05000316/LER-1985-035-01, :on 851029,reactor Trip Signal Received from RCS Low Flow & Reactor Trip Breaker a Failed to Open on Trip Signal.Trip Signal Caused by Momentary Dip in Output Voltage Due to Intermittent Short.Breaker Replaced

:on 851029,reactor Trip Signal Received from RCS Low Flow & Reactor Trip Breaker a Failed to Open on Trip Signal.Trip Signal Caused by Momentary Dip in Output Voltage Due to Intermittent Short.Breaker Replaced

ML20137U691
Person / Time
Site:	Cook
Issue date:	11/27/1985
From:	Blind A INDIANA MICHIGAN POWER CO. (FORMERLY INDIANA & MICHIG
To:
Shared Package
ML20137U657	List: 05000316/LER-1985-035-01, :on 851029,reactor Trip Signal Received from RCS Low Flow & Reactor Trip Breaker a Failed to Open on Trip Signal.Trip Signal Caused by Momentary Dip in Output Voltage Due to Intermittent Short.Breaker Replaced 05000316/LER-1985-036-01, :on 851030,discovered Cardox Fire Protection Sys for Emergency Diesel Generator Room AB Isolated W/O Fire Watch Coverage.Caused by Personnel Error.Appropriate Administrative Action Taken W/Involved Personnel ML20137U651
References
LER-85-035-01, LER-85-35-1, NUDOCS 8512090375
Download: ML20137U691 (3)

LER-1985-035, on 851029,reactor Trip Signal Received from RCS Low Flow & Reactor Trip Breaker a Failed to Open on Trip Signal.Trip Signal Caused by Momentary Dip in Output Voltage Due to Intermittent Short.Breaker Replaced

Event date:
Report date:
3161985035R01 - NRC Website

text

U s. NUCLEAR KEGULATOXV COMMitSION

' NRC Fere Jee AMROVED OMS NO 3150-4104 LICENSEE EVENT REPORT (LER)

FACILITY NAME til DOCKET NUMBER 41)

PAGEi3 D.C. COOK NUCLEAR PLANT, UNIT 2 015101010l31116 1 lOFl 0l3 flTLE tal REACTOR TRIP EVENT DATE 166 LER NuweER 161 REPORT DATE 17)

OTHER F ACILITIES INVOLVED itt MONTH DAY YEAR YEAR 58,0

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NAME TELEPMONE NUMBER ARE A COOE 4 615 l -l 5 l910 l 1 A.A. BLIND - ASSISTANT PLANT MANAGER 6l1 6 1

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ON OCTOBER 29,1985, AT 1357 HQR5 '9711 UNIT 2 AT 79 PEPCENT PFXYOR 711FWAL TEER, A FFAC70R 'ITGP SIGNAL MS 11CEIVED FT<M RF1CIOR COOI1Mr SYSTEM Im FILW. REACIOR TRIP BPEAKER "A" (TDE/BRK) FAIIED TO OPEN ON PECEIPT OF TIE TRIP SIGNAL. TIIE INSERVICE "B" FEAC70R TRIP BREAKER FUNCTICNED CORFECTLY AfD 11E REACTOR WAS PIOPERLY SHLT DOhW.

POST-TRIP REVIEW SHChED 71IAT THE ORIGINAL TIGP INITIA70R kAS A SPURICUS INDICATION OF IOSS OF FIN DUE 'IO FAILE OPEN INDICATION OF THE NO. 2 REACIOR COOIANT PWP (ICP) BIEAKER. EE BELIEVE illAT 7EE TPIP SIGNAI., KAS IN PEACTICN TO l

A MCAD7 FAIT DIP IN TIE CUTPITT VOL7 AGE OF TIE CRID AND 71E "IDSS OF FCP" KAS THE FIRST REETION 70 71 TIS VOLTAGE DIP. 71IIS VOLTAGE DIP IS BELTEVED TO l' AVE BEEN CAUSED BY AN IhTEIMITYINr SHORT, ACTIVA 7TD BY PWPING A RADIATION MONI'IOR DURING TROUBLE SHOOTING ACTIVITIFS. TIE BREAKER FAIIED TO TRIP DUE TO FAILUPE CF TIE UNDEFVOLTAGE TRIP ASSEFTLY DEVICE TO FUNCTICN PFOPERLY. TIE UNIT 2 "A" T&.C70R TRIP BFFAIIR HAS DEEN REPI1CED WITH A SPAPE BREAKER tHICH HAS BEEN TliOTCUCHLY ESPICIED AhD 71S71D PER PPESCRIBED PIOCEDL4ES.

