ML17223A542

Special Rept:On 900103,emergency Diesel Generator 2A Experienced Load Control Problems.Caused by Loose Connections in Governor Load Sensor Circuit.Loose Connections Tightened & Replacement Relay Installed

ML17223A542
Person / Time
Site:	Saint Lucie
Issue date:	03/02/1990
From:	Sager D FLORIDA POWER & LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9003090158
Download: ML17223A542 (3)

Text

ACCELERATED DNTRIBUTION SYSI'EM DEMONSTRATION REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9003090158 DOC.DATE: 90/03/02 NOTARIZED: NO DOCKET FACIL:50-389 St. Lucie Plant, Unit 2, Florida Power & Light Co. 05000389 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 900104,emergency diesel generator 2A failure.

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/DS P/TPAB ,.1 1 AEOD/ROAB/DSP 2 2 DEDRO 1 1 NRR/DET/ECMB 9H 1 1 NRR/DET/EMEB9H3 1 1 NRR/DET/ESGB 8D 1 1 NRR/DLPQ/LHFB11 1 1 NRR/DLPQ/LPEB10 1 1 NRR/DOEA/OEAB11 1 1 NRR/DREP/PRPBll 2 2 NRR/DST/SELB 8D 1 1 NRR/DST/SICB 7E 1 1 S 3?LB8Dl 1 1 NRR/DST/SRXB 8E 1 1 REG FAUTE 02 1 1 RES/DSIR/EIB 1 1 CH" LE 01 1 1 EXTERNAL EG&G WILLIAMSi S 4 4 L ST LOBBY WARD 1 1 LPDR 1 1 NRC PDR 1 1 NSIC MAYS,G 1 1 NSIC MURPHY,G.A 1 1 NUDOCS FULL TXT 1 1 NOTE TO ALL"RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASfEl CONTACT THE. DOCUMENT CONIROL DESK, ROOM Pl-37 (EXT. 20079) TO ELIMINATEYOUR NAME FROM DISTIUBUTION LISTS FOR DOCUMENIS YOU DON'T NEEDl TOTAL NUMBER OF COPIES REQUIRED: LTTR 37 ENCL 37

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P.O. Box 14000, Juno Beach, FL 33408.0420 L-90-70 lNROH 02 ]ggO U. S.'uclear Regulatory Commission Attn: Document Control Desk Washington, D. C. 20555 Gentlemen:

Re: St. Lucie Unit 2 Docket No. 50-389 Date of Event: January 4, 1990 S ecial Re ort on Diesel Generator Failure The attached Special Report is being transmitted pursuant to the requirements of Technical 'pecification 4.8.1.1.3 to provide notification of a 2A Emergency Diesel Generator failure.

Very truly yours, D. A. er Vice r sident St. Lu e Plant DAS/GRM/slh Attachment cc: Stewart D. Ebneter, Regional Administrator, USNRC Region II Senior Resident Inspector, USNRC, St. Lucie Plant 9003090i58 900302 PDR ADOCK 050003S9 fig 1 PDC an FPL Gyoup company

DIE EL ENERAT R N N-VALIDFAIL RE At 2209 hours0.0256 days <br />0.614 hours <br />0.00365 weeks <br />8.405245e-4 months <br /> on January 3, 1990, the St. Lucie 2A Emergericy Diesel Generator (EDG) was started for a monthly surveillance run. The EDG started in 8.17 seconds, within the required 10 seconds. After attaining proper speed and being synched the grid, the EDG experienced load control problems; these were characterized by erratic response and wide load swings. The 2A EDG was shut down for investigation of the problem. Trouble shooting revealed some loose connections in the governor load

-sensor circuit. Also, relay 52X1 was observed to provide erratic contact; contact resistance on the relay varied between the normal 0 ohms and approximately 100 ohms.

Corrective actions: The loose connections were tightened. Also, Plant Work Orders (PWO) were written to inspect all four EDG sets for loose connections. A replacement relay 52X1, with an acceptable 0 ohm contact resistance, was installed.

At 0440 hours0.00509 days <br />0.122 hours <br />7.275132e-4 weeks <br />1.6742e-4 months <br /> on January 4, the 2A EDG was again started. The start time was 8.2 seconds. The EDG operated properly and a very good surveillance run followed.

This problem was evaluated to be a non-valid failure per Regulatory Guide 1.108 C.2.e.2, because the affected governor circuitry was the droop section. The droop circuitry is only used for surveillance testing; in the event of a Loss of Offsite Power, the governor control is isochronous. This failure mode was such that the governor control was swapped over to its safety function mode of operation. At no time during this event was the EDG unable to perform its design safety function.

Failure summary: There have been three valid failures of the 2A EDG in the last 100 starts: September 2, 1987; January 12, 1988; and April 6,1989. The surveillance frequency remains as once per 31 days, which is in conformance with Regulatory Position C.2.d of Regulatory Guide 1.108.