ML18038B566

LER 95-007-00:on 951108,unplanned Esfa Occurred Following Transfer of 480V Rmov Board 3B to Normal Power Supply After Temporary Normal Supply Breaker Was Replaced.Caused by Faulty Amptector Trip actuator.W/951206 Ltr

ML18038B566
Person / Time
Site:	Browns Ferry
Issue date:	12/06/1995
From:	Machon R, Jay Wallace TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-95-007-02, LER-95-7-2, NUDOCS 9512110280
Download: ML18038B566 (18)

Text

j. Mj.~&(.j.'I Y 1 ACCELERATED RIDS PROCI'.SSIiG)

REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR 9512110280 DOC DATE: 95/12/06 NOTARIZED- NO . DOCKET FACIL:50-296 Browns Ferry Nuclear Power Station, Unit 3, Tennessee 05000296 AUTH. NAME AUTHOR AFFILIATION WALLACE,J.E. 'ennessee Valley Authority MACHON,R.D. Tennessee Valley Authority RECIP.NAME ,

RECIPIENTAFFILIATION'UBJECT:

LER 95-007-00:on 951108,unplanned ESFA occurred following transfer of 480V.RMOV board 3B to .normal power supply after temporary normal supply'breaker was replaced. Caused by faulty amptector trip actuator.W/951206 ltr.

DISTRIBUTION CODE: IE22T COPIES RECEIVED:LTR ENCL SIZE TITLE: 50.73/50.9 Licensee Event Report (LER), ncident Rpt, etc.

NOTES:

RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME PD2-3-PD LTTR ENCL ID CODE/NAME LTTR ENCL 1 1 WILLIAMS,J. 1 1 INTERNAL: ACRS. 1 1 2 2 AEOD/S PD/RRAB NRR/DE/ECGB 1 1 ILE CEN~gh 1 1 1 1 DE/EELB 1 1

.NRR/DE/EME B 1 1 NRR/DRCH/HHFB 1 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' NRR/DSSA/SRXB 1 1 RES/DSIR/EIB 1 1 RGN2 FILE Ol 1 1 EXTERNAL: L ST LOBBY WARD 1 '1 LITCO BRYCE i J H 2 2 NOAC MURPHY,G.A 1 1 NOAC POORE,W. 1 1 NRC PDR 1 1 NUDOCS FULL TXT 1 1 VOTE TO ALL"RI DS" RECIPIENTS:

PLEASE ICELP US TO REDUCE 4VKSTE! CONTACT'I'IIE DOLL'i!CiTCOiTROI.

DESk, ROOil Pl-37 (I'.XT. 04-~OS' TO I;Ll%Ill:%TE 5'OI.'R iAiILI ROil DIS I'Rl DU I'IOi LIS'I'S I'OR DOCI'XII'.i'I'SYOU lmi "I' I I'.I)!

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

Tennessee vattey Autronty. post office Box 2000. Decatur. Alabaina 35609.2000 R. D. (Rick) Machon Vice PresiCent. Browns Ferry Huctear Pant December 6, 1995 U..S. Nuclear Regulatory Commission 10 CFR 50.73 ATTN: Document Control Desk Washington, D.C. 20555

Dear Sir:

BROWNS PERRY NUCLEAR PLANT (BFN) - UNZTS 1g .2g AND 3 - DOCKET NOS ~ '50-259~ 50-260~ AND 50-296 FACILITY OPERATING LICENSE DPR-33~ 52~ AND 68 - LZCENSEE EVENT .REPORT 50-296/95007 The enclosed report provides details concerning the unplanned Engineered Safety Feature (ESF) actuation resulting from the transfer of 480V Reactor Motor Operated Valve Board 3B from its alternate power supply to its normal power supply. This report is submitted in accordance with 10 CFR 50.73(a)(2)(iv) as an event or condition that resulted in an automatic actuation of an ESF.

