ML17292A336

LER 96-002-00:on 960504,critical Bus SM-8 Lost Power When Supply Breaker 3-8 Tripped.Caused by Personnel Error. Operators Counselled & Procedures revised.W/960620 Ltr

ML17292A336
Person / Time
Site:	Columbia
Issue date:	06/20/1996
From:	Bemis P, Pfitzer B WASHINGTON PUBLIC POWER SUPPLY SYSTEM
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GO2-96-124, LER-96-002, LER-96-2, NUDOCS 9606260184
Download: ML17292A336 (8)

Text

CATEGORY REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSIOH NBR:9606260184 DOC.DATE: 96/06/20 NOTARIZED: NO DOCKET FACIL:50-397 WPPSS Nuclear Project, Unit 2, Washington Public Powe 05000397 AUTH. NAME AUTHOR AFFILIATION PFITZER,B. Washington Public Power Supply System BEMIS,P.R. Washington Public Power Supply System RECIP.NAME RECIPIENT AFFILIATION

SUBJECT:

LER 96-002-00:on 960504,critical bus SM-8 lost power when Supply breaker 3-8 tripped. Caused by personnel error.

Operators counselled s procedures revised.W/960620 ltr.

DISTRIBUTION CODE: IE22T COPIES RECEIVED:LTR I ENCL ( SIEE:

TITLE: 50.73/50.9 Licensee Event Report (LER), Incident Rpt, etc.

5 T E

NOTES:

RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD4-2 PD 1 1 COLBURN,T 1 1 R

INTERNAL: ACRS 1 1 AEOD D AB 2 2

~~

AEOD/SPD/RRAB 1 1 E C TER 1 1 NRR/DE/ECGB 1 1 R~~B 1 1 NRR/DE/EMEB 1 1 NRR/DRCH/HHFB 1 NRR/DRCH/HICB 1 1 NRR/DRCH/HOLB 1 1 NRR/DRCH/HQMB 1 1 NRR/DRPM/PECB 1 1 NRR/DSSA/SPLB 1 1 NRR/DSSA/SRXB 1 1 RES/DSIR/EIB 1 1 RGN4 FILE 01 1 1 D

EXTERNAL: L ST LOBBY WARD 1 1 LITCO BRYCE,J H 2 2 NOAC MURPHY,G.A 1 1 NOAC POOREEW. 1 1 NRC PDR 1 1 NUDOCS FULL TXT 1 1 M

N NOTE TO ALL "RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOM OWFN 5D-5(EXT. 415-2083) TO ELIMINATE YOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED'.

FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED: LTTR 26 ENCL 26

WASH I.'iGTO.'v PUBLIC POWER SUPPLY SYSTEM PO. Box 968 ~ 3000 George 11rrshirrgton 11'ar ~ Richland, 11raslrington 99352-0968 ~ (509) 372-5000 June 20, 1996 G02-96-124 Docket No. 50-397 Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Gentlemen:

Subject:

NUCLEAR PLANT WNP-2, OPERATING LICENSE NPF-21, VOLUNTARYLICENSEE EVENT REPORT NO. 96-002-00 Transmitted herewith is voluntary Licensee Event Report No. 96-002-00 for WNP-2. This event is not reportable under 10CFR50.72 or 10CFR50.73. This report is submitted voluntarily for information.

Should you have any questions or desire additional information regarding this matter, please call me or Ms. Lourdes Fernandez at (509) 377-4147.

Res tfully, P. R Bemis (Mail Drop PE20)

Vice President, Nuclear Operations Enclosure cc: LJ Callan, NRC RIV NRC Sr. Resident Inspector, MD927N (2)

TG Colburn, NRR INPO Records Center - Atlanta, GA KE Perkins, Jr., NRC RIV, WCFO DL Williams, BPA, MD399 NS Reynolds, Winston & Strawn 9606260i84 960620 PDR ADOCK 05000397 8 PDR

0 LICENSEE EVENT REPORT (LER)

TACAI TV NAME (I I DocxET MA(TER (I(

Washington Nuclear Plant Unit 2 0 5 0 0 0 3 9 7 1 ( 4 TITLE(e( INADVERTENT LOSS OF POWER TO CRITICAL BUS AND EDG START DUE TO CLEARANCE ORDER RESTORATION ACTIVITY (ER NVMSER (el 0 IIRR TACAITKS e(VOLV(D ee DOCKET (ARISTA(et N/A 0 5 0 0 05 04 96 96 0 0 2 0 0 06 20 96 0 5 0 0 OtERATSIC Uee R(PORT IS SUOMI(TEO tVRSVANT TO THE REOUIR(MENTS Oc 'lo CIR: II II MODE (SI

