ML18026A242

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Forwards Response to Generic Ltr 91-06, Resolution of Generic Issues A-30, 'Adequacy of Safety-Related DC Power Supplies.'
ML18026A242
Person / Time
Site: Susquehanna  Talen Energy icon.png
Issue date: 10/24/1991
From: KEISER H W
PENNSYLVANIA POWER & LIGHT CO.
To: MILLER C L
Office of Nuclear Reactor Regulation
References
REF-GTECI-A-30, REF-GTECI-EL, TASK-A-30, TASK-OR GL-91-06, GL-91-6, PLA-3673, NUDOCS 9111010196
Download: ML18026A242 (94)
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ACCELERATEDDTRIBUTIONDEMONS~TIONSYSTEMREGULATORYINFORMATIONDISTRIBUTIONSYSTEM(RIDS)ACCESSIONNBR:9111010196DOC.DATE:91/10/24NOTARIZED:NOFACIL:50-387SusquehannaSteamElectricStation,Unit1,Pennsylva50-388SusquehannaSteamElectricStation,Unit2,PennsylvaAUTH.NAMEAUTHORAFFILIATIONKEISER,H.W.PennsylvaniaPower&LightCo.RECIP.NAMERECIPIENTAFFILIATIONMILLER,C.L.ProjectDirectorateI-2

SUBJECT:

ForwardsresponsetoGenericLtr91-06,"ResolutionofGenericIssuesA-30,'AdequacyofSafety-RelatedDCPowerSupplies.'"DISTRIBUTIONCODE:AOOIDCOPIESRECEIVED:LTR7ENCL/SIZE:TITLE:ORSubmittal:GeneralDistributionDOCKET0500038705000388DCOPIESLTTRENCL1122NOTES:LPDR1cyTranscripts.~'PDR1cyTranscripts.5:~~8~~r>>RECIPIENTIDCODE/NAMEPDl-2LARALEIGH,J.RECIPIENTIDCODE/NAMEPD1-2PDCOPIESLTTRENCL11/0500038705000388ADiDINTERNAL:ACRSNRR/DET/ESGBNRR/DST8E2NRR/DST/SICB8H7NUDOCS-ABSTRACTOGC/HDS2RES/DSIR/EIBEXTERNAL:NRCPDRNOTES:661111111110111122NRR/DET/ECMB7DNRR/DOEA/OTSB11NRR/DST/SELB7ENRR/DST/SRXB8EOC/LFQEF-Kl'SIC111111111011RDNOTETOALL"RIDS"RECIPIENTS:DDPLEASEHELPUSTOREDUCEXVASTE!CONTACTTHEDOCUMENTCONTROLDESK,ROOMPl-37(EXT.20079)TOELIMINATEYOURNAMEFROMDISTRIBUTIONLISTSFORDOCUMENTSYOUDON'TNEED!TOTALNUMBEROFCOPIESREQUIRED:LTTR26ENCL24 0PennsylvaniaPower8LightCompanyTwoNorthNinthStreet~Allentown,PA,18101-1179,~,215/774-5151HaroldW.KeiserSeniorVicePresident-Nuclear215/77441941'CT24jtIQ)DirectorofNuclearReactorRegulationAttention:Hr.C.L.Hiller,ProjectDirectorProjectDirectorateI-2DivisionofReactorProjectsU.S.NuclearRegulatoryCommissionWashington,D.C.20555SUSQUEHANNASTEANELECTRICSTATIONRESPONSETOGENERICLETTER91-06LA-3673FILESR41-1DDocketNos.50-387and50-388

DearHr.Hiller:

EnclosedisourresponsetoGenericLetter91-06,"ResolutionofGenericIssueA-30".InanefforttoavoidconfusioncausedbyextensiveexplanatoryremarksprovidedforeachDCsystem,ourresponseisdividedintofourparts:ATTACHMENTI:24VDCSYSTEMATTACHMENTII:125VDCSYSTEMATTACHMENTIII:250VDCSYSTEMATTACHMENTIV:DG'-E125VDCSYSTEMShouldyouhaveanyquestions,pleasecontactHr.W.W.Williams,at(215)774-7910.Verytrulyyours,glH.W.KeiserEnclosure9111p1Kp5ppp38701'9691102%PDRADOCP OCT24lg01FILESA17-8/so-24PLA-'3673Mr.C.L.Millercc:iiiLCD~ocumen.Control-Desk-(original.)PNRCRegionIMr.G.S.Barber,NRCSr.ResidentInspectorMr.J.J.Raleigh,NRCProjectManagerWWW:llrPLA/021.WWW SUSUEHANNAS.E.S.24VDCSYSTENATTACHMENTIPage1ENCLOSURE1ThefollowinginformationisapplicabletoeitherUnit1or2atSusquehannaSES.l.UnitSusuehannaS.E.S.Unit1or224VDC2.a~ThenumberofindependentredundantdivisionsofClasslEorfty-lddtftllyltl~t.(lldanyseparateClasslEorsafety-relateddc,suchasanydcdedicatedtothedieselgenerators.)b.Thenumberoffunctionalsafety-relateddivisionsofdcpowerytttlfttdftllltd3.Doesthecontrolroomatthisunithavethefollowingseparate,independentlyannunciatedalarmsandindicationsforeachdivisionofdcpower?a.Alarms1.Batterydisconnectorcircuitbreakeropen?No2.Batterychargerdisconnectorcircuitbreakeropen(bothinputacandoutputdc)?No3.dcsystemground?No4.dcbusundervoltage?No5.dcbusovervoltage?No6.Batterychargerfailure?No...9111010196 C4' SUSUEHANNAS.E.S.24VDCSYSTEMATTACHMENTI7.Batterydischarge?NoPage2b.Indications1.Batteryfloatchargecurrent?No2.Batterycircuitoutputcurrent?No3.Batterydischarge?No4.Busvoltage?Noc.Doestheunithavewrittenproceduresforresponsetotheabovealarmsandindications?No4.Doesthisunithaveindicationofbypassedandinoperablestatusofcircuitbreakersorotherdevicesthatcanbeusedtodisconnectthebatteryandbatterychargerfromitsdcbusandthebatterychargerfromitsacpowersourceduringmaintenanceortesting?NoSeeremarktl5.Iftheanswertoanypartofquestion3or4isno,thenprovideinformationjustifyingtheexistingdesignfeaturesofthefacility'ssafety-relateddcsystems.*Seenotebelow.SeeremarkOl6.(I)Haveyouconductedareviewofmaintenanceandtestingactivitiestominimizethepotentialforhumanerrorcausingmorethanonedcdivisiontobeunavailablet~esand(2)doplantproceduresprohibitmaintenanceortestingonredundantDCdivisionsatthesametime'I~esIfthefacilityTechnicalSpecificationshaveprovisionsequivalenttothosefoundintheWestinghouseandCombustionEngineeringStandardTechnicalSpecificationsformaintenanceandsurveillance,thenquestion7maybeskippedandastatementtothateffectmaybeinsertedhere.

SUSUEHANNAS.E.S.~YYTATTACHMENTIPage37.Aremaintenance,surveillanceandtestproceduresregardingstationbatteriesconductedroutinelyatthisplant?Specifically:a.Atleastonceper7daysarethefollowingverifiedtobewithinacceptablelimits:1.Pilotcellelectrolytelevel?Yes2.Specifygravityorchargingcurrent?Yes3.Floatvoltage?Yes4.Totalbusvoltageonfloatcharge?Yes5.Physicalconditionofallcells?Yesb.Atleastonceper92days,orwithin7daysafterabatterydischarge,overcharge,orifthepilotcellreadingsareoutsidethe7-daysurveillancerequirementsarethefollowingverifiedtobewithinacceptablelimits:l.Electrolytelevelofeachcell?Yes2.Theaveragespecificgravityofallcells?Yes3.Thespecificgravityofeachcell?Yes4.Theaverageelectrolytetemperatureofarepresentativenumberofcells?Yes5.Thefloatvoltageofeachcell?Yes6.Visuallyinspectormeasureresistanceofterminalsandconnectors(includingtheconnectorsatthedcbus)?Yes SUSUEHANNAS.E.S.24VDCSYSTEMATTACHMENTIc.Atleastevery18monthsarethefollowingverified:Page41.Lowresistanceofeachconnection(bytest)?Yes2.Physicalconditionofthebattery?Yes3.Batterychargercapabilitytodeliverratedampereoutputtothedcbus?Yes4.Thecapabilityofthebatterytodeliveritsdesigndutycycletothedcbus?Yes5.Eachindividualcellvoltageiswithinacceptablelimitsduringtheservicetest?Yesd.Atleastevery60months,iscapacityofeachbatteryverifiedbyperformanceofadischargetest?Yese.Atleastannually,isthebatterycapacityverifiedbyperformancedischargetest,ifthebatteryshowssignsofdegradationorhasreached85Xoftheexpectedservicelife?Yes8.Doesthisplanthaveoperationalfeaturessuchthatfollowinglossofonesafety-relateddcpowersupplyorbus:a.Capabilityismaintainedforensuringcontinuedandadequatereactorcooling?Yesb.Reactorcoolantsystemintegrityandisolationcapabilityaremaintained?Yesc.Operatingprocedures,instrumentation(includingindicatorsandannunciators),andcontrolfunctionsareadequatetoinitiatesystemsasrequiredtomaintainadequatecorecooling?Yes9.Iftheanswertoanypartofquestion6,7or8isno,thenprovideyourbasisfornotperformingthemaintenance,surveillanceandtestproceduresdescribedand/orthebasesfornotincludingtheoperationalfeaturescited.*Seenotebelow.

N SUSUEHANNAS.E.S.24VDCSYSTEMATTACHMENTIPage5*Note:Forquestionsinvolvingsupportingtypeinformation(questionnumbers5and9)insteadofdevelopingandsupplyingtheinformationinresponsetothisletter,youmaycommittofurtherevaluatetheneedforsuchprovisionsduringtheperformanceofyourindividualplantexaminationforsevereaccidentvulnerabilities(IPE).Ifyouselectthisoption,youarerequiredto:(1)Sostateinresponsetothesequestions,and(2)Committoexplicitlyaddressquestions5and9inyourIPEsubmittalpertheguidelinesoutlinedinNUREG-1335(Section2.1.6,Subitem7),"IndividualPlantExamination:SubmittalGuidance."c:iwp51idocsi24VDCSYS.PCD(18)10/24/919:20am RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.24VDCSUBSYSTEMPAGE1REMARK1:1.0Thefollowingindicationsandalarmsforthe24Vdcclass1Esubsystemareprovided.JustificationforthisdesignhasbeenpreviouslyprovidedinPLA-959totheNRCdated11/6/81,regardingControlRoommonitoringofClasslEdcpowersystems.Each24Vdcsubsystemconsistsoftwo24voltbatterybanksconnectedinserieswithacommongroundbusconnectedtothecommon(center)pointofthetwobatterybanks.Thegroundbusissolidlygroundedtothestationgroundgrid.Each24voltbatterybankisdesignatedaseitherthepositiveornegativebusasreferencedtoground.Thealarms/indicationsinthefollowingtableanddiscussionaretypicalforeachpositiveandnegativebus.AlarmorIndication,LocationLocalControlRoomNotesBusUndervoltageAlarmBatteryMonitorAlarmBatteryChargerTroubleAlarmBusOvervoltageAlarmBusVoltmeterBatteryChargerAmmeterBatteryChargerVoltmeterDCSystemTroubleAlarm1,21,2,41,2,51,23NOTES:1.SeeTable1andFigure2forspecificlocalalarmindication.

RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.24VDCSUBSYSTEMPAGE22.Thesearelocallyindicatedandactuatedcsubsystemtroublealarm,seeTable1andFigure1.3.Hetersareprovidedlocally.SeeFigure3.4.Batterymonitor'comparesbatterycenterpointvoltagewithhighandlowthresholdreferencepointsofthehighandlowvoltagecomparators.Thedegradedcellconditions(suchasashortedcell)oranopencircuitcondition(suchasanopenfuse)aredetectedbythebatterymonitor.5.BatterychargertroublealarmindicationisprovidedforbatterychargerACpowerfailure,DCoutputbreakeropen,batterychargerfailurealarmoperation.6.Oneannunciatorwindowforeach24Vdcsubsystemisprovided.(Includesinputsfromeitherthepositiveornegativebus).2.0Themonitoringschemeprovidedforthedcpowersubsystemisbasedonthedegreeofcontrolprovidedtothecontrolroomoperator.Sincethedcpowersystemequipmentcannotberemotelycontrolled,asingledcsystemtroubleannunciatorwindowforeachsubsystemisprovidedinthecontrolroom,consistentwiththesystemlevelalarmcriteriasetforthinSection8ofR.G.1.47.TheSSESdesignisbasedonthegeneralcriteriathat,iftheoperatorcanperformsomecorrectiveactioninthecontrolroominresponsetoaspecificinput,thatinformationisspecificallyprovided.Thedcpowersystemequipmentcannotbecontrolledfromthecontrolroom.Annunciatingspecificinputsfromthe24Vdcsysteminthecontrolroomdoesnotenhancethecontrolroomoperators'sabilitytodealwiththesituationanditwouldnotbeconsistentwithSSESalarmdesignphilosophy.However,iftheonlyresponserequiredistodispatchanoperatortoanarearemovedfromthecontrolroom,thentheonlyinformationrequiredinthecontrolroomisgeneralinformationwithonlythelevelofspecificityrequiredtodirectthatoperatortotheproperlocation.Thismethodisfasterandmorereliablesinceabnormal

RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.24VDCSUBSYSTEMPAGE3conditionsareautomaticallyalarmed.Furthermore,thisapproachisconsistentwiththehumanfactorsengineeringgoaltonotoverburdentheoperatorwithunnecessaryinformation.24Vdcsysteminstrumentation,locallyprovided,isinfullcompliancewiththerequirementofIEEE308-1974andRegulatoryGuide1.47.TheDCsystemgeneraltroublealarmsandspecificlocalindicatorsinconjunctionwiththeroutineoperatorsurveillanceprovidepositiveassurancethattheClasslEdcpowersystemaremaintainedinasteadystatereadytoperform-therequiredsafetyfunction.3.0FollowingisthejustificationforeachalarmandindicationlistedinGenericLetter91-06.3.1BatterDisconnectorCircuitBreaker0enAlarm:TheSusquehannaS.E.S.(SSES)24Vdcsubsystemutilizesfusesasthebatterydisconnect.Thisconditionisdetectedbythebatterymonitor.Thebatterymonitorutilizesavariablethresholdcircuittogetherwithtwocomparators(highandlow)todetectthelossofbatterycapabilityduetoanopencircuit(i.e.,anopenfuseordegradedcellcondition).Avariablethresholdcircuitacceptsthebatterychargervoltageanddevelopstwothresholdvoltagesforusewiththecomparators.Whenthemonitoredvoltagesgoaboveorbelowthethresholds,thebatterymonitoroutputrelaycontactsinitiatealocalbatterymonitoralarmwhichisreflashedtothecontrolroomasa24Vdcsystemtroublealarm.ThisisconsistentwiththegeneraldesignphilosophydiscussedinSection2.0.3.2BatterCharerDisconnectorCircuitBreaker0enBothInutACandOututDCAlarm3.2.1BatteryChargerACInputDisconnectorCircuitBreaker:SSESutilizesacircuitbreakerinthebatterychargerasadisconnectfortheacinputpowersupply.Anacpower RESPONSETOGENERIC.LETTER91-06SUSUEHANNAS.E.S.24VDCSUBSYSTENPAGE4failurealarmrelayisinstalledinternaltothebatterychargertodetectlossofacinputpower.Thisconditioncouldbecausedbyanopeninputcircuitbreakerorlossofthe120Vacpowersupplytothecharger.Theacpowerfailurealarmrelayinitiatesabatterychargertroublealarmatthelocalreflasherpanel,whichisreflashedtothecontrolroomasa24Vdcsystemtroublealarm.Thisisconsistentwiththegeneraldesignphilosophydiscussedinsection2.0.3.2.2BatteryChargerDCOutputCircuitBreakerSSESutilizesacircuitbreakerinthebatterychargerasadisconnectforthedcoutputcircuit.Thecircuitbreakerisprovidedwithanauxiliarypositionindicatingswitch.Aswitchcontactwhichisclosedwhenthecircuitbreakerisopenisusedtoinitiateabatterychargertroublealarmatthelocalreflasherpanel.Adcsystemtroublealarmisreflashedtothecontrolroombythelocalreflasherpanel.ThisisconsistentwiththegeneraldesignphilosophydiscussedinSection2.0.3.3DCSstemGroundAlarmThe24Vdcsubsystemisasolidlygroundedsystem.Therefore,asystemgroundalarmisnotrequired.Asecondgroundoneitherthepositiveornegativebuswillcauseprotectivedevicesinthecircuittooperate.Thisconditionwillbedetectedatthelocalreflasherpanelbyeitherthebatterymonitoralarm(forbatteryfuseopen)orthebatterychargertroublealarm(forbatterychargerDCoutputbreakeropen).Ineithercase,thelocalreflasherpanelwillreflasha24Vdcsystemtroublealarmtothecontrolroomannunciator.ThisisconsistentwiththegeneraldesignphilosophydiscussedinSection'.0.

RESPONSETOGENERICLETTER91-0624VDCSUBSYSTEMSUSUEHANNAS.E.S.PAGE53.4DCBusUndervoltaeAlarmThe24Vdcsubsystemisprovidedwithpositiveandnegativedcbusundervoltagerelays.Eachrelayisconnectedacrossthesystembuses(positivebustoground,negativebustoground).Therelaysarenormallyenergizedand,settodropoutatthespecifiedsetpoint.Apositivebusornegativebuslowvoltagealarmatthelocalreflasherpanelisinitiatedaftertheundervoltagerelaydropsout.Thelocalreflasherpanel,inturn,reflashesthealarmtothecontrolroomannunciatorasadcsystemtroublealarm.ThisisconsistentwiththegeneraldesignphilosophydiscussedinSection2.0.3.5DCBusOvervoltaeAlarmThe24Vdcsubsystemsareprovidedwithovervoltagerelays.Therelaysarelocatedinsidethe24Vdcdistributionpanels.Eachrelayisconnectedacrossthesystembuses(positivebustoground,negativebustoground)andsettopickupatthespecifiedsetpoint.Anormallyopencontactoftheover'voltagerelay,whenclosed,initiatesapositivebusornegativebushighvoltagealarmatthelocalreflasherpanelwhichinturnwillreflashadcsystemtroubletothecontrolroomannunciator.ThisisconsistentwiththegeneraldesignphilosophydiscussedinSection2.0.3.6BatterCharerFailureAlarmEach24Vdcsubsystembatterychargerisprovidedwithabatterychargerfailurerelay.Thisrelaywilldetectthelossofthechargeroutputcurrentwiththeinputandoutputcircuitbreakersclosed.Thisconditionisindicativeofabatterychargerfailureanditinitiatesabatterychargertroublealarmatthelocalreflasher RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.24VDCSUBSYSTEMPAGE6panelwhichinturnwillreflashadcsystemtroublealarmtothecontrolroomannunciator.ThisisconsistentwiththegeneraldesignphilosophydiscussedinSection2.0.3.7BatterDischareAlarmThebatterycanonlydischargewhenits.terminalvoltageislessthanthenominalopencircuitvoltage.Thisisindicativeofabatterychargerfailureorsystemcurrentinexcessofthechargercapability.AbatterychargerfailurealarmisprovidedanditsoperationisdiscussedinSection3.6.Whensystemcurrentexceedsbatterychargercapability,adcsystemundervoltageconditionwilloccur,andwillbedetectedbythedcbusundervoltagerelay(seeSection3.4).Chargerfailureandbusundervoltageinitiatealarmsatthelocalreflasherpanelwhichinturnwillreflashadcsystemtroublealarmtothecontrolroomannunciator.ThisisconsistentwiththegeneraldesignphilosophyasdiscussedinSection2.0.3.8BatterFloatChareCurrentIndicationUndernormalconditions,thebatteryfloatchargecurrentisverysmallcomparedtobatterydischargecurrent.Measurementofthiscurrentrequiresaverysensitiveammeter.Shuntbypassesareemployedtoprotecttheammetermovementfromthemuchlargerbatterydischargecurrentpossibleinthiscircuit.Theseshuntsmustbemanuallyremovedwhenreadingnormalsmallfloatcurrent.Thusthisreadingcannotbecontinuousandnoautomaticindicationoralarmscanbegiven.Sincetheintentofindicating"BatteryFloatChargeCurrent"istodeterminethebatterycondition,themethodusedtoaccomplishthispurposeshouldnotbeimportant.Thebusundervoltage,batterymonitorandbatterychargerfailure RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.24VDCSUBSYSTEMPAGE7alarms(previouslydescribed)providecontinuousmonitoringtodetectdegradationofbatterycapability.Thesealarmswillreflashthedcsystemtroublealarminthecontrolroom,andanoperatorisdispatchedlocallytodeterminethecauseoftheconditionandinitiatecorrectiveaction.Specificindicationisprovidedonthelocalreflasherpanel.Thisresponseisexactlywhatwould'beachievedifanimproperstateofbatterycurrentwereindicatedonanammeterinthecontrolroom.ThisisconsistentwiththegeneraldesignphilosophydiscussedinSection2.0.3.9BatterCircuitOututCurrentIndicationInnormalconditionwhenthebatterychargerissupplyingthe24Vdcpower,thebatterycircuit(batteryandthebatterycharger)outputcurrentisindicatedbyanammeterlocatedatthebatterycharger.Intheconditionofabatterychargerfailure,thebatterysuppliesthedcpower.Inthisconditionthebatterycircuitoutputcurrentcannotbedeterminedsinceanammeterisnotprovidedatthe24Vdcdistributionpanels.AsindicatedinSection3.8,theintentofindicating"batterycurrent"istodeterminethebatterycondition,andthereforethemethodusedtoaccomplishthispurposeshouldnotbeimportant.3.10BatterDischareIndicationAspreviouslydiscussedinSection3.7,abatterydischargewilloccurasaresultofabatterychargerfailureorsystemcurrentinexcesstobatterychargercapability.Sincetheseconditionsareautomaticallyalarmedinthecontrolroom(viathesystemtroublealarm),anoperatorwillbedispatchedlocallyto IRESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.24VDCSUBSYSTEMPAGE8determinethecauseoftheconditionandinitiatecorrectiveaction.Thisresponseisexactlywhatwouldbeachievedifbatterydischargecurrentwasindicatedonanammeterinthecontrolroom.3.11BusVoltaeIndicationThebattery,thebatterychargerandthe24Vdcdistributionpanelarelocatedincloseproximityofeachother.Thebatterychargerandthedcdistributionpanelareeachprovidedwithavoltmeter.Thepurposeofabusvoltmeteratthecontrolroomwouldbetoenabletheoperatortodispatchsomeonetotakecorrectiveactionlocallytocorrectabnormalbusvoltage.AtSSESbusundervoltageandovervoltageismonitoreddirectlyatthedistributionpanel.Thebusundervoltageandovervoltageconditionsareannunciatedas24Vdcsystemloworhighvoltageatthelocalreflasherpanel.Adcsystemtroublealarmisreflashedtothecontrolroomannunciatorbythelocalreflasherpanel.Thisdesignautomaticallyalertsthecontrolroomoperatortounusualvoltageconditionswithoutunnecessarilyrequiringhisperiodicattentionandanalysis.Asaresult,24Vdcbusvoltageindicationisnotprovidedinthecontrolroomandhasbeenprovidedonthefrontofthedistributionpanelwhereitprovidesusefulinformationduringsurveillanceandmaintenanceactivities.Avoltmeterislocatedonthefrontofthebatterychargerpanel.Withthechargeroutputcircuitbreakerclosed,thechargeroutputandthebusvoltagesareessentiallythesameduetothecloseproximityofthechargertotheloadcenter.Allabnormalvoltageconditionsofthebatterychargerareannunciatedatthelocalreflasherpanelwhichisreflashedtothecontrolroomasadcsystemtroublealarm.ThisisconsistentwiththegeneraldesignphilosophydiscussedinSection2.0.

RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.24VDCSUBSYSTENPAGE93.12AlarmResonseProcedureControlroomalarmresponseproceduresfora24Vdcsystemtroublealarmdirecttheoperatortorespondtothelocalreflasherpaneltodeterminetheconditionwhichcausedthealarm.Localalarmresponseproceduresforthereflasherpanelareprovidedtodirecttheoperatortodeterminethecauseoftheconditionandtoinitiatecorrectiveaction.3.13IndicationofBassedandInoerableStatusofCircuitBreakersorOtherDisconnectinDevicesAlthoughindicationofbypassedandinoperablestatusofcircuitbreakersorotherdisconnectingdevicesisnotprovidedasapartoftheBypassIndicationSystem,the24VdcSystemTroubleAlarminthecontrolroomisinitiatedforthefollowingcondition(whicharedisconnectingdevicesinthesystem):Hainbatteryfuseopen.Batterychargeracinputcircuitbreakeropen.Batterychargerdcoutputcircuitbreakeropen,ordcdistributionpanelfeederbreakeropen.

P RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.24VDCSUBSYSTEMPAGE10TABLE124VDCSstemReflashPanelIndicators1L610(Typicalforpositiveandnegativebuses)l.24VDCSystemLowVoltage2.,24VDCSystemHighVoltage3.BatteryHonitor(indicatesbatterydegradationoropenbatteryfuses)4.BatteryChargerTroubleindicates(1)ACpowerfailure,(2)DCoutputbreakeropen,or(3)batterychargerfailureC:KWP51%00CSK24VDCSS~PGO(18)10/24/919:168AI 124DCLOCALREHASHPANELWITHINDICATION1L670MULTIPLEALARMINPUTSFROM%24VDCPOWERSYSTEMPERTABLE1DCSYSTEMAlARMINPUTSFROMOTHERREFLASHPANELS(8MILARTOABOVE)CONTROLROOMPANEL1C651ANNUNCIATOR+24VDCSYSTEMTROUBLE1L670FIGURE1

INDICATORUGHI'ERASHERPANELPOWERFAILUREPOSITIVEBUSLOWVOLTAGENEGATIVEBUSHIGHVOLTAGEBATlERYCHARGER41TROUBLE0NEGATIVEBUSLOWVOLTAGEBATTERYPOSITIVEMONITORBATIERYCHARGERWTROUBLE0POSITIVEBUSHIGHVOLTAGEBATlERYNEGATIVEMONITOR224VDCSYSTEMLOCALREHASHERPANELQYPICAOFIGURE2 IBATIERYBANK1D670I+24-24I96PCLQ>0+24VDCBA11ERYCHARGERDCBKRQvQ~-24VDCBA11ERYCHAI&ERDCBKRQvQA59y27P27y69NNSPARECOMPOUTPUTAMPPOSVOLTSNEG}VOLTSNEGSPAREMPUIEROUTPUTPROCESSRADIATIONMONITORSSOURCERNG.MON'SINIERMRNG.MON'S1RIP.AUX,UNITSNOTE1+24VCOMMON-24V24VDCSYSTEMOYPICAQNOTE1:COMMONBUSGROUNDED SUSUEHANNAS.E.S.125VDCSYSTEMATTACHMENTIIPage1ENCLOSURE1ThefollowinginformationisapplicabletoeitherUnit1or2atSusquehannaSES.1.UnitSUSUEHANNAS.E.S.UNIT-1or2125VDCSYSTEM2.a0ThenumberofindependentredundantdivisionsofClasslEorsafety-relatedDCpowerforthisplantisSeeRemark1(IncludeanyseparateClass1Eorsafety-relatedDC,suchasanyDCdedicatedtothedieselgenerators).b.Thenumberoffunctionalsafety-relateddivisionsofDCpowernecessarytoattainsafeshutdownforthisunitisSeeRemark2.3.Doesthecontrolroomatthisunithavethefollowingseparate,independentlyannunciatedalarmsandindicationsforeachdivisionofDCpower?a~3.5.Alarms1.Batterydisconnectorcircuitbreakeropen?No2.Batterychargerdisconnectorcircuitbreakeropen(bothinputACandoutputDC)?NoDCsystemground?NoDCbusundervoltage?NoDCbusovervoltage?No6.Batterychargerfailure?No7.Batterydischarge?Nob.Indicationsl.2.3.Batteryfloatchargecurrent?NoBatterycircuitoutputcurrent?NoBatterydischarge?NoBusvoltage?No SUSUEHANNAS.E.S.125VDCSYSTENATTACHMENTII4.Page2c.Doestheunithavewrittenproceduresforresponsetotheabove'alarmsandindications?NoI*,IDoesthisunithaveindicationofbypassedandinoperable'statusofcircuitbreakersorotherdevicesthatcanbeusedtodisconnectthebatteryandbatterychargerfromitsDCbus,andthebatterychargerfromitsACpowersourceduringmaintenanceortes'ting?NoSeeremark¹35.Iftheanswertoanypartofquestion3or4isno,thenprovideinformationjustifyingtheexistingdesignfeaturesofthefacility'ssafety-relatedDCsystems.*Seeendnote.Seeremark¹36.(I)HaveyouconductedareviewofmaintenanceandtestingactivitiestominimizethepotentialforhumanerrorcausingmorethanoneDCdivisiontobeunavailablet~esand(2)DoplantproceduresprohibitmaintenanceortestingonredundantDCdivisionsatthesametime?~esIfthefacilityTechnicalSpecificationshaveprovisionsequivalenttothosefoundintheWestinghouseandCombustionEngineeringStandardTechnicalSpecificationformaintenanceandsurveillance,thenquestion7maybeskippedandastatementtothateffectmaybeinsertedhere.7.Aremaintenance,surveillanceandtestproceduresregardingstationbatteriesconductedroutinelyatthispoint?Specifically:a.Atleastonceper7daysarethefollowingverifiedtobewithinacceptablelimits:I.2.3.4.5.Pilotcellelectrolytelevel?YesSpecificgravityorchargingcurrent?YesFloatvoltage?YesTotalbusvoltageonfloatcharge?YesPhysicalconditionofallcells?Yes

SUSUEHANNAS.E.S.125VDCSYSTEMATTACHMENTIIb.Page3Atleastonceper92days,orwithin7daysafterabatterydischarge,overcharge,orifthepilotcellreadingsareoutsidethe7-daysurveillancerequirementsarethefollowingverifiedtobewithinacceptablelimits:l.2.3.4.5.6.Electrolytelevelofeachcell?YesTheaveragespecificgravityofallcells?YesThespecificgravityofeachcell?YesTheaverageelectrolytetemperatureofarepresentativenumberofcells?YesThefloatvoltageofeachcell?YesVisually.inspectormeasureresistanceofterminalsandconnectors(includingtheconnectorsattheDCbus)?Yesc.Atleastevery18monthsarethefollowingverified:2.3.5.Lowresistanceofeachconnection(bytest)?YesPhysicalconditionofthebattery?YesBatterychargercapabilitytodeliverratedampereoutputtotheDCbus?YesThecapabilityofthebatterytodeliveritsdesigndutycycletotheDCbus'?YesEachindividualcellvoltageiswithinacceptablelimitsduringtheservicetest?Yesd.Atleastevery60months,iscapacityofeachbatteryverifiedbyperformanceofadischargetest'?Yese.Atleastannually,isthebatterycapacityverifiedbyperformancedischargetest,ifthebatteryshowssignsofdegradationorhasreached85Xoftheexpectedservicelife?Yes8.Doesthisplanthaveoperationalfeaturessuchthatfollowinglossofonesafety-relatedDCpowersupplyorbus:a.Capabilityismaintainedforensuringcontinuedandadequatereactorcooling?Yes SUSUEHANNAS.E.S.125VDCSYSTENATTACHMENTIIPage4b.Reactorcoolantsystemintegrityandisolationcapabilityaremaintained7Yesc.Operatingprocedures,instrumentation(includingindicatorsandannunciators),andcontrolfunctionsareadequatetoinitiatesystemsasrequiredtomaintainadequatecorecooling7Yes9.Iftheanswertoanypartofquestion6,7,or8isno,thenprovideyourbasisfornotperformingthemaintenance,surveillanceandtestproceduresdescribedand/orthebasesfornotincludingtheoperationalfeaturescited.*SeeNotebelow.*Note:Forquestionsinvolvingsupportingtypeinformation(questionnumbers5and9)insteadofdevelopingandsupplyingtheinformationinresponsetothisletter,youmaycommittofurtherevaluatetheneedforsuchprovisionsduringtheperformanceofyourindividualplantexaminationforsevereaccidentvulnerabilities(IPE).Ifyouselectthisoption,youarerequired,to:1)Sostateinresponsetothesequestions,and2)Committoexplicitlyaddressquestions5and9inyourIPEsubmittalpertheguidelinesoutlinedinNUREG-1335(section2.1.6,Subitem7),"IndividualPlantExamination:SubmittalGuidance."C:KIIP51I,docshadeqofsa.pgd(18)10/24/918:57am

RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.125VDCSUBSYSTEMPAGE1REMARK1:TheUnit1Class1Edirectcurrent,(dc)systemconsistsoffourindependent125voltdcsubsystems.ThesefoursubsystemsareidentifiedaschannelsA,B,C,andD.EachsubsystemprovidesthecontrolpowerforitsassociatedclasslEacpowerloadgroupconsistingof:'.16kVswitchgear,480Vloadcenters,andastandbydieselgenerator.The125Vdcsubsystemsalsoprovidedcpowerforsafetyfeaturevalveactuation,dieselgeneratorauxiliaries,andplantalarmandindicationcircuits.REMARK2:Fourseparateandindependentclass1E125Vdcsubsystemssupplycontrolpowerforeachoftheclass1Eloadgroups.Lossofanyoneofthesubsystemsdoesnotpreventtheminimumsafetyfunctionfrombeingperformed(i.e.,threeoutoffoursubsystemsarenecessarytoattainsafeshutdownforUnit1).REMARK3:1.0Thefollowingindicationsandalarmsforthe125VdcclasslEsubsystemareprovided.JustificationforthisdesignhasbeenpreviouslyprovidedinPLA-959totheNRCdatedll/6/81,regardingControlRoommonitoringofClass1Edcp'owersystems.

RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.125VDCSUBSYSTEMPAGE2AlarmorIndicationLocationLocalControlRoomNotesBusUndervoltageAlarmBusGroundAlarmBatteryMonitorAlarmBatteryChargerTroubleAlarmBusAmmeterBusVoltmeterBatteryChargerAmmeterBatteryChargerVoltmeterDCSystemTroubleAlarm1,21,21,2,41,2,5NOTES:1.SeeTable1andFigure2forspecificlocalalarmindication.2.Thesearelocallyannunciatedandactuatedcsubsystemtroublealarm,seeTable1andFigurel.3.Hetersareprovidedlocally.SeeFigure3.Batterymonitorcomparesbatterycenterpointvoltagewithhighandlowthresholdreferencepointsofthehighandlowvoltagecomparators.Thedegradedcellconditions(suchasashortedcell)oranopencircuitcondition(suchasanopenfuse)aredetectedbythebatterymonitor.

RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.125VDCSUBSYSTEMPAGE35.BatterychargertroublealarmindicationisprovidedforbatterychargerACpowerfailure,DCoutputbreakeropen,batterychargerfailurealarmoperation,andbusovervoltage.6.Oneannunciatorwindowforthe125Vdcsubsystemisprovided.2.0Themonitoringschemeprovidedforthedcpowersubsystemisbasedonthedegreeofcontrolprovidedtothecontrolroomoperator.Sincethedcpowersystemequipmentcannotberemotelycontrolled,asingledcsystemtroubleannunciatorwindowforeachsubsystemisprovidedinthecontrolroom,consistentwiththesystemlevelalarmcriteriasetforthinSectionBofR.G.1.47.TheSSESdesignisbasedonthegeneralcriteriathat,iftheoperatorcanperformsomecorrectiveactioninthecontrolroominresponsetoaspecificinput,thatinformationisspecificallyprovided.Thedcpowersystemequipmentcannotbecontrolledfromthecontrolroom.Annunciatingspecificinputsfromthe125Vdcsysteminthecontrolroomdoesnotenhancethecontrolroomoperators'sabilitytodealwiththesituationanditwouldnotbeconsistentwithSSESalarmdesignphilosophy.However,iftheonlyresponserequiredistodispatchanoperatortoanarearemovedfromthecontrolroom,thentheonlyinformationrequiredinthecontrolroomisgeneralinformationwithonlythelevelofspecificityrequiredtodirectthatoperatortotheproperlocation.Thismethodisfasterandmorereliablesinceabnormalconditionsareautomaticallyalarmed.Furthermore,thisapproachisconsistentwiththehumanfactorsengineeringgoaltonotoverburdentheoperatorwithunnecessaryinformation.125Vdcsysteminstrumentation,locallyprovided,isinfullcompliancewiththerequirementof,IEEE308-1974andRegulatoryGuide1.47.TheDCsystemgeneraltroublealarmsandspecificlocalindicatorsinconjunctionwiththeroutineoperatorsurveillanceprovidepositiveassurancethattheClass1Edcpowersystemaremaintainedinasteadystatereadytoperformtherequiredsafetyfunction.

RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.125VDCSUBSYSTEMPAGE43.0FollowingisthejustificationforeachalarmandindicationlistedinGenericLetter91-06.3.1BatterDisconnectorCircuitBreaker0enAlarm:TheSusquehannaS.E.S.(SSES)125Vdcsubsystemutilizesfusesasthebatterydisconnect.Thisconditionisdetectedbythebatterymonitor.Thebatterymonitorutilizesavariablethresholdcircuittogetherwithtwocomparators(highandlow)todetectthelossofbatterycapabilityduetoanopencircuit(i.e.,anopenfuseordegradedcellcondition).Avariablethresholdcircuitacceptsthebatterychargervoltageanddevelopstwothresholdvoltagesforusewiththecomparators.Whenthemonitoredvoltagesgoaboveorbelowthethresholds,thebatterymonitoroutputrelaycontactsinitiatealocalbatterymonitoralarmwhichisreflashedtothecontrolroomasa125Vdcsystemtroublealarm.ThisisconsistentwiththegeneraldesignphilosophydiscussedinSection2.0.3.2BatterCharerDisconnectorCircuitBreaker0enBothInutACandOututDCAlarm3.2.1BatteryChargerACInputDisconnectorCircuitBreaker:SSESutilizesacircuitbreakerinthebatterychargerasadisconnectfortheacinputpowersupply.Anacpowerfailurealarmrelayisinstalledinternaltothebatterychargertodetectlossofacinputpower.Thisconditioncouldbecausedbyanopeninputcircuitbreakerorlossofthe480Vacpowersupplytothecharger.Theacpowerfailurealarmrelayinitiatesabatterychargertroublealarmatthelocalreflasherpanel,whichisreflashedtothecontrolroomasa125Vdcsystemtroublealarm.ThisisconsistentwiththegeneraldesignphilosophydiscussedinSection2.0.

RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.125VDCSUBSYSTENPAGE53.2.2BatteryChargerDCOutputCircuitBreakerSSESutilizesacircuitbreakerinthebatterychargerasadisconnectforthedcoutputcircuit.Thecircuitbreakerisprovidedwithanauxiliarypositionindicatingswitch.Aswitchcontactwhichisclosedwhenthecircuitbreakerisopenisusedtoinitiateabatterychargertroublealarmatthelocalreflasherpanel.Adcsystemtroublealarmisreflashedtothecontrolroombythelocalreflasherpanel.ThisisconsistentwiththegeneraldesignphilosophydiscussedinSection2.0.3.3DCSstemGroundAlarmThe125Vdcsubsystemisungroundedandisprovidedwithagrounddetectioncircuit.Itconsistsofarelayhavingacentertappedcoil.Thecoilisconnectedacrossthepositiveandnegativebusanditscenterpointisgrounded.Thegrounddetectionrelaycoilisnotactuatedduringnormaloperationofthe125Vdcsubsystemwhenagroundisnotpresent.Agroundoneitherthepositiveornegativebusofthe125Vdcsubsystemcausesone-halfoftherelaycoiltobeshortcircuited,thusprovidingsufficientvoltagetotheremainingrelaycoilhalftopickuptherelay.Anormallyopencontactoftherelayclosesandinitiatesa125Vdcsystem.groundalarmatthelocalreflasherpanel.Adcsystemtroublealarmisreflashedtothecontrolroomannunciatorbythelocalreflasherpanel.ThisisconsistentwiththegeneraldesignphilosophydiscussedinSection2.0.3.4DCBusUndervoltaeAlarmThe125Vdcsubsystemisprovidedwithadcbusundervoltagerelay.Therelayisconnectedacrossthepositiveandnegativebusofthe125Vdcsubsystem.Therelayisnormallyenergizedandsettodropoutatthespecifiedsetpoint.A125Vdcbusundervoltagealarmatthelocalreflasherpanelisinitiatedaftertheundervoltagerelaydropsout.

RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.125VDCSUBSYSTENPAGE6Thelocalreflasherpanel,inturn,reflashesthealarmtothecontrolroomannunciatorasadcsystemtroublealarm.ThisisconsistentwiththegeneraldesignphilosophydiscussedinSection2.0.3.5DCBusOvervoltaeAlarmThe125Vdcsubsystemisprovidedwithanovervoltagerelay.Therelayislocatedinsidethebatterychargercabinet.Itisconnectedacrossthepositiveandnegative125Vdcbusofthebatterychargerandsettopickupatthespecifiedsetpoint.Anormallyopencontactoftheovervoltagerelay,whenclosed,initiatesabatterychargertroublealarmatthelocalreflasherpanelwhichinturnwillreflashadcsystemtroubletothecontrolroomannunciator.Sincethebattery,thebatterychargerandthedcloadcenterareincloseproximityofeachother,thebatterychargervoltageisrepresentativeofthe125Vdcbusvoltage.ThisisconsistentwiththegeneraldesignphilosophydiscussedinSection2.0.3.6BatterCharerFailureAlarmThe125Vdcsubsystembatterychargerisprovidedwithabatterychargerfailurerelay.Thisrelaywilldetectthelossofthechargeroutputcurrentwiththeinputandoutputcircuitbreakersclosed.Thisconditionisindicativeofabatterychargerfailureanditinitiatesabatterychargertroublealarmatthelocalreflasherpanelwhichinturnwillreflashadcsystemtroublealarm'tothecontrolroomannunciator.ThisisconsistentwiththegeneraldesignphilosophydiscussedinSection2.0.

RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.125VDCSUBSYSTEMPAGE73.7BatterDischareAlarmThebatterycanonlydischarge,whenitsterminalvoltageislessthanthenominalopencircuitvoltage.Thisisindicativeofabatterychargerfailureorsystemcurrentinexcessofthechargercapability.AbatterychargerfailurealarmisprovidedanditsoperationisdiscussedinSection3.6.'Whensystemcurrentexceedsbatterychargercapability,adcsystemundervoltageconditionwilloccur,andwillbedetectedbythedcbusundervoltagerelay.(SeeSection3.4.)Chargerfailureandbusundervoltageinitiatealarmsatthelocalreflasherpanelwhichinturnwillreflashadcsystemtroublealarmtothecontrolroomannunciator.ThisisconsistentwiththegeneraldesignphilosophyasdiscussedinSection2.0.3.8BatterFloatChareCurrentIndicationUndernormalconditions,thebatteryfloatchargecurrentisverysmallcomparedtobatterydischargecurrent.measurementofthiscurrentrequiresaverysensitiveammeter.Shuntbypassesareemployedtoprotecttheammetermovementfromthemuchlargerbatterydischargecurrentpossibleinthiscircuit.Theseshuntsmustbemanuallyremovedwhenreadingnormalsmallfloatchargecurrent.Thusthisreadingcannotbecontinuousandnoautomaticindicationoralarmscanbegiven.Sincetheintentofindicating"BatteryFloatChargeCurrent"istodeterminethebatterycondition,themethodusedtoaccomplishthispurposeshouldnotbeimportant.Thebusundervoltage,busground,batterymonitorandbatterychargerfailurealarms(previouslydescribed)providecontinuousmonitoringtodetectdegradationofbatterycapability.Thesealarmswillreflashthedcsystemtroublealarminthecontrolroom,andanoperatorisdispatchedlocallytodeterminethecauseoftheconditionandinitiatecorrectiveaction.

RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.125VDCSUBSYSTEMPAGE8Specificindicationisprovidedonthelocalreflasherpanel.Thisresponseisexactlywhatwouldbeachievedifanimproperstateofbatterycurrentwereindicatedonanammeterinthecontrolroom.ThisisconsistentwiththegeneraldesignphilosophydiscussedinSection2.0.3.9BatterCircuitOututCurrentIndication.Innormalconditionwhenthebatterychargerissupplyingthe125Vdcpower,thebatterycircuit(batteryandthebatterycharger)outputcurrentisindicatedbyanammeterlocatedatthebatterycharger.Intheconditionofabatterychargerfailure,thebatterysuppliesthedcpower.Inthisconditionthebatterycircuitoutputcurrentisindicatedbyanammeterlocatedatthedcloadcenter.AsindicatedinSection3.8,theintentofindicating"batterycurrent"istodeterminethebatterycondition,andthereforethemethodusedtoaccomplishthispurposeshouldnotbeimportant.3.10BatterDischareIndicationAspreviouslydiscussedinSection3.7,abatterydischargewilloccurasaresultofabatterychargerfailureorsystemcurrentinexcesstobatterychargercapability.Sincetheseconditionsareautomaticallyalarmedinthecontrolroom(viathesystemtroublealarm),anoperatorwillbedispatchedlocallytodeterminethecauseoftheconditionandinitiatecorrectiveaction.Thisresponseisexactlywhatwouldbeachievedifbatterydischargecurrentwasindicatedonanammeterinthecontrolroom.

RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.125VDCSUBSYSTEMPAGE93.11BusVoltaeIndicationThebattery,thebatterychargerandthedcloadcenterof125Vdcsubsystemarelocatedincloseproximityofeachother.Thebatterychargerandthedcloadcenterareeachprovidedwithavoltmeter.Thepurposeofabusvoltmeteratthecontrolroomwouldbetoenabletheoperatortodispatchsomeonetotakecorrectiveactionlocallytocorrectabnormalbusvoltage.AtSSESthebusundervoltageismonitoreddirectlyandthebusovervoltageconditionsaremonitoredatthebatterychargeroutput.Thebusundervoltageandthebatterychargeroutputovervoltageconditionsareannunciatedas125Vdcsystemlowvoltageorbatterychargertroubleatthelocalreflasherpanel.Adcsystemtroublealarmisreflashedtothecontrolroomannunciatorbythelocalreflasherpanel.Thisdesignautomaticallyalertsthecontrolroomoperatortounusualvoltageconditionswithoutunnecessarilyrequiringhisperiodicattentionandanalysis.Asaresult,125Vdcbusvoltageindicationisnotprovidedinthecontrolroomandhasbeenprovidedonthefrontoftheloadcenterwhereitprovidesusefulinformationduringsurveillanceandmaintenanceactivities.Avoltmeterislocatedonthefrontofthebatterychargerpanel.Withthechargeroutputcircuitbreakerclosed,thechargeroutputandthebusvoltagesareessentiallythesameduetothecloseproximityofthechargertotheloadcenter.Allabnormalvoltageconditionsofthebatterychargerareannunciatedatthelocalreflasherpanelwhichisreflashedtothecontrolroomasadcsystemtroublealarm.ThisisconsistentwiththegeneraldesignphilosophydiscussedinSection2.0.3.12,AlarmResonseProcedureControlroomalarmresponseproceduresfora125Vdcsystemtroublealarmdirecttheoperatortorespondtothelocalreflasherpaneltodeterminetheconditionwhichcausedthealarm.

RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.125VDCSUBSYSTEHPAGE10Localalarmresponseproceduresforthereflasherpanelareprovidedtodirecttheoperatortodeterminethecauseoftheconditionandtoinitiatecorrectiveaction.3.13IndicationofBassedandInoerableStatusofCircuitBreakersorOtherOisconnectinDevicesAlthoughindicationofbypassedandinoperablestatusofcircuitbreakersorotherdisconnectingdevicesisnotprovidedasapartoftheBypassIndicationSystem,the125VdcSystemTroubleAlarminthecontrolroomisinitiatedforthefollowingcondition(whicharedisconnectingdevicesinthesystem):Hainbatteryfuseopen.Batterychargeracinputcircuitbreakeropen.Batterychargerdcoutputcircuitbreakeropenor125Vdcloadcenterinputbreakeropen.125Vdcloadcenterfeederbreakerto125Vdcdistributionpanelsopen.r(Theundervoltagerelayatthedistributionpanelsinitiatesthedistributionpanellowvoltagealarmatthelocalreflasherpanelwhichisreflashedtothecontrolroom125Vdcsystemtroublealarm.)

RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.125VDCSUBSYSTENPAGE11TABLE1125VDCSstemReflashPanelAlarms1L6101.125VDCSystemLowVoltage2.125VDCSystemGround3.BatteryMonitor(indicatesbatterydegradationoropenbatteryfuses)4.BatteryChargerTroubleindicates(1)ACpowerfailure,(2)DCoutputbreakeropen,(3)batterychargerfailure,or(4)busovervoltage5.125VDCDistributionPanel1D614LowVoltage6.125VDCDistributionPanel1D615LowVoltageC:XWP51XDDCSX125VDCSS.PGD(18)10/24/919:00am CHANNELA125VDCLOCALREHASHPANELWITHINDICATION1L610MULTIPLEAIARMINPUTSFROM125VDCCHANNELAPOWERSYSTEMPERTABK1DCSYSTEMALARMINPUTSFROMOTHERREFLASHPANELS(SIMILARTOABOVE)CONTROLROOMPANEL1C651ANNUNCIATOR125VDCSYSTEMTROUBLE1L610FIGURE1 INDICATORUGHTREFLASHERPANELPOWERFAILURENAMEPlATE125VDCSYSTEMLOWVOLTAGEBATTERYCHARGERSPARE125VDCSYSTEMGROUND125VDCDISTPANEL10614LOWVOLTAGESPAREBATTERYMONITOR125VDCPANEL1D615LOWVOLTAGESPARE125VDCSYSTEMLOCALREFlASHERPANELOYPfCADFIGURE2 59BATTERYCHARGERAMMETERVOLTMETERBATTERYBANKFUSEBATTERYMONITORAMMETERQVOLTMETER27SYSTEMGROUNDINDICATORSDCLOADCENTERLOADSLOADSSEETABLE1FORALARMS125VDCSYSTEMQYPICADFIGURE3 SUSUEHANNAS.E.S.250DCSYSTEMATTACHMENTIIIPage1ENCLOSURE1ThefollowinginformationisapplicabletoeitherUnit1orUnit2atSusquehannaSES.1.UnitSusuehannaS.E.S.Unit-1or2250VDC2.,ThenumberofindependentredundantdivisionsofClass1Eorsafety-relateddcpowerforthisplantis~2two.(IncludeanyseparateClasslEorsafety-relateddc,suchasanydcdedicatedto,thedieselgenerators.)b.Thenumberoffunctionalsafety-relateddivisionsofdcpowernecessarytoattainsafeshutdownforthisunitis~1one3.Doesthecontrolroomatthisunithavethefollowingseparate,independentlyannunciatedalarmsandindicationsforeachdivisionofdcpower?a.Alarms1.Batterydisconnectorcircuitbreakeropen?No2.Batterychargerdisconnectorcircuitbreakeropen(bothinputacandoutputdc)?No3.dcsystemground?No4.dcbusundervoltage?No5.dcbusovervoltage?No6.Batterychargerfailure?No SUSUEHANNAS.E.S.250DCSYSTENATTACHNENTIII7.Batterydischarge?NoPage2b.Indications1.Batteryfloatchargecurrent?No2.Batterycircuitoutputcurrent?No3.Batterydischarge?No4.Busvoltage?Noc.Doestheunithavewrittenproceduresforresponsetotheabovealarmsandindications?NoDoesthisunithaveindicationofbypassedandinoperablestatusofcircuitbreakersorotherdevicesthatcanbeusedtodisconnectthebatteryandbatterychargerfromitsdcbusandthebatterychargerfromitsacpowersourceduringmaintenanceortesting?NoSeeremark¹15.Iftheanswertoanypartofquestion3or4isno,thenprovideinformationjustifyingtheexistingdesignfeaturesofthefacility'ssafety-relateddcsystems.*Seenotebelow.SeeRemark¹16.(1)Haveyouconductedareviewofmaintenanceandtestingactivitiestominimizethepotentialforhumanerrorcausingmorethanonedcdivisiontobeunavai1ablet~esand(2)doplantproceduresprohibitmaintenanceortestingonredundantdcdivisionsatthesametime?~es(Seeresponsefromthesite)IfthefacilityTechnicalSpecificationshaveprovisionsequivalenttothosefoundintheWestinghouseandCombustionEngineeringStandardTechnicalSpecificationsformaintenanceandsurveillance,thenquestion7maybeskippedandastatementtothateffectmaybeinsertedhere.

SUSUEHANNAS.E.S.250OCSYSTENATTACHMENTIIIPage37.Aremaintenance,surveillanceandtestproceduresregardingstationbatteriesconductedroutinelyatthisplant?Specifically:a.Atleastonceper7daysarethefollowingverifiedtobewithinacceptablelimits:1.Pilotcellelectrolytelevel?Yes2.Specifygravityorchargingcurrent?Yes3.Floatvoltage?Yes4.Totalbusvoltageonfloatcharge?Yes5.Physicalconditionofallcells?Yesb.Atleastonceper92days,orwithin7daysafterabatterydischarge;overcharge,orifthepilotcellreadings,areoutsidethe7-daysurveillancerequirementsarethefollowingverifiedtobewithinacceptablelimits:l.Electrolytelevelofeachcell?Yes2.Theaveragespecificgravityofallcells?Yes3.Thespecificgravityofeachcell?Yes4.Theaverageelectrolytetemperatureofarepresentativenumberofcells?Yes5.Thefloatvoltageofeachcell?Yes6.Visuallyinspectormeasureresistanceofterminalsandconnectors(includingtheconnectorsatthedcbus)?Yes SUSUEHANNAS.E.S.250DCSYSTEMATTACHMENTIIIc.Atleastevery18monthsarethefollowingverified:Page41.Lowresistanceofeachconnection(bytest)?Yes2.Physicalconditionofthebattery?Yes3.Batterychargercapabilitytodeliverratedampereoutputtothedcbus?Yes4.Thecapabilityofthebatterytodeliveritsdesigndutycycletothedcbus?Yes5.Eachindividualcellvoltageiswithinacceptablelimitsduringtheservicetest?Yesd.Atleastevery60months,iscapacityofeachbatteryverifiedbyperformanceofadischargetest?Yese.Atleastannually,isthebatterycapacityverifiedbyperformancedischargetest,ifthebatteryshowssignsofdegradationorhasreached85Koftheexpectedservicelife?Yes8.Doesthisplanthaveoperationalfeaturessuchthatfollowinglossofonesafety-relateddcpowersupplyorbus:a.Capabilityismaintainedforensuringcontinuedandadequatereactorcooling?Yesb.Reactorcoolantsystemintegrityandisolationcapabilityaremaintained?Yesc.Operatingprocedures,instrumentation(includingindicatorsandannunciators),andcontrolfunctionsareadequatetoinitiatesystemsasrequiredtomaintainadequatecorecooling?Yes9.Iftheanswertoanypartofquestion6,7or8isno,thenprovideyourbasisfornotperformingthemaintenance,surveillanceandtest SUSUEHANNAS.E.S.250DCSYSTEMATTACHNENTIIIPage5proceduresdescribedand/orthebasesfornotincludingtheoperationalfeaturescited.*Seenotebelow.*Note:Forquestionsinvolvingsupportingtypeinformation(questionnumbers5and9)insteadofdevelopingandsupplyingtheinformationinresponsetothisletter,youmaycommittofurtherevaluatetheneedforsuchprovisionsduringtheperformanceofyourindividualplantexaminationforsevereaccidentvulnerabilities(IPE).Ifyouselectthisoption,youarerequiredto:(1)Sostateinresponsetothesequestions,and(2)Committoexplicitlyaddressquestions5and9inyourIPEsubmittalpertheguidelinesoutlinedinNUREG-1335(Section2.1.6,Subitem7),"IndividualPlantExamination:SubmittalGuidance."c:~sp51~docsQR106001.PGD(18)10/24/919:06am RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.250VDCSUBSYSTEMPAGE1REMARK1:1.0Thefollowingindicationsandalarmsforthe250VdcclasslEsubsystemareprovided.JustificationforthisdesignhasbeenpreviouslyprovidedinPLA-959totheNRCdated11/6/81,regardingControlRoommonitoringofClass1Edcpowersystems.AlarmorIndicationBusUndervoltageAlarmBusGroundAlarmBatteryMonitorAlarmBatteryChargerTroubleAlarmBusAmmeterBusVoltmeterBatteryChargerAmmeterBatteryChargerVoltmeterDCSystemTroubleAlarmLocalLocationControlRoomNotes1,21,21,2,41,2,5NOTES:1.SeeTable1andFigure2forspecificlocalalarmindication.2.Thesearelocallyindicatedandactuatedcsubsystemtroublealarm,seeTable1andFigurel.3.Metersareprovidedlocally.SeeFigure3.

RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.250VDCSUBSYSTEMPAGE24.Batterymonitorcomparesbatterycenterpointvoltagewithhighandlowthresholdreferencepointsofthehighandlowvoltagecomparators.Thedeg}adedcellconditions(suchasashortedcell)oranopencircuitcondition(suchasanopenfuse)aredetectedbythebatterymonitor.5.BatterychargertroublealarmindicationisprovidedforbatterychargerACpowerfailure,DCoutputbreakeropen,batterychargerfailurealarmoperation,andbusovervoltage.6.Oneannunciatorwindowforeach250Vdcsubsystemisprovided.2.0Themonitoringschemeprovidedforthedcpowersubsystemisbasedonthedegreeofcontrolprovidedtothecontrolroomoperator.Sincethedcpowersystemequipmentcannotberemotelycontrolled,asingledcsystemtroubleannunciatorwindowforeachsubsystemisprovidedinthecontrolroom,consistentwiththesystemlevelalarmcriteriasetforthinSectionBofR.G.1.47.TheSSESdesignisbasedonthegeneralcriteriathat,iftheoperatorcanperformsomecorrectiveactioninthecontrolroominresponsetoaspecificinput,thatinformationisspecificallyprovided.Thedcpowersystemequipmentcannotbecontrolledfromthecontrolroom.Annunciatingspecificinputsfromthe250Vdcsysteminthecontrolroomdoesnotenhancethecontrolroomoperators'sabilitytodealwiththesituationanditwouldnotbeconsistentwithSSESalarmdesignphilosophy.However,iftheonlyresponserequiredistodispatchanoperator,toanarearemovedfromthecontrolroom,thentheonlyinformationrequiredinthecontrolroomisgeneralinformationwithonlythelevelofspecificityrequiredtodirectthatoperatortotheproperlocation.Thismethodisfasterandmorereliablesinceabnormalconditionsareautomaticallyalarmed.Furthermore,thisapproachisconsistentwiththehumanfactorsengineeringgoaltonotoverburdentheoperatorwithunnecessaryinformation.250Vdcsysteminstrumentation,locallyprovided,isinfullcompliancewiththerequirementofIEEE308-1974andRegulatoryGuide1.47.

RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.250VDCSUBSYSTEMPAGE3TheDCsystemgeneraltroublealarmsandspecificlocalindicatorsinconjunctionwiththeroutineoperatorsurveillanceprovidepositiveassurancethattheClasslEdcpowersystemaremaintainedinasteadystatereadytoperformtherequiredsafetyfunction.3.0FollowingisthejustificationforeachalarmandindicationlistedinGenericLetter91-06.3.1BatterDisconnectorCircuitBreaker0enAlarm:TheSusquehannaS.E.S.(SSES)250Vdcsubsystemutilizesfusesasthebatterydisconnect.Thisconditionisdetectedbythebatterymonitor.Thebatterymonitorutilizesavariablethresholdcircuittogetherwithtwocomparators(highandlow)todetectthelossofbatterycapabilityduetoanopencircuit(i.e.,anopenfuseordegradedcellcondition).Avariablethresholdcircuitacceptsthebatterychargervoltageanddevelopstwothresholdvoltagesforusewiththecomparators.Whenthemonitoredvoltagesgoaboveorbelowthethresholds,thebatterymonitoroutputrelaycontactsinitiatealocalbatterymonitoralarmwhichisreflashedtothecontrolroomasa250Vdcsystemtroublealarm.ThisisconsistentwiththegeneraldesignphilosophydiscussedinSection2.0.3.2BatterCharerDisconnectorCircuitBreaker0enBothInutACandOututDCAlarm3.2.1BatteryChargerACInputDisconnectorCircuitBreaker:SSESutilizesacircuitbreakerinthebatterychargerasadisconnectfortheacinputpowersupply.Anacpowerfailurealarmrelayisinstalledinternaltothebatterychargertodetectlossofacinputpower.Thisconditioncouldbecausedbyanopeninputcircuitbreakerorlossofthe480Vacpowersupplytothecharger.Theacpowerfailurealarmrelayinitiatesabatterychargertroublealarmatthelocalreflasherpanel,whichisreflashedto

RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.250VDCSUBSYSTEMPAGE4thecontrolroomasa250Vdcsystemtroublealarm.Thisisconsistentwiththegeneraldesignphilosophydiscussedinsection2.0.3.2.2BatteryChargerDCOutputCircuitBreakerSSESutilizesacircuitbreakerinthebatterychargerasadisconnectforthedcoutputcircuit.Thecircuitbreakerisprovidedwithanauxiliarypositionindicatingswitch.Aswitchcontactwhichisclosedwhenthecircuitbreakerisopenisusedtoinitiateabatterychargertroublealarmatthelocalreflasherpanel.Adcsystemtroublealarmisreflashedtothecontrolroombythelocalreflasherpanel.ThisisconsistentwiththegeneraldesignphilosophydiscussedinSection2.0.3.3DCSstemGroundAlarmThe250Vdcsubsystemisungroundedandisprovidedwithagrounddetectioncircuit.Itconsistsofarelayhavingacentertappedcoil.Thecoilisconnectedacrossthepositiveandnegativebusanditscenterpointisgrounded.Thegrounddetectionrelaycoilisnotactuatedduringnormaloperationofthe250Vdcsubsystemwhenagroundisnotpresent.Agroundoneitherthepositiveornegativebusofthe250Vdcsubsystemcausesone-halfoftherelaycoiltobeshortcircuited,thusprovidingsufficientvoltagetotheremainingrelaycoilhalftopickuptherelay.Anormallyopencontactoftherelayclosesandinitiatesa250Vdcsystemgroundalarmatthelocalreflasherpanel.Adcsystemtroublealarmisreflashedtothecontrolroomannunciatorbythelocalreflasherpanel.ThisisconsistentwiththegeneraldesignphilosophydiscussedinSection2.0.,3.4DCBusUndervoltaeAlarmThe250Vdcsubsystemisprovidedwithadcbusundervoltagerelay.Therelayisconnectedacrossthepositiveandnegative RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.250VDCSUBSYSTEMPAGE5busofthe250Vdcsubsystem.Therelayisnormallyenergizedandsettodropoutatthespecifiedsetpoint.A250Vdcbusundervoltagealarmatthelocalreflasherpanelisinitiatedaftertheundervoltagerelaydropsout.Thelocalreflasherpanel,inturn,reflashesthealarmtothecontrolroomannunciatorasadcsystemtroublealarm.ThisisconsistentwiththegeneraldesignphilosophydiscussedinSection2.0.3.5DCBusOvervoltaeAlarmThe250Vdcsubsystemisprovidedwithanovervoltagerelay.Therelayislocatedinsidethebatterychargercabinet.Itisconnectedacrossthepositiveandnegative250Vdcbusofthebatterychargerandsettopickupatthespecifiedsetpoint.Anormallyopencontactoftheovervoltagerelay,whenclosed,initiatesabatterychargertroublealarmatthelocalreflasherpanelwhichinturnwillreflashadcsystemtroubletothecontrolroomannunciator.Sincethebattery,'hebatterychargerand,thedcloadcenterareincloseproximityofeachother,thebatterychargervoltageisrepresentativeof250Vdcbusvoltage.ThisisconsistentwiththegeneraldesignphilosophydiscussedinSection2.0.3.6BatterCharerFailureAlarmThe250Vdcsubsystembatterychargerisprovidedwithabatterychargerfailurerelay.Thisrelaywilldetectthelossofthechargeroutputcurrentwiththeinputandoutputcircuitbreakersclosed.Thisconditionisindicativeofabatterychargerfailureanditinitiatesabatterychargertroublealarmatthelocalreflasherpanelwhichinturnwillreflashadcsystemtroublealarmtothecontrolroomannunciator.

RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.250VDCSUBSYSTEMPAGE6ThisisconsistentwiththegeneraldesignphilosophydiscussedinSection2.0.3.7BatterDischareAlarmThebatterycanonlydischargewhenitsterminalvoltageislessthanthenominalopen.circuitvoltage.Thisisindicativeofabatterychargerfailureorsystemcurrentinexcessofthe,chargercapability.AbatterychargerfailurealarmisprovidedanditsoperationisdiscussedinSection3.6.Whensystemcurrentexceedsbatterycharger'apability,adcsystemundervoltageconditionwilloccur,andwillbedetectedbythedcbusundervoltagerelay.(SeeSection3.4)Chargerfailureandbusundervoltageinitiatealarmsatthelocalreflasherpanelwhichinturnwillreflashadcsystemtroublealarmtothecontrolroomannunciator.ThisisconsistentwiththegeneraldesignphilosophyasdiscussedinSection2.0.3.8BatterFloatChareCurrentIndicationUndernormalconditions,thebatteryfloatchargecurrentisverysmallcomparedtobatterydischargecurrent.Measurementofthiscurrentrequiresaverysensitiveammeter.Shuntbypassesareemployedtoprotecttheammetermovementfromthemuchlargerbatterydischargecurrentpossibleinthiscircuit.Theseshuntsmustbemanuallyremovedwhenreadingnormalsmallfloatchargecurrent.Thusthisreadingcannotbecontinuousandnoautomaticindicationoralarmscanbegiven.Sincetheintentofindicating"BatteryFloatChargeCurrent"istodeterminethebatterycondition,themethodusedtoaccomplishthispurposeshouldnotbeimportant.Thebusundervoltage,busground,batterymonitorandbatterychargerfailurealarms(previouslydescribed)providecontinuousmonitoringtodetectdegradationofbatterycapability.Thesealarmswillreflashthedcsystemtroublealarminthecontrol RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.250VDCSUBSYSTEMPAGE7room,andanoperatorisdispatchedlocallytode'terminethecauseoftheconditionandinitiatecorrectiveaction.Specificindicationisprovidedonthelocalreflasherpanel.Thisresponseisexactlywhatwouldbeachievedifanimproperstateofbatterycurrentwereindicatedonanammeterinthecontrolroom.ThisisconsistentwiththegeneraldesignphilosophydiscussedinSection2.0.3.9BatterCircuitOututCurrentIndicationInnormalconditionwhenthebatterychargerissupplyingthe250Vdcpower,thebatterycircuit(batteryandthebatterycharger)outputcurrentisindicatedbyanammeterlocatedatthebatterycharger.Intheconditionofabatterychargerfailure,thebatterysuppliesthedcpower.Inthiscondition,thebatterycircuitoutputcurrentisindicatedbyanammeterlocatedatthedcloadcenter.AsindicatedinSection3.8,theintentofindicating"batterycurrent"istodeterminethebatterycondition,andthereforethemethodusedtoaccomplishthispurposeshouldnotbeimportant.3.10BatterOischareIndicationAspreviouslydiscussedinSection3.7,abatterydischargewilloccurasaresultofabatterychargerfailureorsystemcurrentinexcesstobatterychargercapability.Sincetheseconditionsareautomaticallyalarmedinthecontrolroom(viathesystemtroublealarm),anoperatorwillbedispatchedlocallytodeterminethecauseoftheconditionandinitiatecorrectiveaction.Thisresponseisexactlywhatwouldbeachievedifbatterydischargecurrentwasindicatedonanammeterinthe RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.250VDCSUBSYSTEMPAGE8controlroom.3.11BusVoltaeIndicationThebattery,thebatterychargerandthedcloadcenterof250Vdcsubsystemarelocatedincloseproximityofeachother.Thebatterychargerandthedcloadcenterareeachprovidedwithavoltmeter.Thepurposeofabusvoltmeteratthecontrolroomwouldbetoenabletheoperatortodispatchsomeonetotakecorrectiveactionlocallytocorrectabnormalbusvoltage.AtSSESthebusundervoltageismonitoreddirectlyand'thebusovervoltageconditionsaremonitoredatthebatterychargeroutput.Thebusundervoltageandthebatterychargeroutputovervoltage.conditionsareannunciatedas250Vdcsystemlowvoltageorbatterychargertroubleatthelocalreflasherpanel.Adcsystemtroublealarmisreflashedtothecontrolroomannunciatorbythelocalreflasherpanel.Thisdesignautomaticallyalertsthecontrolroomoperatortounusualvoltageconditionswithoutunnecessarilyrequiringhisperiodicattentionandanalysis.Asaresult,250Vdcbusvoltageindicationisnotprovidedinthecontrolroomandhasbeenprovidedonthefrontoftheloadcenterwhereitprovidesusefulinformationduringsurveillanceandmaintenanceactivities.Avoltmeterislocatedonthefrontofthebatterychargerpanel.Withthechargeroutputcircuitbreakerclosed,thechargeroutputandthebusvoltagesareessentiallythesameduetothecloseproximityofthechargertotheloadcenter.Allabnormalvoltageconditionsofthebatterychargerareannunciatedatthelocalreflasherpanelwhichisreflashedtothecontrolroomasadcsystemtroublealarm.ThisisconsistentwiththegeneraldesignphilosophydiscussedinSection2.0.

RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.250VDCSUBSYSTEMPAGE93.12AlarmResonseProcedureControlroomalarmresponseproceduresfora250Vdcsystemtroublealarmdirecttheoperatortorespondtothelocalreflasherpaneltodeterminetheconditionwhichcausedthealarm.Localalarmresponseproceduresforthereflasherpanelareprovidedtodirecttheoperatortodeterminethecauseoftheconditionandtoinitiatecorrectiveaction.3.13IndicationofBassedandInoerableStatusofCircuitBreakersorOtheDisconnectinDevicesAlthoughindicationofbypassedandinoperablestatusofcircuitbreaker'sorotherdisconnectingdevicesisnotprovidedasapartoftheBypassIndicationSystem,the250VdcSystemTroubleAlarminthecontrolroomisinitiatedforthefollowingcondition(whicharedisconnectingdevicesinthesystem):Mainbatteryfuseopen.Batterychargeracinputcircuitbreakeropen.Batterychargerdcoutputcircuitbreakeropen,or250Vdcloadcenterbreakeropen.250Vdcloadcenterfeederbreakerto250Vdcmotorcontrolcentersopen.(Eachoftheloadcenterfeederbreakerstothe250VdcMCC'sisprovidedwithanauxiliarypositionindicatingswitchwhichinitiatesanalarmonthelocalreflasherpanelwhenthecircuitbreakerisopen.A250Vdcsystemtroublealarmisreflashedtothecontrolroombythelocalreflasherpanel.)

RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.250VDCSUBSYSTEMPAGE10TABLE1250VDCSstemReflashPanelIndicatorsTicall.250VDCSystemLowVoltage2.250VDCSystemGround3.BatteryMonitor(indicatesbatterydegradationoropenbatteryfuses)4.BatteryChargerTroubleindicates(1)ACpowerfailure,(2)DCoutputbreakeropen,(3)batterychargerfailure,or(4)busovervoltage(DivisionIhas2chargers,DivisionIIhas1charger)5.LoadCenterIncomingBreakersTrip6.RCIC&IsolationValveControlCenter1D254trouble7.TurbineBldg.ControlCenter1D155trouble8.ComputerUPSSupplyBreakerTripC:XMP51%00CSX250VDCSS.PGD(18)10/24/919:08am CHANNELA250VDCLOCALRERASHPANELWITHINDICATION1L650MULTIPLEALARMINPUISFROM250VDCCHANNELAPOWERSYStEMPERTABLE1DCSYSTEMALARMINPUTSFROMOTHERREFLASHPANELS(SIMILARTOABOVE)CONTROLROOMPANEL1C651ANNUNCIATOR250VDCSYSTEMTROUBLE1L650FIGURE1 INDICATORUGHTREFLASHERPANELPOWERFAILURESYSTEMLOWVOLTAGEBATTERYCHAIWERATROUBLERCIC&ISOVLVSCONTROLCENTER1D254TROUBLE250VDCSYSTEMGROUNDBATTERYCHARGERBTROUBLETURBBU)GCONTROLCENTER1D155TROUBLEBATTERYMONITORLCINCOMINGBKR7245212/22TRIPCOMPUTERUPSSUPPLYBKRTRIP250VDCSYStEMLOCALREFLASHERPANELOYPICAOFIGURE2 59BATTERYCHARGERAMMETERVOLTMETERBATTERYBANKFUSEBATTERYMONITORAMMETERQVOLTMETER27SYSTEMGROUNDINDICATORSDCLOADCENTERLOADSLOADSSEETABLE1FORALARMS250VDCSYSTEMOYPICAQFIGURE3

