ML20005F856

Special Rept:On 891211,invalid Failure of Div II Diesel Generator Occurred During Monthly Surveillance Test Procedure STP-309-0202.Caused by Failed GE Breaker in Exhaust Fan.Breaker Replaced & Generator Returned to Svc

ML20005F856
Person / Time
Site:	River Bend
Issue date:	01/08/1990
From:	Booker J GULF STATES UTILITIES CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
RBG-32065, NUDOCS 9001170328
Download: ML20005F856 (3)

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January 8, 1990 RBG- 32065 File}os.G9.5,G9.25.1.4 l l U. S. Nuclear Regulatory Commission ,

Document Control Desk

• i Washington, D.C. 20555 Gentlemen:

River Bend Station - Unit 1 i Docket No. 50-458  :

i Enclosed is Gulf States Utilities Company's Special Report concerning an invalid failure of the Division 11 diesel generator-at River Bend Station. This report is being submitted pursuant l to River Bend Station Technical Specification 4.8.1.1.3 and

• 6.9.2.

Sincerely,

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f E.-Booker Manager-River Bend Oversight I

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River Bend Nuclear Group ,

I JEB/TFP GW/DNL/6CH/JCH/pg .

Enclosure 1

cc: U.S. Nuclear Regulatory Commission Region IV 611 Ryan Plaza Drive. Suite 1000  :

l Arlington, -Texas 76011 i NRC Senior Resident Inspector Post Office Box 1051

• St. Francisville, LA 70775 l i l

OM8 900108 P amcx 03000433 PDC P,i

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s-SPECIAL REPORT At 1117 on 12/11/89, with the reactor in Operational Condition 1 at 95 percent power, while perfonning the monthly surveillance test procedure (STP) 309-0202, " Diesel Generator Division II Operability Test", the diesel generator exhaust fan 1HVP*FN2B did not start. The Division II diesel generator was manually shutdown approximately three (3) minutes into the STP run. This is considered an invalid failure in accordance with Regulatory Guide 1.108 position C.2.e.2. This Special Report is hereby submitted in accordance with the requirements of River Bend Station Technical Specifications 4.8.1.1.3 and 6.9.2.

Reported Condition At 1117 on 12/11/89 with the reactor in Operationel Condition 1 at 95 percent power, the Division II diesel generator 1EGS*EG1B was given a normal start signal for the performance of the regularly scheduled monthly surveillance test, " Diesel Generator Division II Operability Test", STP-309-0202.

Approximately twenty (20) seconds after a successful diesel start it was noted that exhaust fan, 1HVP*FN2B did not start. After verification that the fan did not start, performance of STP-309-0202 was terminated and the Division II diesel generator was manually stopped approximately three (3) minutes after starting. The cause of the failure of the exhaust fan,1HVP*FN2B to start was not immediately apparent. This is considered an invalid failure in accordance with Regulatory Guide 1.108 position C.2.e.2. This Special Report is hereby submitted in accordance with the requirements of River Bend Station Technical Specification 4.8.1.1.3 and 6.9.2.

Investigation

/

Immediately after the STP was terminated Operations and Field Engineering  !

personnel present during the start noted that both the amber and green lights were present on the Division 11 diesel engine control panel for the exhaust fan (1HVP*FN2B). The illumination of the amber light with the green light indicates that the breaker tripped or " tripped free" when given the "close" >

signal. Investigation by Operations at switchgear IEJS*SWGIB indicated that the breaker position was correct and aligned for a "close" signal, Further investigation by electrical maintenance determined that the fan motor was not damaged and did not contribute to the start failure. Electrical Maintenance and Operations then attemated to place the breaker for exhaust fan 1HVP*FN2B back in service but the c1arging motor would not charge the breaker. A second attempt was made to place the breaker in service by placing the breaker in the

" disconnect" position and then returning the breaker to the " connect" position. The charging motor operated very slowly and again would not charge the breaker. The breaker was removed from service and was inspected by Field Engineering. The inspection revealed that the ratchet pawl was cocked to the side and the charging linkage appeared to be bound up. The breaker is being shipped to the General Electric (GE) service shop for failure analysis. At this time, the actual cause of the 1HVP*FN2B breaker failure is indeterminate.

A review of the failed breaker's history indicates that it was placed in service on 5/3/88, and has been operated a minimum of fifty six (56) times from May 1988 until failure. The failed breaker was replaced with a new breaker removed from another cubicle in IEJS*SWG1B. After replacing the breaker, exhaust fan 1HVP*FN2B was manually started and stopped. The exhaust fan 1HVP*FN2B was returned to Operations control and STP-309-0202 was completed satisfactorily with the Division II diesel generator declared operable.

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'Cause of Failure i

Engineering and Maintenance personnel found that the General Electric AKR-30 breaker had failed. The cause of the breaker failure is not known at this time. This will be determined by failure analysis conducted by the General Electric service shop, and witnessed by a GSU Field Engineering representative.

Corrective Action The failed breaker was replaced with a spare breaker having identical settings. After the breaker was replaced, exhaust fan 1HVP*FN2B was started and stopped to demonstrate that the replacement breaker would function correctly. The STP was performed satisfactorily and the Division II diesel generator was declared operational upon completion. When General Electric has completed their failure analysis and advised GSU of corrective actions, GSU will submit a supplemental Special Report to provide additional information concerning this matter.

Length of Time Diesel Generator was Out-of-service: 10.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> Current Surveillance Interval:

Division 1 Monthly Division II Monthly Division III Monthly Test Intervals Conforms to Technical Specification:

Yes Failures of Division I:

0 Valid failures in the last 20 Valid Tests 0 Valid failures in the last 100 Valid Tests Failures of Division II:*

O Valid failures in the last 20 Valid Tests 4 Valid failures in the last 94 Valid Tests Failures of Division III:

0 Valid failures in the last 20 Valid Tests 2 Valid failures in the last 100 Valid Tests

• 100 Valid tests have not been completed on this Division.

Number of Valid Failures in Previous 100 Valid Tests of all Diesel Generators at River Bend Station:

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