ML19324C461

LER 89-019-00:on 891012,4.16-kV Bus 3A2 Metering Potential Transformer Fuse Door Inadvertently Opened,Causing Feeder Breaker & Supply Breaker to Open & Load Sequencer to Reset. Caused by Personnel Error.Drawers relabeled.W/891113 Ltr

ML19324C461
Person / Time
Site:	Waterford
Issue date:	11/13/1989
From:	Mcgaha J, Packer D LOUISIANA POWER & LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-89-019, LER-89-19, W3A89-0204, W3A89-204, NUDOCS 8911170142
Download: ML19324C461 (5)

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Ref: 10CFR50.73(a)(2)(iv)  !

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POWER & L1GHT WATUVORD 3 SES

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, November 13, 1989 l r

U.S. Nuc1 car Regulatory Commission  ;

l ATTENTION: Document Control Desk '

l. Washington, D.C. 20555 l

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Subject:

Waterford 3 SES  :

L Docket No. 50-382 i License No. NPF-38 Reporting of Licensee Event Report r Centlemen's i

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, Attached is Licensee Event Report Number LER-89-019-00 for Waterford  :

Steam Electric Station Unit 3. This Licenst:e Event Report is submitted I putsuant to 10CFR50.73(a)(2)(iv).  !

t Very truly yours. j (J.R.McGaha Plant Manager - Nuclear 1 f

-JRM/PTG/rk  !

(w/ Attachment) ,

cci Messrs. R.D. Martin J.T. Wheelock - INPO Records Center  !

E.L. Blake I W.M. Stevenson l D.L. Wigginton  !

NRC Resident Inspectors Office  !

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At 1326 hours0.0153 days <br />0.368 hours <br />0.00219 weeks <br />5.04543e-4 months <br /> on October 12. 1989 Waterford Steam Electric Station Unit 3 was in Mode 6. Refueling, when an electrician inadvertently opened the 4.16 KV bus 3A2 metering Potential Transionner (PT) fuse drawer initiating a loss of voltage signal for the 3A2 electrical bus. The above indicated loss of voltage caused the feeder breaker from bus 3A2 and supply breaker to sciety bus 3A3S to open and Diesel Cenerator A Load Sequencer to reset.

The metering PT fuse drawer was closed and all breakers returned to the appropriate lineup by 1335 hours0.0155 days <br />0.371 hours <br />0.00221 weeks <br />5.079675e-4 months <br />. Because of the inadvertent actuation of an engineered safety feature (loss of voltage circuit), this event is reportable per 10 CFR 50.73(a)(2)(iv).

The root cause of this event is personnel error. Contributing to this event vere unnecessary work instructions and inadequate labeling and control of the notering pT fuse drawer. Because there was no loss of power to the operating shutdown cooling pump or other required safety related equipment, this e<ent did not threaten the health and safety of the public or plant personnel.

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UCENSEE EVENT REPORT (LE] TEXT G^NTINUATION ***aovioowsno mo-om -

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flKT s/ auswo apanse a recessesi, ease m #4C 7enn m W nh At 1326 hours0.0153 days <br />0.368 hours <br />0.00219 weeks <br />5.04543e-4 months <br /> on October 12, 1989 Waterford Steam Electric Station Unit 3 was in Mode 6, when an electrician and a Nucicar Auxiliary Operator (NAO) performed the preparatory lineup required by procedure ME-004-061, " Unit Auxiliary Transformer," for preventative maintenance on Unit Auxiliary Transformer (UAT) 3A (EIIS Identifier - XFMR). This procedure required the removal of the grounding Potential Transformer (PT) fuses (EIIS Identifier - FU) for UAT 3A in cubical 2 of the 4.16 KV Bus 3A2 switchgear (EIIS Identifier -

SWGR). The NA0 opened the grounding PT breaker (EIIS Identifier - BKR) then unlocked the drawer containing the grounding PT fuses. The electrician opened this drawer, removed the grounding PT fuses and then closed the drawer. The drawer above the grounding PT fuse drawer was marked "UV fuses". This drawer did not have either a lock or watning concerning opening the drawer. The electriciun did not know that these were the metering PT fuses for bus 3A2 and were not related to the UAT 3A grounding PT fuses. The electrician mistakenly unlatched the metering PT fuse drawer handle and opened the drawer. After a small amount of travel, the drawer electrical connection " fingers" were disconnected, deenergizing the bus voltage monitoring cirecit. Opening the drawer has the same effect as a loss of voltage on the 4.16 KV Bus 3A2 and ccused the feeder breaker and supply breaker to safety bus 3A3S from bus 3A?. to open and Diesel Generator A Load Sequencer to reset.

Upon hearing the operation of the feeder breaker, the NA0 directed the electrician to shut the metering PT fuse drawer. The NA0 then contacted the ,

control room to report the incident. All breakers were returned to the proper lineup by 1335 hours0.0155 days <br />0.371 hours <br />0.00221 weeks <br />5.079675e-4 months <br /> (event duration - nine minutes).

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Ob 0l3 M 0l4 The root cause of this event was personnel error. The electrician mistakenly performed actions, opening the metering PT fuse drawer, not in the work package, lie did not know the difference between the metering and ground PT fuse drawers and did not know the offccts on the electrical distribution system of opening the drawers. Of larger consequence, he did not stop and get more information before prcceeding. A contributing cause was that the preparatory steps in procedure ME-004-061, " Unit Auxiliary Transf ormer," which called for removal of the UAT 3A grounding PT fuses were not required. These steps should not have been in the procedure. Additional contributing causes were: lack of a locking mechanism on the metering PT fuse drawer; imprecise labeling of the drawers, and no cautionary warnings on the drawer stating that opening the drawer could cause loss of voltage to safety bus 3A3S.

In response to the root cause, the electrician was counselled on proper conduct of maintenance ar.d proper action, in the event he does not understand a procedure step. Procedure compliance is being covered with maintenance personnel in individual counseling sessions to be completed by January 1, 1990.

In response to the contributing causes, procedure ME-004-061, " Unit Auxiliary Transformer" will be revised to remove steps not actually required. This will be completed by October 31, 1990. In addition, the metering and grounding PT fuse circuit drawers have been relabeled. Cautions have been added concerning opening of these drawers, l

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UCENSEE EVENT REPORT (LER) TEXT C3NTINUATION u*aove n owe wo. mo-oim

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0l0 0 l4 0F 0l4 vent v . w =c == =v nn Because there was no loss of power to the operating shutdown cooling pump or other required safety related equipment, this event did not threaten the health and safety of the public or plant personnel.

SIMILAR EVENTS NONE PLANT CONTACT D.F. Packer. Assistant Plant Manager. Operations & Hafntenance. 504/464-3134.

NicPERW&#A ou,3, cPos 1909 520 689 00079

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