ML20246J723
| ML20246J723 | |
| Person / Time | |
|---|---|
| Site: | Mcguire |
| Issue date: | 08/28/1989 |
| From: | Tucker H DUKE POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 8909050245 | |
| Download: ML20246J723 (2) | |
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- Subjects.McGuire Nuclear Station, Unit 2
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' Docket No.~ 50-370 3
Special Report Concerning Diesel Generator 2B:
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Gentlemen:-
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- Pursuant to Technical Specification (T.S.) 6.9.2 as specified by T.S. 4.8.1.1.3, M
find attached aspecial report concerning-Diesel Generator'2B.
.-If you have any questions, please contact S.E. LeRoy'at (704) 373-6233.
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Very truly yours, L1 W
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'Hal:B.= Tucker-
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.Mr.--S.V. Ebneter, Administrator Mr. P.K. Van Doorn U.S. Nuclear Regulatory Commission-
'NRC Senior. Resident Inspector Region II.
McGuire Nuclear Station
.101 Marietta St., NW, Suite 2900 Atlanta, Georgia 30323-Mr. Darl Hood
- Office of Nuclear Reactor Regulation JU.S. Nuclear-Regulatory Commission l'-
Washington, DC 20555 INPO Records Center Suite 1500-7 1100 Circle 75 Parkway Atlanta, Georgia 30339 f
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Document Control Desk
. August 28, 1989 Attachment l
Duke Power Company L
McGuire Nuclear Station Diesel Generator 2B Spec 41 Report On July 27, 1989, Unit 2 was in no mode and DG 2B was started (start attempt no.
713) to perform a post maintenance 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> break-in run.
At 0237, approximately 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> into the DG run, a valid failure occurred on Diesel Generator (DG) 2B.
when control voltage was lost. Generator amps pegged high and transformer control current was also lost.
Operations initiated a work request to investigate and repair the problem, and Instrument and Elcctrical (IAE) personnel were contacted to troubleshoot the DG.
IAE discovered fuses blown on the transformer, and found a breakdown in the transformer insulation.
IAE replaced the faulty transformer, two fuses, and a voltage regulator printed circuit board.
A governor and voltage regulator benchmark were performed per PT/2/A/4350/36B. DG 2B was then successfully run per PT/2/A/4350/36B (start attempt no. 718).
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The failed transformer was the root cause of the DG trip.
Upon loss of the transformer, the voltage regulator board detected an imbalance between the generator and the bus lines which increased DG speed.
IAE plans to obtain equipment to test the transformer winding insulation on the remaining DGs. The critical transformers / motor windings for all DGs will then be tested periodically to increase reliability.
In the last 20 valid tests for DG 2B, there has been 1 valid failure. In the last 100 tests for DG 2B, there have been 5 valid failures.
This failure is not rep rtable to the Nuclear Plant Reliability Data System (NPRDS) because the trar.sformer is approximately twenty years old and was installed where the ambient temperature was high.
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