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{{#Wiki_filter: | {{#Wiki_filter:ACCELERATED DTRIBUTION DEMONS~TION SYSTEMREGULATORY INFORMATION DISTRIBUTION SYSTEM(RIDS)ACCESSION NBR:9111010196 DOC.DATE:91/10/24NOTARIZED: | ||
NOFACIL:50-387 Susquehanna SteamElectricStation,Unit1,Pennsylva 50-388Susquehanna SteamElectricStation,Unit2,Pennsylva AUTH.NAMEAUTHORAFFILIATION KEISER,H.W. | |||
Pennsylvania Power&LightCo.RECIP.NAME RECIPIENT AFFILIATION MILLER,C.L. | |||
ProjectDirectorate I-2 | |||
==SUBJECT:== | ==SUBJECT:== | ||
ForwardsresponsetoGenericLtr91-06," | ForwardsresponsetoGenericLtr91-06,"Resolution ofGenericIssuesA-30,'Adequacy ofSafety-Related DCPowerSupplies.'" | ||
DISTRIBUTION CODE:AOOIDCOPIESRECEIVED:LTR 7ENCL/SIZE:TITLE:ORSubmittal: | |||
GeneralDistribution DOCKET0500038705000388DCOPIESLTTRENCL1122NOTES:LPDR 1cyTranscripts. | |||
~'PDR1cyTranscripts. | |||
5:~~8~~r>>RECIPIENT IDCODE/NAME PDl-2LARALEIGH,J. | |||
RECIPIENT IDCODE/NAME PD1-2PDCOPIESLTTRENCL11/0500038705000388ADiDINTERNAL: | |||
ACRSNRR/DET/ESGB NRR/DST8E2NRR/DST/SICB8H7 NUDOCS-ABSTRACT OGC/HDS2RES/DSIR/EIB EXTERNAL: | |||
NRCPDRNOTES:661111111110111122NRR/DET/ECMB 7DNRR/DOEA/OTS B11NRR/DST/SELB 7ENRR/DST/SRXB 8EOC/LFQEF-Kl'SIC111111111011RDNOTETOALL"RIDS"RECIPIENTS: | |||
DDPLEASEHELPUSTOREDUCEXVASTE!CONTACTTHEDOCUMENTCONTROLDESK,ROOMPl-37(EXT.20079)TOELIMINATE YOURNAMEFROMDISTRIBUTION LISTSFORDOCUMENTS YOUDON'TNEED!TOTALNUMBEROFCOPIESREQUIRED: | |||
LTTR26ENCL24 0Pennsylvania Power8LightCompanyTwoNorthNinthStreet~Allentown, PA,18101-1179,~,215/774-5151 HaroldW.KeiserSeniorVicePresident-Nuclear 215/7744194 1'CT24jtIQ)DirectorofNuclearReactorRegulation Attention: | |||
Hr.C.L.Hiller,ProjectDirectorProjectDirectorate I-2DivisionofReactorProjectsU.S.NuclearRegulatory Commission Washington, D.C.20555SUSQUEHANNA STEANELECTRICSTATIONRESPONSETOGENERICLETTER91-06LA-3673FILESR41-1DDocketNos.50-387and50-388 | |||
==DearHr.Hiller:== | ==DearHr.Hiller:== | ||
EnclosedisourresponsetoGenericLetter91-06," | EnclosedisourresponsetoGenericLetter91-06,"Resolution ofGenericIssueA-30".Inanefforttoavoidconfusion causedbyextensive explanatory remarksprovidedforeachDCsystem,ourresponseisdividedintofourparts:ATTACHMENT I:24VDCSYSTEMATTACHMENT II:125VDCSYSTEMATTACHMENT III:250VDCSYSTEMATTACHMENT IV:DG'-E125VDCSYSTEMShouldyouhaveanyquestions, pleasecontactHr.W.W.Williams, at(215)774-7910. | ||
SUSUEHANNAS.E.S.~ | Verytrulyyours,glH.W.KeiserEnclosure 9111p1Kp5ppp38701'9691102%PDRADOCP OCT24lg01FILESA17-8/so-24 PLA-'3673 Mr.C.L.Millercc:iiiLCD~ocumen. | ||
N SUSUEHANNAS.E.S. | Control-Desk-(original.)P NRCRegionIMr.G.S.Barber,NRCSr.ResidentInspector Mr.J.J.Raleigh,NRCProjectManagerWWW:llrPLA/021.WWW SUSUEHANNAS.E.S.24VDCSYSTENATTACHMENT IPage1ENCLOSURE 1Thefollowing information isapplicable toeitherUnit1or2atSusquehanna SES.l.UnitSusuehannaS.E.S.Unit1or224VDC2.a~Thenumberofindependent redundant divisions ofClasslEorfty-lddtftllyltl~t.(lldanyseparateClasslEorsafety-related dc,suchasanydcdedicated tothedieselgenerators.) | ||
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S. | b.Thenumberoffunctional safety-related divisions ofdcpowerytttlfttdftllltd3.Doesthecontrolroomatthisunithavethefollowing | ||
: separate, independently annunciated alarmsandindications foreachdivisionofdcpower?a.Alarms1.Batterydisconnect orcircuitbreakeropen?No2.Batterychargerdisconnect orcircuitbreakeropen(bothinputacandoutputdc)?No3.dcsystemground?No4.dcbusundervoltage? | |||
No5.dcbusovervoltage? | |||
No6.Batterychargerfailure?No...9111010196 C4' SUSUEHANNAS.E.S.24VDCSYSTEMATTACHMENT I7.Batterydischarge? | |||
NoPage2b.Indications 1.Batteryfloatchargecurrent?No2.Batterycircuitoutputcurrent?No3.Batterydischarge? | |||
No4.Busvoltage?Noc.Doestheunithavewrittenprocedures forresponsetotheabovealarmsandindications? | |||
No4.Doesthisunithaveindication ofbypassedandinoperable statusofcircuitbreakersorotherdevicesthatcanbeusedtodisconnect thebatteryandbatterychargerfromitsdcbusandthebatterychargerfromitsacpowersourceduringmaintenance ortesting?NoSeeremarktl5.Iftheanswertoanypartofquestion3or4isno,thenprovideinformation justifying theexistingdesignfeaturesofthefacility's safety-related dcsystems.*Seenotebelow.SeeremarkOl6.(I)Haveyouconducted areviewofmaintenance andtestingactivities tominimizethepotential forhumanerrorcausingmorethanonedcdivisiontobeunavailablet | |||
~esand(2)doplantprocedures prohibitmaintenance ortestingonredundant DCdivisions atthesametime'I~esIfthefacilityTechnical Specifications haveprovisions equivalent tothosefoundintheWestinghouse andCombustion Engineering StandardTechnical Specifications formaintenance andsurveillance, thenquestion7maybeskippedandastatement tothateffectmaybeinsertedhere. | |||
SUSUEHANNAS.E.S.~YYTATTACHMENT IPage37.Aremaintenance, surveillance andtestprocedures regarding stationbatteries conducted routinely atthisplant?Specifically: | |||
a.Atleastonceper7daysarethefollowing verifiedtobewithinacceptable limits:1.Pilotcellelectrolyte level?Yes2.Specifygravityorchargingcurrent?Yes3.Floatvoltage?Yes4.Totalbusvoltageonfloatcharge?Yes5.Physicalcondition ofallcells?Yesb.Atleastonceper92days,orwithin7daysafterabatterydischarge, overcharge, orifthepilotcellreadingsareoutsidethe7-daysurveillance requirements arethefollowing verifiedtobewithinacceptable limits:l.Electrolyte levelofeachcell?Yes2.Theaveragespecificgravityofallcells?Yes3.Thespecificgravityofeachcell?Yes4.Theaverageelectrolyte temperature ofarepresentative numberofcells?Yes5.Thefloatvoltageofeachcell?Yes6.Visuallyinspectormeasureresistance ofterminals andconnectors (including theconnectors atthedcbus)?Yes SUSUEHANNAS.E.S.24VDCSYSTEMATTACHMENT Ic.Atleastevery18monthsarethefollowing verified: | |||
Page41.Lowresistance ofeachconnection (bytest)?Yes2.Physicalcondition ofthebattery?Yes3.Batterychargercapability todeliverratedampereoutputtothedcbus?Yes4.Thecapability ofthebatterytodeliveritsdesigndutycycletothedcbus?Yes5.Eachindividual cellvoltageiswithinacceptable limitsduringtheservicetest?Yesd.Atleastevery60months,iscapacityofeachbatteryverifiedbyperformance ofadischarge test?Yese.Atleastannually, isthebatterycapacityverifiedbyperformance discharge test,ifthebatteryshowssignsofdegradation orhasreached85Xoftheexpectedservicelife?Yes8.Doesthisplanthaveoperational featuressuchthatfollowing lossofonesafety-related dcpowersupplyorbus:a.Capability ismaintained forensuringcontinued andadequatereactorcooling?Yesb.Reactorcoolantsystemintegrity andisolation capability aremaintained? | |||
Yesc.Operating procedures, instrumentation (including indicators andannunciators), | |||
andcontrolfunctions areadequatetoinitiatesystemsasrequiredtomaintainadequatecorecooling?Yes9.Iftheanswertoanypartofquestion6,7or8isno,thenprovideyourbasisfornotperforming themaintenance, surveillance andtestprocedures described and/orthebasesfornotincluding theoperational featurescited.*Seenotebelow. | |||
N SUSUEHANNAS.E.S.24VDCSYSTEMATTACHMENT IPage5*Note:Forquestions involving supporting typeinformation (question numbers5and9)insteadofdeveloping andsupplying theinformation inresponsetothisletter,youmaycommittofurtherevaluatetheneedforsuchprovisions duringtheperformance ofyourindividual plantexamination forsevereaccidentvulnerabilities (IPE).Ifyouselectthisoption,youarerequiredto:(1)Sostateinresponsetothesequestions, and(2)Committoexplicitly addressquestions 5and9inyourIPEsubmittal pertheguidelines outlinedinNUREG-1335 (Section2.1.6,Subitem7),"Individual PlantExamination: | |||
Submittal Guidance." | |||
c:iwp51idocsi24VDCSYS.PCD (18)10/24/919:20am RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.24VDCSUBSYSTEM PAGE1REMARK1:1.0Thefollowing indications andalarmsforthe24Vdcclass1Esubsystem areprovided. | |||
Justification forthisdesignhasbeenpreviously providedinPLA-959totheNRCdated11/6/81,regarding ControlRoommonitoring ofClasslEdcpowersystems.Each24Vdcsubsystem consistsoftwo24voltbatterybanksconnected inserieswithacommongroundbusconnected tothecommon(center)pointofthetwobatterybanks.Thegroundbusissolidlygroundedtothestationgroundgrid.Each24voltbatterybankisdesignated aseitherthepositiveornegativebusasreferenced toground.Thealarms/indications inthefollowing tableanddiscussion aretypicalforeachpositiveandnegativebus.AlarmorIndication | |||
,LocationLocalControlRoomNotesBusUndervoltage AlarmBatteryMonitorAlarmBatteryChargerTroubleAlarmBusOvervoltage AlarmBusVoltmeter BatteryChargerAmmeterBatteryChargerVoltmeter DCSystemTroubleAlarm1,21,2,41,2,51,23NOTES:1.SeeTable1andFigure2forspecificlocalalarmindication. | |||
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.24VDCSUBSYSTEM PAGE22.Thesearelocallyindicated andactuatedcsubsystem troublealarm,seeTable1andFigure1.3.Hetersareprovidedlocally.SeeFigure3.4.Batterymonitor'compares batterycenterpointvoltagewithhighandlowthreshold reference pointsofthehighandlowvoltagecomparators. | |||
Thedegradedcellconditions (suchasashortedcell)oranopencircuitcondition (suchasanopenfuse)aredetectedbythebatterymonitor.5.Batterychargertroublealarmindication isprovidedforbatterychargerACpowerfailure,DCoutputbreakeropen,batterychargerfailurealarmoperation. | |||
6.Oneannunciator windowforeach24Vdcsubsystem isprovided. | |||
(Includes inputsfromeitherthepositiveornegativebus).2.0Themonitoring schemeprovidedforthedcpowersubsystem isbasedonthedegreeofcontrolprovidedtothecontrolroomoperator. | |||
Sincethedcpowersystemequipment cannotberemotelycontrolled, asingledcsystemtroubleannunciator windowforeachsubsystem isprovidedinthecontrolroom,consistent withthesystemlevelalarmcriteriasetforthinSection8ofR.G.1.47.TheSSESdesignisbasedonthegeneralcriteriathat,iftheoperatorcanperformsomecorrective actioninthecontrolroominresponsetoaspecificinput,thatinformation isspecifically provided. | |||
Thedcpowersystemequipment cannotbecontrolled fromthecontrolroom.Annunciating specificinputsfromthe24Vdcsysteminthecontrolroomdoesnotenhancethecontrolroomoperators's abilitytodealwiththesituation anditwouldnotbeconsistent withSSESalarmdesignphilosophy. | |||
However,iftheonlyresponserequiredistodispatchanoperatortoanarearemovedfromthecontrolroom,thentheonlyinformation requiredinthecontrolroomisgeneralinformation withonlythelevelofspecificity requiredtodirectthatoperatortotheproperlocation. | |||
Thismethodisfasterandmorereliablesinceabnormal | |||
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S. | RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.24VDCSUBSYSTEM PAGE3conditions areautomatically alarmed.Furthermore, thisapproachisconsistent withthehumanfactorsengineering goaltonotoverburdentheoperatorwithunnecessary information. | ||
24Vdcsysteminstrumentation, locallyprovided, isinfullcompliance withtherequirement ofIEEE308-1974andRegulatory Guide1.47.TheDCsystemgeneraltroublealarmsandspecificlocalindicators inconjunction withtheroutineoperatorsurveillance providepositiveassurance thattheClasslEdcpowersystemaremaintained inasteadystatereadytoperform-the requiredsafetyfunction. | |||
==3.0 Following== | |||
isthejustification foreachalarmandindication listedinGenericLetter91-06.3.1BatterDisconnect orCircuitBreaker0enAlarm:TheSusquehanna S.E.S.(SSES)24Vdcsubsystem utilizesfusesasthebatterydisconnect. | |||
Thiscondition isdetectedbythebatterymonitor.Thebatterymonitorutilizesavariablethreshold circuittogetherwithtwocomparators (highandlow)todetectthelossofbatterycapability duetoanopencircuit(i.e.,anopenfuseordegradedcellcondition). | |||
Avariablethreshold circuitacceptsthebatterychargervoltageanddevelopstwothreshold voltagesforusewiththecomparators. | |||
Whenthemonitored voltagesgoaboveorbelowthethresholds, thebatterymonitoroutputrelaycontactsinitiatealocalbatterymonitoralarmwhichisreflashed tothecontrolroomasa24Vdcsystemtroublealarm.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.2BatterCharerDisconnect orCircuitBreaker0enBothInutACandOututDCAlarm3.2.1BatteryChargerACInputDisconnect orCircuitBreaker:SSESutilizesacircuitbreakerinthebatterychargerasadisconnect fortheacinputpowersupply.Anacpower RESPONSETOGENERIC.LETTER91-06SUSUEHANNAS.E.S.24VDCSUBSYSTEN PAGE4failurealarmrelayisinstalled internaltothebatterychargertodetectlossofacinputpower.Thiscondition couldbecausedbyanopeninputcircuitbreakerorlossofthe120Vacpowersupplytothecharger.Theacpowerfailurealarmrelayinitiates abatterychargertroublealarmatthelocalreflasher panel,whichisreflashed tothecontrolroomasa24Vdcsystemtroublealarm.Thisisconsistent withthegeneraldesignphilosophy discussed insection2.0.3.2.2BatteryChargerDCOutputCircuitBreakerSSESutilizesacircuitbreakerinthebatterychargerasadisconnect forthedcoutputcircuit.Thecircuitbreakerisprovidedwithanauxiliary positionindicating switch.Aswitchcontactwhichisclosedwhenthecircuitbreakerisopenisusedtoinitiateabatterychargertroublealarmatthelocalreflasher panel.Adcsystemtroublealarmisreflashed tothecontrolroombythelocalreflasher panel.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.3DCSstemGroundAlarmThe24Vdcsubsystem isasolidlygroundedsystem.Therefore, asystemgroundalarmisnotrequired. | |||