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']O PFEVINT DICUFEENCE; 1) THE CCN7 POL AND INSTRUMENTATIUN SUPERVISOR HAS CAUTICNED AIL SIGNICIANS AND SUPERVISORS ON 71E EUTElfrIAL IFEACT OF ACCIDI27fAL SIIORTING OR CWPCNENT FAIIEFE IN ECUIPMENT POWER FFCl4 CRID PES INVER'IERS. 2) PRIOR 70 TIOUBIESFCfffING 71ESE TYPES OF ICADS, EFEORTS WILL BE MADE 70 ISOIATE TIE CCNICNENT Fim TIE CRID BUS Il&ER7EPS. 3) TIE PEJCIOR TRIP AND BYPASS BPEAKEFS CN foril D.C. CCOK UNITS HAVE BEFN 71iOFOUGULY IhSPICTED AND 7ESTED AND CAN BE RELIED g

UFCN TO IUNC'fICN AS REGUIRED.

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"^a D.C. COOK NUCLEAR PLANT, UNIT 2 olsl0l0lol3l1l6 8l5 0l3l5 0[0 0[2 OF 0 l3 TEXT (# more space as aguared. use addoonef N#C Fern J6 ens 1(17)

CN OCIOBER 29,1985, AT 1357 HOURS WITH UNIT 2 AT 79 PERCENT PChER, A PEACTOR TRIP SIWAL 1GS RECEIVED FPOM REACTOR COOIAhT SYSTEM IN FICW. REACIOR TRIP BREAIER "A" (IEEE/BKR) FAILED TO OPEN ON RECEIPT OF THE TRIP SIGAL. TIE INSERVICE "B" REACTOR TRIP BREAKER FMCTICtGD CDPFECTLY AND 71E PEJCIOR KAS PEOPERLY SHUR DOWN.

ICST-7 RIP REVIEW SHOKED TUAT TIE ORIGINAL TRIP INITIATOR hAS A SPURIOUS INDICATION OF IOSS OF FIM DUE 70 FJJSE OPEN INDICATION OF TIE NO. 2 RF1CIOR 0001AhT PG'P (FCP) BREAIER. SUBSEQUENT TFSTING SHCkED 'IEAT TIE "A" REACTOR 2 RIP PREAKER UNDERVOLTAGE TRIP ASSDGLY HAD RECEIVED A VALID TRIP SIGAL ETG THE PPUIECTION SYSTD1 (VOLTAGE HAD IN FACT BEEN RD0VED FROM TIE UNDEIsVOLTAGE TRIP ASSD4BLY COIL)

IED THAT THE FIGELTIVE SYSTEN POUID IN FAC'I GDEPATE THIS TRIP SIGNAL CN RECEIPT OF NEED-70-TRIP IhtICATIm S.

TFOUBLESIf00fEG OF TIE ASSCCIATED POWER SUPPLY (CRID-II) SliOWED IT 70 BE OPEPATING PFOPERLY. THE CONCLUSION REACllED (CONFIBMATION OF 71E ORIGINAL HYrGIISIS) KAS THAT 7HE TRIP SIGNAL KAS IN RFJCTION 70 A b0MENTARY DIP IN TIE COIPUT VOLTAE]F illE CRID AND TIE "IOSS OF FCP" WAS THE FIRST REACTION

'IO THIS \\tLTAGE DIP.

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INVESTIGATICN OF ACTIVITIES IN PROGRFSS AT TifE TIbE CF THE REACIOR TRIP REVEALED

'lEAT TFOUBIESHOOTING OF A RADIATION FONITORING UNIT, THAT RECEIVES INSTRUFENT AND CCNITOL PChER FIM CRID II, KAS IN PFOGRESS. RECONSTEUCTICN OF TIE 1CTIONS OF THE 7ECifNICIAN CCNDUCTING 7BE TROUBLESHOCTING FAILED TO IDENTIFY ANY ICTIm THAT KOUID IIAVE AITFCTED THE CPlD II OUTFUT VOLTAGE. HCEEVER, SUBSECUENT TFOUBLESHCOTING OF 7HIS RADIATION bONITOPlNG UNIT REVEAIID A FAILED EIEffRICAL ENPOND7f (PHOIDHELIC CEIL) b11ICH GAVE INDICATICN OF PRIOR INTEDTITENT FAIIERE BEFORE ITS FINAL FAILURE.

THIS KAS DISCOVERED BY "BWPIhG" 7EE PADIATION bDNITORING UNIT, AN ICTIm THAT VERY COhCEIVABLY COUID FAVE OOCURFED DURING THE 7ECHNICIAN'S TFOUBLESHOOTING ICflVITIES.

7EIS PIGOIELIC CELL IS KhERED DIRIC7LY OFF 'IEE CRID II AND FAILURE IN THE MANNER OBSERVED, EVEN INTEPEITlHTILY, VEUID VERY LIKELY HAVE RESUL71D IN AN UNNOTICEABLE, F0MEhTARY DIP IN ThE CRID II OUTPUT VOLTAGE TliEREBY INITIATING THE TRIP SIGNAL.

ALTilOUGH THEFE IS NO FOSITIVE EVIDENCE 7 EAT TIE THE PliOIOIELIC CELL SliOl(IID OR 01EEIUISE AETICIED 7BE CPlD II OUTPUT VOLTAGE, KE MLTFVE 7 EAT 7 BIS h76 TIE CAUSE.