Sincerel R. D. Machon Enclosure cc: See page 2 9512ii0280 PDR 8

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4i U.S. Nuclear Regulator Commission Page 2 December 6, 1995 Enclosure c'c (Enclosure):

INPO Records Center Suite 1500 1100 Circle 75 Parkway Atlanta, Georgia 30339 Paul Krippner American Nuclear Insurers Town Center, Suite 300S 29 South Main Street West Hartford, Connecticut 06107 NRC Resident Inspector Browns Ferry Nuclear Plant 10833 Shaw Road Athens, Alabama 35611 Regional Administrator U.S. Nuclear Regulatory Commission Region 101 II Marietta Street; NW, Suite 2900 Atlanta, Georgia 30323 Mr. Z. F. Williams, Project Manager U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike-Rockville, Maryland 20852

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NRC FORH 366 ~ S. NUCLEAR REGULATORY CQSIISSION ROVED BY (RIB NO. 3150-0104 (5-92) EXPIRES 5/31/95 ESTIHATED BURDEN PER RESPONSE TO COHPLY IIITH THIS INFORHATION COLLECTION REQUEST: 50.0 HRS LZCENSEE EVENT REPORT (LER) FORMARD COHHENTS REGARDING BURDEN ESTIHATE TO THE INFORHATIOH AND RECORDS HANAGEHENT BRANCH (HNBB 7714) ~ U.ST NUCLEAR REGULATORY COHHISSION, (See reverse for required naker of digits/characters for each block) NASHINGTOH, DC 20555-0001 AND TO THE PAPERMORK REDUCTION PROJECT (3140-0104), OFFICE OF HANAGEHENT AMD BUDGET UASHIMGTON DC 20503.

FACILITY IWK (1> DOCKET NINRIER (2) PAGE (3)

Browns Fer Nuclear Plant BFN Unit.3 05000296 1 OF 5 TITLE (4>Unplanned Engineered Safety Feature Actuation following transfer of 480V RHOV Board 38 to its normal power supply after the replacement of a temporary normal supply breaker.

EVENT DATE 5 REP(XIT DATE 7 OTHER FACILITIES INVOLVED 8

'EQUENTIAL FACILITY NAHE N/A DOCKET NUMBER MONTH DAY YEAR NUMBER'EVISIOM NUHBER HONTH DAY YEAR 11 08 95 '5 007 00 12 06 95 FACILITY NAHE N/A DOCKET NUMBER GYRATING THIS REPIXIT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR": Check one or'more 11 INX)E (9) 20.402(b) 20.405(c) 50.73(a)(2)(iv) 73.71(b) 20.405(a)(1)(i) 50.36(c)(1) 50.73(a)(2)(v) 73.71(c) 000 LEVEL (10) 20.405(a)(1) (i i) 50.36(c)(2) 50.73(a)(2)(vii) OTHER 20 405(a)(1)(iii) 50.73(a)(2)(i)(B) 50.73(a)(2)(viii)(A> (Specify in

!cist 4+i,%,'xwg4~clj'c';isa";> <'xiPxy+ ~ 20 e 405 ( a ) ( 1 ) ( i v) 50.73(a)(2)(ii) 5073()(2)(vf I I )(B)Abstract and in Text, hei ou 50.73(a)(2)(iii) 50.73(a)(2)(x) MRC Form 366A LICENSEE CONTACT 'FOR THIS LER 12 NAHE TELEPHONE NUHBER (Include Area Code)

James E. Wallace, Compliance Engineer (205) 729-7874 C(SIPLETE ONE LINE'FOR EACH IXNPONENT FAILURE DESCRIBED IN THIS REPORT '13 REPORTABLE CAUSE SYSTEH COHPONENT HANUFACTURER CAUSE SYSTEH COMPONENT HANUFACTURER TO NPRDS TO NPRDS X EC BKR G080 SUPPLEMENTAL REPIXIT EXPECTED 14 EXPECTED HOMTH DAY YEAR YES SUBHI SSI Ql (I f,yes, complete EXPECTED SUBHISSION DATE). DATE (15)

ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten Lines) (16) ~

On November 8, 1995, at approximately 1347 hours0.0156 days <br />0.374 hours <br />0.00223 weeks <br />5.125335e-4 months <br /> Central Standard Time (CST), Unit 3 480V Reactor Motor Operated Valve (RMOV) Board 3B was transferred from its normal power supply to i.ts alternate power supply to support the installation of the permanent normal supply breaker. At 1357 hours0.0157 days <br />0.377 hours <br />0.00224 weeks <br />5.163385e-4 months <br />, after the permanent supply breaker was installed, an attempt to transfer 480V RMOV Board 3B back to i.ts permanent normal supply breaker resulted i.n the board de-energizing. This loss of power to the 480V RMOV Board caused Reactor Protection System Bus 3B to de-energize, resulting in the initiation of the standby gas treatment system, control room emergency, venti.lation, system, and primary contai.nment isolation. At the time of this event, Unit 3 was in cold shutdown and in the refueling mode. Unit 2 was operating at 100 percent power. Unit 1 was shutdown and defueled. The root cause of this event was a faulty Westinghouse Amptector Tri.p Actuator on the permanent normal supply breaker. Corrective acti.ons included replacing the faulty trip actuator and forwarding the faulty trip actuator to Westinghouse for failure analysis. This report is submitted in accordance wi.th 10 CFR 50.73(a)(2)(iv) as an event or condition that resulted in automatic actuation of an Engineered Safety Feature.