Asecondgroundoneitherthepositiveornegativebuswillcauseprotective devicesinthecircuittooperate.Thiscondition willbedetectedatthelocalreflasher panelbyeitherthebatterymonitoralarm(forbatteryfuseopen)orthebatterychargertroublealarm(forbatterychargerDCoutputbreakeropen).Ineithercase,thelocalreflasher panelwillreflasha24Vdcsystemtroublealarmtothecontrolroomannunciator. | |||
Thisisconsistent withthegeneraldesignphilosophy discussed inSection'.0. | |||
RESPONSETOGENERICLETTER91-0624VDCSUBSYSTEM SUSUEHANNAS.E.S.PAGE53.4DCBusUndervolta eAlarmThe24Vdcsubsystem isprovidedwithpositiveandnegativedcbusundervoltage relays.Eachrelayisconnected acrossthesystembuses(positive bustoground,negativebustoground).Therelaysarenormallyenergized and,settodropoutatthespecified setpoint. | |||
Apositivebusornegativebuslowvoltagealarmatthelocalreflasher panelisinitiated aftertheundervoltage relaydropsout.Thelocalreflasher panel,inturn,reflashes thealarmtothecontrolroomannunciator asadcsystemtroublealarm.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.5DCBusOvervolta eAlarmThe24Vdcsubsystems areprovidedwithovervoltage relays.Therelaysarelocatedinsidethe24Vdcdistribution panels.Eachrelayisconnected acrossthesystembuses(positive bustoground,negativebustoground)andsettopickupatthespecified setpoint. | |||
Anormallyopencontactoftheover'voltage relay,whenclosed,initiates apositivebusornegativebushighvoltagealarmatthelocalreflasher panelwhichinturnwillreflashadcsystemtroubletothecontrolroomannunciator. | |||
Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.6BatterCharerFailureAlarmEach24Vdcsubsystem batterychargerisprovidedwithabatterychargerfailurerelay.Thisrelaywilldetectthelossofthechargeroutputcurrentwiththeinputandoutputcircuitbreakersclosed.Thiscondition isindicative ofabatterychargerfailureanditinitiates abatterychargertroublealarmatthelocalreflasher RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.24VDCSUBSYSTEM PAGE6panelwhichinturnwillreflashadcsystemtroublealarmtothecontrolroomannunciator. | |||
Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.7BatterDischareAlarmThebatterycanonlydischarge whenits.terminal voltageislessthanthenominalopencircuitvoltage.Thisisindicative ofabatterychargerfailureorsystemcurrentinexcessofthechargercapability. | |||
Abatterychargerfailurealarmisprovidedanditsoperation isdiscussed inSection3.6.Whensystemcurrentexceedsbatterychargercapability, adcsystemundervoltage condition willoccur,andwillbedetectedbythedcbusundervoltage relay(seeSection3.4).Chargerfailureandbusundervoltage initiatealarmsatthelocalreflasher panelwhichinturnwillreflashadcsystemtroublealarmtothecontrolroomannunciator. | |||
Thisisconsistent withthegeneraldesignphilosophy asdiscussed inSection2.0.3.8BatterFloatChareCurrentIndication Undernormalconditions, thebatteryfloatchargecurrentisverysmallcomparedtobatterydischarge current.Measurement ofthiscurrentrequiresaverysensitive ammeter.Shuntbypassesareemployedtoprotecttheammetermovementfromthemuchlargerbatterydischarge currentpossibleinthiscircuit.Theseshuntsmustbemanuallyremovedwhenreadingnormalsmallfloatcurrent.Thusthisreadingcannotbecontinuous andnoautomatic indication oralarmscanbegiven.Sincetheintentofindicating "BatteryFloatChargeCurrent"istodetermine thebatterycondition, themethodusedtoaccomplish thispurposeshouldnotbeimportant. | |||
Thebusundervoltage, batterymonitorandbatterychargerfailure RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.24VDCSUBSYSTEM PAGE7alarms(previously described) providecontinuous monitoring todetectdegradation ofbatterycapability. | |||
Thesealarmswillreflashthedcsystemtroublealarminthecontrolroom,andanoperatorisdispatched locallytodetermine thecauseofthecondition andinitiatecorrective action.Specificindication isprovidedonthelocalreflasher panel.Thisresponseisexactlywhatwould'beachievedifanimproperstateofbatterycurrentwereindicated onanammeterinthecontrolroom.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.9BatterCircuitOututCurrentIndication Innormalcondition whenthebatterychargerissupplying the24Vdcpower,thebatterycircuit(batteryandthebatterycharger)outputcurrentisindicated byanammeterlocatedatthebatterycharger.Inthecondition ofabatterychargerfailure,thebatterysuppliesthedcpower.Inthiscondition thebatterycircuitoutputcurrentcannotbedetermined sinceanammeterisnotprovidedatthe24Vdcdistribution panels.Asindicated inSection3.8,theintentofindicating "batterycurrent"istodetermine thebatterycondition, andtherefore themethodusedtoaccomplish thispurposeshouldnotbeimportant. | |||
3.10BatterDischareIndication Aspreviously discussed inSection3.7,abatterydischarge willoccurasaresultofabatterychargerfailureorsystemcurrentinexcesstobatterychargercapability. | |||
Sincetheseconditions areautomatically alarmedinthecontrolroom(viathesystemtroublealarm),anoperatorwillbedispatched locallyto IRESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.24VDCSUBSYSTEM PAGE8determine thecauseofthecondition andinitiatecorrective action.Thisresponseisexactlywhatwouldbeachievedifbatterydischarge currentwasindicated onanammeterinthecontrolroom.3.11BusVoltaeIndication Thebattery,thebatterychargerandthe24Vdcdistribution panelarelocatedincloseproximity ofeachother.Thebatterychargerandthedcdistribution panelareeachprovidedwithavoltmeter. | |||
Thepurposeofabusvoltmeter atthecontrolroomwouldbetoenabletheoperatortodispatchsomeonetotakecorrective actionlocallytocorrectabnormalbusvoltage.AtSSESbusundervoltage andovervoltage ismonitored directlyatthedistribution panel.Thebusundervoltage andovervoltage conditions areannunciated as24Vdcsystemloworhighvoltageatthelocalreflasher panel.Adcsystemtroublealarmisreflashed tothecontrolroomannunciator bythelocalreflasher panel.Thisdesignautomatically alertsthecontrolroomoperatortounusualvoltageconditions withoutunnecessarily requiring hisperiodicattention andanalysis. | |||
Asaresult,24Vdcbusvoltageindication isnotprovidedinthecontrolroomandhasbeenprovidedonthefrontofthedistribution panelwhereitprovidesusefulinformation duringsurveillance andmaintenance activities. | |||
Avoltmeter islocatedonthefrontofthebatterychargerpanel.Withthechargeroutputcircuitbreakerclosed,thechargeroutputandthebusvoltagesareessentially thesameduetothecloseproximity ofthechargertotheloadcenter.Allabnormalvoltageconditions ofthebatterychargerareannunciated atthelocalreflasher panelwhichisreflashed tothecontrolroomasadcsystemtroublealarm.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0. | |||
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.24VDCSUBSYSTEN PAGE93.12AlarmResonseProcedure Controlroomalarmresponseprocedures fora24Vdcsystemtroublealarmdirecttheoperatortorespondtothelocalreflasher paneltodetermine thecondition whichcausedthealarm.Localalarmresponseprocedures forthereflasher panelareprovidedtodirecttheoperatortodetermine thecauseofthecondition andtoinitiatecorrective action.3.13Indication ofBassedandInoerableStatusofCircuitBreakersorOtherDisconnectin DevicesAlthoughindication ofbypassedandinoperable statusofcircuitbreakersorotherdisconnecting devicesisnotprovidedasapartoftheBypassIndication System,the24VdcSystemTroubleAlarminthecontrolroomisinitiated forthefollowing condition (whicharedisconnecting devicesinthesystem):Hainbatteryfuseopen.Batterychargeracinputcircuitbreakeropen.Batterychargerdcoutputcircuitbreakeropen,ordcdistribution panelfeederbreakeropen. | |||
P RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.24VDCSUBSYSTEM PAGE10TABLE124VDCSstemReflashPanelIndicators 1L610(Typicalforpositiveandnegativebuses)l.24VDCSystemLowVoltage2.,24VDCSystemHighVoltage3.BatteryHonitor(indicates batterydegradation oropenbatteryfuses)4.BatteryChargerTroubleindicates (1)ACpowerfailure,(2)DCoutputbreakeropen,or(3)batterychargerfailureC:KWP51%00CSK24VDCSS | |||
~PGO(18)10/24/919:168AI 124DCLOCALREHASHPANELWITHINDICATION 1L670MULTIPLEALARMINPUTSFROM%24VDCPOWERSYSTEMPERTABLE1DCSYSTEMAlARMINPUTSFROMOTHERREFLASHPANELS(8MILARTOABOVE)CONTROLROOMPANEL1C651ANNUNCIATOR | |||
+24VDCSYSTEMTROUBLE1L670FIGURE1 | |||
INDICATOR UGHI'ERASHER PANELPOWERFAILUREPOSITIVEBUSLOWVOLTAGENEGATIVEBUSHIGHVOLTAGEBATlERYCHARGER41TROUBLE0NEGATIVEBUSLOWVOLTAGEBATTERYPOSITIVEMONITORBATIERYCHARGERWTROUBLE0POSITIVEBUSHIGHVOLTAGEBATlERYNEGATIVEMONITOR224VDCSYSTEMLOCALREHASHERPANELQYPICAOFIGURE2 IBATIERYBANK1D670I+24-24I96PCLQ>0+24VDCBA11ERYCHARGERDCBKRQvQ~-24VDCBA11ERYCHAI&ERDCBKRQvQA59y27P27y69NNSPARECOMPOUTPUTAMPPOSVOLTSNEG}VOLTSNEGSPAREMPUIEROUTPUTPROCESSRADIATION MONITORSSOURCERNG.MON'SINIERMRNG.MON'S1RIP.AUX,UNITSNOTE1+24VCOMMON-24V24VDCSYSTEMOYPICAQNOTE1:COMMONBUSGROUNDED SUSUEHANNAS.E.S.125VDCSYSTEMATTACHMENT IIPage1ENCLOSURE 1Thefollowing information isapplicable toeitherUnit1or2atSusquehanna SES.1.UnitSUSUEHANNAS.E.S.UNIT-1or2125VDCSYSTEM2.a0Thenumberofindependent redundant divisions ofClasslEorsafety-related DCpowerforthisplantisSeeRemark1(IncludeanyseparateClass1Eorsafety-related DC,suchasanyDCdedicated tothedieselgenerators). | |||
b.Thenumberoffunctional safety-related divisions ofDCpowernecessary toattainsafeshutdownforthisunitisSeeRemark2.3.Doesthecontrolroomatthisunithavethefollowing | |||
: separate, independently annunciated alarmsandindications foreachdivisionofDCpower?a~3.5.Alarms1.Batterydisconnect orcircuitbreakeropen?No2.Batterychargerdisconnect orcircuitbreakeropen(bothinputACandoutputDC)?NoDCsystemground?NoDCbusundervoltage? | |||
NoDCbusovervoltage? | |||
No6.Batterychargerfailure?No7.Batterydischarge? | |||
Nob.Indications l.2.3.Batteryfloatchargecurrent?NoBatterycircuitoutputcurrent?NoBatterydischarge? | |||
NoBusvoltage?No SUSUEHANNAS.E.S.125VDCSYSTENATTACHMENT II4.Page2c.Doestheunithavewrittenprocedures forresponsetotheabove'alarmsandindications? | |||
NoI*,IDoesthisunithaveindication ofbypassedandinoperable'status ofcircuitbreakersorotherdevicesthatcanbeusedtodisconnect thebatteryandbatterychargerfromitsDCbus,andthebatterychargerfromitsACpowersourceduringmaintenance ortes'ting? | |||
NoSeeremark¹35.Iftheanswertoanypartofquestion3or4isno,thenprovideinformation justifying theexistingdesignfeaturesofthefacility's safety-related DCsystems.*Seeendnote.Seeremark¹36.(I)Haveyouconducted areviewofmaintenance andtestingactivities tominimizethepotential forhumanerrorcausingmorethanoneDCdivisiontobeunavailablet | |||
~esand(2)Doplantprocedures prohibitmaintenance ortestingonredundant DCdivisions atthesametime?~esIfthefacilityTechnical Specifications haveprovisions equivalent tothosefoundintheWestinghouse andCombustion Engineering StandardTechnical Specification formaintenance andsurveillance, thenquestion7maybeskippedandastatement tothateffectmaybeinsertedhere.7.Aremaintenance, surveillance andtestprocedures regarding stationbatteries conducted routinely atthispoint?Specifically: | |||
a.Atleastonceper7daysarethefollowing verifiedtobewithinacceptable limits:I.2.3.4.5.Pilotcellelectrolyte level?YesSpecificgravityorchargingcurrent?YesFloatvoltage?YesTotalbusvoltageonfloatcharge?YesPhysicalcondition ofallcells?Yes | |||
SUSUEHANNAS.E.S.125VDCSYSTEMATTACHMENT IIb.Page3Atleastonceper92days,orwithin7daysafterabatterydischarge, overcharge, orifthepilotcellreadingsareoutsidethe7-daysurveillance requirements arethefollowing verifiedtobewithinacceptable limits:l.2.3.4.5.6.Electrolyte levelofeachcell?YesTheaveragespecificgravityofallcells?YesThespecificgravityofeachcell?YesTheaverageelectrolyte temperature ofarepresentative numberofcells?YesThefloatvoltageofeachcell?YesVisually.inspectormeasureresistance ofterminals andconnectors (including theconnectors attheDCbus)?Yesc.Atleastevery18monthsarethefollowing verified: | |||
2.3.5.Lowresistance ofeachconnection (bytest)?YesPhysicalcondition ofthebattery?YesBatterychargercapability todeliverratedampereoutputtotheDCbus?YesThecapability ofthebatterytodeliveritsdesigndutycycletotheDCbus'?YesEachindividual cellvoltageiswithinacceptable limitsduringtheservicetest?Yesd.Atleastevery60months,iscapacityofeachbatteryverifiedbyperformance ofadischarge test'?Yese.Atleastannually, isthebatterycapacityverifiedbyperformance discharge test,ifthebatteryshowssignsofdegradation orhasreached85Xoftheexpectedservicelife?Yes8.Doesthisplanthaveoperational featuressuchthatfollowing lossofonesafety-related DCpowersupplyorbus:a.Capability ismaintained forensuringcontinued andadequatereactorcooling?Yes SUSUEHANNAS.E.S.125VDCSYSTENATTACHMENT IIPage4b.Reactorcoolantsystemintegrity andisolation capability aremaintained7 Yesc.Operating procedures, instrumentation (including indicators andannunciators), | |||
