ML20086S264

Special Rept:On 950628,generator Output Voltage Dropped Below Normal Rated Value.Caused by Malfunctioning Transformer T3.Voltage Regulator 2 Replaced,Tested & Returned to Svc on 950629

ML20086S264
Person / Time
Site:	Vogtle
Issue date:	07/26/1995
From:	Mccoy C GEORGIA POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LCV-0645, LCV-645, NUDOCS 9508010161
Download: ML20086S264 (2)

Text

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Georg.a Power Company

• 40 inverness Center Parkway e Post Omce Box 1295 B.rmingham, Alabama 35201 Telephone 205 877-7122

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c. K. uccoy Georgia ' Power Vce Presdent, Nuclear Vogtle Pronect the southern elecirc system July 26, 1995 LCV-0645 Docket No. 50-424 U. S. Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555 Gentlemen:

VOGTLE ELECTRIC GENERATING PLANT UNIT 1 - SPECIAL REPORT 1-95-2 VALID DIESEL GENERATOR FAILURE 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 ,

C. K. McCoy CKM/TEW

Enclosure:

Special Report 1-95-2 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 G10018 9508010161 950726 PDR ADOCK 05000424 (P I I S PDR l

,- VOGTLE ELECTRIC GENERATING PLANT - UNIT 1 TECHNICAL SPECIFICATION SPECIAL REPORT 1-95-2 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 diesel generator (DG) failures, valid or non-valid, be reported to the Commission in a special report pursuant to TS 6.8.2.

B. DESCRIPTION OF VALID FAILURE OF DIESEL GENERATOR 1A On June 28,1995, at 0942 EDT, DG1 A was started for a monthly surveillance test with voltage regulator #2 in service. After attaining rated voltage and frequency during the starting sequence, but prior to loading the generator, generator output voltage dropped below the normal rated value. Operators initially experienced difficulty in manually adjusting the voltage above 4000 volts. After a few voltage manipulation attempts with the generator's lower and raise buttons, operators were eventually able to adjust the voltage throughout the normal range with no fluctuations encountered. The surveillance test was completed at 1155 EDT without further problems. Following a review of the test and the receipt of a generator trouble alarm that would not reset (due to the field ground relay), DGI A was declared inoperable at 1634 EDT and removed from service. Troubleshooting ofvoltage regulator #2 found a malfunctioning transformer (T3) used to transform the generator AC output voltage to a level useable by the regulator. A surveil:ance test was again performed using voltage regulator #1 and DGI A was returned to service on June 29,1995, at 0245 EDT. Voltage regulator #2 was replaced, tested and returned to service on July 7,1995. A formal review of this failure and other DG voltage issues is being conducted to determine the cause of the T3 transformer  :

failure and any other contributing problem (s).

C.

SUMMARY

The DGI A start of June 28,1995, at 0942 EDT, has been determined to be a valid failure because the reduced voltage would have affected the DG's ability to perform its intended safety function without operator intervention. DGI A has had 1 valid failure in the last 20 valid tests and 3 valid failures in the last 100 valid tests. The test frequency for DGI A remains at once per 31 days in accordance with the requirements ofTS table 4.8-1.