RBG-24850, Special Rept:On 861025,invalid Failure Occurred on Div II Diesel Generator During Surveillance Testing.Caused by Loose Particle in Relay Inside Voltage Regulator motor-operated Potentiometer.Div I Relay Placed in Div II Generator

Special Rept:On 861025,invalid Failure Occurred on Div II Diesel Generator During Surveillance Testing.Caused by Loose Particle in Relay Inside Voltage Regulator motor-operated Potentiometer.Div I Relay Placed in Div II Generator

ML20214T782
Person / Time
Site:	River Bend
Issue date:	11/21/1986
From:	Booker J GULF STATES UTILITIES CO.
To:	Martin R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
References
RBG-24850, NUDOCS 8612090002
Download: ML20214T782 (2)

Text

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,.J, GULF STATES UTILITIES COMPANY RIVER BEND STATION POST OFFICE 80x 220 ST. FRANCISVILLE. LOutSIANA 70775 AREA CODE 504 635 6094 348 8661 November 21, 1986 RBG- 24850 File Nos. G9.5, G9.25.1.4 Mr. Robert D. Martin, Regional Administrator U.S. Nuclear Regulatory Commission bbb Region IV 611 Ryan Plaza Drive, Suite 100 Arlington, TX 76011 NOV 2 81986

Dear Mr. Martin:

River Bend Station - Unit 1 Docket No. 50-458 Enclosed is Gulf States Utilities Company's Special Report concerning an invalid failure of the Division II Diesel Generator during a surveillance test at River Bend Station. This report is submitted pursuant to Technical Specification 4.8.1.1.3 and 6.9.2.

Sincerely,

. F lW7 J. E. Booker Manager-River Bend Oversight River Bend Nuclear Group f

JEB/TFP/PDG/DAS/je Attachment cc: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555 l kk DO kB s ,y 41 69

, .~* .

SPECIAL REPORT l

At 2240 on 10/25/86 with River Bend Station in cold shutdown (mode 4),

an invalid failure occurred on the River Bend Station Division II ,

Diesel Generator (DG) while performing surveillance testing. In I accordance with Regulatory Guide 1.108, the following information is l provided:

DIESEL GENERATOR UNIT DESIGNATION AND NUMBER: Div. II LEGS *EGlB CAUSE OF FAILURE:

The engine was started at 2212 and loaded at 2222. While attempting to adjust reactive load, it was noted that VARS could not be increased using either the local or control room voltage control switches. The DG was subsequently shut down at 2240. An investigation by maintenance personnel determined that a relay inside the voltage regulator motor-operated potentiometer had failed due to a small foreign particle between the armature and the core of the relay. When the relay was removed and shaken the particle came loose and the relay operated properly. However, because the loose particle was still inside the relay, it was determined that the relay needed to be replaced. This is an invalid failure per Regulatory Guide 1.108 position C.2.e (2) since this control is not operated in the emergency mcde.

CORRECTIVE ACTION:

Because a spare relay was not available on site and because the Division I diesel was in a maintenance outage, the equivalent relay was removed form the Division I diesel and placed into the Division II diesel. The Division II diesel then operated satisfactorily and successfully completed its surveillance test. Subsequently, the relay in Division I was replaced from spares prior to completing its

--intenance outage.

LENGTH OF TIME UNAVAILABLE: 29 hours3.356481e-4 days <br />0.00806 hours <br />4.794974e-5 weeks <br />1.10345e-5 months <br /> CURRENT SURVEILLANCE INTERVAL: 7 days TEST INTERVAL CONFORMS TO TECHNICAL SPECIFICATIONS: Yes Division II DG: 2 valid failures in the last 20 valid tests 3 valid failures in all 31 valid tests performed NUMBER OF VALID FAILURES IN PREVIOUS 100* VALID TESTS OF ALL DIESEL GENERATORS AT RIVER BEND STATION: 6

• 97 valid tests have been performed on all diesel generators at River Bend Station up to and including this test on 10/25/86.

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