andcontrolfunctions areadequatetoinitiatesystemsasrequiredtomaintainadequatecorecooling7Yes9.Iftheanswertoanypartofquestion6,7,or8isno,thenprovideyourbasisfornotperforming themaintenance, surveillance andtestprocedures described and/orthebasesfornotincluding theoperational featurescited.*SeeNotebelow.*Note:Forquestions involving supporting typeinformation (question numbers5and9)insteadofdeveloping andsupplying theinformation inresponsetothisletter,youmaycommittofurtherevaluatetheneedforsuchprovisions duringtheperformance ofyourindividual plantexamination forsevereaccidentvulnerabilities (IPE).Ifyouselectthisoption,youarerequired, to:1)Sostateinresponsetothesequestions, and2)Committoexplicitly addressquestions 5and9inyourIPEsubmittal pertheguidelines outlinedinNUREG-1335 (section2.1.6,Subitem7),"Individual PlantExamination: | |||
Submittal Guidance." | |||
C:KIIP51I,docshadeqofsa.pgd (18)10/24/918:57am | |||
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S. | RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.125VDCSUBSYSTEM PAGE1REMARK1:TheUnit1Class1Edirectcurrent,(dc)systemconsistsoffourindependent 125voltdcsubsystems. | ||
Thesefoursubsystems areidentified aschannelsA,B,C,andD.Eachsubsystem providesthecontrolpowerforitsassociated classlEacpowerloadgroupconsisting of:'.16kVswitchgear, 480Vloadcenters,andastandbydieselgenerator. | |||
The125Vdcsubsystems alsoprovidedcpowerforsafetyfeaturevalveactuation, dieselgenerator auxiliaries, andplantalarmandindication circuits. | |||
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S. | REMARK2:Fourseparateandindependent class1E125Vdcsubsystems supplycontrolpowerforeachoftheclass1Eloadgroups.Lossofanyoneofthesubsystems doesnotpreventtheminimumsafetyfunctionfrombeingperformed (i.e.,threeoutoffoursubsystems arenecessary toattainsafeshutdownforUnit1).REMARK3:1.0Thefollowing indications andalarmsforthe125VdcclasslEsubsystem areprovided. | ||
Justification forthisdesignhasbeenpreviously providedinPLA-959totheNRCdatedll/6/81,regarding ControlRoommonitoring ofClass1Edcp'owersystems. | |||
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.125VDCSUBSYSTEM PAGE2AlarmorIndication LocationLocalControlRoomNotesBusUndervoltage AlarmBusGroundAlarmBatteryMonitorAlarmBatteryChargerTroubleAlarmBusAmmeterBusVoltmeter BatteryChargerAmmeterBatteryChargerVoltmeter DCSystemTroubleAlarm1,21,21,2,41,2,5NOTES:1.SeeTable1andFigure2forspecificlocalalarmindication. | |||
2.Thesearelocallyannunciated andactuatedcsubsystem troublealarm,seeTable1andFigurel.3.Hetersareprovidedlocally.SeeFigure3.Batterymonitorcomparesbatterycenterpointvoltagewithhighandlowthreshold reference pointsofthehighandlowvoltagecomparators. | |||
Thedegradedcellconditions (suchasashortedcell)oranopencircuitcondition (suchasanopenfuse)aredetectedbythebatterymonitor. | |||
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S. | RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.125VDCSUBSYSTEM PAGE35.Batterychargertroublealarmindication isprovidedforbatterychargerACpowerfailure,DCoutputbreakeropen,batterychargerfailurealarmoperation, andbusovervoltage. | ||
6.Oneannunciator windowforthe125Vdcsubsystem isprovided. | |||
==2.0 Themonitoring== | |||
schemeprovidedforthedcpowersubsystem isbasedonthedegreeofcontrolprovidedtothecontrolroomoperator. | |||
Sincethedcpowersystemequipment cannotberemotelycontrolled, asingledcsystemtroubleannunciator windowforeachsubsystem isprovidedinthecontrolroom,consistent withthesystemlevelalarmcriteriasetforthinSectionBofR.G.1.47.TheSSESdesignisbasedonthegeneralcriteriathat,iftheoperatorcanperformsomecorrective actioninthecontrolroominresponsetoaspecificinput,thatinformation isspecifically provided. | |||
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S. | Thedcpowersystemequipment cannotbecontrolled fromthecontrolroom.Annunciating specificinputsfromthe125Vdcsysteminthecontrolroomdoesnotenhancethecontrolroomoperators's abilitytodealwiththesituation anditwouldnotbeconsistent withSSESalarmdesignphilosophy. | ||
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S. | However,iftheonlyresponserequiredistodispatchanoperatortoanarearemovedfromthecontrolroom,thentheonlyinformation requiredinthecontrolroomisgeneralinformation withonlythelevelofspecificity requiredtodirectthatoperatortotheproperlocation. | ||
Thismethodisfasterandmorereliablesinceabnormalconditions areautomatically alarmed.Furthermore, thisapproachisconsistent withthehumanfactorsengineering goaltonotoverburdentheoperatorwithunnecessary information. | |||
125Vdcsysteminstrumentation, locallyprovided, isinfullcompliance withtherequirement of,IEEE308-1974andRegulatory Guide1.47.TheDCsystemgeneraltroublealarmsandspecificlocalindicators inconjunction withtheroutineoperatorsurveillance providepositiveassurance thattheClass1Edcpowersystemaremaintained inasteadystatereadytoperformtherequiredsafetyfunction. | |||
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.125VDCSUBSYSTEM PAGE43.0Following isthejustification foreachalarmandindication listedinGenericLetter91-06.3.1BatterDisconnect orCircuitBreaker0enAlarm:TheSusquehanna S.E.S.(SSES)125Vdcsubsystem utilizesfusesasthebatterydisconnect. | |||
Thiscondition isdetectedbythebatterymonitor.Thebatterymonitorutilizesavariablethreshold circuittogetherwithtwocomparators (highandlow)todetectthelossofbatterycapability duetoanopencircuit(i.e.,anopenfuseordegradedcellcondition). | |||
Avariablethreshold circuitacceptsthebatterychargervoltageanddevelopstwothreshold voltagesforusewiththecomparators. | |||
Whenthemonitored voltagesgoaboveorbelowthethresholds, thebatterymonitoroutputrelaycontactsinitiatealocalbatterymonitoralarmwhichisreflashed tothecontrolroomasa125Vdcsystemtroublealarm.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.2BatterCharerDisconnect orCircuitBreaker0enBothInutACandOututDCAlarm3.2.1BatteryChargerACInputDisconnect orCircuitBreaker:SSESutilizesacircuitbreakerinthebatterychargerasadisconnect fortheacinputpowersupply.Anacpowerfailurealarmrelayisinstalled internaltothebatterychargertodetectlossofacinputpower.Thiscondition couldbecausedbyanopeninputcircuitbreakerorlossofthe480Vacpowersupplytothecharger.Theacpowerfailurealarmrelayinitiates abatterychargertroublealarmatthelocalreflasher panel,whichisreflashed tothecontrolroomasa125Vdcsystemtroublealarm.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0. | |||
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.125VDCSUBSYSTEN PAGE53.2.2BatteryChargerDCOutputCircuitBreakerSSESutilizesacircuitbreakerinthebatterychargerasadisconnect forthedcoutputcircuit.Thecircuitbreakerisprovidedwithanauxiliary positionindicating switch.Aswitchcontactwhichisclosedwhenthecircuitbreakerisopenisusedtoinitiateabatterychargertroublealarmatthelocalreflasher panel.Adcsystemtroublealarmisreflashed tothecontrolroombythelocalreflasher panel.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.3DCSstemGroundAlarmThe125Vdcsubsystem isungrounded andisprovidedwithagrounddetection circuit.Itconsistsofarelayhavingacentertappedcoil.Thecoilisconnected acrossthepositiveandnegativebusanditscenterpointisgrounded. | |||
Thegrounddetection relaycoilisnotactuatedduringnormaloperation ofthe125Vdcsubsystem whenagroundisnotpresent.Agroundoneitherthepositiveornegativebusofthe125Vdcsubsystem causesone-halfoftherelaycoiltobeshortcircuited, thusproviding sufficient voltagetotheremaining relaycoilhalftopickuptherelay.Anormallyopencontactoftherelayclosesandinitiates a125Vdcsystem.groundalarmatthelocalreflasher panel.Adcsystemtroublealarmisreflashed tothecontrolroomannunciator bythelocalreflasher panel.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.4DCBusUndervolta eAlarmThe125Vdcsubsystem isprovidedwithadcbusundervoltage relay.Therelayisconnected acrossthepositiveandnegativebusofthe125Vdcsubsystem. | |||
Therelayisnormallyenergized andsettodropoutatthespecified setpoint. | |||
A125Vdcbusundervoltage alarmatthelocalreflasher panelisinitiated aftertheundervoltage relaydropsout. | |||
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.125VDCSUBSYSTEN PAGE6Thelocalreflasher panel,inturn,reflashesthealarmtothecontrolroomannunciator asadcsystemtroublealarm.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.5DCBusOvervolta eAlarmThe125Vdcsubsystem isprovidedwithanovervoltage relay.Therelayislocatedinsidethebatterychargercabinet.Itisconnected acrossthepositiveandnegative125Vdcbusofthebatterychargerandsettopickupatthespecified setpoint. | |||
Anormallyopencontactoftheovervoltage relay,whenclosed,initiates abatterychargertroublealarmatthelocalreflasher panelwhichinturnwillreflashadcsystemtroubletothecontrolroomannunciator. | |||
Sincethebattery,thebatterychargerandthedcloadcenterareincloseproximity ofeachother,thebatterychargervoltageisrepresentative ofthe125Vdcbusvoltage.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.6BatterCharerFailureAlarmThe125Vdcsubsystem batterychargerisprovidedwithabatterychargerfailurerelay.Thisrelaywilldetectthelossofthechargeroutputcurrentwiththeinputandoutputcircuitbreakersclosed.Thiscondition isindicative ofabatterychargerfailureanditinitiates abatterychargertroublealarmatthelocalreflasher panelwhichinturnwillreflashadcsystemtroublealarm'tothecontrolroomannunciator. | |||
Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0. | |||
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S. | RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.125VDCSUBSYSTEM PAGE73.7BatterDischareAlarmThebatterycanonlydischarge, whenitsterminalvoltageislessthanthenominalopencircuitvoltage.Thisisindicative ofabatterychargerfailureorsystemcurrentinexcessofthechargercapability. | ||
Abatterychargerfailurealarmisprovidedanditsoperation isdiscussed inSection3.6.'Whensystemcurrentexceedsbatterychargercapability, adcsystemundervoltage condition willoccur,andwillbedetectedbythedcbusundervoltage relay.(SeeSection3.4.)Chargerfailureandbusundervoltage initiatealarmsatthelocalreflasher panelwhichinturnwillreflashadcsystemtroublealarmtothecontrolroomannunciator. | |||
Thisisconsistent withthegeneraldesignphilosophy asdiscussed inSection2.0.3.8BatterFloatChareCurrentIndication Undernormalconditions, thebatteryfloatchargecurrentisverysmallcomparedtobatterydischarge current.measurement ofthiscurrentrequiresaverysensitive ammeter.Shuntbypassesareemployedtoprotecttheammetermovementfromthemuchlargerbatterydischarge currentpossibleinthiscircuit.Theseshuntsmustbemanuallyremovedwhenreadingnormalsmallfloatchargecurrent.Thusthisreadingcannotbecontinuous andnoautomatic indication oralarmscanbegiven.Sincetheintentofindicating "BatteryFloatChargeCurrent"istodetermine thebatterycondition, themethodusedtoaccomplish thispurposeshouldnotbeimportant. | |||
Thebusundervoltage, busground,batterymonitorandbatterychargerfailurealarms(previously described) providecontinuous monitoring todetectdegradation ofbatterycapability. | |||
Thesealarmswillreflashthedcsystemtroublealarminthecontrolroom,andanoperatorisdispatched locallytodetermine thecauseofthecondition andinitiatecorrective action. | |||
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.125VDCSUBSYSTEM PAGE8Specificindication isprovidedonthelocalreflasher panel.Thisresponseisexactlywhatwouldbeachievedifanimproperstateofbatterycurrentwereindicated onanammeterinthecontrolroom.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.9BatterCircuitOututCurrentIndication. | |||
Innormalcondition whenthebatterychargerissupplying the125Vdcpower,thebatterycircuit(batteryandthebatterycharger)outputcurrentisindicated byanammeterlocatedatthebatterycharger.Inthecondition ofabatterychargerfailure,thebatterysuppliesthedcpower.Inthiscondition thebatterycircuitoutputcurrentisindicated byanammeterlocatedatthedcloadcenter.Asindicated inSection3.8,theintentofindicating "batterycurrent"istodetermine thebatterycondition, andtherefore themethodusedtoaccomplish thispurposeshouldnotbeimportant. | |||
3.10BatterDischareIndication Aspreviously discussed inSection3.7,abatterydischarge willoccurasaresultofabatterychargerfailureorsystemcurrentinexcesstobatterychargercapability. | |||
