ML17222A771

Special Rept:On 890315,diesel Tripped on High Crankcase Pressure.Caused by Engine Design.Pressure Trip Reset,But Output Breaker Failed to Close.Faulty Voltage Monitoring Relay Replaced.On 890321,same Diesel Generator Tripped

ML17222A771
Person / Time
Site:	Saint Lucie
Issue date:	04/27/1989
From:	Conway W FLORIDA POWER & LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
L-89-167, NUDOCS 8905010241
Download: ML17222A771 (5)

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ACCESSION NBR:8905010241 DOC.DATE: 89/04/27 NOTARIZED: NO DOCKET I FACIL:50-389 St. Lucie Plant, Unit 2, Florida Power & Light Co. 05000389 AUTH. NAME AUTHOR AFFILIATION CONWAY,W.F. Florida Power & Light Co.

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

SUBJECT:

Special rept:on 890315 & 21,diesel generator failure occurred.

DISTRIBUTION CODE: IE22D COPIES RECEIVED:LTR ENCL SIZE TITLE: 50.73/50.9 Licensee Event Report (LER), ncident Rpt, etc. D NOTES:

RECXPIENT 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 D

XNTERNAL: ACRS MICHELSON 1 1 ACRS MOELLER 2 2 ACRS WYLIE 1 1 AEOD/DOA 1 1 AEOD/DSP/TPAB 1 1 AEOD/ROAB/DSP 2 2 D DEDRO 1 1 IRM/DCTS/DAB 1 1 NRR/DEST/ADE 8H 1 1 NRR/DEST/ADS 7E 1 0 NRR/DEST/CEB 8H 1 1 NRR/DEST/ESB 8D 1 1 NRR/DEST/ICSB 7 1 1 NRR/DEST/MEB 9H 1 1 NRR/DEST/MTB 9H 1 1 NRR/DEST/PSB 8D 1 1 NRR/DEST/RSB 8E 1 1 NRR/DESTJSGB 8D 1 1 NHR/DLPQ/HFB 10 1 1 NRR/DLPQ/QAB 10 1 1 NRR/DOEA/EAB 11 1 1 NRR/DREP/RPB 10 2 2 NR~R DRY SIB 9A "1 1""-' NUDOCS-ABSTRACT 1 1 G 'FILE 02 1 RES/DSIR/EIB 1 1 S/DSR RAB 1 1 RGN2 FILE 01 1 1 EXTERNAL: EG&G WILLIAMS,S 4 4 FORD BLDG HOY,A 1 1 L ST LOBBY WARD 1 1 LPDR 1 1 R NRC PDR 1 1 NSIC MAYS,G 1 1 NSIC MURPHY,G.A 1 1 I D

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P.O. Box14000, Juno Beach, FL 33408-0420 APRlL',7 1989 L-89-167 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C. 20555 Gentlemen:

Re: St. Lucie Unit 2 Docket No. 50-389 Date of Events: March 15, 1989 and March 21, 1989 S ecial Re ort on Diesel Generator Failures The attached Special Report is being transmitted pursuant to the recpxirements of Technical Specification 4.8.1.2.2 to provide notification of 2B Emergency Diesel Generator failures.

Very truly yours, W. F. Con y Senior Vi e President Nuclear WFC/JRH/cm Attachment cc: Stewart D. Ebneter, Regional Administrator, Region Senior Resident Inspector, USNRC, St. Lucie Plant II, USNRC g90g0102gl 890427 05 PDR ADOCK on FPL Group company

SPECIAL REPORT DIESEL GENERATOR FAILURES 2B DIESEL GENERATOR FAILURE: 3/15/89 In accordance with NRC Reg. Guide 1.108, section C.2.e, this e'vent is considered a non-valid diesel generator failure, since it was caused by a "malfunction of equipment that is not operative in the emergency operating mode." However, in accordance with Unit 2 Technical Specification 4.8.1.2.2, this event is being submitted as a Special Report.

At 1109 on March 15, 1989, the 2B diesel generator was started for a monthly surveillance run. The 2B diesel tripped on high crankcase pressure. The high crankcase pressure trip was on the 12 cylinder engine. This trip signal is bypassed by design when the diesel generator is in the emergency mode. The high crankcase pressure trip was reset and the 2B diesel was successfully restarted for the surveillance.

