ML17221A454

Special Rept:On 870902,General Motors Emergency Diesel Generator Failed to Start.Caused by 12-cylinder Engine Actuator Friction Clutch Assembly Out of Adjustment.Clutch Assembly Adjusted

ML17221A454
Person / Time
Site:	Saint Lucie
Issue date:	10/19/1987
From:	Woody C FLORIDA POWER & LIGHT CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
L-87-418, NUDOCS 8710230216
Download: ML17221A454 (5)

Text

REGULA Y INFORMATION DISTR IBUTI YSTEM (RIDS).ACCESSION NBR: 8710230216 DOC.DATE: 87/10/19 NOTARIZED:

NO FACIL 50-389 St.Lucie Plantr Unit 2 Florida Poujer Cc Light Co.AUTH.NAME A'UTHOR AFFILIATION WOQDYr C.O.Florida Power h Light Co.REC IP.NAME RECIPIENT AFFILIATION DOCKET ir 05000389

SUBJECT:

Special rept: on 870902r General Motors emergency diesel generator Sailed to start.Caused bg 12 cylinder engine actuator F'riction clutch assembly out oP ad Justment.Clutch assembly adJusted.W/871019 ltr.DISTRIBUTION CODE;IE22D COPIES RECEIVED LTR i ENCL[SIZE;TITLE: 50.73 Licensee Event Report (LER)i Incident Rptr etc.NOTES: RECIPIENT ID CODE/NAME PD2-2 LA TOUR IGNYI E COPIES LTTR ENCL 1 1 1 1 RECIPIENT.COPIES ID CODE/NAME LTTR ENCL PD2-2 PD'1 1 INTERNAL: ACRS MICHELSON.AEOD/DOA AEOD/DSP/ROAB ARM/DCTS/DAB NRR/DEST/ADS NRR/DEST/ELB NRR/DEST/MEB NRR/DEST/PSB NRR/DEST/SGB NRR/DLPG/GAB NRR/DREP/RAB N S/S I B~EG FILE'02 RES TELFORDr J RGN2 FILE 01 EXTERNAL: EGSG QROHI M LPDR NSIC HARRIS'1 1 1 2 2 1 1 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 5 5 1 1 1 1 ACRS MOELLER AEOD/DSP/NAS AEOD/DSP/TPAB DEDRO NRR/DEST/CEB NRR/DEST/I CSB NRR/DEST/MTB NRR/DEST/RSB NRR/DLPG/HFB NRR/DOEA/EAB NRR/DREP/RPB NRR/PMAS/ILRB.RES DEPY GI RES/DE/EIB H ST LOBBY WARD NRC PDR NSIC MAYSr G 2 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 2'1 1'1 1 1 1 1 1 1 1 TOTAL NUMBER OF COPIES REQUIRED: LTTR 45 ENCL 44 P.OX 14000, JUNO BEACH, PL 33408 0420 OCTOBER 1 g 1987 L-87-4I8 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 Event: September 2, l987 S ecial Re ort on Diesel Generator Failure The attached Special Report is being transmitted pursuant to the requirements of Technical Specification 4.8.I.I.3 and 6.9.I to provide notification of the 2A Emergency Diesel Generator failure.Very truly yours, C.O.W Group Vice President Nuclear Energy COW/GRM/gp Attachment cc: Dr.~.'Nelson Grace, Regional Administrator, Region II, USNRC Senior Resident Inspector, USNRC, St.Lucie Plant 87i02302ib 87iOi9 PDR ADOCK 05000389 S GR M2/034/I an FPL Group company SPECIAL REPORT DIESEL GENERATOR FAILURE~~At 0920 hours0.0106 days <br />0.256 hours <br />0.00152 weeks <br />3.5006e-4 months <br /> on September 2, l987, St.Lucie Unit 2 Emergency Diesel Generator (EDG)2A was started for a surveillance run.An alarm was received which indicated that one of the engines in the 2A EDG had failed t'o start.The input signal to this alarm is a high temperature differential between the l6 and the l2 cylinder engines'urbo exhaust temperatures indicating that the engine with the hottest exhaust is picking up more load than the other engine.The two EDG's installed in St.Lucie Unit 2 are General Motors EMD 645-E4 units, each consisting of a l6 cylinder and a l2'cylinder engine mounted in tandem and driving a single generator.

At the time the 2A EDG was started, a plant operator observed locally that the lever for the l2 cylinder engine fuel racks did not move.The lever indicator for the fuel rack is graduated from 62 to l96, with the l96 position being in the idle position and 62 being the fully racked in position.As observed by the operator during the inital start,-the lever was at the I 96 position until approximately one minute after starting whe'n the lever position was noted to be approximately at the l30 position.It was also observed by the operator that the temperature differential between the engines'urbo exhaust was approximately 280 degrees F.The l2 cylinder engine temperature was l50 degrees F and the l6 cylinder engine was at 430 degrees F.When the l2 cylinder engine started, the 12 cylinder engine temperature rose, and the alarm cleared.At 0922, the 2A EDG was stopped.The reactor control operator noted the starting time to be l2 seconds, this exceeded the Technical Specification required time of IO seconds or less.At.0938, the 2A EDG was re-started to allow operations personnel to assess and evaluate its performance.

The sta'rt time was 7.76 seconds and no apparent problem with the fuel racks was noted.The 2A EDG.was then stopped to allow cooldown in preparation for the performance of the required surveillance run't l245, the 2A EDG was re-started for the surveillance run.The start time was noted to be 8.52 seconds.At l350, the 2A EDG was stopped and the surveillance run was deemed satisfactory.

Although the subsequent re-starts of the 2A EDG indicated that the 2A EDG started and accelerated to at least 900 rpm and reached the required voltage and frequency in less than IO seconds, the initial start was determined to be a valid diesel failure.This determination was based on the following: (I)the excessive starting time, (2)the indication that the lever for the l2 cylinder engine fuel racks did not move in until approximately one minute after starting, and (3)the observed high temperature differential between the l6 and the l2 cylinder engines'urbo exhaust temperatures.'he last EDG failure was in July 9, l986.This is the first failure of a St.Lucie Unit 2 Emergency Diesel Generator within the'last l00 valid starts.The surveillance frequency remains as once per 3I days, which is Iri conformance with regulatory position C.2.d of Regulatory Guide I.I08, Revision I, August I 977.GRM2/034/2 On'September 22, l987, the EDG task team supported by electical maintenance,'echanical maintenance and operations personnel performed tests and inspections on the 2A EDG to determined the root cause of the failure.A structure tree was developed an'd from it a recommended test/inspection was generated.

The test revealed that the l2 cylinder engine actuator friction clutch assembly was out of adjustment by 0.5 inch-pounds.(The recommended range.of adjustment is 4.5 to 5.5 inch-pounds)

The as found torque was 4.0 inch-,pounds.

The friction clutch was readjusted to 4.5 inch-pounds and then the act'uator was restored to normal.The~2A EDG was returned to operations for surveillance testing, experienced a normal start sequence and started in 6.99 seconds.The engines loaded normally.The EDG task team concluded that it is possible that the slippage in this assembly could produce intermittent problems with the start sequence.A periodic check of the friction clutch adjustment has been added to the EDG maintenance program.Another potential item of concern was the governor air booster assembly.The air booster assembly will be sent to Woodward Governor for testing and evaluation for wear/degradation, and a report will be provided to the St.Lucie Plant on their findings.This will be done during the upcoming St.Lucie Unit 2 refueling outage in October l 987.GR M2/034/3

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