Sincetheseconditions areautomatically alarmedinthecontrolroom(viathesystemtroublealarm),anoperatorwillbedispatched locallytodetermine thecauseofthecondition andinitiatecorrective action.Thisresponseisexactlywhatwouldbeachievedifbatterydischarge currentwasindicated onanammeterinthecontrolroom. | |||
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.125VDCSUBSYSTEM PAGE93.11BusVoltaeIndication Thebattery,thebatterychargerandthedcloadcenterof125Vdcsubsystem arelocatedincloseproximity ofeachother.Thebatterychargerandthedcloadcenterareeachprovidedwithavoltmeter. | |||
Thepurposeofabusvoltmeter atthecontrolroomwouldbetoenabletheoperatortodispatchsomeonetotakecorrective actionlocallytocorrectabnormalbusvoltage.AtSSESthebusundervoltage ismonitored directlyandthebusovervoltage conditions aremonitored atthebatterychargeroutput.Thebusundervoltage andthebatterychargeroutputovervoltage conditions areannunciated as125Vdcsystemlowvoltageorbatterychargertroubleatthelocalreflasher panel.Adcsystemtroublealarmisreflashed tothecontrolroomannunciator bythelocalreflasher panel.Thisdesignautomatically alertsthecontrolroomoperatortounusualvoltageconditions withoutunnecessarily requiring hisperiodicattention andanalysis. | |||
Asaresult,125Vdcbusvoltageindication isnotprovidedinthecontrolroomandhasbeenprovidedonthefrontoftheloadcenterwhereitprovidesusefulinformation duringsurveillance andmaintenance activities. | |||
Avoltmeter islocatedonthefrontofthebatterychargerpanel.Withthechargeroutputcircuitbreakerclosed,thechargeroutputandthebusvoltagesareessentially thesameduetothecloseproximity ofthechargertotheloadcenter.Allabnormalvoltageconditions ofthebatterychargerareannunciated atthelocalreflasher panelwhichisreflashed tothecontrolroomasadcsystemtroublealarm.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.12,AlarmResonseProcedure Controlroomalarmresponseprocedures fora125Vdcsystemtroublealarmdirecttheoperatortorespondtothelocalreflasher paneltodetermine thecondition whichcausedthealarm. | |||
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S. | RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.125VDCSUBSYSTEH PAGE10Localalarmresponseprocedures forthereflasher panelareprovidedtodirecttheoperatortodetermine thecauseofthecondition andtoinitiatecorrective action.3.13Indication ofBassedandInoerableStatusofCircuitBreakersorOtherOisconnectin DevicesAlthoughindication ofbypassedandinoperable statusofcircuitbreakersorotherdisconnecting devicesisnotprovidedasapartoftheBypassIndication System,the125VdcSystemTroubleAlarminthecontrolroomisinitiated forthefollowing condition (whicharedisconnecting devicesinthesystem):Hainbatteryfuseopen.Batterychargeracinputcircuitbreakeropen.Batterychargerdcoutputcircuitbreakeropenor125Vdcloadcenterinputbreakeropen.125Vdcloadcenterfeederbreakerto125Vdcdistribution panelsopen.r(Theundervoltage relayatthedistribution panelsinitiates thedistribution panellowvoltagealarmatthelocalreflasher panelwhichisreflashed tothecontrolroom125Vdcsystemtroublealarm.) | ||
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.125VDCSUBSYSTEN PAGE11TABLE1125VDCSstemReflashPanelAlarms1L6101.125VDCSystemLowVoltage2.125VDCSystemGround3.BatteryMonitor(indicates batterydegradation oropenbatteryfuses)4.BatteryChargerTroubleindicates (1)ACpowerfailure,(2)DCoutputbreakeropen,(3)batterychargerfailure,or(4)busovervoltage 5.125VDCDistribution Panel1D614LowVoltage6.125VDCDistribution Panel1D615LowVoltageC:XWP51XDDCSX125VDCSS.PGD (18)10/24/919:00am CHANNELA125VDCLOCALREHASHPANELWITHINDICATION 1L610MULTIPLEAIARMINPUTSFROM125VDCCHANNELAPOWERSYSTEMPERTABK1DCSYSTEMALARMINPUTSFROMOTHERREFLASHPANELS(SIMILARTOABOVE)CONTROLROOMPANEL1C651ANNUNCIATOR 125VDCSYSTEMTROUBLE1L610FIGURE1 INDICATOR UGHTREFLASHER PANELPOWERFAILURENAMEPlATE 125VDCSYSTEMLOWVOLTAGEBATTERYCHARGERSPARE125VDCSYSTEMGROUND125VDCDISTPANEL10614LOWVOLTAGESPAREBATTERYMONITOR125VDCPANEL1D615LOWVOLTAGESPARE125VDCSYSTEMLOCALREFlASHER PANELOYPfCADFIGURE2 59BATTERYCHARGERAMMETERVOLTMETER BATTERYBANKFUSEBATTERYMONITORAMMETERQVOLTMETER 27SYSTEMGROUNDINDICATORS DCLOADCENTERLOADSLOADSSEETABLE1FORALARMS125VDCSYSTEMQYPICADFIGURE3 SUSUEHANNAS.E.S.250DCSYSTEMATTACHMENT IIIPage1ENCLOSURE 1Thefollowing information isapplicable toeitherUnit1orUnit2atSusquehanna SES.1.UnitSusuehannaS.E.S.Unit-1or2250VDC2.,Thenumberofindependent redundant divisions ofClass1Eorsafety-related dcpowerforthisplantis~2two.(IncludeanyseparateClasslEorsafety-related dc,suchasanydcdedicated to,thedieselgenerators.) | |||
b.Thenumberoffunctional safety-related divisions ofdcpowernecessary toattainsafeshutdownforthisunitis~1one3.Doesthecontrolroomatthisunithavethefollowing | |||
: separate, independently annunciated alarmsandindications foreachdivisionofdcpower?a.Alarms1.Batterydisconnect orcircuitbreakeropen?No2.Batterychargerdisconnect orcircuitbreakeropen(bothinputacandoutputdc)?No3.dcsystemground?No4.dcbusundervoltage? | |||
No5.dcbusovervoltage? | |||
No6.Batterychargerfailure?No SUSUEHANNAS.E.S.250DCSYSTENATTACHNENT III7.Batterydischarge? | |||
NoPage2b.Indications 1.Batteryfloatchargecurrent?No2.Batterycircuitoutputcurrent?No3.Batterydischarge? | |||
No4.Busvoltage?Noc.Doestheunithavewrittenprocedures forresponsetotheabovealarmsandindications? | |||
NoDoesthisunithaveindication ofbypassedandinoperable statusofcircuitbreakersorotherdevicesthatcanbeusedtodisconnect thebatteryandbatterychargerfromitsdcbusandthebatterychargerfromitsacpowersourceduringmaintenance ortesting?NoSeeremark¹15.Iftheanswertoanypartofquestion3or4isno,thenprovideinformation justifying theexistingdesignfeaturesofthefacility's safety-related dcsystems.*Seenotebelow.SeeRemark¹16.(1)Haveyouconducted areviewofmaintenance andtestingactivities tominimizethepotential forhumanerrorcausingmorethanonedcdivisiontobeunavai1ablet | |||
~esand(2)doplantprocedures prohibitmaintenance ortestingonredundant dcdivisions atthesametime?~es(Seeresponsefromthesite)IfthefacilityTechnical Specifications haveprovisions equivalent tothosefoundintheWestinghouse andCombustion Engineering StandardTechnical Specifications formaintenance andsurveillance, thenquestion7maybeskippedandastatement tothateffectmaybeinsertedhere. | |||
SUSUEHANNAS.E.S.250OCSYSTENATTACHMENT IIIPage37.Aremaintenance, surveillance andtestprocedures regarding stationbatteries conducted routinely atthisplant?Specifically: | |||
a.Atleastonceper7daysarethefollowing verifiedtobewithinacceptable limits:1.Pilotcellelectrolyte level?Yes2.Specifygravityorchargingcurrent?Yes3.Floatvoltage?Yes4.Totalbusvoltageonfloatcharge?Yes5.Physicalcondition ofallcells?Yesb.Atleastonceper92days,orwithin7daysafterabatterydischarge; overcharge, orifthepilotcellreadings, areoutsidethe7-daysurveillance requirements arethefollowing verifiedtobewithinacceptable limits:l.Electrolyte levelofeachcell?Yes2.Theaveragespecificgravityofallcells?Yes3.Thespecificgravityofeachcell?Yes4.Theaverageelectrolyte temperature ofarepresentative numberofcells?Yes5.Thefloatvoltageofeachcell?Yes6.Visuallyinspectormeasureresistance ofterminals andconnectors (including theconnectors atthedcbus)?Yes SUSUEHANNAS.E.S.250DCSYSTEMATTACHMENT IIIc.Atleastevery18monthsarethefollowing verified: | |||
Page41.Lowresistance ofeachconnection (bytest)?Yes2.Physicalcondition ofthebattery?Yes3.Batterychargercapability todeliverratedampereoutputtothedcbus?Yes4.Thecapability ofthebatterytodeliveritsdesigndutycycletothedcbus?Yes5.Eachindividual cellvoltageiswithinacceptable limitsduringtheservicetest?Yesd.Atleastevery60months,iscapacityofeachbatteryverifiedbyperformance ofadischarge test?Yese.Atleastannually, isthebatterycapacityverifiedbyperformance discharge test,ifthebatteryshowssignsofdegradation orhasreached85Koftheexpectedservicelife?Yes8.Doesthisplanthaveoperational featuressuchthatfollowing lossofonesafety-related dcpowersupplyorbus:a.Capability ismaintained forensuringcontinued andadequatereactorcooling?Yesb.Reactorcoolantsystemintegrity andisolation capability aremaintained? | |||
Yesc.Operating procedures, instrumentation (including indicators andannunciators), | |||
andcontrolfunctions areadequatetoinitiatesystemsasrequiredtomaintainadequatecorecooling?Yes9.Iftheanswertoanypartofquestion6,7or8isno,thenprovideyourbasisfornotperforming themaintenance, surveillance andtest SUSUEHANNAS.E.S.250DCSYSTEMATTACHNENT IIIPage5procedures described and/orthebasesfornotincluding theoperational featurescited.*Seenotebelow.*Note:Forquestions involving supporting typeinformation (question numbers5and9)insteadofdeveloping andsupplying theinformation inresponsetothisletter,youmaycommittofurtherevaluatetheneedforsuchprovisions duringtheperformance ofyourindividual plantexamination forsevereaccidentvulnerabilities (IPE).Ifyouselectthisoption,youarerequiredto:(1)Sostateinresponsetothesequestions, and(2)Committoexplicitly addressquestions 5and9inyourIPEsubmittal pertheguidelines outlinedinNUREG-1335 (Section2.1.6,Subitem7),"Individual PlantExamination: | |||
Submittal Guidance." | |||
c:~sp51~docsQR106001.PGD (18)10/24/919:06am RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.250VDCSUBSYSTEM PAGE1REMARK1:1.0Thefollowing indications andalarmsforthe250VdcclasslEsubsystem areprovided. | |||
Justification forthisdesignhasbeenpreviously providedinPLA-959totheNRCdated11/6/81,regarding ControlRoommonitoring ofClass1Edcpowersystems.AlarmorIndication BusUndervoltage AlarmBusGroundAlarmBatteryMonitorAlarmBatteryChargerTroubleAlarmBusAmmeterBusVoltmeter BatteryChargerAmmeterBatteryChargerVoltmeter DCSystemTroubleAlarmLocalLocationControlRoomNotes1,21,21,2,41,2,5NOTES:1.SeeTable1andFigure2forspecificlocalalarmindication. | |||
2.Thesearelocallyindicated andactuatedcsubsystem troublealarm,seeTable1andFigurel.3.Metersareprovidedlocally.SeeFigure3. | |||
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.250VDCSUBSYSTEM PAGE24.Batterymonitorcomparesbatterycenterpointvoltagewithhighandlowthreshold reference pointsofthehighandlowvoltagecomparators. | |||
Thedeg}adedcellconditions (suchasashortedcell)oranopencircuitcondition (suchasanopenfuse)aredetectedbythebatterymonitor.5.Batterychargertroublealarmindication isprovidedforbatterychargerACpowerfailure,DCoutputbreakeropen,batterychargerfailurealarmoperation, andbusovervoltage. | |||
6.Oneannunciator windowforeach250Vdcsubsystem isprovided. | |||
==2.0 Themonitoring== | |||
schemeprovidedforthedcpowersubsystem isbasedonthedegreeofcontrolprovidedtothecontrolroomoperator. | |||
Sincethedcpowersystemequipment cannotberemotelycontrolled, asingledcsystemtroubleannunciator windowforeachsubsystem isprovidedinthecontrolroom,consistent withthesystemlevelalarmcriteriasetforthinSectionBofR.G.1.47.TheSSESdesignisbasedonthegeneralcriteriathat,iftheoperatorcanperformsomecorrective actioninthecontrolroominresponsetoaspecificinput,thatinformation isspecifically provided. | |||
Thedcpowersystemequipment cannotbecontrolled fromthecontrolroom.Annunciating specificinputsfromthe250Vdcsysteminthecontrolroomdoesnotenhancethecontrolroomoperators's abilitytodealwiththesituation anditwouldnotbeconsistent withSSESalarmdesignphilosophy. | |||
However,iftheonlyresponserequiredistodispatchanoperator, toanarearemovedfromthecontrolroom,thentheonlyinformation requiredinthecontrolroomisgeneralinformation withonlythelevelofspecificity requiredtodirectthatoperatortotheproperlocation. | |||
Thismethodisfasterandmorereliablesinceabnormalconditions areautomatically alarmed.Furthermore, thisapproachisconsistent withthehumanfactorsengineering goaltonotoverburdentheoperatorwithunnecessary information. | |||
250Vdcsysteminstrumentation, locallyprovided, isinfullcompliance withtherequirement ofIEEE308-1974andRegulatory Guide1.47. | |||
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.250VDCSUBSYSTEM PAGE3TheDCsystemgeneraltroublealarmsandspecificlocalindicators inconjunction withtheroutineoperatorsurveillance providepositiveassurance thattheClasslEdcpowersystemaremaintained inasteadystatereadytoperformtherequiredsafetyfunction. | |||
==3.0 Following== | |||
isthejustification foreachalarmandindication listedinGenericLetter91-06.3.1BatterDisconnect orCircuitBreaker0enAlarm:TheSusquehanna S.E.S.(SSES)250Vdcsubsystem utilizesfusesasthebatterydisconnect. | |||
Thiscondition isdetectedbythebatterymonitor.Thebatterymonitorutilizesavariablethreshold circuittogetherwithtwocomparators (highandlow)todetectthelossofbatterycapability duetoanopencircuit(i.e.,anopenfuseordegradedcellcondition). | |||
Avariablethreshold circuitacceptsthebatterychargervoltageanddevelopstwothreshold voltagesforusewiththecomparators. | |||
