ML17261B146: Difference between revisions

From kanterella
Jump to navigation Jump to search
(Created page by program invented by StriderTol)
 
(Created page by program invented by StriderTol)
Line 28: Line 28:
~~~~~''II~IJ~y~~~II~~'-~~~~~~~~~~~~~~-~~-~~s~0~~-~~~00~~>-~~~~~II~~~~~~~0~II~~~~~~~~~Il~~e~~~~~~~~~~~~~~~~~~~0~~0~~II~0~~~0~~~~0~~  
~~~~~''II~IJ~y~~~II~~'-~~~~~~~~~~~~~~-~~-~~s~0~~-~~~00~~>-~~~~~II~~~~~~~0~II~~~~~~~~~Il~~e~~~~~~~~~~~~~~~~~~~0~~0~~II~0~~~0~~~~0~~  


NNCevtttSSSAI94JILICENSEEEVENTREPORT(LERITEXTCONTINUATIONV.S.NVCLTAAAlOVLATONYCOMMISSION/AIteAOvlOOMl40JISOWIOSlNItIA$$SI$11$FACILITYNANOIIIOOCNSTNVMOSIIITIL$1NVMllNISIseovsttTtALVUttettIStOtt4U~AR.E.GinnaNuclearPowerPlantTTXTu'ttenSecrernewer.tretaeerttNACAetttt~1IIITIosooo24490-0080l080r-08B.ACTIONTAKENORPLANNEDTOPREVENTRECUE&ENCE:oThetestconditionsthatexistedonApril26,1990,willbeevaluated.Asaresultofthisevaluation,itisexpectedthatimprovementswillberecommended.,0AnyrelayscalibratedafterApril25,1990,willbeidentified.Theresultsofthesecalibrationswillbereviewedforgenericconcernswithtestconditions.Ananalysiswillbe,performedtoobtaintheoptimumsetpointandsetpointtolerancefortheDegradedVoltageRelays.,oCalibrationprocedurePR-l.lwillberevisedto-incorporate-thesenewsetpointsandsetpointtolerances.oAnewmethodologyfortestingtheserelayswillbeincorporatedintoPeriodicTestprocedurePT-9.1.VIADDITIONALINFORMATIONA.AFFECTEDCOMPONENTS:TheDegradedVoltageRelaysareaModel211B1175DTypeITE-27relaymanufacturedbyITECorporation.B.PREVIOUSLER'SONSIMILAREVENTS:Asimilar.LEReventhistoricalsearchwasconductedwiththefollowingresults:nodocumentationofsimilarLEReventswiththesamerootcauseatGinnaStationcouldbeidentified.C.SPECIALCOMMENTS:None.  
NNCevtttSSSAI94JILICENSEEEVENTREPORT(LERITEXTCONTINUATIONV.S.NVCLTAAAlOVLATONYCOMMISSION/AIteAOvlOOMl40JISOWIOSlNItIA$$SI$11$FACILITYNANOIIIOOCNSTNVMOSIIITIL$1NVMllNISIseovsttTtALVUttettIStOtt4U~AR.E.GinnaNuclearPowerPlantTTXTu'ttenSecrernewer.tretaeerttNACAetttt~1IIITIosooo24490-0080l080r-08B.ACTIONTAKENORPLANNEDTOPREVENTRECUE&ENCE:oThetestconditionsthatexistedonApril26,1990,willbeevaluated.Asaresultofthisevaluation,itisexpectedthatimprovementswillberecommended.,0AnyrelayscalibratedafterApril25,1990,willbeidentified.Theresultsofthesecalibrationswillbereviewedforgenericconcernswithtestconditions.Ananalysiswillbe,performedtoobtaintheoptimumsetpointandsetpointtolerancefortheDegradedVoltageRelays.,oCalibrationprocedurePR-l.lwillberevisedto-incorporate-thesenewsetpointsandsetpointtolerances.oAnewmethodologyfortestingtheserelayswillbeincorporatedintoPeriodicTestprocedurePT-9.1.VIADDITIONALINFORMATIONA.AFFECTEDCOMPONENTS:TheDegradedVoltageRelaysareaModel211B1175DTypeITE-27relaymanufacturedbyITECorporation.B.PREVIOUSLER'SONSIMILAREVENTS:Asimilar.LEReventhistoricalsearchwasconductedwiththefollowingresults:nodocumentationofsimilarLEReventswiththesamerootcauseatGinnaStationcouldbeidentified.C.SPECIALCOMMENTS:None.}}
}}