• ( 20.402(b) ( 20.405c ( 50.73(e)(2)(iv) I I 73.71(b)

( 20.405(s)(l)(i) ( ( 50.36(c)(l) ) 50.73(s)(2)(v) ) 73.71(c) tOWER LEV(L 20.405(s) (1) (ii) 50.36(c)(2) 50.73(e)(2)(vrl) X OTHER (Specify (n Abstrect be(ow end

) ( ( (

(I(e in Text, NRC Form 366A)

Q 0 Q ( 20.405(e)(l)(iii) ) ( 50.73(s)(2)(i) ) 50.73(e)(2)(vii)A I 20.405(s)(l)(iv) ) ( 50.73(s)(2)(ii) 50.73(s)(2)(viii) B 20.405(s)(1)(v) I I 50.73(s)(2)(NI) ) 50.73(SH2)(x)

Uc(NTEE CONTACT SOR Ties LER I It(

I(((tIIONE NUMI(R Bill Pfitzer, Licensing Engineer 509 377-2419 COMt(ETE OtC LSC IOR EACH COMt(HANT TALVRE DESCRR(D IN TITS R(toRT ((el MAIREAD. R(toRTAS(E MAIREAD. R(PORTA(LE TURLR TO MVDS TVR(R TO MV(DS SVttLEMENTAL REtoel EXTEC(m ((4( EXPECTED SUBMISSION YES (i) yes, complete EXPECTED SUBM(SSION DATE) (X( ko DATE (15)

ABSTRACI')6)

On May 4, 1996 at 0142, with the reactor defueled, critical bus SM-8 lost power when supply breaker 3-8 tripped. As a result, emergency diesel generator (EDG) 2 auto started and the backup transformer automatically provided power to SM-8. Detailed investigation into this event determined the cause to be accidental opening of the non-critical bus SM-3 potential transformer (PT) fuse compartment by an equipment operator (EO) performing restoration activities for a clearance order.

Event notification was made to the NRC pursuant to the requirements of 10 CFR 50.72(b)(2) as an Engineered Safety Feature (ESF) actuation. This notification was subsequently retracted after a detailed review of the event and the actuated equipment. The WNP-2 FSAR does not specify the EDGs as an Engineered Safety Feature. This LER is submitted on a voluntary basis.

• - Defueled

LICENS EVENT REPORT (LER) TEXT CO INUATlON stovcM lal stvMMst Washington Nuclear Plant - Unit 2 0 5 0 0 0 3 9 7 96 002 0 0 2 " 4 TEXT (17)

Even De cri i n On May 4, 1996 at 0142, with the reactor defueled, the control room received alarms indicating an undervoltage condition on non-critical bus [BU] SM-3. Breaker [BKR] 3-8 tripped due to the undervoltage condition causing a loss of power to critical bus SM-8. As a result, EDG-2 [DG]

auto started, the backup transformer [XFMR] automatically provided power to the SM-8 bus, and residual heat removal pump 2B (RHR-P-2B) [BO,P], which was operating in the fuel pool cooling

[DA] assist mode, experienced a temporary loss of power. Plant restoration activities were completed at approximately 0306.

Immediate orrective Action Immediately after the incident, Operations management suspended ongoing clearance order restoration activities and secured the area around the SM-3 auxiliary electrical cubicle to support investigation activities.

A Problem Evaluation Request (PER) was initiated.

RHR-P-2B was returned to service in the fuel pool cooling assist mode after approximately 45 minutes.

Plant electrical lineup and equipment restoration was completed at approximately 0306.

Further Evalua ion During the Incident Review Board (IRB) investigation, the EO reported that he had opened and closed the door of the SM-3 auxiliary electrical cubicle in preparation for restoration of a clearance order associated with transformer TR-S. The EO stated that after looking inside the cubicle he shut the door and then heard relays chatter. He speculated he had jarred the relays while closing the cabinet door. Event evaluation, including further interviews of the EO involved, determined the following:

~ Momentary opening of the SM-3 bus PT fuse compartment, which is a~d'scent to the compartment specified by the clearance, would have caused all the auto actions which occurred during this event. Both fuse compartments are located inside the SM-3 auxiliary electrical cubicle which must be opened to view the compartments. The compartment doors utilize a protective feature which disconnects the fuses as the compartment door is opened.