Whenthemonitored voltagesgoaboveorbelowthethresholds, thebatterymonitoroutputrelaycontactsinitiatealocalbatterymonitoralarmwhichisreflashed tothecontrolroomasa250Vdcsystemtroublealarm.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.2BatterCharerDisconnect orCircuitBreaker0enBothInutACandOututDCAlarm3.2.1BatteryChargerACInputDisconnect orCircuitBreaker:SSESutilizesacircuitbreakerinthebatterychargerasadisconnect fortheacinputpowersupply.Anacpowerfailurealarmrelayisinstalled internaltothebatterychargertodetectlossofacinputpower.Thiscondition couldbecausedbyanopeninputcircuitbreakerorlossofthe480Vacpowersupplytothecharger.Theacpowerfailurealarmrelayinitiates abatterychargertroublealarmatthelocalreflasher panel,whichisreflashed to | |||
RESPONSETOGENERICLETTER91- | RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.250VDCSUBSYSTEM PAGE4thecontrolroomasa250Vdcsystemtroublealarm.Thisisconsistent withthegeneraldesignphilosophy discussed insection2.0.3.2.2BatteryChargerDCOutputCircuitBreakerSSESutilizesacircuitbreakerinthebatterychargerasadisconnect forthedcoutputcircuit.Thecircuitbreakerisprovidedwithanauxiliary positionindicating switch.Aswitchcontactwhichisclosedwhenthecircuitbreakerisopenisusedtoinitiateabatterychargertroublealarmatthelocalreflasher panel.Adcsystemtroublealarmisreflashed tothecontrolroombythelocalreflasher panel.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.3DCSstemGroundAlarmThe250Vdcsubsystem isungrounded andisprovidedwithagrounddetection circuit.Itconsistsofarelayhavingacentertappedcoil.Thecoilisconnected acrossthepositiveandnegativebusanditscenterpointisgrounded. | ||
Thegrounddetection relaycoilisnotactuatedduringnormaloperation ofthe250Vdcsubsystem whenagroundisnotpresent.Agroundoneitherthepositiveornegativebusofthe250Vdcsubsystem causesone-halfoftherelaycoiltobeshortcircuited, thusproviding sufficient voltagetotheremaining relaycoilhalftopickuptherelay.Anormallyopencontactoftherelayclosesandinitiates a250Vdcsystemgroundalarmatthelocalreflasher panel.Adcsystemtroublealarmisreflashed tothecontrolroomannunciator bythelocalreflasher panel.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.,3.4DCBusUndervolta eAlarmThe250Vdcsubsystem isprovidedwithadcbusundervoltage relay.Therelayisconnected acrossthepositiveandnegative RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.250VDCSUBSYSTEM PAGE5busofthe250Vdcsubsystem. | |||
Therelayisnormallyenergized andsettodropoutatthespecified setpoint. | |||
A250Vdcbusundervoltage alarmatthelocalreflasher panelisinitiated aftertheundervoltage relaydropsout.Thelocalreflasher panel,inturn,reflashes thealarmtothecontrolroomannunciator asadcsystemtroublealarm.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.5DCBusOvervolta eAlarmThe250Vdcsubsystem isprovidedwithanovervoltage relay.Therelayislocatedinsidethebatterychargercabinet.Itisconnected acrossthepositiveandnegative250Vdcbusofthebatterychargerandsettopickupatthespecified setpoint. | |||
Anormallyopencontactoftheovervoltage relay,whenclosed,initiates abatterychargertroublealarmatthelocalreflasher panelwhichinturnwillreflashadcsystemtroubletothecontrolroomannunciator. | |||
Sincethebattery,'he batterychargerand,thedcloadcenterareincloseproximity ofeachother,thebatterychargervoltageisrepresentative of250Vdcbusvoltage.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.6BatterCharerFailureAlarmThe250Vdcsubsystem batterychargerisprovidedwithabatterychargerfailurerelay.Thisrelaywilldetectthelossofthechargeroutputcurrentwiththeinputandoutputcircuitbreakersclosed.Thiscondition isindicative ofabatterychargerfailureanditinitiates abatterychargertroublealarmatthelocalreflasher panelwhichinturnwillreflashadcsystemtroublealarmtothecontrolroomannunciator. | |||
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.250VDCSUBSYSTEM PAGE6Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.7BatterDischareAlarmThebatterycanonlydischarge whenitsterminalvoltageislessthanthenominalopen.circuitvoltage.Thisisindicative ofabatterychargerfailureorsystemcurrentinexcessofthe,chargercapability. | |||
Abatterychargerfailurealarmisprovidedanditsoperation isdiscussed inSection3.6.Whensystemcurrentexceedsbatterycharger'apability, adcsystemundervoltage condition willoccur,andwillbedetectedbythedcbusundervoltage relay.(SeeSection3.4)Chargerfailureandbusundervoltage initiatealarmsatthelocalreflasher panelwhichinturnwillreflashadcsystemtroublealarmtothecontrolroomannunciator. | |||
Thisisconsistent withthegeneraldesignphilosophy asdiscussed inSection2.0.3.8BatterFloatChareCurrentIndication Undernormalconditions, thebatteryfloatchargecurrentisverysmallcomparedtobatterydischarge current.Measurement ofthiscurrentrequiresaverysensitive ammeter.Shuntbypassesareemployedtoprotecttheammetermovementfromthemuchlargerbatterydischarge currentpossibleinthiscircuit.Theseshuntsmustbemanuallyremovedwhenreadingnormalsmallfloatchargecurrent.Thusthisreadingcannotbecontinuous andnoautomatic indication oralarmscanbegiven.Sincetheintentofindicating "BatteryFloatChargeCurrent"istodetermine thebatterycondition, themethodusedtoaccomplish thispurposeshouldnotbeimportant. | |||
Thebusundervoltage, busground,batterymonitorandbatterychargerfailurealarms(previously described) providecontinuous monitoring todetectdegradation ofbatterycapability. | |||
Thesealarmswillreflashthedcsystemtroublealarminthecontrol RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.250VDCSUBSYSTEM PAGE7room,andanoperatorisdispatched locallytode'termine thecauseofthecondition andinitiatecorrective action.Specificindication isprovidedonthelocalreflasher panel.Thisresponseisexactlywhatwouldbeachievedifanimproperstateofbatterycurrentwereindicated onanammeterinthecontrolroom.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.9BatterCircuitOututCurrentIndication Innormalcondition whenthebatterychargerissupplying the250Vdcpower,thebatterycircuit(batteryandthebatterycharger)outputcurrentisindicated byanammeterlocatedatthebatterycharger.Inthecondition ofabatterychargerfailure,thebatterysuppliesthedcpower.Inthiscondition, thebatterycircuitoutputcurrentisindicated byanammeterlocatedatthedcloadcenter.Asindicated inSection3.8,theintentofindicating "batterycurrent"istodetermine thebatterycondition, andtherefore themethodusedtoaccomplish thispurposeshouldnotbeimportant. | |||
3.10BatterOischareIndication Aspreviously discussed inSection3.7,abatterydischarge willoccurasaresultofabatterychargerfailureorsystemcurrentinexcesstobatterychargercapability. | |||
Sincetheseconditions areautomatically alarmedinthecontrolroom(viathesystemtroublealarm),anoperatorwillbedispatched locallytodetermine thecauseofthecondition andinitiatecorrective action.Thisresponseisexactlywhatwouldbeachievedifbatterydischarge currentwasindicated onanammeterinthe RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.250VDCSUBSYSTEM PAGE8controlroom.3.11BusVoltaeIndication Thebattery,thebatterychargerandthedcloadcenterof250Vdcsubsystem arelocatedincloseproximity ofeachother.Thebatterychargerandthedcloadcenterareeachprovidedwithavoltmeter. | |||
Thepurposeofabusvoltmeter atthecontrolroomwouldbetoenabletheoperatortodispatchsomeonetotakecorrective actionlocallytocorrectabnormalbusvoltage.AtSSESthebusundervoltage ismonitored directlyand'thebusovervoltage conditions aremonitored atthebatterychargeroutput.Thebusundervoltage andthebatterychargeroutputovervoltage | |||
.conditions areannunciated as250Vdcsystemlowvoltageorbatterychargertroubleatthelocalreflasher panel.Adcsystemtroublealarmisreflashed tothecontrolroomannunciator bythelocalreflasher panel.Thisdesignautomatically alertsthecontrolroomoperatortounusualvoltageconditions withoutunnecessarily requiring hisperiodicattention andanalysis. | |||
Asaresult,250Vdcbusvoltageindication isnotprovidedinthecontrolroomandhasbeenprovidedonthefrontoftheloadcenterwhereitprovidesusefulinformation duringsurveillance andmaintenance activities. | |||
Avoltmeter islocatedonthefrontofthebatterychargerpanel.Withthechargeroutputcircuitbreakerclosed,thechargeroutputandthebusvoltagesareessentially thesameduetothecloseproximity ofthechargertotheloadcenter.Allabnormalvoltageconditions ofthebatterychargerareannunciated atthelocalreflasher panelwhichisreflashed tothecontrolroomasadcsystemtroublealarm.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0. | |||
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.250VDCSUBSYSTEM PAGE93.12AlarmResonseProcedure Controlroomalarmresponseprocedures fora250Vdcsystemtroublealarmdirecttheoperatortorespondtothelocalreflasher paneltodetermine thecondition whichcausedthealarm.Localalarmresponseprocedures forthereflasher panelareprovidedtodirecttheoperatortodetermine thecauseofthecondition andtoinitiatecorrective action.3.13Indication ofBassedandInoerableStatusofCircuitBreakersorOtheDisconnectin DevicesAlthoughindication ofbypassedandinoperable statusofcircuitbreaker's orotherdisconnecting devicesisnotprovidedasapartoftheBypassIndication System,the250VdcSystemTroubleAlarminthecontrolroomisinitiated forthefollowing condition (whicharedisconnecting devicesinthesystem):Mainbatteryfuseopen.Batterychargeracinputcircuitbreakeropen.Batterychargerdcoutputcircuitbreakeropen,or250Vdcloadcenterbreakeropen.250Vdcloadcenterfeederbreakerto250Vdcmotorcontrolcentersopen.(Eachoftheloadcenterfeederbreakerstothe250VdcMCC'sisprovidedwithanauxiliary positionindicating switchwhichinitiates analarmonthelocalreflasher panelwhenthecircuitbreakerisopen.A250Vdcsystemtroublealarmisreflashed tothecontrolroombythelocalreflasher panel.) | |||
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.UNITIANDUNIT2DG- | RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.250VDCSUBSYSTEM PAGE10TABLE1250VDCSstemReflashPanelIndicators Ticall.250VDCSystemLowVoltage2.250VDCSystemGround3.BatteryMonitor(indicates batterydegradation oropenbatteryfuses)4.BatteryChargerTroubleindicates (1)ACpowerfailure,(2)DCoutputbreakeropen,(3)batterychargerfailure,or(4)busovervoltage (Division Ihas2chargers, DivisionIIhas1charger)5.LoadCenterIncomingBreakersTrip6.RCIC&Isolation ValveControlCenter1D254trouble7.TurbineBldg.ControlCenter1D155trouble8.ComputerUPSSupplyBreakerTripC:XMP51%00CSX250VDCSS.PGD (18)10/24/919:08am CHANNELA250VDCLOCALRERASHPANELWITHINDICATION 1L650MULTIPLEALARMINPUISFROM250VDCCHANNELAPOWERSYStEMPERTABLE1DCSYSTEMALARMINPUTSFROMOTHERREFLASHPANELS(SIMILARTOABOVE)CONTROLROOMPANEL1C651ANNUNCIATOR 250VDCSYSTEMTROUBLE1L650FIGURE1 INDICATOR UGHTREFLASHER PANELPOWERFAILURESYSTEMLOWVOLTAGEBATTERYCHAIWERATROUBLERCIC&ISOVLVSCONTROLCENTER1D254TROUBLE250VDCSYSTEMGROUNDBATTERYCHARGERBTROUBLETURBBU)GCONTROLCENTER1D155TROUBLEBATTERYMONITORLCINCOMINGBKR7245212/22 TRIPCOMPUTERUPSSUPPLYBKRTRIP250VDCSYStEMLOCALREFLASHER PANELOYPICAOFIGURE2 59BATTERYCHARGERAMMETERVOLTMETER BATTERYBANKFUSEBATTERYMONITORAMMETERQVOLTMETER 27SYSTEMGROUNDINDICATORS DCLOADCENTERLOADSLOADSSEETABLE1FORALARMS250VDCSYSTEMOYPICAQFIGURE3 | ||
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.UNIT1ANDUNIT2DG- | |||
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.UNIT1ANDUNIT2DG- | SUSUEHANNAS.E.S.UNIT-1ANDUNIT2DG-E125VDCSYSTEMATTACHMENT IVPage1ENCLOSURE 1Thefollowing information isapplicable toeitherUnitatSusquehanna SES.UnitSusuehannaS.E.S.CommontoUnit1&2DG-E125VDCSYSTEM'a~Thenumberofindependent redundant divisions ofClass1Eorsafety-related dcpowerforthisplantisseeRemarkl.(IncludeanyseparateClass1Eorsafety-related dc,suchasanydcdedicated tothedieselgenerators.) | ||
b.Thenumberoffunctional safety-related divisions ofdcpowernecessary toattainsafeshutdownforthisunitisseeRemark1.3.Doesthecontrolroomatthisunithavethefollowing | |||
: separate, independently annunciated alarmsandindications foreachdivisionofdcpower?a.alarms1.Batterydisconnect orcircuitbreakeropen?No2.Batterychargerdisconnect orcircuitbreakeropen(bothinputacandoutputdc)?No3.dcsystemground?No4.dcbusundervoltage? | |||
No5.dcbusovervoltage? | |||
No6.Batterychargerfailure?No7.Batterydischarge? | |||
No 0 | |||
SUSUEHANNAS.E.S.UNIT-1ANDUNIT2DG-E125VDCSYSTEMb.Indications ATTACHMENT IVPage21.Batteryfloatchargecurrent?No2.Batterycircuitoutputcurrent?No3.Batterydischarge? | |||
No4.Busvoltage?Noc.Doestheunithavewrittenprocedures forresponsetotheabovealarmsandindications? | |||
NoDoesthisunithaveindication ofbypassedandinoperable statusofcircuitbreakersorotherdevicesthatcanbeusedtodisconnect thebatteryandbatterychargerfromitsdcbusandthebatterychargerfromitsacpowersourceduringmaintenance ortesting?NoSeeRemark25.Iftheanswertoanypartofquestion3or4isno,thenprovideinformation justifying theexistingdesignfeaturesofthefacility's safety-related dcsystems.*Seenotebelow.SeeRemark26.(I)Haveyouconducted areviewofmaintenance andtestingactivities tominimizethepotential forhumanerrorcausingmorethanonedcdivisiontobeunavailablet | |||