Revision as of 12:52, 18 May 2018

LER 90-008-01:on 900524,safeguards Buses Degraded Voltage Relays Miscalibrated.Caused by Wrong Setpoint Tolerance Being Specified in Calibr Procedure.Degraded Voltage Relays Calibr to Conservative Tolerance setpoint.W/900820 Ltr
ML17261B146
Person / Time
Site: Ginna Constellation icon.png
Issue date: 08/20/1990
From: BACKUS W H, MERCREDY R C
ROCHESTER GAS & ELECTRIC CORP.
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-90-008, LER-90-8, NUDOCS 9008290105
Download: ML17261B146 (14)


Text

ACCELERATEDDISTRIBUTIONDEMREGULATORYXNFORMATIONDISTRIBUTIONSYSTEM(RIDS)ACCESSIONNBR:9008290105DOC.DATE:90/08/20NOTARIZED-NODOCKETFACIL:50-244RobertEmmetGinnaNuclearPlant,Unit1,RochesterG05000244AUTH.NAMEAUTHORAFFILIATIONBACKUS,W.H.RochesterGasSElectricCorp.MERCREDY,R.C.RochesterGas6Electric.Corp.RECIP.NAMERECIPIENTAFFILIATION

SUBJECT:

LER90-008-01:on900524,safeguardsbusesdegradedvoltagerelaysmiscalibratedduetoprocedureinadequacy.W/9ltr.DISTRXBUTIONCODE:IE22TCOPIESRECEXVED:ILTRENCLSIZE:TITLE:50.73/50.9LicenseeEventReport(LNOTES:LicenseExpdateinaccordancewith10CFR2,2.109(9/19/72)~/05000244pRECIPIENTIDCODE/NAMEPD1-3LAJOHNSON,ACOPIESLTTRENCL1111PDRECIPXENTDCODE/NAME-3PDCOPIESLTTRENCL11INTERNAL:ACNWAEOD/DSP/TPABNRR/DET/ECMB9HNRR/DLPQ/LHFB11NRR/DOEA/OEAB11NRR/DST/SELB8D-DSLB8D1G02RGN1FILE01EXTERNAL:EGGGBRYCE,J.ALPDRNSICMAYS,GNUDOCSFULLTXT22111111111111111133111111AEOD/DOAAEdD/ROAB/DSPNR6/DET/EMEB9H3NRR/DLPQ/LPEB10NRR/DREP/PRPB11NRR/DST/SICB7ENRR/DST/SRXB8ERES/DSIR/EIBLSTLOBBYWARDNRCPDRNSgCMURPHY,G.AI1122111122111111111111DNOTETOALL"RIDS"RECIPIENTS:PLEASEHELPUSTOREDUCEIVASTE!CONTACTTHEDOCUMENTCONTROLDESK,ROOMPl-37(EXT.20079)TOELIMINATEYOURNAMEFROMDISTRIBUTIONLISTSFORDOCUMENTSYOUDON'TNEED!A,DDFULLTEXTCONVERSIONREQUIREDTOTALNUMBEROFCOPIESREQUIRED:LTTR32ENCL32tiDQ