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Sf QUCMNl RKVISKIH NUMSOI HUMOR Washington Nuclear Plant - Unit 2 05 0 0 0 3 9 7 96 002 0 0 3 oF 4 TEXT (l7)

The door latch for the SM-3 bus PT fuse compartment was found in the 11:30 (just closed) position rather than the 9:00 (fully closed) position as expected.

PT fuse disconnects of this type can be easily opened and re-closed in approximately 1-2 seconds.

~ The control room alarm printer "SM-3 UNDERVOLTAGE" indication took about 2 seconds to return to normal.

~ In an effort to reproduce an inadvertent relay operation, the SM-3 auxiliary electrical cubicle door was repeatedly slammed. No operation of SM-3 undervoltage relays due to mechanical jarring or bumping was observed.

~ The maximum length of time for an HFA undervoltage relay to trip and return to normal due to mechanical jarring or bumping is approximately 40 to 50 milliseconds. In this case, the relay which must actuate after the undervoltage relay to effect opening of breaker 3-8 requires the undervoltage signal to be approximately 1.0 second in duration.

The physical evidence listed above led the IRB to postulate three possible causes for the SM-3 undervoltagb condition. These potential causes were:

~ Slamming the SM-3 auxiliary electrical cubicle door which jarred the undervoltage relays of SM-3 causing breaker 3-8 to trip.

~ Dirty contacts on the SM-3 bus PT fuse stabs which caused poor contact, an undervoltage condition and tripping of breaker 3-8.

~ Opening of the SM-3 bus PT fuse compartment which caused an undervoltage condition and tripping of breaker 3-8.

After careful consideration, Operations management concluded the cause of the event was momentary opening of the SM-3 bus PT fuse compartment by the EO. It was further concluded that the EO operated the SM-3 bus PT fuse compartment and, upon realizing his error, hastily reclosed the PT compartment leaving the compartment in the abnormal condition found by the IRB investigators. This conclusion is further supported by the information recorded on the control room alarm printer and the information obtained during testing of the components involved.

This LER is submitted on a voluntary basis.

0 LICENS EVENT REPORT (LER) TEXT CO INUATION SfOUCMtNL ROI5ON

~MA NVM80l Washington Nuclear Plant - Unit 2 05 0 0 0 3 9 7 96 002 0 0 4 o" 4 TEXT u7)

Root au e The root cause for this event is personnel error. The SM-3 bus PT fuse compartment was inadvertently opened, causing an SM-3 undervoltage signal.

A contributing cause was inadequate pre-job brief. The Production Reactor Operator (RO) and Senior Reactor Operator (SRO) did not address the potential adverse consequences of operation of the bus PT fuse compartment.

An additional contributing cause was failure to follow the procedure requirements to identify clearance order steps for PT fuse restoration as requiring simultaneous verification.

Further orrective Action Personnel action appropriate to the circumstances was taken with the EO.

The Production RO and SRO were counseled concerning the necessity of performing adequate pre-job briefs prior to performance of critical clearance activities.

The procedures/instructions governing clearance order preparation will be revised to ensure the need for simultaneous verification is noted on the required clearance order steps.

Assessment f fe Conse uence The safety consequences of this event are minimal. The reactor was defueled at the time this event occurred. Expected automatic actions occurred including auto starting of EDG-2 and re-energization of SM-8 from the backup transformer. RHR-P-2B, which was operating in the fuel pool cooling assist mode, tripped as a result of the loss of power but was restored after approximately 45 minutes. Estimated time to boil at the time of this event was 52 hours6.018519e-4 days <br />0.0144 hours <br />8.597884e-5 weeks <br />1.9786e-5 months <br />.

Previous Similar Events Previous LERs documenting personnel error resulting in actuation of safety-related equipment are as follows:

LER 96-001 involved inadvertent ESF actuations due to tripping of a temporary power supply to IN-3 by outage electricians.

LER 95-002 involved Operations personnel operating the wrong lever during a main turbine test resulting in turbine trip and reactor scram.