ML17284A757

LER 98-014-00:on 980807,completion of TS 3.8.1.F Required Shutdown Due to Inoperability of EDG-2 Was Noted.Caused by Degraded Voltage Regulator for DG-2.Replaced Voltage Regulator & Associated Scrs.With 980902 Ltr

ML17284A757
Person / Time
Site:	Columbia
Issue date:	09/02/1998
From:	Bemis P, Pfitzer B WASHINGTON PUBLIC POWER SUPPLY SYSTEM
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GO2-98-158, LER-98-014, LER-98-14, NUDOCS 9809150154
Download: ML17284A757 (9)

Text

CATEGORY 1

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REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9809150154 DOC.DATE: 98/09/02 NOTARIZED: NO DOCKET ¹ FACIL:50-397 WPPSS Nuclear Project, Unit 2, Washington Public Powe 05000397 AUTH. NAME 'UTHOR AFFILIATION PFITZER,B. Washington Public Power Supply System BEMIS,P.R. Washington Public Power Supply System RECIP.NAME RECIPIENT AFFILIATION

SUBJECT:

LER 98-014-00:on 980807,completion of TS 3.8.1.F required shutdown due to inoperability of EDG-2 was noted. Caused by degraded voltage regulator for DG-2.Replaced voltage regulator R associated SCRs.With 980902 ltr.

DISTRIBUTION CODE: IE22T COPIES RECEIVED:LTR ENCL SIZE:

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

RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD4-2 PD 1 1 POSLUSNY,C 1 1 1

INTERNAL: ACRS 1 AEOD SPD/RAB 2. '2 AEOD/SPD/RRAB 1 1 1 1 NRR/DE/ECGB 1 1 1 1 NRR/DE/EMEB 1 1 NRR/DRCH/HICB 1 1 NRR/DRCH/HOHB 1 1 NRR/DRCH/HQMB 1 1 NRR/DRPM/PECB 1 1 NRR/DSSA/SPLB 1 1 RES/DET/EIB 1 1 RGN4 FILE 01 1 1 EXTERNAL: L ST LOBBY WARD 1 1 LITCO BRYCE,J H 1 1 NOAC POORE,W. 1 1 NOAC'UEENER, DS 1 1 NRC PDR 1 1 NUDOCS FULL TXT 1 1 NOTE TO ALL "RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTE. TO HAVE YOUR NAME OR ORGANIZATION REMOVED FROM DZSTRZBUTION LISTS OR REDUCE THE NUMBER OF COPIES RECEIVED BY YOU OR YOUR ORGANIZATION, CONTACT THE DOCUMENT CONTROL DESK (DCD) ON EXTENSION 415-2083 FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED: LTTR 23 ENCL 23

WASHI'NGTOY PUBLIC POPOVER SUPPLY SYSTEWI I'.O. Box 968 ~ Richlcutrl, I l'ashinglou 99352-0968 September 2, 1998 G02-98-158 Docket No. 50-397 Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555

'I Gentlemen:

Subject:

NUCLEAR PLANT WNP-2, OPERATING LICENSE NPF-21, LICENSEE EVENT REPORT NO. 98-014-00 Transmitted herewith is Licensee Event Report No. 98-014-00 for WNP-2. This report is submitted pursuant to 10 CFR 50.73 and discusses the items of reportability, corrective action taken, and action to preclude recurrence.

Should you have any questions or desire additional information regarding this matter, please call me or Mr. Paul Inserra at (509) 377-41'47.

Respectfully, R Bemis Vice President, Nuclear Operations Mail Drop PE23 EnClosure cc: EW Merschoff, NRC RIV NRC Sr. Resident Inspector, MD927N (2)

DF Kirsch, NRC RIV, WCFO INPO Records Center - Atlanta, GA C Poslusny, Jr., NRR DL Williams, BPA, MD1399 PD'Robinson, Winston & Strawn 9809150i54 980902 PDR ADOCK 05000397 8 PDR

LICENSEE EVENT REPORT (LER)

FACILITY NAME (1) DOCKET NUMBER (2) PAGE (3)

Washman ton Nuclear Plant - Unit 2 50-397 1OF3 TITLE (4)

Com letion of Technical S ecification 3.8.1.F R uired Shutdown Due to Ino erabilit of EDG-2 EVENT DATE (5) LER NUMBER (6) REPORT DATE (7 I OTHER FACILITIES INVOLVED (8)

MONTH OAY SEQUENIIAL REV. OAY FATTYNAME NUMBER NUMBER FACN/IYNAME 08 07 98 98 014 00 09 02 98 N/A OPERATING HQDE THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS Of 10 CPR 5: (Check one or mace) (11) 20.402(b) 20.405(c) 50.73(a)(2)(iv) 73.71(b) 20.405(a)(1) Qi 50.36(c)(1) 50.73(a)(2)(v) 73.71(c) 20.405(a)(1)(ii) 50.36(c)(2) 70 50.73(a)(2)(vii) OTHER 20.405(a)(1) (III) 50.73(a)(2)(I) 50.73(a)(2)(viii)(A) 20.405(a)(1) Ov) 50.73(a)(2)(ii) 50.73(a)(2)(viii)(B) 20A05(a)(1)(v) 50.73(a)(2)(iii) 50.73(a)(2)(x)