HRC FORH ( )

0ll ts, NRC FORH 366A U.S. ISICLEAR REGIRATORY C(SSIISS ION APPROVED SY aNI NO. 3150-0104 (5-92) EXPIRES 5/31/95 ESTIHATED BURDEN'PER RESPONSE TO CDHPLY WITH THIS INFORHATION COLLECT ION REQUEST: 50.0 HRS. FORWARD COHHENTS REGARDING BURDEN EST IHATE TO THE INFORMATION AMD RECORDS HAMAGEHENT BRANCH (HMBS 77N) ~ U.S. NUCLEAR REGULATORY CDHHISSIONg IsICENSEE EVENT REPORT WASNINGTOM, DC 20555-0001 ~ AMD TO THE PAPERWORK REDUCI'ION TEXT'ONTZNUATZON PROJECT (3150-0104), OFFICE OF HANAGEHENT AND BUDGET, WASHINGTON DC 20503 FACILITY NAIE C1) DocKET NIsmER (2) LER NISISER C6) PAGE C3)

TEAR SEQUENTIAL REVISION MUHBER2 2 NUHBER Browne Ferry Unit 3 05000296 95 007 00 2 of 5 TEXT If more s ce is r ired use addi lone( c ies of MRC Form 366A C17)

I ~ PLANT CONDITIONS At the time of this event, Unit 3 was in cold shutdown and in the refueling mode. Unit 2, was operating at 100 percent power. Unit 1 was shutdown and defueled.

II'ESCRIPTION OF EVENT ho Events On November 8, 1995, at approximately 1347 hours0.0156 days <br />0.374 hours <br />0.00223 weeks <br />5.125335e-4 months <br /> Central Standard Time (CST), 'Unit 3 480V Reactor Motor Operated Valve (RMOV) Board (BD) 3B [ED] was transferred from its normal power supply to its alternate power supply to allow the replacement of the temporary normal supply breaker with the permanent normal supply breaker. At 1357 hours0.0157 days <br />0.377 hours <br />0.00224 weeks <br />5.163385e-4 months <br />, after the permanent normal supply breaker was installed, an attempt to transfer 480V RMOV BD 3B back to its normal supply resulted in the board de-energi.zi.ng because the permanent normal supply breaker failed to latch closed (tripped free). The board was re-energized by its alternate power supply.

This loss of power to 480V RMOV BD 3B resulted in the Reactor Protecti.on System (RPS) [JC] Bus 3B de-energizing, which caused a half scram in channel B. This also resulted in primary containment i.solation [JM] system groups 2 [BO], 3 [CE], and 6

[VB] isolations, and standby gas treatment system [BH] and control room emergency ventilation system [VZ] actuations.

At 1403 hours0.0162 days <br />0.39 hours <br />0.00232 weeks <br />5.338415e-4 months <br />, the half scram was reset, the .RPS was re-energi.zed and the ESF systems were returned to standby readiness. At 1443 hours0.0167 days <br />0.401 hours <br />0.00239 weeks <br />5.490615e-4 months <br />, the temporary normal supply breaker was installed and placed in service without any additional problems. This event is reportable in accordance with 10 CFR 50.73 (a)(2)(iv) as an event or condition that resulted in an unplanned actuation of an engineered safety feature (ESF).

B~ Ino erable Structures Cam nents or S stems that Contributed to the Events A trip actuator for a Westinghouse Amptector 1A solid state trip devi.ce installed in a General Electric AK type breaker.

