ML17292A948

LER 97-007-00:on 970611,voluntary Rept of Automatic Start of DG-1 & DG-2 Was Experienced.Caused by Undervoltage Condition on Electrical Busses SM-7 & SM-8.Circulating Water Pump CW-P-1C Control Switch Placed in pull-to-lock.W/970723 Ltr

ML17292A948
Person / Time
Site:	Columbia
Issue date:	07/23/1997
From:	BEMIS P R, PFITZER B WASHINGTON PUBLIC POWER SUPPLY SYSTEM
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GO2-97-147, LER-97-007, LER-97-7, NUDOCS 9707300094
Download: ML17292A948 (7)

Text

~CATEGORY 1~~REGULATORY INFORMATION DISTR IBUTIQNWYSTEM (R IDS)ACCESSION NBR: 9707300094

'DOC.DATE: 97/07/23 NOTARIZED:

NO FACIL: 50-3>>7 WPPSS Nuclear Pro Ject.Unit 2>Washington Public Pore AUTH.NAME AUTHOR AFFILIATION PFITZEP>B.'ashington Public Poeer Supp 1!J S!Jstem BEMIS>P.R.Washington P0b lie Poeer Supp 1!J S!Jstem RECIP.NAME RECIPIENT AFFILIATION DOCKET 0 05000397

SUBJECT:

LER 97-007-00:

on'>>70611>voluntar!J rept oF automatic start oP DG-1 5 DG-2 was experienced.

Caused b!J undervoltage condition on electrical busses SM-7 b SM-8.Circulating eater pump CW-P-1C control switch eas placed in pull-to-lock.

DISTRIBUTION CODE: IE22T COPIES RECEIVED: LTR ENCL SIZE: TITLE: 50.73/50.9 Licensee Event Report (LER)>Incident Rpt>etc.NOTES: RECIPIENT ID CODE/NAME PD4-2 PD CQP IES LTTR ENCL 1 1 REC IP IENT ID CODE/NAME CQLBURN>T CQP IES LTTR ENCL 1 1 INTERNAL: ACRS AEOD/SPD/RRAB NRR/DE/ECGB NRR/DE/EMEB NRR/DRCH/HICB NRR/DRCH/HGMB NRR/DSSA/SPLR RES/DET/EIB AE J FILE CE ER L NRR/DRCH/HHFB NRR/DRCH/HOLB NRR/DRPM/PECB NRR/DSSA/SRXB RGN4 FILE 01 1 1 1 1 1 1, 1 2 1 1 1 1 1 1 1 EXTERNAL: L ST LOBBY WARD 1 1 NOAC POORE>W.1 1 NRC PDR 1 1 LITCO BRYCE>J H NOAC GUEENER>DS NUDOCS FULL TXT 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!FUL'EXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED: LTTR 25 ENCL 25 WASHINGTON PUBLIC POWER SUPPLY SYSTEM P.O.Box 968~Richlanrl, 1Virshi>i@tow 99352-0968 July 23, 1997 G02-97-147 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, LICENSEK EVIPW REPORT NO.97-007-00 Transmitted herewith is voluntary Licensee Event Report No.97-007-00 for WNP-2.This report is submitted in response to the recommendations contained in NUREG-1022.

Should you have any questions or desire additional information regarding this matter, please call me or Mr.Paul Inserra at (509)377-4147.Respectfully, mls Vi President, Nuclear Operations Mail Drop PE23 Enclosure cc: EW Merschoff, NRC RIV KE Perkins, Jr., NRC RIV, WCFO TG Colburn, NRR PD Robinson, Winston&Strawn NRC Sr.Resident Inspector, MD927N (2)INPO Records Center-Atlanta, GA DL Williams, BPA, MD399 9707300094 970723 PDR ADQCK 05000397 S PDR llllllllllllllllllllllllllllllllllllllll LICENSEE EVENT REPORT (LER)FACILITY NAME (1)Washin ton Nuclear Plant-Unit 2 DOCKET NUMBER (2)50-397 PAGE (3)1 OF 3 TITLE (4)VOLUNTARY REPORT OF AUTOMATIC START OF DG-1 AND DG-2 DUE TO SM-7 AND SM-8 UNDERVOLTAGE EVENT DATE (5)LER NUMBER (6)REPORT DATE (7)OTHER FACILITIES INVOLVED (Bl DAY SEOUENIIAL NUMBER REV.NUMBER DAY YEAR FACILHY NAME 06 11 97 97 00 07 23 97 FACILHY NAME N/A DOCKET NUMBER 05000 OPERATING MODE THIs REpoRT Is sUBMITTED pURsUANT To THE REQUIRENENTs op 10 cpR 5I (check one or more)(11)0%20A02(b)20A05(a)(1)(I) 20.405(a)(1)(ii) 20A05(a)(1)(iii)20.405(a)(1)(iv) 20A05(a)(1)(v) 20A05(c)50.36(c)(1) 50.36(c)(2) 50.73(a)(2)0) 50.73(a)(2)(ii) 50.73(a)(2)(iii) 50.73(a)(2)(iv)50.73(a)(2)(v) 50.73(a)(2)(vii) 50.73(a)(2)(viii)(A) 50.73(a)(2)(viii)(B) 50.73(a)(2)(x)