CUR IbVESTICATICN HAS DE7ED11hTD THAT TIE BPEAIER FAILED TO TRIP DUE 'IO FAIIURE OF TIE UNDEFNOL7 AGE TRIP ASSDGLY DEVICE 70 FUNCTION PEOPERLY. 7EE UNIT 2 "A" REAC70R TRIP BREA]ER IfAS BEEN REPIACED WI7E A SPAPE BREAFER KHICH !!AS BEDI THOFOUGHLY INSPIC11D AhD 71E7ED PER PRESCRIBED PPOCEDURES. 711E UNDERVOLTAGE TRIP ASSDELY kHIC11 FAIIJD IfAS BEEN IbTOUhDED, AND TIE ORIGINAL "A" BREAKER HAS BEEN SET ASIDE, BOIH FOR FUR 7EER INVESTICATION. AL711CUGH EE PAVE NCff CChTIDED THE EXACT CAUSE OF TIE DEGRADED PERFOD'ANCE OF SllE UNDEINOLTAGE TRIP ASSEFBLY, KE SUSPFCf THAT 71iE PROBLIM MAY BE REIATED TO LUBPICATICN OF TEE ChDLEVOLTAGE TRIP ASSDSLY LINKAGE.

TliE PEJCIOR FIGECTION SYSTDI FUNCTIONED AND CONTINUES TO EUNCTICN COPFECTLY, CCNSERVATIVELY, AND AS DESIWED. TIEREEDPI, 71fEFE KAS NO 711 PEAT TO THE HEALTH AND SAFLTY OF TIIE PUBLIC.

70 PEEVD7f RECUREDiCE; 1) 71E CON 71ROL AND INSTREFD7fATION SUPERVISOR HAS CAIIIIONED AIL 7ECbNICIANS AND SUPERVISOPS ON TIE FMIETIAL IIIPACC OF ACCIDENTAL SHORTING OR COTCNEAT FAILUPE IN EQUIPMENT KEER FPOM CPlD IES INVER'IERS.

2) PRIOR 'IO NIC poRM 366A in $31

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NRC Pesan JetA U S. NUCLEAA REGULATORY COMMISSION LICENSEE EVENT REPORT (LER) TEXT CONTINUATION amovio oMe o uso-oio.

EXPimES. S/3185 PacauTV Naast its DOCKET muasSEA L21 ggg nynaggg,e page gas

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D.C. COOK NUCLEAR PLANT, UNIT 2 o ls to jo lo l 3l1l6 8l5

_ 013 p 0 l0 0l 3 or 0l3 nxr -

wi m.onm TICUE%CCfrING TFIEE 7YPES OF ICADS, EFFORTS WILL BE MADE TO ISOIATE 1]IE COMPONET FTm TIE CRID EUS INVERTERS. 3) TIE REACTOR TRIP AND BYPASS EREAKERS CN EOIII D.C.

CCOK UNITS HAVE BEEN 71TOPOLGiLY 3NSPEC7FD AhD TESTED AND CAN BE RELIED UPON TO FUNCTICN AS FECUIPID EUR TliE FOIICWP'G REASONS:

REPLACDHT OF 11E SUSPEUT UNDERTOLTAGE TRIP ASSDELY'S WITH TIE NEN UNDERVOLTAGE TRIP ASSDELY'S AND SUESECUFNT THOFOUGli TESTEG.

CCEFIM%TICN 11!AT 71E PERFOMENCE CHAPACTERISTICS OF 7]E DPEAlEFS THD*SELVES hERE CONSIS7ET 7HFOUGFOUT 71E SECUECE OF TESTHE.

INSTALIATICN AND FUNCTIONAL TESTING OF SHUNT TRIP ATTACFMNTS.

PEMOFFINCE OF TIE TECENICAL SPECIFICATION 18-MCNIII SURVEILIANCES ON BOIII UNITS PRIOR TO STARIUP.

CAREFUL EVALUATION IN CCMIUNCTION hTIII K'ESTINGECUSE ELFLTRIC COFFORATION, UTE MAhl;TICIUPER OF 71E EREAKER, OF TIE EVENT TO MSURE THAT TIE ROOT CAUSE COUID EE ISOIATED '10 71E UNDERVOLTAGE TRIP ASSD11LY.

IMPLDETATICN IN UNIT 2 OF TIE UNIT 17ECliNICAL SPECIFICATION TESTING PEGIPD7NTS FOR ShUff TRIP A7TIGFa7S.

AS AN IhTERIM FFASLTE, INCDEASE ETGi BI-MCh"I11LY (FS CLTRaTLY FFCUIFFD)

TO MONTHLY OF TIE TECENICAL SPECIFICATION ACTIVE TESTING RECUIRDINT OF 71E TRIP ERFRTR, PEDING FUR 11ER EVALUATION OF TIE EVENT, INCIUDING AhT DESIPABLE 11 CLINICAL SPECIFICATICN CHANGES.

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