41 0 HRC FORH 366A U.S. WCLEAR REGULATORY COHIISSIOH APPROVED BY QS NO. 3150-0104 (5-92) EXPIRES 5/31/95 ESTIHATED BURDEN PER RESPOHSE TO COHPLY llITH THIS INFORHATION COLLECTION REOUEST: 50.0 HRS. FORMARD COHHENTS REGARD IHG BURDEN EST IHATE TO THE INFORNATION AND RECORDS HANAGEHENT BRANCH (HNBB 7714) ~ U.S. NUCLEAR REGULATORY COHHISSION, LICENSEE EVENT REPORT NASH INGTOH, DC 20555-0001 ~ AND TO THE PAPERUORK REDUCTION TEXT CONTINUATION PROJECT '(3150-0104), OFFICE OF HANAGEHENT AND BN)GET ~

IIASHINGTON DC 20503 FACILITY HA% (1) DOCKET HQSER (2) LER HISSER (6) PAGE (3)

YEAR SEQUENTIAL REVISION NUHBER3 3 HUHBER Browns Ferry Unit 3 05000296 95 007 '00 3 of 5 TEXT If more s ce is r ired use sdditionsl co ies of NRC Form 366A (17)

Co Dates and A roximate Times of Ma or Occurrencest November 8, 1995 at 1347 hours0.0156 days <br />0.374 hours <br />0.00223 weeks <br />5.125335e-4 months <br />, CST Transferred 480V RMOV BD 3B to its alternate .power supply to replace the temporary normal supply breaker with the permanent normal supply breaker.

at 1357 hours0.0157 days <br />0.377 hours <br />0.00224 weeks <br />5.163385e-4 months <br />, CST Attempt to transfer 480V RMOV BD 3B back to its normal power supply resulted in the board de-energizing. The board was re-energized from its alternate power supply-at 1403 hours0.0162 days <br />0.39 hours <br />0.00232 weeks <br />5.338415e-4 months <br />, CST Reset the half scram, re-energized the RPS, and returned ESF, systems to standby readiness.

at 1443 hours0.0167 days <br />0.401 hours <br />0.00239 weeks <br />5.490615e-4 months <br />, CST Re-installed the temporary normal supply breaker and placed 480V RMOV BD 3B on its normal power supply.

Do Other S stems 'or Seconds Functions Affecteds None.

Xethod of Discove I This condition was discovered when the Unit Operator [utility, 1'icensed] received the half scram on RPS Bus 3B, which initiated the ESFs.

erator Actionst The RPS was re-energized, and the ESF systems were returned to standby readiness.

Safet S stem Res onsess Safety systems responded as designed for this type of event.

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NRC F(RH 366A 0 S. IRICLEAR REGUIAT(XIY CQHISSImi APPROVED BY (NNI NO. 3150-0104 (5.92) EXPIRES 5/31/95 ESTIHATED BURDEN PER RESPONSE TO COHPLY llITH THIS INFORHATION COLLECTION REQUEST: 50.0 HRS. FORNARD COHHENTS REGARDING BURDEN EST IHATE TO THE INFORHATI ON AND RECORDS HAMAGEHENT BRANCH (HNBB 7714), U.S. NUCLEAR REGULATORY COHHISS IONg LICENSEE BVENT REPORT NASHINGTON, DC 20555 0001, AMD TO THE PAPERNORK REDUCTIOH TEXT CONTINUATION , PROJECT. (3150-0104) ~ OFFICE OF HANAGEHENT AND BUDGET, NASHINGTON DC 20503 FACILITY'AIK(1) DOCKET NINBER (2) LER RIBBER (6) PAGE (3)

YEAR SEQUENTIAL REVISION

.NUHBER4 4 NUHBER Browns Ferry Unit 3 05000296 95 007 00 4 of 5 TEXT If more s ce is r ired use additional co ies of NRC Form 366A (17)

ZIZ ~ CAUSE OF THE EVENT Immedi.ate Causet During the transfer of the 480V RMOV BD 3B from its alternate to its normal power supply, the permanent normal supply breaker for 480V RMOV BD 3B failed to latch closed (tripped free).'oot B Causet The root cause of this event was a faulty breaker trip actuator.

Specifically, a magnet that was glued to the trip actuator became unglued resulting in an unplanned operation of the trip device.

ZVo ANALYSIS OF THE BVENT

'The systems affected during this event are designed to shutdown the reactor, to contain and process any radioactive releases, and to fulfilltheir safety functions upon loss of initiation logic power.