SUSUEHANNAS.E.S.UNIT-1ANDUNIT2DG-E125VDCSYSTEMATTACHMENTIVPage1ENCLOSURE1ThefollowinginformationisapplicabletoeitherUnitatSusquehannaSES.UnitSusuehannaS.E.S.CommontoUnit1&2DG-E125VDCSYSTEM'a~ThenumberofindependentredundantdivisionsofClass1Eorsafety-relateddcpowerforthisplantisseeRemarkl.(IncludeanyseparateClass1Eorsafety-relateddc,suchasanydcdedicatedtothedieselgenerators.)b.Thenumberoffunctionalsafety-relateddivisionsofdcpowernecessarytoattainsafeshutdownforthisunitisseeRemark1.3.Doesthecontrolroomatthisunithavethefollowingseparate,independentlyannunciatedalarmsandindicationsforeachdivisionofdcpower?a.alarms1.Batterydisconnectorcircuitbreakeropen?No2.Batterychargerdisconnectorcircuitbreakeropen(bothinputacandoutputdc)?No3.dcsystemground?No4.dcbusundervoltage?No5.dcbusovervoltage?No6.Batterychargerfailure?No7.Batterydischarge?No 0

SUSUEHANNAS.E.S.UNIT-1ANDUNIT2DG-E125VDCSYSTEMb.IndicationsATTACHMENTIVPage21.Batteryfloatchargecurrent?No2.Batterycircuitoutputcurrent?No3.Batterydischarge?No4.Busvoltage?Noc.Doestheunithavewrittenproceduresforresponsetotheabovealarmsandindications?NoDoesthisunithaveindicationofbypassedandinoperablestatusofcircuitbreakersorotherdevicesthatcanbeusedtodisconnectthebatteryandbatterychargerfromitsdcbusandthebatterychargerfromitsacpowersourceduringmaintenanceortesting?NoSeeRemark25.Iftheanswertoanypartofquestion3or4isno,thenprovideinformationjustifyingtheexistingdesignfeaturesofthefacility'ssafety-relateddcsystems.*Seenotebelow.SeeRemark26.(I)Haveyouconductedareviewofmaintenanceandtestingactivitiestominimizethepotentialforhumanerrorcausingmorethanonedcdivisiontobeunavailablet~esand(2)doplantproceduresprohibitmaintenanceortestingonredundantdcdivisionsatthesamatime?~esIfthefacilityTechnicalSpecificationshaveprovisionsequivalenttothosefoundintheWestinghouseandCombustionEngineeringStandardTechnicalSpecificationsformaintenanceandsurveillance,thenquestion7maybeskippedandastatementtothateffectmaybeinsertedhere.

SUSUEHANNAS.E.S.UNIT-1ANDUNIT2DG-E125VDCSYSTEMATTACHMENTIVPage37.Aremaintenance,surveillanceandtestprocedures.regardingstationbatteriesconductedroutinelyatthisplant?'pecifically:a.Atleast,onceper7daysarethefollowingverifiedtobewithinacceptablelimits:1.Pilotcellelectrolytelevel?Yes2.Specifygravityorchargingcurrent?Yes3.Floatvoltage?Yes4.Totalbusvoltageonfloatcharge?Yes5.Physicalconditionofallcells?Yesb.Atleastonceper92days,orwithin7daysafterabatterydischarge,overcharge,orifthepilotcellreadingsareoutsidethe7-daysurveillancerequirementsarethefollowingverifiedtobewithinacceptablelimits:l.Electrolytelevelofeachcell?Yes2.Theaveragespecificgravityofallcells?Yes3.Thespecificgravityofeachcell?Yes4.Theaverageelectrolytetemperatureofarepresentativenumberofcells?Yes5.Thefloatvoltageofeachcell?Yes6.Visuallyinspectormeasureresistanceofterminalsandconnectors(includingtheconnectorsatthedcbus)?Yes SUSUEHANNAS.E.S.UNIT-1ANDUNIT2DG-'E125VDCSYSTEMc.Atleastevery18monthsarethefollowingverified:ATTACHMENTIVPage41.Lowresistanceofeachconnection(bytest)?Yes2.Physicalconditionofthebattery?Yes3.Batterychargercapabilitytodeliverratedampereoutputtothedcbus?YestThecapabilityofthebattery-todeliveritsdesigndutycycletothedcbus?Yes5.Eachindividualcellvoltageiswithinacceptablelimitsduringtheservicetest?Yesd.Atleastevery60months,iscapacityofeachbatteryverifiedbyperformanceofadischargetest?Yese.Atleastannually,isthebatterycapacityverifiedbyperformancedischargetest,ifthebatteryshowssignsofdegradationorhasreached85Xoftheexpectedservicelife?Yes8.Doesthisplanthaveoperationalfeaturessuchthatfollowinglossofonesafety-relateddcpowersupplyorbus:a.Capabilityismaintainedforensuringcontinuedandadequatereactorcooling?Yesb.Reactorcoolantsystemintegrityandisolationcapabilityaremaintained?Yesfc.Operatingprocedures,instrumentation(includingindicatorsandannunciators),andcontrolfunctionsareadequatetoinitiatesystemsasrequiredtomaintainadequatecore,cooling?Yes SUSUEHANNAS.E.S.UNIT-1ANDUNIT2DG-E125VDCSYSTEMATTACHMENTIVPage59Iftheanswertoanypartofquestion6,7or8isno,thenprovideyourbasisfornotperformingthemaintenance,surveillanceandtestproceduresdescribedand/orthebasesfornotincludingtheoperationalfeaturescited.*Seenotebelow.*Note:Forquestionsinvolvingsupportingtypeinformation(questionnumbers5and9)insteadofdevelopingandsupplyingtheinformationinresponsetothisletter,youmaycommittofurtherevaluatetheneedforsuchprovisionsduringtheperformanceofyourindividualplantexaminationforsevereaccidentvulnerabilities(IPE).Ifyouselectthisoption,youarerequiredto:(1)Sostateinresponsetothesequestions,and(2)Committoexplicitlyaddressquestions5and9inyourIPEsubmittalpertheguidelinesoutlinedinNUREG-1335(Section2.1.6,Subitem7),"IndividualPlantExamination:SubmittalGuidance."c:Xup51hdocshdg-e125v.pgd(18)10/24/918:48am RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.UNIT1ANDUNIT2DG-E125VDCSUBSYSTEMPAGE1REMARK1:DieselGeneratorEisaninstalledsparedieselgeneratorcapableofsubstitutingasanemergencypowersourceforanyoneoftheexistingemergencydieselgenerators(A,B,C,D).TheDieselGeneratorE125VdcpowersubsystemisidentifiedasChannelHandisdedicatedtoprovidingdcpowertoESWvalvesforDieselGeneratorEcooling,DieselGeneratorEcontrols,andDieselGeneratorE4.16kVSwitchgear.ThisequipmentisalllocatedinaseparateDieselGeneratorEbuilding.TheDieselGeneratorE125VdcSubsystemisrequiredonlywhenthisdieselgeneratorissubstitutingforoneoftheexistingdieselgenerators.Itisinadditionto,independentandisolatedfromtheotherfourClasslE125VdcSubsystems.Lossofanyoneofthe125VdcSubsystemsdoesnotpreventtheminimumsafetyfunctionfrombeingperformed.REMARK2:1.0ThefollowingindicationsandalarmsfortheDG-E125VdcclasslEsubsystemareprovided.JustificationforthisdesignisconsistentwiththedesignphilosophyregardingControlRoommonitoringofClass1EdcpowersystemsaspreviouslyprovidedinPLA-959totheNRCdated11/6/81.

RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.UNIT1ANDUNIT2DG-E125VDCSUBSYSTEMPAGE2AlarmorIndicationLocalLocationControlRoomNotesBusUndervoltageAlarmBusGroundAlarmBatteryMonitorAlarmBatteryChargerTroubleAlarmBusAmmeter1,21,21,2,41,2,5BusVoltmeterBatteryChargerAmmeterBatteryChargerVoltmeterDCSystemTroubleAlarmNOTES:1.SeeTable1forspecificlocalalarmannunciation.2.ThesealarmsarelocallyprovidedonDG-Eannunciator/reflasherpanelOC577E.Adcsubsystemtroublealarm.isreflashedtothecontrolroombythisannunciator.SeeTable1,Figure1.3.Hetersareprovidedlocally.SeeFigure2.4.Batterymonitorcomparesbatterycenterpointvoltagewithhighandlowthresholdreferencepoints,,ofthehighandlowvoltagecomparators.Thedegradedcellconditions(such"asashortedcell)oranopencircuitcondition(suchasanopenfuse)aredetectedbythebatterymonitor.

RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.UNIT1ANDUNIT2DG-E125VDCSUBSYSTEMPAGE35.BatterychargertroublealarmindicationisprovidedforbatterychargerACpowerfailure,DCoutputbreakeropen,batterychargerfailurealarmoperation,batterychargerhigh/lowvoltageandbatterychargerhighvoltage(shutdown).6.OneannunciatorwindowfortheDG-E125Vdcsubsystemisprovided.2.0Themonitoringschemeprovidedforthedcpowersubsystemisbasedonthedegreeofcontrolprovidedtothecontrolroomoperator.Sincethedcpowersystemequipmentcannotberemotelycontrolled,asingledcsystemtroubleannunciatorwindowforeachsubsystemisprovidedinthecontrolroom,consistentwiththesystemlevelalarmcriteriasetforthinSectionBofR.G.1.47.TheSSESdesignisbasedonthegeneralcriteriathat,iftheoperatorcanperformsomecorrectiveactioninthecontrolroominresponsetoaspecificinput,thatinformationisspecificallyprovided.Thedcpowersystemequipmentcannotbecontrolledfromthecontrolroom.Annunciatingspecificinputsfromthe125Vdcsysteminthecontrolroomdoesnotenhancethecontrolroomoperators'sabilitytodealwiththesituationanditwouldnotbeconsistentwithSSESalarmdesignphilosophy.However,.iftheonlyresponserequiredistodispatchanoperatortoanarearemovedfromthecontrolroom,thentheonlyinformationrequiredinthecontrolroomisgeneralinformationwithonlythelevelofspecificityre'quiredtodirectthatoperatortotheproperlocation.Thismethodisfasterandmorereliablesinceabnormalconditionsareautomaticallyalarmed.Furthermore,thisapproachisconsistentwiththehumanfactorsengineeringgoaltonotoverburdentheoperatorwithunnecessaryinformation.125Vdcsysteminstrumentation,locallyprovided,isinfullcompliancewiththerequirementofIEEE308-1974andRegulatoryGuide1.47.eTheDCsystemgeneraltroublealarmsandspecificlocalindicatorsinconjunctionwiththeroutineoperatorsurveillanceprovidepositiveassurancethattheClass1Edcpowersystemaremaintainedinasteadystatereadytoperformtherequiredsafetyfunction.

RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.UNIT1ANDUNIT2DG-E125VDCSUBSYSTEMPAGE43.0FollowingisthejustificationforeachalarmandindicationlistedinGenericLetter91-06.3.1BatterDisconnectorCircuitBreaker0enAlarm:TheSusquehannaS.E.S.(SSES)DG-E125Vdcsubsystemutilizesafuseddisconnectasthebatterydisconnect.Thisconditionisdetectedbythebatterymonitor.Thebatterymonitorutilizesavariablethresholdcircuittogetherwithtwocomparators(highandlow)todetectthelossofbatterycapabilityduetoanopencircuit(i.e.,anopenfuseor,degradedcellcondition).Avariablethresholdcircuitacceptsthebattery'chargervoltageanddevelopstwothresholdvoltagesforusewiththecomparators.Whenthemonitoredvoltagesgoaboveorbelowthethresholds,thebatterymonitoroutputrelaycontactsinitiatealocalbatterymonitorannunciatorwhichisreflashedtothecontrolroomasaDG-E125Vdcsystemtroublealarm.ThisisconsistentwiththegeneraldesignphilosophydiscussedinSection2.0.3.2BatterCharerDisconnectorCircuitBreaker0enBothInutACandOututDCAlarm3.2.1BatteryChargerACInputDisconnectorCircuitBreaker:SSESutilizesacircuitbreakerinthebatterychargerasadisconnectfortheacinputpowersupply.Anacpowerfailurealarmrelayisinstalledinternaltothebatterychargertodetectlossofacinputpower.Thisconditioncouldbecausedbyanopeninputcircuitbreakerorlossofthe480Vacpowersupplytothecharger.Theacpowerfailurealarmrelayinitiatesabatterychargertroublealarmatthelocalannunciatorpanel,whichisreflashedtothecontrolroomasaDG-E125Vdcsystemtroublealarm.Thisisconsistentwiththegeneraldesignphilosophydiscussedinsection2.0.

RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.UNIT1ANDUNIT2DG-E125VDCSUBSYSTEMPAGE53.2.2BatteryChargerDCOutputCircuitBreakerSSESutilizesacircuitbreakerinthebatterychargerasadisconnectforthedcoutputcircuit.Thecircuitbreakerisprovidedwithanauxiliarypositionindicatingswitch.Aswitchcontactwhichisclosedwhenthecircuitbreakerisopenisusedtoinitiateabatterychargertroublealarmatthelocalannunciatorpanel.ADG-Edcsystemtroublealarmisreflashedtothecontrolroombythelocalannunciator'anel.Thisisconsistentwiththe,generaldesignphilosophydiscussedinSection2.0.3.3DCSstemGroundAlarm'heDG-E125Vdcsubsystemisungroundedandisprovidedwithagrounddetectioncircuit.Itconsistsofarelayhavingacentertappedcoil.Thecoilisconnectedacrossthepositiveandnegativebusanditscenterpointisgrounded.Thegrounddetectionrelaycoilisnotactuatedduringnormaloperationofthe125Vdcsubsystemwhenagroundisnotpresent.Agroundoneitherthepositiveornegativebusofthe125Vdcsubsystemcausesone-halfoftherelaycoiltobeshortcircuited,thusprovidingsufficientvoltagetotheremainingrelaycoilhalftopickuptherelay.Anormallyopencontactoftherelayclosesandinitiatesa125Vdcsystemgroundalarmatthelocalannunciatorpanel.ADG-Edcsystemtroublealarmisreflashedtothecontrolroomannunciatorbythelocalannunciatorpanel.ThisisconsistentwiththegeneraldesignphilosophydiscussedinSection2.0.3.4DCBusUndervoltaeAlarmTheDG-E125Vdcsubsystemisprovidedwithabatterychargerundervoltagerelay.Therelayisconnectedacrossthepositiveandnegativebusofthe125Vdcbatterycharger.Therelayisnormallyenergizedandsettodropoutatthespecifiedsetpoint.Abatterychargertroublealarmatthelocalannunciatorpanelis

RESPONSETOGENERICLETTER91-06SUSUEMANNAS.E.S.UNIT1ANDUNIT2DG-E125VDCSUBSYSTEPAGE6initiatedaftertheundervoltagerelaydropsout.Thelocalannunciatorpanel,inturn,reflashesthealarmtothecontrolroomannunciatorasaDG-Edcsystemtroublealarm.ThisisconsistentwiththegeneraldesignphilosophydiscussedinSection2.0.Inadditiontothebatterychargerundervoltagerelay,abusundervoltagerelayisprovidedtodetectalossofbusvoltage.ThemostprobablecauseofaDCsystemundervoltageconditionisaresultofabatterychargerproblem,whichwillbedetectedbythebatterycharger,failurealarmrelay(seeSection3.6).Thechargerfailurerelayinitiatesabatterychargertroublealarmatthelocalannunciatorpanel,whichinturn,reflashesaDG-Edcsystemtroublealarmtothecontrolroomannunciator.ThisisconsistentwiththegeneraldesignphilosophydiscussedinSection2.0.3.5DCBusOvervoltaeAlarmTheDG-E125Vdcsubsystemisprovidedwithanovervoltagerelay.Therelayislocatedinsidethebatterychargercabinet.Itisconnectedacrossthepositiveandnegative125Vdcbusofthebatterychargerandsettopickupatthespecifiedsetpoint.Anormallyopencontactoftheovervoltagerelay,whenclosed,initiatesabatterychargertroublealarmatthelocalannunciatorpanelwhichinturnwillreflashaDG-Edcsystemtroublealarmtothecontrolroomannunciator.Sincethebattery,thebatterychargerandthedcloadcenterareincloseproximityofeachother,thebatterychargervoltageisrepresentativeoftheDG-E125Vdcbusvoltage.ThisisconsistentwiththegeneraldesignphilosophydiscussedinSection2.0.

RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.UNITIANDUNIT2DG-E125VDCSUBSYSTEMPAGE73.6BatterCharerFailureAlarmTheDG-E125Vdcsubsystembatterychargerisprovidedwithabatterychargerfailurerelay.Thisrelaywilldetectthelossofthechargeroutputcurrentwiththeinputandoutputcircuitbreakersclosed.ThisconditionisindicativeofabatterychargerfailureanditinitiatesabatterychargertroublealarmatthelocalannunciatorpanelwhichinturnwillreflashaDG-Edcsystemtroublealarmtothecontrolroomannunciator.ThisisconsistentwiththegeneraldesignphilosophydiscussedinSection2.0.3.7BatterDischareAlarmThebatterycanonlydischargewhenitsterminalvoltageislessthanthenominalopencircuitvoltage.Thisisindicativeofabatterychargerfailureorsystemcurrentinexcessofthechargercapability.Abatterycharger,failurealarmisprovidedanditsoperationisdiscussedinSection3.6.Whensystemcurrentexceedsbatterychargercapability,adcsystemundervoltageconditionwilloccur,andwillbedetectedbythebatterychargerundervoltagerelay(seeSection3.4).ChargerfailureandbatterychargerundervoltageinitiatealarmsatthelocalannunciatorpanelwhichinturnwillreflashaDG-Edcsystemtroublealarmtothecontrolroomannunciator.ThisisconsistentwiththegeneraldesignphilosophyasdiscussedinSection2.0.3.8BatterFloatChareCurrentIndicationUndernormalconditions,thebatteryfloatchargecurrentisverysmallcomparedtobatterydischargecurrent.Measurementofthiscurrentrequiresaverysensitiveammeter.Shuntbypassesareemployedtoprotecttheammetermovementfromthemuchlargerbatterydischargecurrentpossibleinthiscircuit.'heseshu'ntsmustbemanuallyremovedwhenreadingnormalsmallfloatchargecurrent.Thusthisreadingcannotbecontinuousandnoautomatic RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.UNIT1ANDUNIT2DG-E125VDCSUBSYSTEMPAGE8indicationoralarmscanbegiven.Sincetheintentofindicating"BatteryFloatChargeCurrent"istodeterminethebatterycondition,themethodusedtoaccomplishthispurposeshouldnotbeimportant.Thebatterychargerundervoltage,busground,batterym'onitorandbatterychargerfailurealarms(previouslydescribed)providecontinuousmonitoringtodetectdegradationofbatterycapability.ThesealarmswillreflashtheDG-Edcsystemtroublealarminthecontrolroom,andanoperatorisdispatchedlocallytodeterminethecauseoftheconditionandinitiatecorrectiveaction.Specificindicationisprovidedonthelocalannunciatorpanel.Thisresponseisexactlywhatwouldbeachievedifanimproperstateofbatterycurrentwereindicatedonanammeterinthecontrolroom.ThisisconsistentwiththegeneraldesignphilosophydiscussedinSection2.0.3.9BatterCircuitOututCurrentIndicationInnormalconditionwhenthebatterychargerissupplyingthe125Vdcpower,thebatterycircuit(batteryandthebatterycharger)outputcurrentisindicatedbyanammeterlocatedatthebatterycharger.Intheconditionofabatterychargerfailure,thebatterysuppliesthedcpower.Inthisconditionthebatterycircuitoutputcurrentisindicatedbyanammeterlocatedatthedcswitchboard.AsindicatedinSection3.8,theintentofindicating"batterycurrent"istodeterminethebatterycondition,andthereforethemethodusedtoaccomplishthispurposeshouldnotbeimportant.

RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.UNIT1ANDUNIT2DG-E125VDCSUBSYSTEMPAGE93.10BatterDischareIndicationAspreviouslydiscussedinSection3.7,abatterydischargewilloccurasaresultofabatterychargerfailureorsystemcurrentinexcesstobatterychargercapability.Sincetheseconditionsareautomaticallyalarmedinthecontrolroom(viathesystemtroublealarm),anoperator'willbedispatchedlocallytodeterminethecauseoftheconditionandinitiatecorrectiveaction.Thisresponseisexactlywhatwouldbeachievedifbatterydischargecurrentwasindicatedonanammeterinthecontrolroom.3.11BusVoltaeIndicationThebattery,thebatterychargerandthedcswitchboardoftheDG-E125Vdcsubsystemarelocatedincloseproximityofeachother.Thebatterychargerandthedcswitchboardareeachprovidedwithavoltmeter.Thepurposeofabusvoltmeteratthecontrolroomwouldbetoenabletheoperatortodispatchsomeonetotakecorrectiveactionlocallytocorrectabnormalbusvoltage.Thisconditionwilloccurwhenabatterychargerproblemispresent.Undervoltageandovervoltageconditionsaremonitoredatthebatterycharger,andareannunciatedasbatterychargertroubleatthelocalannunciatorpanel.ADG-Edcsystemtroublealarmisreflashedtothecontrolroomannunciatorbythelocalannunciatorpanel.Thisdesignautomaticallyalertsthecontrolroomoperatortounusualvoltageconditionswithoutunnecessarilyrequiringhisperiodicattentionandanalysis.Asaresult,125Vdcbusvoltageindicationisnotprovidedinthecontrolroomandhasbeenprovidedonthefrontofthedcswitchboardwhereitprovidesusefulinformationduringsurveillanceandmaintenanceactivities.Avoltmeterislocatedonthefrontofthebatterychargerpanel.Withthechargeroutputcircuitbreakerclosed,thechargeroutputandthebusvoltagesareessentiallythesameduetotheclose RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.UNIT1ANDUNIT2DG-E125VDCSUBSYSTEMPAGE10proximityofthechargertotheloadcenter.AllabnormalvoltageconditionsofthebatterychargerareannunciatedatthelocalannunciatorpanelwhichisreflashedtothecontrolroomasaDG-Edcsystemtroublealarm.ThisisconsistentwiththegeneraldesignphilosophydiscussedinSection2.0.3.12AlarmResonseProcedureControlroomalarmresponseproceduresforaDG-E125Vdcsystemtroublealarmdirecttheoperatortorespondtothelocalannunciatorpaneltodeterminetheconditionwhichcausedthealarm.Localalarmresponseproceduresfortheannunciatorpanelareprovidedtodirecttheoperatortodeterminethecauseoftheconditionandtoinitiatecorrectiveaction.3.13IndicationofBassedandInoerableStatusofCircuitBreakersorOtherDisconnectinDevicesAlthoughindicationofbypassedandinoperablestatusofcircuitbreakersorotherdisconnectingdevicesisnotprovidedasapartoftheBypassIndicationSystem,the125VdcSystemTroubleAlarminthecontrolroomisinitiatedforthefollowingcondition(whicharedisconnectingdevicesinthesystem):Hainbatteryfuseddisconnectopen.Batterychargeracinputcircuitbreakeropen.Batterychargerdcoutputcircuitbreakeropenor125Vdcswitchboardbreakeropen.

RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.UNIT1ANDUNIT2DG-E125VDCSUBSYSTEMPAGE11TABLE1125VDG-EDCSstemAnnunciatorPanelAlarmsl.125VDCSystemLowVoltage2.125VDCSystemGround3.BatteryHonitor(indicatesbatterydegradationoropenbatteryfuses)4.BatteryChargerTroubleindicates(1)ACpowerfailure,(2)DCoutputbreakeropen,(3),batterychargerfailure,(4)batterychargerhigh/lowvoltage,or(5)batterycharger'ighvoltage(shutdown).C:XQP51%00CS~RGL91-06.PGD(18)10/24/918:35am DG-EBLDGPANELOC577EMULTIPLEALARMINPUTSFROMDG-E125VDCPOWERSYSTEMPERTABlE1CONTROLROOMPANELOC653ANNUNCIATORDG-EBLDGPANELOC577EDCSYSTEMTROUBLEFIGURE1 7/5959BATTERYCHARGERAMMETERVOLTMETERBATTERYBANKFUSEBATTERYMONITORAMMETERVOLTMETER27SYSTEMGROUNDINDICATORSDCSWITCHBOARDLOADSLOADSSEETABLE1FORALARMSDG-E125VDCSYSTEMFIGURE2

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