ML20209F862

Special Rept Spr 85-004:on 850508,during Surveillance Testing of Diesel Generator A,Unit locked-in at 6,700 Volts & Declared Inoperable.Caused by Gear Binding in Motor Drive Assembly.Voltage Regulator Replaced

ML20209F862
Person / Time
Site:	Summer
Issue date:	06/07/1985
From:	Dixon O SOUTH CAROLINA ELECTRIC & GAS CO.
To:	Grace J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
SPR-85-004, SPR-85-4, NUDOCS 8507120560
Download: ML20209F862 (3)

Text

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s SOUTH CAROLINA ELECTRIC & GAS COMPANY POST OFFICE 764 COLuwsiA. South CAROLINA 29218 o.w.omon.a.

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. uvetsa o...arious jane J"g 1985 Dr. J. Nelson Grace LRegional Administrator U.S. Nuclear Regulatory Commission Suite 2900 101 Marietta Street, NW Atlanta, Georgia 30323

SUBJECT:

-Virgil C. Summer Nuclear Station Docket No. 50/395 Operating License No. NPF-12 Special Report (SPR 85-004)

Dear Dr. Grace:

Attached is a Special Report.for the Virgil C. Summer Nuclear Station. This Special Report is required by Section 6 of the Technical Specifications.

Should there be any questions, please call us at your convenience.

Very truly yours, O. W. ix , Jr.

RJB:0WD/ led Attachment cc: V. C. Summer K. E. Nodland T. C. Nichols, Jr./0. W. Dixon, Jr. R. A. Stough E. H. Crews, Jr. G. Percival E. C. Roberts C. W. Hehl W. A. Williams, Jr. J. B. Knotts, Jr.

D. A. Nauman S. D. Hogge Group Managers I&E Washington

0. S. Bradham Document Management C. A. Price Branch S. R. Hunt INPO Records Center J. F. Heilman ANI Library C. L. Ligon (NSRC) NPCF File 0 850607 hyk71jgg{A05000395 S

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Dr. J. Nelson Grace SPR 85-004 Page Two June 7, 1985 EVENT DESCRIPTION On May 8, 1985 at 1930 hours0.0223 days <br />0.536 hours <br />0.00319 weeks <br />7.34365e-4 months <br />, Operations personnel were conducting surveillance testing on Diesel Generator (DG) "A". The unit was satisfactorily started and was operating in a stable condition.

During an attempt to vary the unit's voltage, the unit responded to a lower voltage demand and locked-in at 6700 Volts (V). The unit was shutdown and declared inoperable.

Due to DG "A" being declared inoperable, DG "B" war tested at 1950 hours0.0226 days <br />0.542 hours <br />0.00322 weeks <br />7.41975e-4 months <br />. During the testing activity, a fuel injector water side failure occurred and DG "B" was declared in o p e r ab l e .

As a result of both diesel generators being declared inoperable, a Notification of an Unusual Event (NOUE) was declared at 0520 hours0.00602 days <br />0.144 hours <br />8.597884e-4 weeks <br />1.9786e-4 months <br /> on May 9, 1985. The station secured from the NOUE at 1330 hours0.0154 days <br />0.369 hours <br />0.0022 weeks <br />5.06065e-4 months <br /> on May 9, 1985. The delay in. declaring the NOUE resulted in the issuance of a potential violation by the Resident Inspector.

CAUSE AND CORRECTIVE ACTION The failure of DG "A" was due to gear binding in the motor d r iv e assembly associated with the automatic raise-lower voltage control for the voltage regulator. The voltage regulator was replaced and the unit was satisfactorily tested and declared operable at 1330 hours0.0154 days <br />0.369 hours <br />0.0022 weeks <br />5.06065e-4 months <br />.

The failure of DG "B" was due to a water side failure of a new fuel injector which had been installed during a recent engine overhaul - May 4, 1985. A new injector was installed; the unit was satisfactorily tested and was declared operable at 1530 hours0.0177 days <br />0.425 hours <br />0.00253 weeks <br />5.82165e-4 months <br /> on May 11, 1985.

Nonconformance Notices have been initiated requesting Engineering to review the failures of the fuel injector for 10CFR21 evaluations. In addition, revisions are being mad e to the applicable maintenance procedures to include testing of the water side of new fuel injectors. The revision to the procedures will be completed by July 1, 1985.

The cause of the delay in the declaration of a NOUE has been attributed to personnel error. The condition was not immediately recognized as requiring an initiation of the Plant's Emergency Plan. The Licencee will continue to emphasize the Emergency Action Levels and Emergency Plan Initiating Conditions during operator annual requalification training.

9 Dr. J. Nelson Grace SPR 85-004 Page Three June 7, 1985 COMMENTS The failure of DG "A" has been determined to be a n on-va lid test failure per the criteria of Regulatory Guide 1.108, " Periodic Testing of Diesel Generator Units Used as Onsite Electric Power Systems at Nuclear Power Plants". The unit was satisfactorily started and stabilized at rated voltage and frequency prior to the attempt to vary voltage. The failure of the unit to respond to a voltage change and locking in at 6700 V would not have prevented the unit from responding to an emergency signal in that the unit was within the rated limits (i.e, 7200 + 720 V). The unit was removed from service for a period of eighteen (18) hours for repairs.

The failure of DG "B" is a valid test failure per the criteria of Regulatory Guide 1.108. The injector lenkage would have caused engine failure and as such constitutes a va lid test failure. The unit was inoperable for a period of approximately sixty-eight (68) hours.

As of June 3, 1985, DG "B" has had one failure in the last 100 valid tests and DG "A" has had three. The diesel generators are presently being tested every three days on a staggered basis.

Seven (7) valid successful tests are required in order to satisfy the requirements for decreasing surveillance testing to every thirty-one (31) days on a staggered basis.