ROCHESTERGASANDELECTRICCORPORATIONnt~Vi"srelic'c'tare~89EASTAVENUE,ROCHESTERN.Y.14649-0001ROBERTC.MECREOYVicePresidentCinnaNuclearProductionTELEPHONEAstEACOOE71B54627COAugust20,1990U.S.NuclearRegulatoryCommissionDocumentControlDeskWashington,DC20555Sub)ect:LER90-008(Revision01),SafeguardsBusesDegradedVoltageRelaysMiscalibratedDueTo.ProcedureInadequacyCausesaConditionProhibitedByPlantTechnicalSpecificationsR.E.GinnaNuclearPowerPlantDocketNo.50-244Inaccordancewith10CFR50.73,LicenseeEventReportSystem,Item(a)(2)(i)(B),whichrequires*areportofanyoperationprohibitedbythePlant,'sTechnicalSpecifications",theattachedLicenseeEventReportLER90-008(Revision01)isherebysubmitted.ThisrevisionisnecessarytoaddressapplicableTechnicalSpecificationactionstatementsandtoclarifyrecalibrationmethodology.Verytrulyyours,RobertC.Mecredyxc:U.S.NuclearRegulatoryCommissionRegionI475Allendale.RoadKingofPrussia,PA19406GinnaUSNRCSeniorResidentInspector.0gIPzIP~9008290i05900820PDFlADOCK050002448PDC aaACHNSNr&4$1UCENSEEEVENTREPORTLER)UJ.attcLtAA1IQULATOAPcoa>>owoNAto10VIOONIaNLSIN.0IO>>1tktaAIIIISallltocIUTTNooolIIIR.E.GinnaNuclearPowerPlantICOCIITNa>>oOI1Qlo4o00244~0s08"~'"SafeguardsBusesDegradedVoltageRelaysMisca1ibratedDueToProceudreInadaCausesAConditionProhibitedBPlantTechnicalScificationsCVCNTOATII4LC1NUaaICAI4Att011OATIlllOTIIIIIACILITII~INVOLVlONIaaONT>>a'ATTCA1TCANi;.~LaarliarAL~>>a>>a>>OOA11VN>>O>>a~>>arWI1aoONTNOAV1CANtAOUTTaaoaaaoOOCAI1NUaaIIAla0400005249090000108209004000OtIAATINOaaOOINl~OaaIALcvIL098N.ANNIIIlllSI.ONlaIllIIIISI.AN4IIIHNISIANIINIOalSO.AN4InllNSt.oNlalNM4IIIINMNIQlN.T$4IQIION.TSiolQlIllN.1$4I0III4LICtNIIICONTACft01TIIQLI1IltlNQSNIQIININ.1$4IQllalNJSNIQIIaOSN5SlaIQIlaoOIAIN.1$4IQllaNIQIN.1$4lQIIol0TNtAIOVIAlllINTIOtllC11faICaoooo>>>>ooroaoroorOao~oa>>oaatrIlllTIIII1lt01fItW4OITTCOtUAWANTTI11IOISLT141OTNC1ItoaooVIo>>IA>>oooo~o>>oaro>>ataoTooc>>1ctanSNAIWesleyH.BackusTechnicalAssistanttotheOperationsManager*IIIACOOITILttaaONINUIIIC1CO>>tLITIONILINC501CACNCCNotONCNT5AILUIIOIIC1I~COINTNal1Ct011IlllCAVSISTlfillCoaotONINTaoANUtACTVAC1C101TAILITONt10I:%~~'r.PI""A*>>~$~~~&k4CAVSCUANUtAC>>TUAI1lt01TAITONtAOINNrkl>>Ior','~~'>~~g~ggrSVttLtlltNTAL1lt01fCXtlCTCOIIIIYllIIIt>>.r>>>>U>>r>>55tCCTCO5VC>>I5510>>OATCIaktfAAcfIU>>o>>eIo>>NIaooo>>.l1,aooroooaao>>rtIII>>ooaa>>at>>~Ittoorra>>oo>>>>a>>ll4lstlCTIOLUINICSIONOATIIIIIaaONTNC*TTCA1OnMay24,1990at1604EDSTwiththereactoratapproximately984fullpower,anevaluationofundervoltagerelaytest;datarevealedthatfive(5)oftheeight(8)DegradedVoltageRelayson480voltsafeguardbuseswerecalibratedsuchthatrelayactuationwouldnotoccurwithinthelimitsofTechnicalSpecifi-cations.AsthiswasasetpointproblemwiththeDegradedVoltageRelays,noimmediateplant.oroperatorresponseswerenecessary.1Theunderlyingcause.oftheeventwasattributedtothewrongsetpointandsetpointtolerancebeingspecifiedinacalibrationprocedure.ImmediatecorrectiveactionwastocalibratetheDegradedVoltageRelaystoasetpointontheconservativesideofthetolerance.Subsequenttothecalibration,theDegradedVoltageRelaysweretestedsatisfactorilyandreturnedtoservice.11CtaeSNQADI I

