ML20059B832

Special Rept 2-93-3:on 931001,DG 2B Invalid Failure Occurred When DG Failed to Attain Rated Voltage & Frequency in Required Time & on 931002,DG 2A Invalid Failure Occurred When DG Tripped on Overspeed

ML20059B832
Person / Time
Site:	Vogtle
Issue date:	10/25/1993
From:	Mccoy C GEORGIA POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
2-93-3, LCV-0175, LCV-175, NUDOCS 9310290111
Download: ML20059B832 (3)

Text

,' . Georgia Powe Com.oany 40 invemen Center Pa4way Post o%m Bon 1295 Gwm ngham, Abt;xna 3520 t feiephone 205 677 7122 m

C. K, McCoy Georgia Power Vce Pres oer,t, %cier vue m'" October 25, 1993 "*"""""'""'

LCV-0175 Docket No. 50-425 U. S. Nuclear R.egulatory Commission ATTN: Document Control Desk i Washington, D. C. 20555 Gentlemen:

VOGTLE ELECTRIC GENERATING P!. ANT SPECIAL REPORT IbiVALID DIESEL GEV . f JR FAILURES in accordance with the requirements of the Vo p uectric Generating Plant Technical Specifications, sections 4.8.1.1.3 and 6.8.2, Georgia Power Company submits the enclosed special report concerning two invalid diesel generator failures.

Sincerely, (VfWf '

C. K. McCoy CKM/NJS

Enclosure:

Special Report 2 93-3 xc: Ogorgia Power Company Mr. J. B. Beasley, Jr.

Mr. M. Sheibani NORMS U. S. Nuclear Renulatory Commission Mr. S. D. Ebneter, Regional Administrator Mr. D. S. Hood, Licensing Project Manager, NRR Mr. B. R. Bonser, Senior Resident Inspector, Vogtle 290021 ,

9310290111 931025 S' h i

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.l VOGTLE ELECTRIC GENERATING - UNIT 2 TECHNICAL SPECIFICATION SPECIAL REPORT 2-93-3

, INVALID DIESEL GENERATOR 2A & 2B FAILURES A. REQUIREMENT FOR REPORT This repon is required in accordance with the Vogtle Electric Generating Plant Technical Specifications (TS), section 4.8.1.1.3, which requires all diesel generator (DG) failures, valid ,

or invalid, be reported to the Commission in a special report pursuant to TS 6.8.2.

B. DESCRIPTION OF INVALID FAILURES OF DIESEL GENERATOR 2A & 2B

1. At 0755 EDT on October 1,1993, DG 2B failed to attain rated voltage and frequency -

within the time period specified by Technical Specification (TS).4.8.1.1.2.a.4. Diesel generator 2B had just completed a 24-hour run pursuant to TS 4.8.LI.2.h.7, and an attempt was made to restart the DG as required by TS within 5 minutes of completing the 24-hour run. However, when the start was made, shortly after the initial shutdown, the DG failed to attain rated voltage and frequency within 11.4 seconds of the start signal.

The delay was caused by the initiation of a second shutdown sequence resulting from the  ;

failure of a pneumatic logic element. Until complete, the second shutdown sequence prevented fuel admission to the DG during the ensuing normal start sequence. Diesel generator 2B was subsequently declared inoperable.

'I The pneumatic logic element was replaced, and DG 2B was successfully restarted under ,

the same conditions as the original failure condition. Diesel generator 2B was declared operable at 0204 EDT, October 2,1993.  !

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2. At 0142 EDT on October 2,1993, DG 2A tripped on overspeed while a post-maintenance run and setup was being performed after a 5-year inspection. The DG was started for a  ;

mechanical governor setup with a temporary gauge installed at the governor to provide immediate indication of engine speed for the individual adjusting the governor during the '

engine start. After all of the air was vented out of the governor, engine speed was set at 470 rpm using the speed control knob. Proper governor response was verified by decreasing engine speed to approximately 350 rpm using the load limit knob, then quickly l increasing engine speed to the original setting. During performance of this procedure, the I engine tripped on overspeed. The engine was restarted and the speed checked using a hand-held tachometer. This action confirmed that the overspeed trip was the result of the temporary gauge indicating approximately 25 rpm higher than actual engine speed. The overspeed occurred within the accepted range for this function, verifying the correct I 1

operation of the trip function. The temporary gauge was properly adjusted and post-maintenance testing was resumed. l l

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VOGTLE ELECTRIC GENERATING - UNIT 2 TECilNICAL SPECIFICATION SPECIAL REPORT 2-93-3

. INVALID DIESEL GENERATOR 2A & 2B FAILURES C.

SUMMARY

1. The DG 2B event has been determined to be an invalid failure because it involved the malfunction of equipment that does not function in the emergency operating mode. The DG would have been available for emergency operation.

Diesel Generator 2B has had 0 valid failures in the last 20 valid tests and 1 valid failure in the last 100 valid tests. Test frequency remains at once per 31 days in accordance with the requirements of TS table 4.8-1.

2. The DG 2A event was determined to be an invalid failure because it occurred while the DG was undergoing post-maintenance testing, was attributed to test equipment error, and the DG was removed from service for scheduled maintenance.

Diesel generator 2A has had 0 valid failures in the last 20 valid tests and 0 valid failures in the last 100 valid tests. Test frequency remains at once per 31 days in accordance with the. ,

requirements of TS table 4.8-1.

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