
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Dear Dr. Morris:
1 This is to report a condition relating to the operation of the station, when the mechanical vacuum pump suction valve (3-5402B) failed to close, thus rendering the mechanical vacuum pump incapable of being isolated as required by Section 3.8.B.1 of the Dresden Unit #3 Technical Specifications.
Problem and Investigation On December 30, 1971, at 2310, with the reactor in the run mde at 150 We, condenser flow reversal tests were in progress, when valve 3-5402B failed to fully close. The manual suction valve for the mechanical vacuum pump was closed and the reactor placed in a cold shutdown condition. Subsequent investiration revealed that the failure of the valve was the result of the valve disc binding in the guices due to a slight overtravel in the valve.
_ Corrective Action .
A three inch slug was installed in the valve operator to reduce the valve travel in the open direction. After the installation p[,, d of the slug, the valve was cycled and the anomaly could not be reproduced, fI 31ugs will be added to the remaining similar mechanical vacuum punp g'jl suction valves on Units 2 and 3 at the earliest practical time. ,
8311010483 720107 Sincerely
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W. P. Worden
(, Superintendent
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