ML17228A978

Special Rept:On 941214,2A Emergency Diesel Generator Failed. Caused by Excessive Clearance Between Speed Adjusting Shaft & Shaft Bushing.Electrical Maint Replaced Failed Governor/ Actuator Assembly on 2A2 EDG

ML17228A978
Person / Time
Site:	Saint Lucie
Issue date:	01/09/1995
From:	Sager D FLORIDA POWER & LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
L-95-007, L-95-7, NUDOCS 9501200347
Download: ML17228A978 (5)

Text

~ +~~ J. A KCCEI.ECTED RIDS PROCI'.SSIiG)

I A REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9501200347 DOC.DATE: 95/01/09 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 941214,2A emergency diesel generator failed.

Caused by excessive clearence between speed adjusting shaft

& shaft bushing. Electrical maint replaced failed governor/

actuator assembly on 2A2 EDG.

DISTRIBUTION CODE: IE22D COPIES RECEIVED:LTR TITLE: 50.73/50.9 Licensee Event Report (LER),

ENCL 4 SIZE:

Incident Rpt, etc.

NOTES:

RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD2-2 PD 1 1 NORRIS,J 1 1 INTERNAL: ACRS 1 1 AEOD/SPD/~B 2 2 AEOD/SPD/RRAB NRR/DE/ECGB 1

1 1

1

~E CENTZR~02 NRR/DE/EELB 1

1 1

1 NRR/DE/EMEB 1 1 NRR/DISP/PIPB 1 1 NRR/DOPS/OECB 1 1 NRR/DRCH/HHFB 1 1 NRR/DRCH/HICB 1 1 NRR/DRCH/HOLB 1 .1 NRR/DRSS/PRPB 2 2 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 NOAC MURPHY,G.A 1 1 NOAC POORE,W. 1 1 NRC PDR 1 1 NUDOCS FULL TXT 1 1, NOTE TO ALL"RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE iVKSTE! CONTACT'I'IIE DOC!.'iIENTCONTROL DISTRIBUTION LIS'I'S I'OR DOCI. NIEN'I'S YOI.'ON" I'I DESk, ROONI Pl.37 (EP. 504.~0S3 ) TO I;Llhl!NATE5'OI.'R %ANIL FROil I'.D!

TOTAL NUMBER OF COPIES REQUIRED: LTTR 28 ENCL 28

Florida Power 8 Light Company, P.O. Box 128, Fort Pierce, FL 34954-0128 January 9, 1995 L-95-007 10 CFR 50.36 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 Re: St. Lucie Unit 2 Docket No. 50-389 Special Report Date of Event: December 14, 1994 Emer enc Diesel Generator Failure The attached Special Report is being submitted pursuant to the requirements of the St. Lucie Technical Specifications. This report provides notification of one valid failure of the 2A Diesel Generator.

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

Very truly yours, D. A. ger Vice esident St. ie Plant DAS/JWH Attachment cc: Stewart D. Ebneter, Regional Administrator, USNRC Region XX Senior Resident Inspector, USNRC, St. Lucie Plant 9501200347 95010'P PDR ADOCK 05000389 8 PDR an FPL Group company

SPECIEl'EPORT TITLE 2A Emergen Diesel Generator valid failure due to mechanical binding inside the 2A2 Woodward Governor/Actuator.

INITIAL CONDITIONS St. Lucie Unit 1 was at 100'. power and St. Lucie Unit 2 was at 75% power (downpower due to cleaning condenser waterboxes) .

EWZÃZ SEQUENCE On December 14, 1994 the 2A Emergency Diesel Generator (EDG) was started to perform a surveillance in accordance with Technical Specification Table 4.8-1. Surveillance testing of the 2A EDG is recpired evexy 31 days. The 2A EDG was started locally and after attaining 900 RPN the "2A2 Engine Failure to Start" annunciator alarmed indicating that the 12 cylinder engine had failed to pick up load. While responding to the alarm the 2A2 (12 cylinder) engine loaded and the alarm cleared. The EDG parameters were then verified to be satisfactory and the surveillance was continued.

The failure of the 2A2 engine to load constitutes a valid failure of the 2A EDG. The 2A EDG may not have been able to achieve the designed full rated voltage and fre ency in the required 10 seconds and subsequent full load in the following 1 minute due to the failure of the 2A2 engine to load on demand.

Testing was conducted on the 2A EDG to determine the cause for the delay in the loading of the 2A2 engine. Testing showed that the operation of the speed adjusting shaft to the speed adjusting lever gear (located inside of the

~ Woodward Governor) was being interrupted. The 2A2 EDG Woodward Governor/Actuator assembly was replaced, surveillance testing performed and the 2A EDG was declared back in service at 0500 December 15, 1994.

IV. CAUSE OP THE EVEKT The cause for the failure of the 2A2 EDG was determined to be excessive clearance between the speed adjusting shaft and its shaft bushing. This clearance would allow the shaft gear to ride up the lever gear and become locked, causing a friction clutch to slip, which prevented the shifting of the mechanical governor out of the operating .

range of the electrical governor. With the mechanical governor held at a location below its setpoint the governor/actuator would not function to position the fuel rack to an open position and allow the 2A2 engine to load.

An inspection of the failed governor/actuator will be performed by the Woodward Governor Company at their

'acilities. A report on the root cause for this failure and for corrective actions to preclude another similar failure will be provided to FPL by Woodward following their inspection.

V. CORRECTIVE ACTIONS

1) Electrical Maintenance replaced the failed governor/actuator assembly on the 2A2 EDG.

2) Operations performed a surveillance on the 2A EDG in accordance with Technical Specification 3.8.1.1 and returned the 2A EDG to service.')

Electrical Maintenance will send the governor/actuator assembly to the Woodward Governor Company for inspection and root cause determination and will evaluate the report to determin'e what additional preventive maintenance measures need to be implemented.

4) A visual inspection of the Woodward Governors on the other engines showed that a similar problem was not present.

VZ. SUPPORTING INFORMATION

-This was the second valid failure of the 2A EDG in the previous 100 valid tests (last failure was 4/6/89) .

-The 2A EDG was out of service for approximately 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> until the governor/actuator could be replaced and a successful surveillance test performed.

-The surveillance schedule required because of this failure remains at once per 31 days.