X 73.71(b)73.71(c)OTHER Voluntary NAME Bill Pfitzer, Licensing Engineer LICENSEE CONTACT FOR THIS LER (12)TELEPHONE NUMBER ((nclude Area Code)509-377-2419 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)CAUSE COMPONENT MPIAIFACTURER REPORTABLE TO NPRDS CAUSE SYSTEM COMPONENT MANUFACTURER REPORTABLE TO NPRDS SUPPLEMENTAL REPORT EXPECTED (14)YES corn le(ed EXPECTED SUBMISSION DATE NO EXPECTED MONTH DAY ABSTRACT On 6/11/97, with the plant in Operating Mode 4, Circulating Water Pump motor CW-M-P/1C experienced internal electrical faulting shortly after pump startup.The pump ran for approximately 15 seconds prior to tripping the CW-M-P/1C feeder breaker.due to phase differential current.The motor fault caused a momentary undervoltage condition on electrical busses SM-7 and SM-8 which initiated an automatic start of emergency diesel generators, EDG-1 and EDG-2.The diesel generators started and ran unloaded, as designed, until manually shutdown by operating personnel.

The output breakers for EDG-1 and EDG-2 did not close and load the EDGs because the undervoltage condition was only momentary, and plant busses continued to be fed from the startup transformer, TR-S.Immediate corrective actions were to return EDG-1 and EDG-2 to standby readiness and initiate an investigation into the cause of CW-M-P/1C trip.The root cause of EDG-1 and EDG-2 auto start was an undervoltage condition on electrical busses SM-7 and SM-8 This event is voluntarily reported, The safety significance of this event is considered minimal.

FACILITY NAME (I)LICENSEE EVENT REPORT (LER)TEXT CONT(NUATION DOCKET NUMBER (2)YEAR LER NUMBER (6)SEQUENT iAL NUMBER RCVI6 1 ON NJNB6R PAGE (3)Washington Nuclear Plant-Unit 2 50-397 97 007 00 2 OF 3 TEXT (If more space Is reqU(red, use additional copies of NRC Form 366A)(17)Even De cri ti n On 6/11/97, with the plant in Operating Mode 4 with electrical distribution being supplied by the startup transformer TR-S[XFMR], Circulating Water Pump motor CW-M-P/1C[KE][P][MO]

experienced internal electrical faulting shortly after pump startup.The pump ran for approximately 15 seconds prior to tripping the CW-M-P/1C feeder breaker[BKR]due to phase differential current.The motor fault caused a momentary undervoltage condition on electrical busses SM-7 and SM-8[BU]which initiated an automatic start of emergency diesel generators, EDG-1 and EDG-2[DGJ.The diesel generators started and ran unloaded, as designed, until manually shutdown by operating personnel.

The output breakers for EDG-1 and EDG-2 did not close and load the EDGs because the undervoltage condition was only momentary, and plant buses continued to be fed from the startup transformer, TR-S.This event was voluntarily reported within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, and this report is being voluntarily submitted since the EDGs are not engineered safety features at WNP-2.Immediate orr ive Acti n Circulating Water pump CW-P-1C control switch was placed in pull-to-lock.

EDG-1 and EDG-2 were returned to standby readiness.

Investigation was initiated into the cause of CW-M-P/1C trip.A significant Problem Evaluation Request was initiated to resolve this problem.h Control room personnel reported that CW-M-P/1C started normally with the expected starting current, and operated with a running current of approximately 600 amps for approximately 15 seconds prior to tripping.Following the trip, phase voltages on the bus supplying the motor were observed to be 4250, 4400, and 4300 volts on each of the A, B, and C phases respectively with the 230kV voltage at Ashe substation reported at 242kV.Throughout this event, plant busses continued to be fed from the startup transformer, TR-S.The WNP-2 electrical distribution system relay scheme operated as designed to isolate the fault and terminate the undervoltage condition on the affected busses.Had the undervoltage condition on SM-7 and SM-8 continued for approximately four seconds, the supply breakers from Backup Auxiliary Transformer, TR-B, would have auto closed and SM-7 and SM-8 would have been supplied by TR-B.If the undervoltage condition had continued for approximately 7 seconds the EDG output breakers would have auto closed and SM-7 and SM-8 would have been supplied by the EDGs.

0~LICENSEE EVENT REPORT (LER)TEXT CONTINUATION FACILITY NAME tl)DOCKET NUMBER)2)LER NUMBER I6)SEQUENT)AL NUMBER A6V)ATION NAQER PAGE I 3)Washington Nuclear Plant-Unit 2 50-397 97 007 00 3'F 3 TEXT (lf more space is required, use additional copies of NRC Form 366A)(17)In this case the feeder breaker for CW-M-P/IC tripped, isolating the fault immediately, and the standby sources designed to automatically supply the safety-related electrical busses were not needed.mRafXame The auto start of EDG-1 and EDG-2 was caused by an undervoltage condition on SM-7 and SM-8.The undervoltage condition was caused by internal faulting of the non-safety related CW-M-P/1C which developed shortly after start of the motor.F her orr tive Ac i n None required.EDG response to the undervoltage condition was normal.Appropriate corrective actions associated with CW-P-P/IC have been taken.A e mn f fet n uence WNP-2's electrical distribution system relay scheme operated as designed to isolate the fault without unnecessary challenges to the plant electrical distribution system.In this case the feeder breaker for CW-M-P/IC tripped, isolating the fault immediately.

Offsite and onsite sources designed to automatically supply the safety-related electrical busses were available at the time from transformer TR-8 and the EDGs.The safety significance of this event is considered minimal.E There have been no similar previous events of motor faults causing starts of the EDGs.