ML20154C255

Special Rept:On 880412,valid Failure of Diesel Generator 2B Occurred While Performing Surveillance Testing.Caused by Lube Oil Pressure Sensors Venting Approx 30 Psi Above Setpoint Due to Moisture & Residue.Sensors Replaced

ML20154C255
Person / Time
Site:	Catawba
Issue date:	05/12/1988
From:	Tucker H DUKE POWER CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
NUDOCS 8805180092
Download: ML20154C255 (2)

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Duxe Powen GOMPANY P.O. HOX 33180 CitAHLOTTE. N.O. 28242 HALB. TUCKER re Arnsons vice paraanswr 0 04)373-4531 stuaan reopecrime May 12, 1988 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D. C. 20555

Subject:

Catawba Nuclear Station, Unit 2 .

Docket No. 50-414 Special Report

i. C*entlemen:

Pursuant to Technical Specification 4.8.1.1.3, please find attached a Special Report concerni.4g a Diesel Generator 2B valid failure due to mc.isture/ corrosion affecting the lube oil pressure sensors which took place on April 12, 1988.

Very truly yours, A '

Hal B. Tucker JGT/18/sbn Attachment xc: Dr. J. Nelson Grace, Regional Administrator U. S. Nuclear Regulatory Commission Region II .

' 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 l Mr. P. K. Van Doorn NRC Resident Inspector

. Catawba Nuclear Station l  % $

8805180092 880512 PDR ADOCK 05000414 g\

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SPECIAL REPORT CATAWBA NUCLEAR STATION, UNIT 1 DIESEL GENERATOR 2B VALID FAILURE DUE TO MOISTURE / CORROSION AFFECTING THE LUBE OIL PRESSURE SENSORS A Valid Failure of Diesel Generator.(D/G)'2B (Start Attempt #489) occurred on April 12, 1988, at 1135 hours0.0131 days <br />0.315 hours <br />0.00188 weeks <br />4.318675e-4 months <br />, while performing surveillance testing. This was the second Valid Failure in the last 20 Valid Starts and the fourth Valid Failure in the last 100 Valid Starts. There had also been 4 Valid Failures in the last 100 Valid Starts on Unit 2 D/Gs. Ccnsequently, the testing interval following this Valid Failure was at 7 days, which is in accordance with Technical Specifications Surveillance 4,8.1.1.2.

While performing PT/2/A/4350/02B, D/G 2B Operability Test, the D/G tripped after approximately 77 seconds into the run. Annunciators were received for Low Turbocharger Oil Pressure, High Jacket Water Temperature, Vibration, and Low and Low-Low Lube Oil Pressure. Two Invalid Failures (Start Attempts #490 and 491) were incurred while troubleshooting the Valid Failure on #489.

Work Request 40074 OPS was initiated to investigate / repair the unexpected trip. .

Two lube oil pressure senscrs were found to be venting approximately 30 pai above setpoint. The sensors were replaced and the D/G performed satisfactorily. The sensors were found to have moisture-induced corrosion which has been determined to be introduced from the D/G Starting Air Sys 4 Three Invalid Failures on D/G 2B which occurred on January 15, 1988 were sim .r to this event. The cause of the Invalid Failures was also found to be moisture and other residue affecting  ;

the lube oil pressure sensors. The sensors were cleaned and recalibrated at that i

time. A Valid Failure of D/G 1A on March 22, 1988, was also attributed to a similar pressure switch corrosion problem. Further corrective actions were  !

identified in the respective report.

Offsite power and the alternate train D/G were verified to be operable during this period of D/G 2B inoperability as required by Technical Specifications. D/G ,

2B was inoperable for approximately 11 hours1.273148e-4 days <br />0.00306 hours <br />1.818783e-5 weeks <br />4.1855e-6 months <br /> and 25 minutes due to the surveillance testing and repair of this problem. Unit 2 was in Power Operation ,

at the time of the D/G 2B Valid Failure.

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