IIAC4'~444AraeSILICENSEEEVENTREPORTILER)TEXTCONTINUATIONCOCKETIIVMACAIllV.4.AVCLCAAASCVLATOAYCOMMIS4IOH444AOv40OM4vOSISO&IOs4IItIA444IS)%$R.E.GinnaNuclearPowerPlantrEXrnr~SOSCee~~OaeeOW+AC~~'SSIITSo5ooo24490LSAAVM44AI~ISSOVSHTtILVVUA-008AIVISIQHvtIU4A-0102o~08I~PRE-EVENTPLANTCONDIT10NSTheunitwasatapproximately984reactorpower.TheResultsandTestDepartmentandanElectricalEngineeringrepresentativewereobservingtheRelayDepartmentperformingprotectiverelaycalibrationprocedurePR-1.1(480VoltUndervoltageAndGroundAlarmSchemeForBuses14;16,17and18.)II.DESCRIPTIONOFEVENTA.DATESANDAPPROXIMATETIMESOFMAJOROCCURRENCES:0Modificationinstallationin1982:Eventdate00May24,1990,1115EDST:DiscoverydateandtimeofthefirstoffiverelaysfoundbelowthelimitofTechnicalSpecifications.May244199041604EDST,Allaffectedrelaysrecalibrated,testedsatisfactorily.andrestoredtoservice.B.EVENT:OnMay24,1990at1604EDST,withthereactorhtapproximately984fullpowerPR-1.1wascompleted.EvaluationofthePR-l.ldatarevealedthatfive(5)oftheeight.(8)DegradedVoltageRelayson480voltsafeguardsbuses14,16,17,and18hadbeencalibratedsuchthatrelayactuationwouldnotoccurwithinthelimitsofTechnicalSpecifications,page2.3-10,Figure2.3-1.Therelaysaffectedwereasfollows:relays27/14onBus14,27B/16onBus16,27/17and27B/17onBus17and27/18onBus18.Thisdeterminationoccur-redafterevaluationandanalysisoftestdataandTechnicalSpecificationrecpxirementsasfollows:vaCeOsMS44g MAC/elmSSSA1$41lLICENSEEEVENTREPORT(LERITEXTCONTINUATIONV.S.NVCLSAAAlOVLATOAVCCSSAIISSIOIIASPAOV$0OMSHO11$0&IOs/$)ISIA$$SI$I%$OOCIICTHVMOSAITILCAHVSSCIAISISSQUSNTI4L~0MAIISvISlONHMR.E.GinnaNuclearPowerPlantosooo24490-0080103OFQ8TKXTIIT~aWCeSwaver,~~lVACAnn~'llIITI0o0Thecurrent480voltsafeguardsbusundervoltagesystemwasfirstputinservicein1982.SetpointswerespecifiedbyCorporateElectricalEngineering,andthesesetpoints(withtolerancesestablishedbytheRelayandTest,Department)wereusedtocalibratetheserelaysoverthepasteightyears.OnApril4,1990thenormalannualcalibrationwasperformedonthe480voltsafeguardsbusesDegradedVoltageRelays,perPR-l.l.Thisprocedurechecksandcalibratesthedropoutvoltageoftherelays.Theprocedurespecifieda+54calibrationtoler-anceonthedropout,setpointwitha"desired$'pecifiedsetpointof103.5'olts.AllDegradedVoltageRelayswerecalibratedtothesespecifica-tions.Becauseofthe+toleranceallowedbytheproceduresomeoftherelayswerecalibratedtolessthanthe"desired"103.5voltswhichwasconsideredacceptable.IOnApril12,1990thenormalpostcalibrationtestwasperformedonthe480voltsafeguardsbusesDegradedVoltageRelaysperperiodictestprocedurePT-9.1(UndervoltageProtection-480VoltSafeguardBuses).,Thisprocedurecheckstheresetvoltageoftherelaysandalsothedropoutresponsetime,butdoesnotcheckthedropoutvoltage.AllDegradedVoltageRelayswerefoundtobewithinthespecificationsoftheprocedure.PriortoApril26,1990areviewofthecalibrationdatafromApril4,1990andareviewofplantTechnicalSpecificationswasperformedbytheISI/ISTCoordinatorandanElectricalEngineeringrepresentative.Followingthisreview,thesein-dividualsrequestedthatallDegradedVoltage

