ML20127H316
| ML20127H316 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 01/15/1993 |
| From: | Feigenbaum T NORTH ATLANTIC ENERGY SERVICE CORP. (NAESCO) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NYN-93008, NUDOCS 9301220285 | |
| Download: ML20127H316 (2) | |
Text
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P.O. Box 300
[tj Seabrook, N H 03074 Telephone (603)474+0521 Facsimite (603)474 2987 Ener0y Servico Corporation Ted C, Folgenbaum Senior Vice President and Chief Nuclear Officer j
NYN 93008 j
January 15, 1993 United States Nuclear Regulatory Commission Washington, D.C. 20555 Attention:
Document Control Desk Referenec:
Facility Operating License No. NI'F-86, Docket No. 50 443
Subject:
Diesel Generator Special Report Gentlemen:
The following Diesel Generator Special Report documents a diesel generator failure that occurred at Seabrook-Station and is repor;ed pursuant to Technical Specification 4.S.1.1.3. On December 16,1992 while performing the A Train Emergency Diesel Generator (EDG) monthly surveillance, it was noted, prior to closing the EDG quiput breaker,that the diesel generator output voltage was offscale high. The EDG was manually shutdown to investigate the cause of the high voltage condition. In accordance with Regulatory Position C.3.b of !'egulatory Guide 1.108, Revision 1, August 1977,it was determined that this event was a vaaJ EDG start failure At the time of the event the plant was in Mode 1 at 100%
power.
'I he U Train EDG was operable.
Chronoloey of Events On Dece:nber 16, 1992, the A Train EDG was started for testing pursuant to Technical Specification Surycillance Requirement 4.8.1.1.2. Af ter energizing the synchronizing circuit in preparation for closing the EDO output breaker,it was noted that the EDG output voltage was offscale high, The A Train EDG was manually shutdown four minutes after being started to investigate the high voltage condition.
Each EDG has two Silicon Controlled Rectifier (SCR) banks which are part of the EDG voltage regulator. The SCRs are used to rectify a portion of the diesel generator output to produce DC voltage for the field. Only one of the SCR banks is inservice when the EDG is operating, if a failure of the inservice SCR bank occurs, the second bank can be placed into service once the EDO it. shutdown. Prior to the December 16, 1992 surveillance it was decided to alternate the use of the two SCR banks, this was the first time that the A Train EDG was run using SCR bank U.
Following the shutdown, SCR bank A was placed into service and the A Train EDG surveillance was succesrifully completed.
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9301220205 930115 a member of the Northeast Utilities system 1
E PDR ADOCK 05000443
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UniJed States Nuclear Regulatory Commission January 15,1993 Attention:
Document Control Desk Page two j
1 i
Pont Cause The failure of the A Train EDG is attributed to a malfunction in SCR bank 11. The cause of the SCR bank f ailure will be deterrnined during the next EDG outage. The installed sparc SCR bank, bank A, was utilized to return the A Train EDG to operable status, i
l A supplemental report will be submitted to the NRC after the SCR benk 11 failure mechanista has been determined. It is expected that this report will be submitted by June 30,1994.
Corrective Action Following the EDG shutdown, SCR bank A was placed into service aad the monthly !!DG surveillance was completed. SCR bank 11 will be repaired or replaced during the next EDG outage.
This is the first failure of the A Train EDG in the last hundred starts. Pursuant to Technical Specification Table 4.81, the tcquired test schedule for the A Tsain EDG is at least once per 31 days. The A Train EDG was inoperable for approxlinately fourteen hours.
Should you require further information regarding this matter, please contact Mr. James hl. l'eschel, Regulatory Compliance hianager, nt (603) 474 9521 extension 3772.
Very truly yours,
,,s/p t< b ' "
Ted C. Feigenbaum TCF: M D O/act ec:
Mr. Tnomas T. Martin Regional Administrator United States Nuclear Regulatory Commission Region 1 475 Allendale Road King of Prussia, P A 19406 Mr. Albert W. De Agazio, Sr. Project Manager Project Directorate 1-3 Division of Reactor Projects U.S. Nuclear Regulatory Commission Washington, DC 20555 Mr. Noel Dudley NRC Senior Resident tr>spector P O. Box 1149 Seabrook, Nil 03874
.