ML20086L948

Special Rept:On 950517,operators Experienced Difficulties W/Excitation of Generator in Form of Voltage Swings When Utilizing Each of Two Voltage Regulators

ML20086L948
Person / Time
Site:	Vogtle
Issue date:	07/14/1995
From:	Mccoy C GEORGIA POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LCV-0622-A, LCV-622-A, NUDOCS 9507240064
Download: ML20086L948 (2)

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tv scorrem ecc system LCV-0622-A 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, REVISION 1 DIESEL GENERATOR FAILURES 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 revised special report concerning diesel generator failures. Further review of the test records has revealed that a diesel generator troubleshooting start should be classified as a non-valid failure since it exhibited the same unstable voltage problem with voltage regulator #2 that led to the original valid failure.

Sincerely, CE%'

C. K. hicCoy CKhVTEW  !

Enclosure:

Special Repon 1-95-1, Revision 1 xc: Georgia Power Company Mr. J. B. Beasley, Jr.

Mr. M. Sheibani NORMS U. S. Nuclear Regulatory Commission Mr. S. D. Ebneter, Regional Administrator Mr. D. S. Hood, Licensing Project Manager, NRR Mr. B. R. Bonser, Senior Resident Inspector, Vogtle 9507240064 PDR 950714

' ADDCK 05000424 PDR i}

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VOGTLE ELECTRIC GENERATING PLANT - UNIT I TECHNICAL SPECIFICATION SPECIAL REPORT 1-95-1, REVISION 1

_ DIESEL GENERATOR (DG) FAILURES 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 failures, valid or invalid, be reported to the Commission in a special report pursuant to TS 6.8.2.

B. DESCRIPTION OF FAILURES OF DIESEL GENERATOR IB l On May 17,1995, at 0918 EDT, DGlB was started for a monthly surveillance test. Operators experienced difIiculties 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 normal levels. 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. At 1341 EDT, DG1B was started for troubleshooting. When voltage regulator #2 was placed into service, voltage again became erratic and unstable. DGlB was stopped at 1553 EDT This DG start represents a non-valid failure because the engine had been removed from service and it exhibited one of the same problems that led to the valid failure.

Integrated circuit chips were replaced in voltage regulator #2, and DGlB 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 start of May 17,1995, at 0918 EDT, has been determined to be a valid failure because it could have affected the engine's emergency start capability.

Diesel Generator 1B has had I 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.  ;

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