ML20084M717

Special Rept:On 950517,operators Experienced Difficulties W/Excitation of Generator in Form of Voltage Swings When Utilizing Each of Two Voltage Regulators.Caused by Oxidation of Potentiometer Contact Surface.Surface Wiped Clear

ML20084M717
Person / Time
Site:	Vogtle
Issue date:	06/02/1995
From:	Mccoy C GEORGIA POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LCV-0622, LCV-622, NUDOCS 9506070545
Download: ML20084M717 (2)

Text

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~ Georga Power Company

• y - 40 inverneca Center Parkway

, Post Omce Der 1295 '

B:rmsvgham, Alabama 35201 Telephone 205 877 7122 L

C. K. McCoy Georgia' Power Vice Presxient Nuclear Vogne Prorect tte southem ehttre system LCV-0622 Docket No. 50 424 U. S. Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555 Ladies and Gentlemen:

VOGTLE ELECTRIC GENERATING PLANT SPECIAL REPORT l-95-1 VALID DIESEL GENERATOR FATLURE In accordance with the requirements of Vogtle Electric Generating Plant Technical Specifications (TS) sections 4.8.1.1.3 and 6.8.2, Georgia Power Company submits the enclosed special report concerning a valid diesel generator failure.

Sincerel, f'&'

C. K. hicCoy i

l CKhi/TEW i l

Enclosure:

Special Report 1-95-1 xc: Georgia Power Company hir. J. B. Beasley, Jr.

hir, bl. Sheibani I

NORhiS U. S. Nuclear Regulatory Commission hir S. D. Ebneter, Regional Administrator hir. D. S. Hood, Licensing Project hianager, NRR hir. B. R. Bonser, Senior Resident Inspector, Vogtle  !

9506070545 950602 PDR ADDCK 05000424 ff

VOGTLE ELECTRIC GENERATING PLANT - UNIT 1 TECIINICAL SPECIFICATION SPECIAL REPORT l-95-1 VALID DIESEL GENERATOR (DG) FAILURE A. REQUIREMENT FOR REPORT This report is required in accordance with the Vogtle Electric Generating Plant Technical Specifications (TS), section 4.8.1.1.3, which requires that all DG L failures, valid or invalid, be reported to the Commission in a special report l pursuant to TS 6.8.2.

1 B. DESCRIPTION OF VALID FAILURE OF DIESEL GENERATOR 1B On May 17,1995, at 0918 EDT, DGlB was started for a monthly surveillance test. Operators experienced difliculties with excitation of the generator in the form of voltage swings when utilizing each of the two voltage regulators. During the initial test sequence, while operating on voltage regulator #1, the generator experienced a voltage drop but recovered to normallevels. The problem did not recur. When voltage regulator #2 was placed into service, the voltage was erratic / unstable. DGlB was stopped at 1022 EDT for troubleshooting.

Integrated circuit chips were replaced in voltage regulator #2, and DGIB was successfully tested and returned to service on May 18,1995, at 0400 EDT.

Voltage regulator #1 was tested, but no discrepancies were found. It has been determined that a potentiometer, located external to the voltage regulator, experienced some oxidation on the potentiometer contact surface, that was later wiped clear. This finding was supported by vendor input.

C.

SUMMARY

The DGlB failure has been determined to be valid because it could have affected the engine's emergency start capability. Diesel Generator IB has had 1 valid failure in the last 20 valid tests and 2 valid failures in the last 100 valid tests. Test frequency for DGlB remains at once per 31 days in accordance with the requirements of TS table 4.8-1.

I

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