ML17252A532
| ML17252A532 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 06/21/1974 |
| From: | Stephenson B Commonwealth Edison Co |
| To: | O'Leary J US Atomic Energy Commission (AEC) |
| References | |
| BBS Ltr.#452-74, D12-3-74-14 | |
| Download: ML17252A532 (2) | |
Text
- !) commonweal*h Ecia One First National Plaza, Chicago, Illinois
~Adat~ss Reply to: Post Office Box 767 Chicago, Illinois 60690 BBS Ltr.1452-74
. -- -~----------- -
.Mr. J.P. O'Leary, Director Directorate of Licensing U. s. Atomic Energy COD1Dission Washington, D. C.
20545
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5o-2~
SUBJECf:
LICENSE DPR-25 DRESDEN NUCLEAR POWER STATION UNIT #3 REPORT OF UNUSUAL EVBNT PER SECfION 6.6.B.2 OF THE TECHNICAL SPEC IO
- BREAKER TRIP OF M0-3-1501-32A.
Reference:
Dresden Station Deviation Report Number Dl2-3-74 May 4, 1974.
Dear Mr. O'Leary:
This letter is-to report a condition relating to the~~~~~
the unit at about 0330 hours0.00382 days <br />0.0917 hours <br />5.456349e-4 weeks <br />1.25565e-4 months <br /> on May 4, 1974.
At that time, the breaker for LPCI valve M0*3-1501-32A tripped.
This malfunction contrary to section 3.5.A.l which requires that the LPCI syst,em be operable when irradiated fuel is in the core.
PROBLEM On May 4, 1974, local leak rate testing of the LPCI system was in
.progress. For the test* it was necessary to drain the LPCI system which required the operation of M0-3-1501-32A.
During the closing of the valve, its supply breaker tripped. At the time of the occurrence, the unit was in shutdown with all control rods inserted.
INVESTIGATION AND CORRECTIVE ACTION On investigation, it was discovered that the cause of the breaker trip was due to the breaker being under sized.
The supply breaker for MO*
3-1501-32A is presently a 10 amp breaker. A recent modification calls for the 10 amp breaker to be replaced with a 25 amp breaker.
The 25 amp breaker is presently on order and will be installed immediately upon its arrival.
The increase in breaker size is a satisfactory corrective action in light of cumulative experience. A review of breaker sizing for all motor operated valves at Dresden has been under investigation for about one year.
As a REGULATORY DOCKET FILE COPY*
Mr. J. F. O'Leary,,
June 21, 1974 1
result of this invest iga t iQp, _n\\.llllerous_breaker.s--were-found-to-be-un-der-sf.Zed.
-Tb*e-1:>realterror-MO*J*l:SOf::32A was one found to.be under sized, and needed to be changed to a 25 amp breaker.
EVALUATIONS During the failure: of LPCI-J-1501-32A valve, the safety of the plant and public was not in jeopardy. At the time of the failure, the unit was in shutdown with all control rods inserted. _In addition, 'the valve was operable as soon as the i.brj!aker was._reset.
Also~.at_ th~ time *of.the fa*uure, all other safety ;ystenu(~ere opera,ble.
BBS:TEL:do