The systems responded correctly to the loss of power; therefore, plant safety was not adversely affected. The plant's safe shutdown capabilities would not have been diminished had Unit 3 been in power operation. Accordingly, this event did not affect the health and safety of plant personnel or the public.

Vs CORRBCTIVE ACTIONS Ao Immediate Corrective Actionss The. 480V RMOV BD was re<<energized by its alternate power .supply.

The RPS was re-energized and the ESF systems were returned to standby readiness.

The breakers and actuator had been successfully bench tested and field tested prior to installation.

i> i NRC FORM 366A U S IN)CLEAR REGULATORY CQBII SSI IXI APPROVED BY (HEI. NO 3150-0104 (5-92) EXPran 5I31/95 ESTIMATED BURDEN PER RESPONSE TO'COMPLY IJITH THIS INFORMATION COLLECTION REQUEST: 50.0 HRS. FORNARD COMMENTS REGARDING BURDEN ESTIMATE TO THE 'INFORHATION AND RECORDS NAMAGENENT BRANCH (HHBB 7714), .U.S. NUCLEAR REGULATORY COMMISSION, LICENSEE EVENT REPORT NASHIMGTON, DC 20555-0001, AMD TO THE PAPERlQRK REDUCTION

'TEXT CONTZNUATZON PROJECT (3150-0104) ~ OFFICE OF HAMAGEHENT AMD BUDGET ~

l!ASHINGTOM DC 20503 FACILITY NJUK (1) DOCKET NINBER (2) LER NIHQKR (6) PAGE (3)

YEAR SEQUENTIAL REVISION NUMBERS 5 NUMBER Browns Ferry Unit 3 05000296 95 007 00 5 of 5 TEXT If more s ce is r ired use additional co ies of NRC Form 366A (17)

Bi Corrective Actions to Prevent Recurrencel Corrective actions included reinstalling the temporary normal supply breaker, re-energixing the board, and troubleshooting the permanent normal supply breaker. Following troubleshooting, the faulty trip actuator was disassembled, and the temporary breaker was removed from the board. After a new actuator was installed in the breaker, the 'breaker was reinstalled and the board was transferred successfully.

The faulty actuator was forwarded to Westinghouse for failure analysis. Zf the results of Westinghouse's investigation significantly alter either the .cause or the coriective actions for this event, a supplemental report will be submitted.

Additionally, any further corrective actions. that are developed as a result of the investigation will be implemented in accordance with TVA's corrective action process.

VZ ~ ADDITIONAL INFORNATZON Ao Failed Com nentsI h A trip actuator for a Westinghouse Amptector 1A solid state device installed in a General Electric AK type breaker. There are currently 11 other AK breakers with the Westinghouse amptector trip device installed in Unit 3 (none installed i.n Units 1 or 2). Prior to installati.on, these breakers were simi'larly bench tested and fi.eld tested. However, none of these breakers have experienced similar failures.

Bo Previous LERs on Similar Events!

LER 260/88009 addressed three separate occasions where the normal/alternate, supply breakers failed to close because of the dirty conditions of the sli.ding secondary di.sconnects in the breaker control logic. The root cause of LER 260/88009 was the lack of preventive maintenance. LER 296/95007 was not caused:by a lack of, preventive maintenance.

VZ I ~ COMMITMENTS None.

Energy Industry Identification System (EIIS) system and component codes are identified in the text with brackets (e.g., [XX)).

U.S. Nuclear Regulatory Commission Page 3 December 6, 1995 PS: SAW: JEW:MTN Enclosure cc (Enclosure):

C. W. Beasley, PAB 1B-BFN P. P. Carier, BR .4G-C L. S. Clardy, CFC 1C-BFN C. T. Dexter, 'BFT 3A-BFN J. A. Frost,, POB 2E-BFN O..D. Kingsley, LP 6A-C John P. Maciejewski, LP 3B-C J. Scott Martin, PMC 1D-BFN T. J. McGrath, LP 3B-C M. 0. Medford, LP 3B-C G. D. Pierce, PEB 1B-BFN E. Preston, POB 2C-BFN C. M. Root, CFC 1D-BFN R. H. Shell, 0&PS 4C-SQN T. D. Shriver, PAB 1A-BFN H. L. Williams, EDB lA-BFN

0. J. Zeringue, LP 3B-C RIMS, WT 3B-K a%m85007a3 e'er

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