>>ACtv>>SSSAW4SILICENSEEEVENTREPORTILER)TEXTCONTINUATIONI>S.>>I>CLCAiASOI>LATOIIYCO>>MISSIO>IA>TAOVSDOMS>>0SISOWI04/S)ttI>ISSS>SI'SSR.E.GinnaNuclearPowerPlantnXr>>>~a>>Ce>>~.~~>>>ICa~'>>Imo5ooo244LCIIMI>>>SillIIIS~QUl>>T>AL%VUA90-008i'IV>>IOUHVUTA-0104ovRelaysthatwerefoundatorbelow103.5voltsbeadjustedtogreaterthan103.5volts.Thegreaterthan103.5voltswasrequestedtoensurethatallrelayswerewithintheTechnicalSpecificationlimitof103.5voltspriortoenteringtheplantmodeforwhichtheserelaysarerequiredtobeoperable.FiveDegradedVoltageRelayswereadjustedonApril26,1990.OnMayll,1990thenormalmonthlyPT-9.1wasperformedonall480voltsafeguardsbusesDegradedVoltageRelays.ThistestwaswitnessedbyanElectricalEngineeringrepresentative.Afterreviewofthetestdata,theElectricalEngineeringrepresentativeexpressedaconcernthat,basedonthetestresetdata,actualdropoutvoltageof,5oftheDegradedVoltageRelaysmaybebelowtheTechnicalSpecification103.5voltlimit.Since,thePT-9.1onlytestedtheresetvoltageforeachrelayanactualrecalibrationmustbeperformedtodeterminethe"asfound"dropoutvoltage.OnMay24,1990PR-l.lwasreperformedonthe5DegradedVoltageRelaystoverifytheirdropoutvoltagesetpoint.At1115EDST,thedropoutvoltageofthefirstrelaywascheckedandfoundbelowtheTechnicalSpecificationlimitof103.5volts.Thedegradedvoltagerelaywasrecalibratedandtestedpriortobeingdeclaredoperable,thenthefouradditionalrelaysinquestionweretestedinthesamemanner.TechnicalSpecificationTable3.5-1,actionstatement7,wasentered.priortothecalibrationofeachrelayandthecalibratedrelaywassubsequentlydeemedoperablefollowingsuccessfulcompletionofPT-9.1.Areviewofthe"asfound"calibrationdateshowedthatthedropoutvoltages..oftheother4relayswerealsobelowtheTechnicalSpecificationlimitof103.5volts.Thisconditionwasdeterminedtobereportableinaccordancewith10CFR50.73(a)(2)(i)(B).0OnMay29,1990PT-9.1.wasreperformedonall480voltsafeguardsbusesDegradedVoltageRelaystocheckforpossiblesetpointdrift.Allrelaystestedsatisfactorily.

