ML20236B887
| ML20236B887 | |
| Person / Time | |
|---|---|
| Site: | Byron  |
| Issue date: | 06/18/1987 |
| From: | Querio R COMMONWEALTH EDISON CO. |
| To: | Davis A NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| BYRON-87-0675, BYRON-87-675, NUDOCS 8707290272 | |
| Download: ML20236B887 (2) | |
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Mr. A. Bert Davis I
Regional Administrator J
Region 3 U. S. Nuclear Regulatory Commission j
799 Roosevelt Road i
Glen Ellyn, Illinois 60137
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Dear Sir:
This report is submitted in accordance with Byron Station Unit 2 Operating License NPF-60 Appendix A, Technical Specification 4.8.1.1.3, reporting of Diesel Generator Failures.
This report addresses one valid test and failure experienced on the 2B Diesel Generator. The criteria to determine valid tests and failures is in accordance with section C.2.e of Regulatory Guide 1.108.
l On April'28,1987 the 2B diesel generator was started per the monthly operability surveillance, 2BOS 8.1.1.2.a-2. Per Technical Specification 4.8.1.1.2 the diesel generators (DG) are required to reach rated speed, voltage, and frequency within l
ten seconds of the start signal. The 2B DG required 10.5 seconds to reach rated conditions. The 2B DG was immediately shutdown and restarted. Rated conditions were achieved in 8.3 seconds.
The root cause for this event is indetermmate. In addition to proving operability of the DG immediately after the event, the DG start time was checked once a week for three weeks with a strip chart recorder. All three starts were within the required Technical Specification starting time. A possible root cause for this event is the method used for determining the DG start time. Currently the Equipment Operators (EOs) are instructed to start the stopwatch when the start pushbutton is depressed, and to stop the stopwatch when the DG reaches 600 RPM and is within 60+-1.2 liz and.4160+-420 volts. Due to the time required to verify that all three parameters are met, the actual DG start may be less than the recorded start time.
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BYRON 87-0675 Page 2 As a result of this event, the DG monthly operability surveillance,1,2BOS 8.1.1.2.a-1,2, are being changed to delete the requirement to verify all three parameters prior to stopping the stopwatch. The revised procedures will instruct the EOs to start the stopwatch when the start pushbutton is depressed, and to stop the stopwatch when the generator initially reaches 4000 volts. After the stopwatch is stopped, the EO will immediately verify that engine speed and generator frequency are within their required bands. A review of previous 18 month surveillance, for all four Byron Station DGs, has indicated that in all cases generator frequency and engine speed were within their required bands before generator voltage reached 4000 volts.
The 2B DG was not inoperable for any length of time following this event. This failure was the first failure since the completion of the preoperational test, therefore the testing frequency of the 2B DG will remain on a monthly basis.
FAS-CM R. E. Querio Station Manager Byron Nuclear Power Station REQ /MMR/bf ec:
P. Brochman, NRC Acting Senior Resident Inspector U. S. NRC Document Control Desk, Washington, D.C.
INPO Record Center CECO Distribution List M. Robert J. Cook
- 027/004