~esand(2)doplantprocedures prohibitmaintenance ortestingonredundant dcdivisions atthesamatime?~esIfthefacilityTechnical Specifications haveprovisions equivalent tothosefoundintheWestinghouse andCombustion Engineering StandardTechnical Specifications formaintenance andsurveillance, thenquestion7maybeskippedandastatement tothateffectmaybeinsertedhere. | |||
SUSUEHANNAS.E.S.UNIT-1ANDUNIT2DG-E125VDCSYSTEMATTACHMENT IVPage37.Aremaintenance, surveillance andtestprocedures. | |||
regarding stationbatteries conducted routinely atthisplant?'pecifically: | |||
a.Atleast,onceper7daysarethefollowing verifiedtobewithinacceptable limits:1.Pilotcellelectrolyte level?Yes2.Specifygravityorchargingcurrent?Yes3.Floatvoltage?Yes4.Totalbusvoltageonfloatcharge?Yes5.Physicalcondition ofallcells?Yesb.Atleastonceper92days,orwithin7daysafterabatterydischarge, overcharge, orifthepilotcellreadingsareoutsidethe7-daysurveillance requirements arethefollowing verifiedtobewithinacceptable limits:l.Electrolyte levelofeachcell?Yes2.Theaveragespecificgravityofallcells?Yes3.Thespecificgravityofeachcell?Yes4.Theaverageelectrolyte temperature ofarepresentative numberofcells?Yes5.Thefloatvoltageofeachcell?Yes6.Visuallyinspectormeasureresistance ofterminals andconnectors (including theconnectors atthedcbus)?Yes SUSUEHANNAS.E.S.UNIT-1ANDUNIT2DG-'E125VDCSYSTEMc.Atleastevery18monthsarethefollowing verified: | |||
ATTACHMENT IVPage41.Lowresistance ofeachconnection (bytest)?Yes2.Physicalcondition ofthebattery?Yes3.Batterychargercapability todeliverratedampereoutputtothedcbus?YestThecapability ofthebattery-todeliveritsdesigndutycycletothedcbus?Yes5.Eachindividual cellvoltageiswithinacceptable limitsduringtheservicetest?Yesd.Atleastevery60months,iscapacityofeachbatteryverifiedbyperformance ofadischarge test?Yese.Atleastannually, isthebatterycapacityverifiedbyperformance discharge test,ifthebatteryshowssignsofdegradation orhasreached85Xoftheexpectedservicelife?Yes8.Doesthisplanthaveoperational featuressuchthatfollowing lossofonesafety-related dcpowersupplyorbus:a.Capability ismaintained forensuringcontinued andadequatereactorcooling?Yesb.Reactorcoolantsystemintegrity andisolation capability aremaintained? | |||
Yesfc.Operating procedures, instrumentation (including indicators andannunciators), | |||
andcontrolfunctions areadequatetoinitiatesystemsasrequiredtomaintainadequatecore,cooling? | |||
Yes SUSUEHANNAS.E.S.UNIT-1ANDUNIT2DG-E125VDCSYSTEMATTACHMENT IVPage59Iftheanswertoanypartofquestion6,7or8isno,thenprovideyourbasisfornotperforming themaintenance, surveillance andtestprocedures described and/orthebasesfornotincluding theoperational featurescited.*Seenotebelow.*Note:Forquestions involving supporting typeinformation (question numbers5and9)insteadofdeveloping andsupplying theinformation inresponsetothisletter,youmaycommittofurtherevaluatetheneedforsuchprovisions duringtheperformance ofyourindividual plantexamination forsevereaccidentvulnerabilities (IPE).Ifyouselectthisoption,youarerequiredto:(1)Sostateinresponsetothesequestions, and(2)Committoexplicitly addressquestions 5and9inyourIPEsubmittal pertheguidelines outlinedinNUREG-1335 (Section2.1.6,Subitem7),"Individual PlantExamination: | |||
Submittal Guidance." | |||
c:Xup51hdocshdg-e125v.pgd (18)10/24/91 8:48am RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.UNIT1ANDUNIT2DG-E125VDCSUBSYSTEM PAGE1REMARK1:DieselGenerator Eisaninstalled sparedieselgenerator capableofsubstituting asanemergency powersourceforanyoneoftheexistingemergency dieselgenerators (A,B,C,D).TheDieselGenerator E125Vdcpowersubsystem isidentified asChannelHandisdedicated toproviding dcpowertoESWvalvesforDieselGenerator Ecooling,DieselGenerator Econtrols, andDieselGenerator E4.16kVSwitchgear. | |||
Thisequipment isalllocatedinaseparateDieselGenerator Ebuilding. | |||
TheDieselGenerator E125VdcSubsystem isrequiredonlywhenthisdieselgenerator issubstituting foroneoftheexistingdieselgenerators. | |||
Itisinadditionto,independent andisolatedfromtheotherfourClasslE125VdcSubsystems. | |||
Lossofanyoneofthe125VdcSubsystems doesnotpreventtheminimumsafetyfunctionfrombeingperformed. | |||
REMARK2:1.0Thefollowing indications andalarmsfortheDG-E125VdcclasslEsubsystem areprovided. | |||
Justification forthisdesignisconsistent withthedesignphilosophy regarding ControlRoommonitoring ofClass1Edcpowersystemsaspreviously providedinPLA-959totheNRCdated11/6/81. | |||
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.UNIT1ANDUNIT2DG-E125VDCSUBSYSTEM PAGE2AlarmorIndication LocalLocationControlRoomNotesBusUndervoltage AlarmBusGroundAlarmBatteryMonitorAlarmBatteryChargerTroubleAlarmBusAmmeter1,21,21,2,41,2,5BusVoltmeter BatteryChargerAmmeterBatteryChargerVoltmeter DCSystemTroubleAlarmNOTES:1.SeeTable1forspecificlocalalarmannunciation. | |||
2.ThesealarmsarelocallyprovidedonDG-Eannunciator/reflasher panelOC577E.Adcsubsystem troublealarm.isreflashed tothecontrolroombythisannunciator. | |||
SeeTable1,Figure1.3.Hetersareprovidedlocally.SeeFigure2.4.Batterymonitorcomparesbatterycenterpointvoltagewithhighandlowthreshold reference points,,of thehighandlowvoltagecomparators. | |||
Thedegradedcellconditions (such"asashortedcell)oranopencircuitcondition (suchasanopenfuse)aredetectedbythebatterymonitor. | |||
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.UNIT1ANDUNIT2DG-E125VDCSUBSYSTEM PAGE35.Batterychargertroublealarmindication isprovidedforbatterychargerACpowerfailure,DCoutputbreakeropen,batterychargerfailurealarmoperation, batterychargerhigh/lowvoltageandbatterychargerhighvoltage(shutdown). | |||
6.Oneannunciator windowfortheDG-E125Vdcsubsystem isprovided. | |||
==2.0 Themonitoring== | |||
schemeprovidedforthedcpowersubsystem isbasedonthedegreeofcontrolprovidedtothecontrolroomoperator. | |||
Sincethedcpowersystemequipment cannotberemotelycontrolled, asingledcsystemtroubleannunciator windowforeachsubsystem isprovidedinthecontrolroom,consistent withthesystemlevelalarmcriteriasetforthinSectionBofR.G.1.47.TheSSESdesignisbasedonthegeneralcriteriathat,iftheoperatorcanperformsomecorrective actioninthecontrolroominresponsetoaspecificinput,thatinformation isspecifically provided. | |||
Thedcpowersystemequipment cannotbecontrolled fromthecontrolroom.Annunciating specificinputsfromthe125Vdcsysteminthecontrolroomdoesnotenhancethecontrolroomoperators's abilitytodealwiththesituation anditwouldnotbeconsistent withSSESalarmdesignphilosophy. | |||
However,.if theonlyresponserequiredistodispatchanoperatortoanarearemovedfromthecontrolroom,thentheonlyinformation requiredinthecontrolroomisgeneralinformation withonlythelevelofspecificity re'quired todirectthatoperatortotheproperlocation. | |||
Thismethodisfasterandmorereliablesinceabnormalconditions areautomatically alarmed.Furthermore, thisapproachisconsistent withthehumanfactorsengineering goaltonotoverburdentheoperatorwithunnecessary information. | |||
125Vdcsysteminstrumentation, locallyprovided, isinfullcompliance withtherequirement ofIEEE308-1974andRegulatory Guide1.47.eTheDCsystemgeneraltroublealarmsandspecificlocalindicators inconjunction withtheroutineoperatorsurveillance providepositiveassurance thattheClass1Edcpowersystemaremaintained inasteadystatereadytoperformtherequiredsafetyfunction. | |||
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.UNIT1ANDUNIT2DG-E125VDCSUBSYSTEM PAGE43.0Following isthejustification foreachalarmandindication listedinGenericLetter91-06.3.1BatterDisconnect orCircuitBreaker0enAlarm:TheSusquehanna S.E.S.(SSES)DG-E125Vdcsubsystem utilizesafuseddisconnect asthebatterydisconnect. | |||
Thiscondition isdetectedbythebatterymonitor.Thebatterymonitorutilizesavariablethreshold circuittogetherwithtwocomparators (highandlow)todetectthelossofbatterycapability duetoanopencircuit(i.e.,anopenfuseor,degradedcellcondition). | |||
Avariablethreshold circuitacceptsthebattery'chargervoltageanddevelopstwothreshold voltagesforusewiththecomparators. | |||
Whenthemonitored voltagesgoaboveorbelowthethresholds, thebatterymonitoroutputrelaycontactsinitiatealocalbatterymonitorannunciator whichisreflashed tothecontrolroomasaDG-E125Vdcsystemtroublealarm.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.2BatterCharerDisconnect orCircuitBreaker0enBothInutACandOututDCAlarm3.2.1BatteryChargerACInputDisconnect orCircuitBreaker:SSESutilizesacircuitbreakerinthebatterychargerasadisconnect fortheacinputpowersupply.Anacpowerfailurealarmrelayisinstalled internaltothebatterychargertodetectlossofacinputpower.Thiscondition couldbecausedbyanopeninputcircuitbreakerorlossofthe480Vacpowersupplytothecharger.Theacpowerfailurealarmrelayinitiates abatterychargertroublealarmatthelocalannunciator panel,whichisreflashed tothecontrolroomasaDG-E125Vdcsystemtroublealarm.Thisisconsistent withthegeneraldesignphilosophy discussed insection2.0. | |||
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.UNIT1ANDUNIT2DG-E125VDCSUBSYSTEM PAGE53.2.2BatteryChargerDCOutputCircuitBreakerSSESutilizesacircuitbreakerinthebatterychargerasadisconnect forthedcoutputcircuit.Thecircuitbreakerisprovidedwithanauxiliary positionindicating switch.Aswitchcontactwhichisclosedwhenthecircuitbreakerisopenisusedtoinitiateabatterychargertroublealarmatthelocalannunciator panel.ADG-Edcsystemtroublealarmisreflashed tothecontrolroombythelocalannunciator | |||
'anel.Thisisconsistent withthe,generaldesignphilosophy discussed inSection2.0.3.3DCSstemGroundAlarm'heDG-E125Vdcsubsystem isungrounded andisprovidedwithagrounddetection circuit.Itconsistsofarelayhavingacentertappedcoil.Thecoilisconnected acrossthepositiveandnegativebusanditscenterpointisgrounded. | |||
Thegrounddetection relaycoilisnotactuatedduringnormaloperation ofthe125Vdcsubsystem whenagroundisnotpresent.Agroundoneitherthepositiveornegativebusofthe125Vdcsubsystem causesone-halfoftherelaycoiltobeshortcircuited, thusproviding sufficient voltagetotheremaining relaycoilhalftopickuptherelay.Anormallyopencontactoftherelayclosesandinitiates a125Vdcsystemgroundalarmatthelocalannunciator panel.ADG-Edcsystemtroublealarmisreflashed tothecontrolroomannunciator bythelocalannunciator panel.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.4DCBusUndervolta eAlarmTheDG-E125Vdcsubsystem isprovidedwithabatterychargerundervoltage relay.Therelayisconnected acrossthepositiveandnegativebusofthe125Vdcbatterycharger.Therelayisnormallyenergized andsettodropoutatthespecified setpoint. | |||
Abatterychargertroublealarmatthelocalannunciator panelis | |||
RESPONSETOGENERICLETTER91-06SUSUEMANNAS.E.S.UNIT1ANDUNIT2DG-E125VDCSUBSYSTEPAGE6initiated aftertheundervoltage relaydropsout.Thelocalannunciator panel,inturn,reflashes thealarmtothecontrolroomannunciator asaDG-Edcsystemtroublealarm.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.Inadditiontothebatterychargerundervoltage relay,abusundervoltage relayisprovidedtodetectalossofbusvoltage.ThemostprobablecauseofaDCsystemundervoltage condition isaresultofabatterychargerproblem,whichwillbedetectedbythebatterycharger,failurealarmrelay(seeSection3.6).Thechargerfailurerelayinitiates abatterychargertroublealarmatthelocalannunciator panel,whichinturn,reflashes aDG-Edcsystemtroublealarmtothecontrolroomannunciator. | |||
Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.5DCBusOvervolta eAlarmTheDG-E125Vdcsubsystem isprovidedwithanovervoltage relay.Therelayislocatedinsidethebatterychargercabinet.Itisconnected acrossthepositiveandnegative125Vdcbusofthebatterychargerandsettopickupatthespecified setpoint. | |||
Anormallyopencontactoftheovervoltage relay,whenclosed,initiates abatterychargertroublealarmatthelocalannunciator panelwhichinturnwillreflashaDG-Edcsystemtroublealarmtothecontrolroomannunciator. | |||
Sincethebattery,thebatterychargerandthedcloadcenterareincloseproximity ofeachother,thebatterychargervoltageisrepresentative oftheDG-E125Vdcbusvoltage.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0. | |||
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.UNITIANDUNIT2DG-E125VDCSUBSYSTEM PAGE73.6BatterCharerFailureAlarmTheDG-E125Vdcsubsystem batterychargerisprovidedwithabatterychargerfailurerelay.Thisrelaywilldetectthelossofthechargeroutputcurrentwiththeinputandoutputcircuitbreakersclosed.Thiscondition isindicative ofabatterychargerfailureanditinitiates abatterychargertroublealarmatthelocalannunciator panelwhichinturnwillreflashaDG-Edcsystemtroublealarmtothecontrolroomannunciator. | |||
Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.7BatterDischareAlarmThebatterycanonlydischarge whenitsterminalvoltageislessthanthenominalopencircuitvoltage.Thisisindicative ofabatterychargerfailureorsystemcurrentinexcessofthechargercapability. | |||
Abatterycharger,failurealarmisprovidedanditsoperation isdiscussed inSection3.6.Whensystemcurrentexceedsbatterychargercapability, adcsystemundervoltage condition willoccur,andwillbedetectedbythebatterychargerundervoltage relay(seeSection3.4).Chargerfailureandbatterychargerundervoltage initiatealarmsatthelocalannunciatorpanelwhichinturnwillreflashaDG-Edcsystemtroublealarmtothecontrolroomannunciator. | |||
Thisisconsistent withthegeneraldesignphilosophy asdiscussed inSection2.0.3.8BatterFloatChareCurrentIndication Undernormalconditions, thebatteryfloatchargecurrentisverysmallcomparedtobatterydischarge current.Measurement ofthiscurrentrequiresaverysensitive ammeter.Shuntbypassesareemployedtoprotecttheammetermovementfromthemuchlargerbatterydischarge currentpossibleinthiscircuit.'hese shu'ntsmustbemanuallyremovedwhenreadingnormalsmallfloatchargecurrent.Thusthisreadingcannotbecontinuous andnoautomatic RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.UNIT1ANDUNIT2DG-E125VDCSUBSYSTEM PAGE8indication oralarmscanbegiven.Sincetheintentofindicating "BatteryFloatChargeCurrent"istodetermine thebatterycondition, themethodusedtoaccomplish thispurposeshouldnotbeimportant. | |||
Thebatterychargerundervoltage, busground,batterym'onitorandbatterychargerfailurealarms(previously described) providecontinuous monitoring todetectdegradation ofbatterycapability. | |||
ThesealarmswillreflashtheDG-Edcsystemtroublealarminthecontrolroom,andanoperatorisdispatched locallytodetermine thecauseofthecondition andinitiatecorrective action.Specificindication isprovidedonthelocalannunciator panel.Thisresponseisexactlywhatwouldbeachievedifanimproperstateofbatterycurrentwereindicated onanammeterinthecontrolroom.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.9BatterCircuitOututCurrentIndication Innormalcondition whenthebatterychargerissupplying the125Vdcpower,thebatterycircuit(batteryandthebatterycharger)outputcurrentisindicated byanammeterlocatedatthebatterycharger.Inthecondition ofabatterychargerfailure,thebatterysuppliesthedcpower.Inthiscondition thebatterycircuitoutputcurrentisindicated byanammeterlocatedatthedcswitchboard. | |||
Asindicated inSection3.8,theintentofindicating "batterycurrent"istodetermine thebatterycondition, andtherefore themethodusedtoaccomplish thispurposeshouldnotbeimportant. | |||
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.UNIT1ANDUNIT2DG-E125VDCSUBSYSTEM PAGE93.10BatterDischareIndication Aspreviously discussed inSection3.7,abatterydischarge willoccurasaresultofabatterychargerfailureorsystemcurrentinexcesstobatterychargercapability. | |||
Sincetheseconditions areautomatically alarmedinthecontrolroom(viathesystemtroublealarm),anoperator'will bedispatched locallytodetermine thecauseofthecondition andinitiatecorrective action.Thisresponseisexactlywhatwouldbeachievedifbatterydischarge currentwasindicated onanammeterinthecontrolroom.3.11BusVoltaeIndication Thebattery,thebatterychargerandthedcswitchboard oftheDG-E125Vdcsubsystem arelocatedincloseproximity ofeachother.Thebatterychargerandthedcswitchboard areeachprovidedwithavoltmeter. | |||
Thepurposeofabusvoltmeter atthecontrolroomwouldbetoenabletheoperatortodispatchsomeonetotakecorrective actionlocallytocorrectabnormalbusvoltage.Thiscondition willoccurwhenabatterychargerproblemispresent.Undervoltage andovervoltage conditions aremonitored atthebatterycharger,andareannunciated asbatterychargertroubleatthelocalannunciator panel.ADG-Edcsystemtroublealarmisreflashed tothecontrolroomannunciator bythelocalannunciator panel.Thisdesignautomatically alertsthecontrolroomoperatortounusualvoltageconditions withoutunnecessarily requiring hisperiodicattention andanalysis. | |||
Asaresult,125Vdcbusvoltageindication isnotprovidedinthecontrolroomandhasbeenprovidedonthefrontofthedcswitchboard whereitprovidesusefulinformation duringsurveillance andmaintenance activities. | |||
Avoltmeter islocatedonthefrontofthebatterychargerpanel.Withthechargeroutputcircuitbreakerclosed,thechargeroutputandthebusvoltagesareessentially thesameduetotheclose RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.UNIT1ANDUNIT2DG-E125VDCSUBSYSTEM PAGE10proximity ofthechargertotheloadcenter.Allabnormalvoltageconditions ofthebatterychargerareannunciated atthelocalannunciator panelwhichisreflashed tothecontrolroomasaDG-Edcsystemtroublealarm.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.12AlarmResonseProcedure Controlroomalarmresponseprocedures foraDG-E125Vdcsystemtroublealarmdirecttheoperatortorespondtothelocalannunciator paneltodetermine thecondition whichcausedthealarm.Localalarmresponseprocedures fortheannunciator panelareprovidedtodirecttheoperatortodetermine thecauseofthecondition andtoinitiatecorrective action.3.13Indication ofBassedandInoerableStatusofCircuitBreakersorOtherDisconnectin DevicesAlthoughindication ofbypassedandinoperable statusofcircuitbreakersorotherdisconnecting devicesisnotprovidedasapartoftheBypassIndication System,the125VdcSystemTroubleAlarminthecontrolroomisinitiated forthefollowing condition (whicharedisconnecting devicesinthesystem):Hainbatteryfuseddisconnect open.Batterychargeracinputcircuitbreakeropen.Batterychargerdcoutputcircuitbreakeropenor125Vdcswitchboard breakeropen. | |||
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.UNIT1ANDUNIT2DG-E125VDCSUBSYSTEM PAGE11TABLE1125VDG-EDCSstemAnnunciator PanelAlarmsl.125VDCSystemLowVoltage2.125VDCSystemGround3.BatteryHonitor(indicates batterydegradation oropenbatteryfuses)4.BatteryChargerTroubleindicates (1)ACpowerfailure,(2)DCoutputbreakeropen,(3),battery chargerfailure,(4)batterychargerhigh/lowvoltage,or(5)batterycharger'igh voltage(shutdown). | |||
C:XQP51%00CS~RGL91-06.PGD (18)10/24/918:35am DG-EBLDGPANELOC577EMULTIPLEALARMINPUTSFROMDG-E125VDCPOWERSYSTEMPERTABlE1CONTROLROOMPANELOC653ANNUNCIATOR DG-EBLDGPANELOC577EDCSYSTEMTROUBLEFIGURE1 7/5959BATTERYCHARGERAMMETERVOLTMETERBATTERYBANKFUSEBATTERYMONITORAMMETERVOLTMETER 27SYSTEMGROUNDINDICATORS DCSWITCHBOARD LOADSLOADSSEETABLE1FORALARMSDG-E125VDCSYSTEMFIGURE2}} |
Revision as of 04:50, 29 June 2018
ML18026A242 | |
Person / Time | |
---|---|
Site: | Susquehanna |
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) | |
Text
ACCELERATED DTRIBUTION DEMONS~TION SYSTEMREGULATORY INFORMATION DISTRIBUTION SYSTEM(RIDS)ACCESSION NBR:9111010196 DOC.DATE:91/10/24NOTARIZED:
NOFACIL:50-387 Susquehanna SteamElectricStation,Unit1,Pennsylva 50-388Susquehanna SteamElectricStation,Unit2,Pennsylva AUTH.NAMEAUTHORAFFILIATION KEISER,H.W.
Pennsylvania Power&LightCo.RECIP.NAME RECIPIENT AFFILIATION MILLER,C.L.
ProjectDirectorate I-2
SUBJECT:
ForwardsresponsetoGenericLtr91-06,"Resolution ofGenericIssuesA-30,'Adequacy ofSafety-Related DCPowerSupplies.'"
DISTRIBUTION CODE:AOOIDCOPIESRECEIVED:LTR 7ENCL/SIZE:TITLE:ORSubmittal:
GeneralDistribution DOCKET0500038705000388DCOPIESLTTRENCL1122NOTES:LPDR 1cyTranscripts.
~'PDR1cyTranscripts.
5:~~8~~r>>RECIPIENT IDCODE/NAME PDl-2LARALEIGH,J.
RECIPIENT IDCODE/NAME PD1-2PDCOPIESLTTRENCL11/0500038705000388ADiDINTERNAL:
ACRSNRR/DET/ESGB NRR/DST8E2NRR/DST/SICB8H7 NUDOCS-ABSTRACT OGC/HDS2RES/DSIR/EIB EXTERNAL:
NRCPDRNOTES:661111111110111122NRR/DET/ECMB 7DNRR/DOEA/OTS B11NRR/DST/SELB 7ENRR/DST/SRXB 8EOC/LFQEF-Kl'SIC111111111011RDNOTETOALL"RIDS"RECIPIENTS:
DDPLEASEHELPUSTOREDUCEXVASTE!CONTACTTHEDOCUMENTCONTROLDESK,ROOMPl-37(EXT.20079)TOELIMINATE YOURNAMEFROMDISTRIBUTION LISTSFORDOCUMENTS YOUDON'TNEED!TOTALNUMBEROFCOPIESREQUIRED:
LTTR26ENCL24 0Pennsylvania Power8LightCompanyTwoNorthNinthStreet~Allentown, PA,18101-1179,~,215/774-5151 HaroldW.KeiserSeniorVicePresident-Nuclear 215/7744194 1'CT24jtIQ)DirectorofNuclearReactorRegulation Attention:
Hr.C.L.Hiller,ProjectDirectorProjectDirectorate I-2DivisionofReactorProjectsU.S.NuclearRegulatory Commission Washington, D.C.20555SUSQUEHANNA STEANELECTRICSTATIONRESPONSETOGENERICLETTER91-06LA-3673FILESR41-1DDocketNos.50-387and50-388
DearHr.Hiller:
EnclosedisourresponsetoGenericLetter91-06,"Resolution ofGenericIssueA-30".Inanefforttoavoidconfusion causedbyextensive explanatory remarksprovidedforeachDCsystem,ourresponseisdividedintofourparts:ATTACHMENT I:24VDCSYSTEMATTACHMENT II:125VDCSYSTEMATTACHMENT III:250VDCSYSTEMATTACHMENT IV:DG'-E125VDCSYSTEMShouldyouhaveanyquestions, pleasecontactHr.W.W.Williams, at(215)774-7910.
Verytrulyyours,glH.W.KeiserEnclosure 9111p1Kp5ppp38701'9691102%PDRADOCP OCT24lg01FILESA17-8/so-24 PLA-'3673 Mr.C.L.Millercc:iiiLCD~ocumen.
Control-Desk-(original.)P NRCRegionIMr.G.S.Barber,NRCSr.ResidentInspector Mr.J.J.Raleigh,NRCProjectManagerWWW:llrPLA/021.WWW SUSUEHANNAS.E.S.24VDCSYSTENATTACHMENT IPage1ENCLOSURE 1Thefollowing information isapplicable toeitherUnit1or2atSusquehanna SES.l.UnitSusuehannaS.E.S.Unit1or224VDC2.a~Thenumberofindependent redundant divisions ofClasslEorfty-lddtftllyltl~t.(lldanyseparateClasslEorsafety-related dc,suchasanydcdedicated tothedieselgenerators.)
b.Thenumberoffunctional safety-related divisions ofdcpowerytttlfttdftllltd3.Doesthecontrolroomatthisunithavethefollowing
- separate, independently annunciated alarmsandindications foreachdivisionofdcpower?a.Alarms1.Batterydisconnect orcircuitbreakeropen?No2.Batterychargerdisconnect orcircuitbreakeropen(bothinputacandoutputdc)?No3.dcsystemground?No4.dcbusundervoltage?
No5.dcbusovervoltage?
No6.Batterychargerfailure?No...9111010196 C4' SUSUEHANNAS.E.S.24VDCSYSTEMATTACHMENT I7.Batterydischarge?
NoPage2b.Indications 1.Batteryfloatchargecurrent?No2.Batterycircuitoutputcurrent?No3.Batterydischarge?
No4.Busvoltage?Noc.Doestheunithavewrittenprocedures forresponsetotheabovealarmsandindications?
No4.Doesthisunithaveindication ofbypassedandinoperable statusofcircuitbreakersorotherdevicesthatcanbeusedtodisconnect thebatteryandbatterychargerfromitsdcbusandthebatterychargerfromitsacpowersourceduringmaintenance ortesting?NoSeeremarktl5.Iftheanswertoanypartofquestion3or4isno,thenprovideinformation justifying theexistingdesignfeaturesofthefacility's safety-related dcsystems.*Seenotebelow.SeeremarkOl6.(I)Haveyouconducted areviewofmaintenance andtestingactivities tominimizethepotential forhumanerrorcausingmorethanonedcdivisiontobeunavailablet
~esand(2)doplantprocedures prohibitmaintenance ortestingonredundant DCdivisions atthesametime'I~esIfthefacilityTechnical Specifications haveprovisions equivalent tothosefoundintheWestinghouse andCombustion Engineering StandardTechnical Specifications formaintenance andsurveillance, thenquestion7maybeskippedandastatement tothateffectmaybeinsertedhere.
SUSUEHANNAS.E.S.~YYTATTACHMENT IPage37.Aremaintenance, surveillance andtestprocedures regarding stationbatteries conducted routinely atthisplant?Specifically:
a.Atleastonceper7daysarethefollowing verifiedtobewithinacceptable limits:1.Pilotcellelectrolyte level?Yes2.Specifygravityorchargingcurrent?Yes3.Floatvoltage?Yes4.Totalbusvoltageonfloatcharge?Yes5.Physicalcondition ofallcells?Yesb.Atleastonceper92days,orwithin7daysafterabatterydischarge, overcharge, orifthepilotcellreadingsareoutsidethe7-daysurveillance requirements arethefollowing verifiedtobewithinacceptable limits:l.Electrolyte levelofeachcell?Yes2.Theaveragespecificgravityofallcells?Yes3.Thespecificgravityofeachcell?Yes4.Theaverageelectrolyte temperature ofarepresentative numberofcells?Yes5.Thefloatvoltageofeachcell?Yes6.Visuallyinspectormeasureresistance ofterminals andconnectors (including theconnectors atthedcbus)?Yes SUSUEHANNAS.E.S.24VDCSYSTEMATTACHMENT Ic.Atleastevery18monthsarethefollowing verified:
Page41.Lowresistance ofeachconnection (bytest)?Yes2.Physicalcondition ofthebattery?Yes3.Batterychargercapability todeliverratedampereoutputtothedcbus?Yes4.Thecapability ofthebatterytodeliveritsdesigndutycycletothedcbus?Yes5.Eachindividual cellvoltageiswithinacceptable limitsduringtheservicetest?Yesd.Atleastevery60months,iscapacityofeachbatteryverifiedbyperformance ofadischarge test?Yese.Atleastannually, isthebatterycapacityverifiedbyperformance discharge test,ifthebatteryshowssignsofdegradation orhasreached85Xoftheexpectedservicelife?Yes8.Doesthisplanthaveoperational featuressuchthatfollowing lossofonesafety-related dcpowersupplyorbus:a.Capability ismaintained forensuringcontinued andadequatereactorcooling?Yesb.Reactorcoolantsystemintegrity andisolation capability aremaintained?
