ML17223B393

Special Rept:On 911129,emergency Diesel Generator 1B Started for Weekly Operational Check & Output Voltage Climbed Above Nominal Voltage.Caused by Failed Component in Voltage Regulator Card.Regulator Card Replaced

ML17223B393
Person / Time
Site:	Saint Lucie
Issue date:	12/20/1991
From:	Sager D FLORIDA POWER & LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
L-91-346, NUDOCS 9201020058
Download: ML17223B393 (3)

Text

ACCELERATED DISTRIB REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR: 9201020058 DOC. DATE: 91/12/20 NOTARIZED: NO DOCKET FACIL:50-335 St. Lucie Plant, Unit 1, Florida Power & Light Co. 05000335 AUTH. NAME AUTHOR AFFILIATION SAGER,D.A. Florida Power & Light Co.

RECIP.NAME RECIPIENT AFFILIATION Document Control Branch "(Document Control 'Desk)

SUBJECT:

Special rept:on 911129,emergency diesel generator 1B started for weekly operational check & output voltage cl'imbed above nominal voltage. Caused by failed component zn voltage regulator card. Regulator card replaced.

DISTRIBUTION CODE: IE22D COPIES RECEIVED:LTR ENCL SIZE:

TITLE: 50.73/50.9 Licensee Event Report (LER), Incident Rpt, etc.

NOTES:

RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD2-2 LA 1 1 PD2-2 PD 1 1 NORRIS,J 1 1 INTERNAL: ACNW 2 2 ACRS 2 2 AEOD/DOA 1 1 AEOD/DSP/TPAB 1 1 AEOD/ROAB/DS P 2 2 NRR/DET/ECMB 9H 1 1 NRR/DET/EMEB 7E 1 1 NRR/DLPQ/LHFB10 1 1 NRR/DLPQ/LPEB10 1 1 NRR/DOEA/OEAB 1 1 NRR/DREP/PRPB11 2 2 NRR/DST/SELB 8D 1 1 NRR/DSX/SQLBSDl NRR/DST/SICB8H3 NRR/DST/SRXB 8E RES/DSIR/EIB 1

1 1

1 1

1 RQG ~FIGE RG =-PIC ~ 01 1

1 1

1 1

1 EXTERNAL: EG&G BRYCE,Z.H 3 3 L ST LOBBY WARD 1 1 NRC PDR 1 1 NSIC MURPHY,G.A 1 1 NSIC POOREIW ~ 1 1 NUDOCS FULL TXT 1 1 NOTE TO ALL "RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE iVASTE! CONTACT THE DOCUMENT CONTROL DESK, ROO'kl Pl-37 (EXT. 20079) TO ELlb IFNATE YOUR NANCE FROM DISTRIBUTION LISTS FOR DOCUAIENTS YOU DOiN'T NEED!

TOTAL NUMBER OF COPIES REQUIRED: LTTR 33 ENCL 33

P.O. Box 1 . Pierce, FL 34954-0128 December 20, 1991 L-91-346 10 CFR 50.36 U. S Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 Gentlemen:

Re: St. Lucie Unit 1 Docket No. 50-335 Special Report Date of Event: November 29, 1991 Emer enc Diesel Generator Failure The attached Special Report is being transmitted pursuant to the requirements of St. Lucie Unit 1 Technical Specifications 4.8.1.2.2 and 6.9.2.. The report provides notification of a 1B Emergency Diesel Generator failure during the weekly operational check.

Should there be any questions on this information, please contact us ~

Very truly yours, St'ger D. A.

Vice P esident ie Plant DAS/JWH/kw Attachment cc: Stewart D. Ebneter, Regional Administrator, Region II, USNRC Senior Resident Inspector, USNRC, St. Lucie Plant DAS/PSL 0588-91 P ""A'j02VO~i8 pany

NRC SPECIAL REP RT DIESEL GENERATOR VALID FAILURE On 29 November 1991 at 1101 the St. Lucie Unit One 1B Emesgency Diesel Generator (EDG) was started for the weekly operational check.

Operations noted that upon generator'excitation the 'output voltage continued to climb above nominal voltage. The 1B EDG was shut down at 1105 and declared out of service. The-1B EDG was restarted for continued.

troubleshooting. The problem was repeated for further troubleshooting and the 1B EDG was shutdown at 1649. St. Lucie Unit One was in a refueling shutdown and the 1B EDG was not required to be in service per Technical Specification 3.8.1.2.

The problem was traced to the voltage regulator circuit. The failed component was the auto voltage regulator card. The voltage regulator circuit is designed to produce high generator voltage in the event of a malfunction of the voltage regulator circuit.

Corrective Actions: The auto voltage regulator card was replaced and at 1817 the diesel generator was successfully started. The generator output voltage controlled normally. After performing the operational check the 1B EDG was declared back in service at 1824. The 1B EDG was unavailable for seven hours and nineteen minutes.

Failure Summary: This is the third valid failure of the 1B EDG in the previous 20 valid tests. The 1B EDG has accumulated 22 valid tests since the implementation of the Technical Specification 3.8.1.1 (July, 1990).

The current surveillance interval is once per seven days per Technical Specification 4.8.1.2.2.