ML17353A533

Special Rept:On 951215,4A EDG Failure Occurred.Caused by Faulty Voltage Regulator.Voltage Regulator Replaced

ML17353A533
Person / Time
Site:	Turkey Point
Issue date:	01/12/1996
From:	Hovey R FLORIDA POWER & LIGHT CO.
To:	Ebneter S NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
L-95-345, NUDOCS 9601220081
Download: ML17353A533 (8)

Text

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C REGULATO INFORMATION DISTRIBUTION ~STEM (RIDS)

ACCESSION NBR:9601220081 DOC.DATE: 96/Ol/12 NOTARIZED: NO DOCKET ¹ FACIL:50-251 Turkey Point Plant, Unit 4, Florida Power and Light C 05000251 AUTH. NAME AUTHOR AFFILIATION HOVEY,R.J. Florida Power a Light Co.

RECIP.NAME RECIPIENT AFFILIATION EBNETER,S.D. Region 2 (Post 820201)

SUBJECT:

Special rept:on 951215,4A EDG failed surveillance test.

Caused by faulty voltage regulator. Voltage regulator replaced.

DISTRIBUTION CODE: IE22D COPIES RECEIVED:LTR ( ENCL ( SIZE:

TITLE: 50.73/50.9 Licensee Event R'eport (LER)., Incident Rpt, etc.

NOTES:

RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD2-1 PD 1 1 CROTEAU,R 1 1 INTERNA 2' AEOD/SPD/RRAB 1 1 E CENTER 1 1 NRR/DE/ECGB 1 1 NRR/DE EELB 1 1 NRR/DE/EMEB 1 1 NRR/DRCH/HHFB 1 1 NRR/DRCH/HICB 1 1 NRR/DRCH/HOLB 1 1 NRR/DRCH/HQMB 1 1 NRR/DRPM/PECB 1 1 NRR/DSSA/SPLB 1 1 NRR/DSSA/SRXB 1 1 RES/DSIR/EIB 1 1 RGN2 FILE 01 1 1 EXTERNAL: L ST LOBBY WARD 1 1 LITCO BRYCE,J H 2 2 D NOAC MURPHYiG.A 1 1 NOAC POORE,W. 1 1 NRC PDR 1 1 NUDOCS FULL TXT 1 1 0, M

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N NOTE TO ALL "RIDS" RECIP1ENTS:

PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOM OWFN SD-5(EXT. 415-2083) TO ELIMINATE YOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!

TOTAL NUMBER OF COPIES REQUIRED: LTTR 25 ENCL 25

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@PL JANET hajj L-95-345 10 CFR 550.36 Stewart D. Ebneter Regional Administrator, Region II U. S. Nuclear Regulatory Commission 101 Marietta St , N.W., Suite 2900 Atlanta,. GA 30323 Mr. Stewart D. Ebneter:

Re: Turkey Point Unit 4 Docket No. 50-251 S ecial Re ort 4A Emer enc Diesel Generator Failure In accordance with Technical Specifications 4.8.1.1.3, the attached Special Report details the 4A Emergency Diesel Generator failure of December 15, 1995.

Should there be any questi'ons on this information please contact us.

Very truly yours, Robert J. Hov y Vice President Turkey Point Plant CLM Attachment cc: USNRC, Document Control Desk, Washington D.C.

Thomas P. Johnson, Senior Resident Inspector, USNRC, Turkey Point Plant 9601220081 960112 PDR ADQCK 05000251 S PDr.

an FPL Group company

4!, 4l Attachment Page 1 of 2 SPE ZAL REP RT 4A EHEGKRNCY DZESEL GENERATOR FAZLURE

~PDRP SE Technical Specification 4.8.1.1.3, requires the submittal of a special report to the NRC in the event of a diesel generator failure. The Technical Specification requires the report to include the information recommended in Regulatory Position C.3.b of Regulatory Guide 1.108, Revision 1, August, 1977.

BACKGROUHD Florida Power and Light's (FPL) Turkey Point Nuclear Units 3 and 4 have

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two Emergency Diesel Generators (EDGs) for each unit. The Unit 3 EDGs were overhauled, and the Unit 4 EDGs installed, during the dual unit outage in 1990/1991.

On December 15, 1995, the 4A EDG was being tested in accordance with surveillance procedure 4-OSP-023.1, Diesel Generator Operability Test.

The operator was taking his last reading at the end of, the one-hour full load run,, when he noted that the output amps on the control room meter were full scale, and EDG voltage was about 4190 VAC. With these abnormal conditions the operator performed an "Emergency Stop" of the EDG.

A review of the ERDADS (Emergency Response Data Acquisition and Display System) printout showed that the 4A EDG output had increased to about 584 amps and 4193 VAC for approximately 3 seconds. Then the output increased to about 616 amps and 4203 VAC foz 3 more seconds, at which point the EDG was stopped as stated above. The EDG output exceeded the half-hour rating of 4119 kVA by 3-9% for about 6 seconds. This overload is within the maximum momentary overload limit of standard MG 1-1987, section MG 1-22-41. Additionally, previous overloads of larger magnitude have been evaluated as acceptable.

After verifying that observable conditions were normal (feedback inputs to the voltage regulator, Silicon Controlled Rectifiers, Remote Gate Firing Module, Motor-Operated Potentiometer, Potential Transformer wiring, fuses, fuse holders, the system grid, etc,.), the EDG was run for troubleshooting. About 30 minutes into the troubleshooting run, voltage spiking was observed during full load operation. The EDG was shut down and the voltage regulator was replaced.

On the subsequent run of the 4A EDG the voltage regulator preset voltage was ad)usted and successfully tested at full load for one hour. An additional rapid start, a one-hour 100 percent load run, and a full load re)ection test were successfully completed. The EDG was returned to service.

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Attachment Page 2 of 2 The following discussion addresses each of the areas listed in Regulatory Position C.3.b of Regulatory Guide 1.108, Revi:ion 1, August, 1977.

(1) DIE EL ENERATOR IT INVOLVED:

The 4A EDG failed its surveillance test.

(2) IDENTIFY THE FAIL RE A BEIN THE N-TH FAIL E IN THE LA T 1 VALID TEST This is the first failure in the last 60 valid tests; was installed.

there have been only 60 valid tests .since the EDG (3) AU E F FAILURE'he cause of the 4A EDG failure was a faulty voltage regulator. The reason for the failure of the voltage regulator is not yet known.

(4) RRECTIVE MEA ES TAKEN failed voltage regulator has been returned to the vendor

'he for root cause analysis.

2. The EDG was tested satisfactorily after the regulator was replaced.

(5) LENGTH F TIME THE DIE EL ENERATOR WAS UNAVAILABLE:

The 4A EDG was unavailable foz 33 hours3.819444e-4 days <br />0.00917 hours <br />5.456349e-5 weeks <br />1.25565e-5 months <br />, 43 minutes.

(6) DEFINITION OF CURRENT SURVEILLANCE TEST INTERVAL:

Unless a trigger value is exceeded (2 failures in the last 20 valid tests, or 5 failures in the last 100 valid tests), the normal surveillance frequency is every 31 days. This is the first failure in the last 20 valid tests, and the first failure since the EDG was installed in 1991 (60 valid tests) . Therefore, the normal 31 day surveillance interval remains in effect for the 4A EDG.

(7) VERIFI ATION OF TEST INTERVAL IN CONFORMANCE WITH REGULATORY POSITION C.2.d:

The current test interval is in conformance with the requirements of Regulatory Position C.2.d of RG 1.108, and Turkey Point Technical Specifications Table 4.8-1.

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