The cause of the high crankcase pressure trip is in the design of the 12 cylinder engine. Under certain conditions, (e. g., fast starts and/or lower lube oil temperatures), the lube oil relief valve will relieve lube oil in close proximity to the crankcase pressure detector, thus causing a high crankcase pressure trip. The high crankcase pressure trip is not operative when the diesel generator is in the emergency operating mode; therefore, this is considered a non-valid failure.

The immediate corrective actions taken were to reset the high crankcase pressure trip and complete the required surveillance for the 2B Diesel Generator.

ln addition, oil splash guards were. installed on both the 2A and 2B 12 cylinder engines. These actions were completed by March 21, 1989. Also, since the recently issued Amendment No. 39 to the Technical Specifications allows idle starSs (450 rpm vice 900 rpm), procedure changes are being prepared in order to perform idle diesel engine starts when the soakback oil system has been out of service for extended periods.

Additional information:

a) One valid failure in the last 100 valid tests b) The diesel was out of service for a brief period to reset the high crankcase pressure trip.

c) The current surveillance interval is once every 31 days.

SPECIAL REPORT DIESEL CENERATOR FAILURES Page Two 2B DIESEL CENERATOR FAILURE: 3/15/89 In accordance with NRC Reg. Cuide 1.108, Section C.2.e, this event is considered a valid diesel generator failure since this event falls under the category of "successful starts followed by an unsuccessful loading attempt". Furthermore, in accordance with Unit 2 Technical Specification 4.8.1.2.2, the event is being submitted as a Special Report.

At 1119 on March 15, 1989, the 2B diesel generator was successfully restarted for the monthly surveillance run after resetting the high crankcase pressure trip from the previous start attempt. The diesel generator output breaker would not close. The 2B diesel generator was secured and declared out of service.

The failure of the diesel generator output breaker to close was due to a faulty Voltage Monitoring Relay (VMR) in the Diesel Cenerator Control Panel. The VMR is one of the permissive contacts that has to be made up before the output breaker can be closed. This relay prevented loading of the diesel generator.

This event was determined to be a valid failure in accordance with Reg. Cuide 1.108, Section C.2.e.

Corrective actions taken were the replacement of the Voltage Monitoring Relay and completion of the required surveillance to return the diesel back to service.

Additional information:

a) This failure is the second valid failure in the last I00 valid tests.

b) The diesel was out of service for this event for 8 hrs. and 12 min.

c) The current surveillance interval is once every 31 days.

SPECIAL REPORT DIESEL GENERATOR FAILURES Page Three 2B DIESEL GENERATOR FAILURE: 3/21/89 In accordance with NRC Reg. Guide 1.108, Section C.2.e, this event is considered a non-valid diesel generator failure, since it was caused by a "malfunction of equipment that is not operative in the emergency operating mode." However, in accordance with Unit 2 Technical Specification 4.8.1.2.2, this event is being submitted as a Special Report.

At 0729 on March 21, 1989, the 2B diesel generator automatically started due to the inadvertent actuation of the Containment Isolation Actuation Signal (see LER 389-89-003). When the Containment Isolation Actuation Signal was reset, the 2B diesel generator tripped on high crankcase pressure. This event occurred prior to the installation of the oil splash guard on the 2B diesel generator. The 2B diesel generator was placed out of service to correct the problem.

The cause of the high crankcase pressure trip is in the design of the 12 cylinder engine. Under certain conditions, (e.g., fast starts and/or lower lube oil temperatures), the lube oil relief valve will relieve lube oil in close proximity to the 'crankcase pressure detector, thus causing a high crankcase pressure trip. The high crankcase pressure trip is not operative when the diesel generator is in the emergency operating mode; therefore, this is considered a non-valid failure.

Corrective actions taken were the installation of oil splash guards on the 2A and 2B 12 cylinder engines. Also, since the recently issued Amendment No.

39 to the Technical Specification-allows idle starts (450 rpm'ice 900 rpm),

procedure changes are being prepared in order to perform idle diesel engine starts when the soakback oil system has been out of service for extended periods.

Additional information:

a) Two valid failures in the last 100 valid tests b) The diesel was out of service for this event for 5 hrs. and 55 min.

c) The current surveillance interval is once every 31 days.