IIACSacro$$$AN4$lLICENSEEEVENTREPORT(LER)TEXTCONTINUATIONV.$.MVCLCA1AlOULAYOAYCCAOMI$$101ASSAOVCOOM$143150MIOOS$)rSI1$$"$r$I%$SACILltY1AM0IllOOCIIlfrlUM0$1Ill<<$AAL$1rIVM4$11$lSoaulrrTrAL'rrrArrtYl5IOrrrrrrMSA4$I$IR.E.GinnaNuclearPowerPlantTEXTIIS'rroroancerlrOOrrooCrroosororrolrrSICSrorrr~$IIITIo5ooo24490-008-01050FQQC.INOPERABLESTRUCTURES,COMPONENTS,ORSYSTEMSTHATCONTRIBUTEDTOTHEEVENT:None.D.OTHERSYSTEMSORSECONDARYFUNCTIONSAFFECTED:None.METHODOFDISCOVERY:TheeventwasmadeapparentduringtheperformanceofPR-1.1onMay24,1990.F.OPERATORACTION:AsthiswasasetpointproblemwiththeDegradedVoltageRelays,noimmediateoperatoractionwasnecessary.G.SAFETYSYSTEMRESPONSES:None.,III.CAUSEOFEVENTA.IMMEDIATECAUSE'heimmediatecauseoftheeventwasdueto5of8DegradedVoltageRelayson480voltsafeguardbuses14,16,17,and18beingcalibratedsuchthatrelayactuationwouldnot,occurwithinthelimitsofTechnicalSpecifi-cations.B.ROOTCAUSE:TherootcauseoftheeventdiscoveredonMay24',1990,wasattributedtothecalibrationconditionsthatexistedonApril.26,1990,duringthepreviouscalibra-tionofthefiveDegradedVoltageRelays.TheunderlyingvolrgorrooOJ HACSetm1SSA.l$4$lLICENSEEEVENTREPORTILERITEXTCONTINUATIONU.S.HUCLSAAAlOULATOIIYCOMMISSIOHASSAOYSOOMSHO)I$0&IOS1)It<A$5~I1I'SSI'ACILITYHAMII'lOOCIISTHUMISIIITILlllHUM'III~ISSOUSHTIALUAtingYISlOHMR.E.GinnaNuclearPowerPlantTSITINmmeSweeenOrreK~aAKanetHIICArm~'MIITIosooo24490-008-01060'8causeoffinding,setpointsbelowlimits(inthepast)isnowevidentandisduetothewrongsetpointandsetpointtolerancebeingspecifiedinacalibrationprocedure.ThecalibrationprocedureforthesafeguardbusDegradedVoltageRelays(PR-1.1)specifiedanacceptancecriteriaof103.5volts+5%.GinnaTechnicalSpecificationfigure2.3-1requirestheDegraded'oltageRelaystoactuatewhentherelayvoltagesdropto103.5volts.(AC)whichcorrespondsto414voltsonthe'480voltsafeguardbus.Therelaysetpointof103.5voltswasdeterminedbyRGGECorporateEngineeringandprovidedtoRelayandTestDepartmentforuse,.inthecalibrationoftheserelays.However,nodefinitivetolerancebandwasprovidedwiththedesiredsetpoint;-Normalvendorrecommendedtoleranceswereappliedupondevelopmentofthecalibrationprocedure.Thisresultedintheactualsetpointoftheserelaystobeacceptablewhenleftbelowthe,requiredminimumdropoutvoltageof103.5volts.IIVANALYSISOF&lENTThiseventisreportableinaccordancewith10CFR50.73,LicenseeEventReportSystem,item(a)(2)(i)(B),whichrequiresareportof,"anyoperationprohibitedbytheplant'sTechnicalSpecifications."The5outof8DegradedVoltageRelaysbeingcalibratedsuchthatrelayactuationwouldnotoccurwithinthelimitsofTechnicalSpecificationswasan,operationprohibitedbytheplantTechnicalSpecifica-tions..Anassessmentwasperformedconsideringboththesafetyconsequencesandimplicationsofthiseventwiththefollowingresultsandconclusions:

~~~~~II~IJ~y~~~II~~'-~~~~~~~~~~~~~~-~~-~~s~0~~-~~~00~~>-~~~~~II~~~~~~~0~II~~~~~~~~~Il~~e~~~~~~~~~~~~~~~~~~~0~~0~~II~0~~~0~~~~0~~

NNCevtttSSSAI94JILICENSEEEVENTREPORT(LERITEXTCONTINUATIONV.S.NVCLTAAAlOVLATONYCOMMISSION/AIteAOvlOOMl40JISOWIOSlNItIA$$SI$11$FACILITYNANOIIIOOCNSTNVMOSIIITIL$1NVMllNISIseovsttTtALVUttettIStOtt4U~AR.E.GinnaNuclearPowerPlantTTXTu'ttenSecrernewer.tretaeerttNACAetttt~1IIITIosooo24490-0080l080r-08B.ACTIONTAKENORPLANNEDTOPREVENTRECUE&ENCE:oThetestconditionsthatexistedonApril26,1990,willbeevaluated.Asaresultofthisevaluation,itisexpectedthatimprovementswillberecommended.,0AnyrelayscalibratedafterApril25,1990,willbeidentified.Theresultsofthesecalibrationswillbereviewedforgenericconcernswithtestconditions.Ananalysiswillbe,performedtoobtaintheoptimumsetpointandsetpointtolerancefortheDegradedVoltageRelays.,oCalibrationprocedurePR-l.lwillberevisedto-incorporate-thesenewsetpointsandsetpointtolerances.oAnewmethodologyfortestingtheserelayswillbeincorporatedintoPeriodicTestprocedurePT-9.1.VIADDITIONALINFORMATIONA.AFFECTEDCOMPONENTS:TheDegradedVoltageRelaysareaModel211B1175DTypeITE-27relaymanufacturedbyITECorporation.B.PREVIOUSLER'SONSIMILAREVENTS:Asimilar.LEReventhistoricalsearchwasconductedwiththefollowingresults:nodocumentationofsimilarLEReventswiththesamerootcauseatGinnaStationcouldbeidentified.C.SPECIALCOMMENTS:None.