ML20070U003

Special Rept 91-002:on 910304,invalid Failure of Emergency Diesel Generator a Occurred.Caused by Failure of Operator to Verify That Correct Switch Adjusted Before Adding Load to Diesel Generator.Operator Counseled

ML20070U003
Person / Time
Site:	Wolf Creek
Issue date:	04/02/1991
From:	Bailey J WOLF CREEK NUCLEAR OPERATING CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
91-002, 91-2, NO-91-0102, NO-91-102, NUDOCS 9104080049
Download: ML20070U003 (3)

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W@ NUCLEAR LF CREEK OPERATING

~ John A. Bailey

2. n..io.ni 6)peratKms April 2, 1991 NO 91-0102 U; S. Nuclear . Regulatory Consnission ATTN: Document-Control Desk Mail Station P1-137.

Washington, D. C.: 20555

Subject:

Docket No. b?-482: .

Special Report 91-002 The attached Special' Report is being submitted in cecordance with Technical Specification 4,8.1.1.3 concerning an invalid failure of Emergency Diesel Generator 'A".

Very truly.yours.

W) 4Ah  %

John A. Bailey j Vice President 4

Operations

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R.'D. Martin (NRC), w/a

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9104080049 9t0402 RO Box 411 ( Burungton. KS 66839 / Phone: (316) 364-8831 / L'

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ADOCK 0500048;' An Loual Opportunity Employer MF HCLVET /

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. Attachment to NO 91-0102 SPICIAL RIGmr 91-002 Invalid Failure of Mantuancy Diesel Cmirator "A" Ttus report describes an invalid failure of DmIgency Diesel Generator (EDG)

"A" which occurred on March 4,1991. 21s report is being subnitted in accordance with %chnical Specifications 4.8.1.1.'3 and 6.9.2.

DHEK3tTFPICM (F EVFNI'S On March 1, 1991, at 1842 hours0.0213 days <br />0.512 hours <br />0.00305 weeks <br />7.00881e-4 months <br />, EDG "A" was taken out of service for  !

mintenance. Following coupletion of the mintenance on March 4,1991, surveillance procedure STS FJ-005A, " Manual / Auto Start, Synchtunizat. ion, and Ioading of Dergency Diesel Generator NE01", was ccmmnced to prove operability of EDG "A" prior to placing-it back in service. The EDG was started at 1252 hours0.0145 days <br />0.348 hours <br />0.00207 weeks <br />4.76386e-4 months <br /> and at 1300 hours0.015 days <br />0.361 hours <br />0.00215 weeks <br />4.9465e-4 months <br /> the operator closed the EDG output breaker and attaupted to apply load. However, instead of adjusting the governor speed control switch to apply load, as stated in the surveillance procedure, the operator mistakenly adjusted the voltage regulator switch.

mis resulted in the EDG output breaker tripping on rwerse power. %e operator imediately discovered his error, readjusted the voltage, reset and reclosed the output breaker and applied load with the governor speed control switch in accordance with the procedure.

The EDG was operated at full load for one hour and the surveillance procedure was successfully coupleted. Following completion of the surveillance procedure, EDG "A" was declared operable at 1447 hours0.0167 days <br />0.402 hours <br />0.00239 weeks <br />5.505835e-4 months <br /> on March 4, 1991 h is event had no effect-on the reliability or availability of the EDG.

HOCT CAlEE NO OCERFMIVE ACTIO6 The root cause of this event was the failure of the operator to verify he was adjusting the correct switch tofore adding load to the EDG. '1his resulted in the output breaker opening on reverse power. This function protects the generator frun notoring when connected to an energized bus.

The Manager of Operations has discussed this event with the operator. Se operator stated he was aware of the correct switch to use, the switch was clearly labeled, and the correct switch was clearly stated in the procedure. Due to the need to quickly add load to the EDG once the output breaker is closed, the operator failed to take time to verify he was operating the correct switch.

Operators have been runLnded of the inportance of self-verification prior to operation of equipmnt. This, along with infonnation currently in the surveillance procedure and current operator training ensures the potential for additional trips of the ED3 output breaker on reverse power due to operator error is minimized.

N Attachment to NO 91-0102 FATIHE CIASSTYICATKN The Im wtput bruaker zuvorse F*or t.rlp function is not nxIuinxi and does not operato in the monjoncy oporating nixie. Uhorufore, the unsuccessf ul load attr5npt discussed in this ruport is considered to to an invalid test and failuru in acconiance with Regulat.ory Position C.2.o(2) of thxyulatory Guido 1.108,Itovision 1. It does not af fact. the current survet.llance test interval of 31 days as requinxi by Shblo 4.8-1 of 'Nchnical Specification 3.8.1.1. 1hrough March 4,1991, thorn have txxan a total el 103 successful valid tests, throo valid failurus, and 12 invalid failures of Em "A". E'run the tino of the laat valid failure of im "A" on Deconbor 11, 1987, Em "A" has undenjono 60 successful valid tests. The last invalid failure of Em "A" occurnxi on October 21, 1985.

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