ML20086F698

AO 50-261/75-7:on 750331,diesel B Tripped Due to Low Lube Oil Pressure.Caused by Lube Oil Filter High Differential Pressure Resulting from Dirty Filters.Lube Oil Filters Replaced

ML20086F698
Person / Time
Site:	Robinson
Issue date:	04/10/1975
From:	Utley E CAROLINA POWER & LIGHT CO.
To:	Moseley N NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
AO-50-261-75-7, NG-75-533, NUDOCS 8401040575
Download: ML20086F698 (3)

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CD&L Carolina Power & L;ght Company April 10, 1975 50-201 j 4-File: NG-3513 (R) Serial: NG-75-533

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Mr. Norman C. Moseley, Director

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Atlanta, Georgia 30303 *i ~~*

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Dear Mr. Moseley:

4 A Q T [/N H. B. ROBINSON UNIT NO. 2 ,

LICENSE NO. DPR-23 TRIPPING OF "B" DIESEL DUE TO LOW LUBE OIL PRESSURE In accordance with 6.6.2.a of the Technical L'pecifications for H. B. Robinson Unit No. 2, the attached Abnormal Occurrence Report is submitted for your information. This report fulfills the requirement -

for a written report within ten days of an Abnormal Occurrence and is in accordance with the format set forth in Regulatory Guideline 1.16, Revision 1.

Yours very t ly, g'-

4 E. E. Utley Vice-President

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Bulk Power Supply DBW;bn Attachment cc: Messrs. N. B. Bessac P. W. Howe R. E. Jones D. Knuth gD 'g y/ ' l y J. B. McGirt [ ,g D. B. Waters a 8401040575 750410 PDR ADOCK 05000261 S PDR 336 Fayetteville Street . P. O. Sox 1551. Raleigh, N. C. 27602

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el o ABNORMAL OCCURRENCE REPORT l

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1. Report No. 50-261/75-7  ;

• 2a. Report Date April 9, 1975 g 2b. _0ccurrence Date March 31, 1975 ,

3. Facility H. B. Robinson Unit No. 2 3-Hartsville, South Carolina 29550 [ .

4. Identification of Occurrence Tripping of "B'.' diesel due to low lube oil pressure

5. Conditions Prior to Occurrence The reactor was operating ~normally at a steady-state power level of 100%.

6. Description of Occurrence '

On March 31, 1975, during performance of P.T.-23.1, Emergency Diesels.

"A" Emergency diesel was test run with satisfactory results. "B" diesel was started at 1655 hours0.0192 days <br />0.46 hours <br />0.00274 weeks <br />6.297275e-4 months <br />; however, the lube oil pressure did not increase above 15 psi which initiated a low lube oil pressure ,

l alarm. The diesel trip defeat switch was positioned to reinstate the

} trips causing the diesel to trip on low lube oil pressure at 1657 hours0.0192 days <br />0.46 hours <br />0.00274 weeks <br />6.304885e-4 months <br />.

This diesel failure constituted an abnormal occurrence as defined in Technical Specification 1.8.d. The trip defeat switch was immediately repositioned to again bypass the trips.

At 1700 hours0.0197 days <br />0.472 hours <br />0.00281 weeks <br />6.4685e-4 months <br /> "B" diesel was restarted, and the lube oil pressure in-creased to 22 psi. The lube oil filter differential pressure indicated 80 psi. "B" diesel was shut down at 1703 hours0.0197 days <br />0.473 hours <br />0.00282 weeks <br />6.479915e-4 months <br />.

At 1836 hours0.0213 days <br />0.51 hours <br />0.00304 weeks <br />6.98598e-4 months <br />, maintenance personnel arrived on site to replace the lube oil filters. At 2032 hours0.0235 days <br />0.564 hours <br />0.00336 weeks <br />7.73176e-4 months <br />, following filter replacement, "B" diesel was returned to service and test operated satisfactorily. The lube oil filter differential pressure was 6 psi at this time.

7. Designation of Apparent Cause of the Incident The low lube oil pressure was caused by lube oil filter high differential pressure resulting from dirty filters.

8. Analysis of Occurrence The "B" diesel generator was being tested from the local panel on routine performance of P.T. 23.1 when the failure occurred. The unit was restarted three minutes after the low lube oil trip, and oil pressure increased to a safe operating range. After the lube oil filters were replaced, the opera-tion of the unit was satisfactory. During the time of this occurrence, "A" Diesel was operable and no violation of a limiting condition for operation occurred.

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Corrective Action ,

As stated previously, the lube oil filters were replaced by plant maintenance personnel. The unit was operated under load for three nours on April 1, 1975, with excellent results. The maximum differen-tial oressure across the filters at this time was 4 psi. The unit was

perated under load again for two hours on April 8, 1975, with a maximum differential pressure of 3 psi. The unit will be operated for one hour '

on April 15, 1975, to again check the differential pressure of the lube '

oil filters. Plant operating procedures will be modified to require differential pressure checks of the lube oil filters each tinic the diese]'

periodic test is performed, as opposed to the monthly frequendy presently required. This action should prevent recurrence of this incident in the future. .

10. Failure Data ..

(1) January 7, 1972 Failure of 2B Diesel to start during weekly test (Incident Report No. 33) . , . ,

(2) July 16, 1974 Failure of "B" Emergency Diesel to start.

Due to plugged injector nozzles. ~

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