LICENSEE CONTACT FOR THIS LER (12I NAME TELEPHONE NUMBER (Inc(ude Area Code)

Bill Pfitzer, Licensing Engineer 509-377-2419 COMPLETE ONE LINE FOR EACH COI4PONENT FAILURE DESCRIBED IN THIS REPORT (13)

CAUSE COMPONENT REPORTABLE CAUSE avarrM COMPONENT MANUFACTURER REPORTABLE TO EPIX TO EPIX Und DG voltage S407 Yes Und DG SCR S407 Yes re lator SUPPLEMENTAL REPORT EXPECTED (14) EXPECTED MONTH DAY YEAR YES NO corn Ieted EXPECTED SUBMISSION DAT ABSTRACT:

On August 4, 1998, while performing the emergency diesel generator 2 (EDG-2) monthly operability test, EDG-2 reactive load (MVAR) oscillations were observed. The oscillations were anomalous and unexpected, and as a result EDG-2 was shutdown and declared inoperable in accordance with Technical Specification (TS) 3.8.1.B. Subsequent troubleshooting and repair efforts for the EDG-2 voltage regulation system failed to restore EDG-2 to an operable condition, and at 1550 on August 7, 1998 plant shutdown was initiated as required by TS 3.8.1.F.

Troubleshooting to isolate the cause for the reactive load oscillations determined that the voltage regulator for DG-2 had degraded.

The voltage regulator and associated silicon control rectifiers (SCRs) for EDG-2 have been replaced, and the removed components have been sent to an offsite test facility for functional evaluation and failure analysis.

The safety significance of this event is considered low.

LICENSEE EVENT REPORT (LER)

TEXT CONTINUAT(ON FACILITY NAME (I ) DOCKET NUHBER (2) LER NUMBER (6) PAGE (3)

SEQUENTIAL REVISION NUMBER NUNilSR Washington Nuclear Plant - Unit 2 50-397 98 014 00 2 OF 3 TEXT (I(more space is required, use additional copies ot NRC Form 366A) ((7)

On August 4, 1998, while performing the emergency diesel generator 2 (EDG-2) tDG] monthly operability test, EDG-2 reactive load (MVAR) oscillations were observed. The oscillations were anomalous and unexpected, and as a result EDG-2 was shutdown and declared inoperable in accordance with Technical Specification (TS) 3.8.1.8. Subsequent troubleshooting and repair efforts for the EDG-2 voltage regulation system failed to restore EDG-2 to an 'operable condition, and at 1550 on August 7, 1998 plant shutdown was initiated with entry into Mode 3 at 2233 on August 7, 1998, in accordance with the requirements of TS 3.8.1.F.

An event notification call was made to the NRC Headquarters Operations Officer at 1907 PDST on August 7, 1998 after plant shutdown was initiated per the requirements of 10 CPR 50.72(b)(1)(i)(A). Event number 34619.

Imm i rr iv A i n A plant shutdown was initiated and maintenance activities were initiated to replace the EDG-2 voltage regulator.

F her Ev lua i n The troubleshooting e6orts for EDG-2 focused primarily on the components of the voltage regulation system.

As a result of these activities it was decided to replace the EDG-2 voltage regulator [RG] and SCRs.

Subsequently it was decided that the replacement activities, including the required post-maintenance testing, could not be performed in the remaining time, or in the plant conditions, allowed by plant Technical Specifications, therefore plant management directed commencement of a plant shutdown.

use f Even Troubleshooting to isolate the cause for the reactive load oscillations determined that components in the voltage regulation system had degraded.

Further rrective Ac ion The EDG-2 voltage regulator and associated components have been replaced.

The voltage regulator and associated SCRs removed from EDG-2 have been sent to a vendor test facility for functional evaluation and failure analysis.

f 1

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME (I) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3)

YEAR SEQUEHTI AL REvrsrctl NUMBER WMBEA Washington Nuclear Plant - Unit 2 50-397 98 014 00 3 OF 3 TEXT (If more space is required, Use addittonal copies of NRC Form 366A) (17) smen of afe ns n s A plant shutdown was initiated and the plant was subsequently taken to Mode 4 within the required time limits of TS 3.8.1.F. The remaining Division 1 and 3 diesel generators were tested in accordance with TS 3.8.1.B to ensure the proper operation of the voltage regulators. Both Division 1 and 3 diesel generators operated nor'mally with no voltage control anomalies noted. Therefore, the safety significance of this event is considered low.

imilar Event There have been no LERs reporting a similar failure of EDG voltage regulator or SCRs.

A search of the EPIX database revealed a total of 30 hits associated with diesel generator voltage regulator failures. Most failures were associated components external to the static exciter (i.e. relays, motor operated potentiometers or blown fuses). One of the reported failures described degraded SCRs and another reported bridge diode failures. Two of the reported problems were with 'Electric Products'oltage regulators, the vendor supplying the subject components of this report. Of these two failures, one was a blown fuse and one was a failure in a model not used at WNP-2. This does not indicate a significant failure trend in static exciter SCRs or Electric Products voltage regulators.

A search of WNP-2 problem evaluation requests revealed several problems dealing with various EDG regulator anomalies over past years. Although several voltage regulation circuit related problems have been documented, none match the high reactive load swing problem in this report.

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