ML20235Z490
| ML20235Z490 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 03/03/1989 |
| From: | Diederich G COMMONWEALTH EDISON CO. |
| To: | Davis A NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| RTR-REGGD-01.108, RTR-REGGD-1.108 NUDOCS 8903150481 | |
| Download: ML20235Z490 (1) | |
Text
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..,k OV Comm:nw;ilth Edistn c
LaSalle County Nuclear Station s
Rural Route #1, Box 220 Marseilles, Illinois 61341 Telephone 815/357-6761 March 3, 1989 Mr. A. B. Davis Regional Administrator Region III U.S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, Illinois 60137
Dear Mr. Davis:
This special report is being submitted in accordance with LaSalle Units 1 and 2 operating Licenses NPF-11 and NPF-18 Technical Specifications 4.8.1.1.3 and 6.6.C, regarding a Unit 1, 1A Diesel Generator (IDG01K) Valid Test failure.
.On February 3, 1989, with Unit 1 operating at 99.5 percent power, the 1A Diesel Generator output breaker ACB 1423 failed to close during a monthly operability surveillance. This was a valid test failure per Technical This was the third test Specification 4.8.1.1.3 and Regulatory Guide 1.108.
Due to failure in the last 100 valid tests for the Unit 1 Diesel Generators.
this failure, the Unit 1 Diesel Generator test frequency was increased from once every 14 days to once every 7 days consistent with Technical Specification Table 4.8.1.1.2.
As of February 23, 1989, the Unit 1 Diesel Generators have only 2 failures in the last 100 valid tests and are presently on a once every 14 day teut frequency.
The cause of the Diesel Generatur output breaker failing to close was a faulty The solid state overvoltage relay used in the closing logic of the breaker.
cause of the relay failure was a failed zener diode. The relay was a model ITE-59N manufactured by Brown Boveri.
As a short term corrective action the relay was replaced on a temporary bcsis with a similar overvoltage relay.
For a long term corrective action the faulty relay was returned to the manufacturer for repair, a new relay was purchased for a spare and the original relay was re-installed on February 23, 1989.
The 1A Diesel Generator was inoperable for a total of 33 hours3.819444e-4 days <br />0.00917 hours <br />5.456349e-5 weeks <br />1.25565e-5 months <br /> due to this event.
//h 8903150481 890303
. J. Diederich h[StationManager PDR ADOCK 05000373 b
PDC f.aSalle County Station GJD/kg Director of Nuclear Reactor. Regulation xc:
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NRC Resident Inspector l
Nuclear Licensing Administrator l 0
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