ML20092G423
| ML20092G423 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 02/17/1992 |
| From: | Diederich G COMMONWEALTH EDISON CO. |
| To: | Davis A NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| NUDOCS 9202200113 | |
| Download: ML20092G423 (1) | |
Text
Comm^ nwealth Edis:n LaSalle County Nuclear Station 2001 N. 21st. Rd.
Marseines, tilinois 61341 February 1*,
1992
+
Telephone 815/357 6761 Mr. A. B. Davis Region III Administrator U.S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, Illinois 60137 Dear Sir This Special Report is submitted in accordance with LaSalle Unit 2 Operating Licenses NPT-18, Technical Specification 4.8.1.1.3 and 6.6.C regarding Unit 2 0 Diesel Generator (DG, ODG01K).
On January 18, 1992, with thSalle Unit 2 Defueled, the Unit 2 Diesel Generator breaker to Bus 241Y (ACB 2413), failed to close, while attempting to parallel with offsite power during a post-maintenance operability surveillance. This failure was not a valid test failure in accordance with Regulatory Guide 1.108 and Technical Specification 4.8.1.1.3.
The cause of the breaker not closing was determined to be a defective Test Switch Control (TSC). The TSC is used in the test position to engage either the local test or remote test closing circuit. The Ucit 2 breaker for the "0" DG (ACB2413) had been racked out as part of the out of service lineup for the DG maintenance work.
It has been concluded that this action caused the failure of the TSC.
This determination was based on the following:
- The last test of Breakers ACB2413 during the previous performance of the "0" DG monthly surveillance test was completed successfully.
- No other work was performed on the breaker other than racking it out.
The switch was replaced under Work Request L12952 and the O DG output breaker to Bus 241Y was tested satisfactorily by paralleling with the offsite power source.
At the time of the event, the O DG was inoperable for Unit 2, and was not required to meet the limiting conditions for Operation for Unit 2.
This event did not affect the operability of the O DG for Unit 1.
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' fr. J. Diederich Station Manager 9202200113 920217 LaSalle County Station PDR ADDCK 05000374 l
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