Yesc.Operating procedures, instrumentation (including indicators andannunciators),
andcontrolfunctions areadequatetoinitiatesystemsasrequiredtomaintainadequatecorecooling?Yes9.Iftheanswertoanypartofquestion6,7or8isno,thenprovideyourbasisfornotperforming themaintenance, surveillance andtestprocedures described and/orthebasesfornotincluding theoperational featurescited.*Seenotebelow.
N SUSUEHANNAS.E.S.24VDCSYSTEMATTACHMENT IPage5*Note:Forquestions involving supporting typeinformation (question numbers5and9)insteadofdeveloping andsupplying theinformation inresponsetothisletter,youmaycommittofurtherevaluatetheneedforsuchprovisions duringtheperformance ofyourindividual plantexamination forsevereaccidentvulnerabilities (IPE).Ifyouselectthisoption,youarerequiredto:(1)Sostateinresponsetothesequestions, and(2)Committoexplicitly addressquestions 5and9inyourIPEsubmittal pertheguidelines outlinedinNUREG-1335 (Section2.1.6,Subitem7),"Individual PlantExamination:
Submittal Guidance."
c:iwp51idocsi24VDCSYS.PCD (18)10/24/919:20am RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.24VDCSUBSYSTEM PAGE1REMARK1:1.0Thefollowing indications andalarmsforthe24Vdcclass1Esubsystem areprovided.
Justification forthisdesignhasbeenpreviously providedinPLA-959totheNRCdated11/6/81,regarding ControlRoommonitoring ofClasslEdcpowersystems.Each24Vdcsubsystem consistsoftwo24voltbatterybanksconnected inserieswithacommongroundbusconnected tothecommon(center)pointofthetwobatterybanks.Thegroundbusissolidlygroundedtothestationgroundgrid.Each24voltbatterybankisdesignated aseitherthepositiveornegativebusasreferenced toground.Thealarms/indications inthefollowing tableanddiscussion aretypicalforeachpositiveandnegativebus.AlarmorIndication
,LocationLocalControlRoomNotesBusUndervoltage AlarmBatteryMonitorAlarmBatteryChargerTroubleAlarmBusOvervoltage AlarmBusVoltmeter BatteryChargerAmmeterBatteryChargerVoltmeter DCSystemTroubleAlarm1,21,2,41,2,51,23NOTES:1.SeeTable1andFigure2forspecificlocalalarmindication.
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.24VDCSUBSYSTEM PAGE22.Thesearelocallyindicated andactuatedcsubsystem troublealarm,seeTable1andFigure1.3.Hetersareprovidedlocally.SeeFigure3.4.Batterymonitor'compares batterycenterpointvoltagewithhighandlowthreshold reference pointsofthehighandlowvoltagecomparators.
Thedegradedcellconditions (suchasashortedcell)oranopencircuitcondition (suchasanopenfuse)aredetectedbythebatterymonitor.5.Batterychargertroublealarmindication isprovidedforbatterychargerACpowerfailure,DCoutputbreakeropen,batterychargerfailurealarmoperation.
6.Oneannunciator windowforeach24Vdcsubsystem isprovided.
(Includes inputsfromeitherthepositiveornegativebus).2.0Themonitoring schemeprovidedforthedcpowersubsystem isbasedonthedegreeofcontrolprovidedtothecontrolroomoperator.
Sincethedcpowersystemequipment cannotberemotelycontrolled, asingledcsystemtroubleannunciator windowforeachsubsystem isprovidedinthecontrolroom,consistent withthesystemlevelalarmcriteriasetforthinSection8ofR.G.1.47.TheSSESdesignisbasedonthegeneralcriteriathat,iftheoperatorcanperformsomecorrective actioninthecontrolroominresponsetoaspecificinput,thatinformation isspecifically provided.
Thedcpowersystemequipment cannotbecontrolled fromthecontrolroom.Annunciating specificinputsfromthe24Vdcsysteminthecontrolroomdoesnotenhancethecontrolroomoperators's abilitytodealwiththesituation anditwouldnotbeconsistent withSSESalarmdesignphilosophy.
However,iftheonlyresponserequiredistodispatchanoperatortoanarearemovedfromthecontrolroom,thentheonlyinformation requiredinthecontrolroomisgeneralinformation withonlythelevelofspecificity requiredtodirectthatoperatortotheproperlocation.
Thismethodisfasterandmorereliablesinceabnormal
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.24VDCSUBSYSTEM PAGE3conditions areautomatically alarmed.Furthermore, thisapproachisconsistent withthehumanfactorsengineering goaltonotoverburdentheoperatorwithunnecessary information.
24Vdcsysteminstrumentation, locallyprovided, isinfullcompliance withtherequirement ofIEEE308-1974andRegulatory Guide1.47.TheDCsystemgeneraltroublealarmsandspecificlocalindicators inconjunction withtheroutineoperatorsurveillance providepositiveassurance thattheClasslEdcpowersystemaremaintained inasteadystatereadytoperform-the requiredsafetyfunction.
3.0 Following
isthejustification foreachalarmandindication listedinGenericLetter91-06.3.1BatterDisconnect orCircuitBreaker0enAlarm:TheSusquehanna S.E.S.(SSES)24Vdcsubsystem utilizesfusesasthebatterydisconnect.
Thiscondition isdetectedbythebatterymonitor.Thebatterymonitorutilizesavariablethreshold circuittogetherwithtwocomparators (highandlow)todetectthelossofbatterycapability duetoanopencircuit(i.e.,anopenfuseordegradedcellcondition).
Avariablethreshold circuitacceptsthebatterychargervoltageanddevelopstwothreshold voltagesforusewiththecomparators.
Whenthemonitored voltagesgoaboveorbelowthethresholds, thebatterymonitoroutputrelaycontactsinitiatealocalbatterymonitoralarmwhichisreflashed tothecontrolroomasa24Vdcsystemtroublealarm.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.2BatterCharerDisconnect orCircuitBreaker0enBothInutACandOututDCAlarm3.2.1BatteryChargerACInputDisconnect orCircuitBreaker:SSESutilizesacircuitbreakerinthebatterychargerasadisconnect fortheacinputpowersupply.Anacpower RESPONSETOGENERIC.LETTER91-06SUSUEHANNAS.E.S.24VDCSUBSYSTEN PAGE4failurealarmrelayisinstalled internaltothebatterychargertodetectlossofacinputpower.Thiscondition couldbecausedbyanopeninputcircuitbreakerorlossofthe120Vacpowersupplytothecharger.Theacpowerfailurealarmrelayinitiates abatterychargertroublealarmatthelocalreflasher panel,whichisreflashed tothecontrolroomasa24Vdcsystemtroublealarm.Thisisconsistent withthegeneraldesignphilosophy discussed insection2.0.3.2.2BatteryChargerDCOutputCircuitBreakerSSESutilizesacircuitbreakerinthebatterychargerasadisconnect forthedcoutputcircuit.Thecircuitbreakerisprovidedwithanauxiliary positionindicating switch.Aswitchcontactwhichisclosedwhenthecircuitbreakerisopenisusedtoinitiateabatterychargertroublealarmatthelocalreflasher panel.Adcsystemtroublealarmisreflashed tothecontrolroombythelocalreflasher panel.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.3DCSstemGroundAlarmThe24Vdcsubsystem isasolidlygroundedsystem.Therefore, asystemgroundalarmisnotrequired.
Asecondgroundoneitherthepositiveornegativebuswillcauseprotective devicesinthecircuittooperate.Thiscondition willbedetectedatthelocalreflasher panelbyeitherthebatterymonitoralarm(forbatteryfuseopen)orthebatterychargertroublealarm(forbatterychargerDCoutputbreakeropen).Ineithercase,thelocalreflasher panelwillreflasha24Vdcsystemtroublealarmtothecontrolroomannunciator.
Thisisconsistent withthegeneraldesignphilosophy discussed inSection'.0.
RESPONSETOGENERICLETTER91-0624VDCSUBSYSTEM SUSUEHANNAS.E.S.PAGE53.4DCBusUndervolta eAlarmThe24Vdcsubsystem isprovidedwithpositiveandnegativedcbusundervoltage relays.Eachrelayisconnected acrossthesystembuses(positive bustoground,negativebustoground).Therelaysarenormallyenergized and,settodropoutatthespecified setpoint.
Apositivebusornegativebuslowvoltagealarmatthelocalreflasher panelisinitiated aftertheundervoltage relaydropsout.Thelocalreflasher panel,inturn,reflashes thealarmtothecontrolroomannunciator asadcsystemtroublealarm.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.5DCBusOvervolta eAlarmThe24Vdcsubsystems areprovidedwithovervoltage relays.Therelaysarelocatedinsidethe24Vdcdistribution panels.Eachrelayisconnected acrossthesystembuses(positive bustoground,negativebustoground)andsettopickupatthespecified setpoint.
Anormallyopencontactoftheover'voltage relay,whenclosed,initiates apositivebusornegativebushighvoltagealarmatthelocalreflasher panelwhichinturnwillreflashadcsystemtroubletothecontrolroomannunciator.
Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.6BatterCharerFailureAlarmEach24Vdcsubsystem batterychargerisprovidedwithabatterychargerfailurerelay.Thisrelaywilldetectthelossofthechargeroutputcurrentwiththeinputandoutputcircuitbreakersclosed.Thiscondition isindicative ofabatterychargerfailureanditinitiates abatterychargertroublealarmatthelocalreflasher RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.24VDCSUBSYSTEM PAGE6panelwhichinturnwillreflashadcsystemtroublealarmtothecontrolroomannunciator.
Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.7BatterDischareAlarmThebatterycanonlydischarge whenits.terminal voltageislessthanthenominalopencircuitvoltage.Thisisindicative ofabatterychargerfailureorsystemcurrentinexcessofthechargercapability.
Abatterychargerfailurealarmisprovidedanditsoperation isdiscussed inSection3.6.Whensystemcurrentexceedsbatterychargercapability, adcsystemundervoltage condition willoccur,andwillbedetectedbythedcbusundervoltage relay(seeSection3.4).Chargerfailureandbusundervoltage initiatealarmsatthelocalreflasher panelwhichinturnwillreflashadcsystemtroublealarmtothecontrolroomannunciator.
Thisisconsistent withthegeneraldesignphilosophy asdiscussed inSection2.0.3.8BatterFloatChareCurrentIndication Undernormalconditions, thebatteryfloatchargecurrentisverysmallcomparedtobatterydischarge current.Measurement ofthiscurrentrequiresaverysensitive ammeter.Shuntbypassesareemployedtoprotecttheammetermovementfromthemuchlargerbatterydischarge currentpossibleinthiscircuit.Theseshuntsmustbemanuallyremovedwhenreadingnormalsmallfloatcurrent.Thusthisreadingcannotbecontinuous andnoautomatic indication oralarmscanbegiven.Sincetheintentofindicating "BatteryFloatChargeCurrent"istodetermine thebatterycondition, themethodusedtoaccomplish thispurposeshouldnotbeimportant.
Thebusundervoltage, batterymonitorandbatterychargerfailure RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.24VDCSUBSYSTEM PAGE7alarms(previously described) providecontinuous monitoring todetectdegradation ofbatterycapability.
Thesealarmswillreflashthedcsystemtroublealarminthecontrolroom,andanoperatorisdispatched locallytodetermine thecauseofthecondition andinitiatecorrective action.Specificindication isprovidedonthelocalreflasher panel.Thisresponseisexactlywhatwould'beachievedifanimproperstateofbatterycurrentwereindicated onanammeterinthecontrolroom.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.9BatterCircuitOututCurrentIndication Innormalcondition whenthebatterychargerissupplying the24Vdcpower,thebatterycircuit(batteryandthebatterycharger)outputcurrentisindicated byanammeterlocatedatthebatterycharger.Inthecondition ofabatterychargerfailure,thebatterysuppliesthedcpower.Inthiscondition thebatterycircuitoutputcurrentcannotbedetermined sinceanammeterisnotprovidedatthe24Vdcdistribution panels.Asindicated inSection3.8,theintentofindicating "batterycurrent"istodetermine thebatterycondition, andtherefore themethodusedtoaccomplish thispurposeshouldnotbeimportant.
3.10BatterDischareIndication Aspreviously discussed inSection3.7,abatterydischarge willoccurasaresultofabatterychargerfailureorsystemcurrentinexcesstobatterychargercapability.
Sincetheseconditions areautomatically alarmedinthecontrolroom(viathesystemtroublealarm),anoperatorwillbedispatched locallyto IRESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.24VDCSUBSYSTEM PAGE8determine thecauseofthecondition andinitiatecorrective action.Thisresponseisexactlywhatwouldbeachievedifbatterydischarge currentwasindicated onanammeterinthecontrolroom.3.11BusVoltaeIndication Thebattery,thebatterychargerandthe24Vdcdistribution panelarelocatedincloseproximity ofeachother.Thebatterychargerandthedcdistribution panelareeachprovidedwithavoltmeter.
Thepurposeofabusvoltmeter atthecontrolroomwouldbetoenabletheoperatortodispatchsomeonetotakecorrective actionlocallytocorrectabnormalbusvoltage.AtSSESbusundervoltage andovervoltage ismonitored directlyatthedistribution panel.Thebusundervoltage andovervoltage conditions areannunciated as24Vdcsystemloworhighvoltageatthelocalreflasher panel.Adcsystemtroublealarmisreflashed tothecontrolroomannunciator bythelocalreflasher panel.Thisdesignautomatically alertsthecontrolroomoperatortounusualvoltageconditions withoutunnecessarily requiring hisperiodicattention andanalysis.
Asaresult,24Vdcbusvoltageindication isnotprovidedinthecontrolroomandhasbeenprovidedonthefrontofthedistribution panelwhereitprovidesusefulinformation duringsurveillance andmaintenance activities.
Avoltmeter islocatedonthefrontofthebatterychargerpanel.Withthechargeroutputcircuitbreakerclosed,thechargeroutputandthebusvoltagesareessentially thesameduetothecloseproximity ofthechargertotheloadcenter.Allabnormalvoltageconditions ofthebatterychargerareannunciated atthelocalreflasher panelwhichisreflashed tothecontrolroomasadcsystemtroublealarm.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.24VDCSUBSYSTEN PAGE93.12AlarmResonseProcedure Controlroomalarmresponseprocedures fora24Vdcsystemtroublealarmdirecttheoperatortorespondtothelocalreflasher paneltodetermine thecondition whichcausedthealarm.Localalarmresponseprocedures forthereflasher panelareprovidedtodirecttheoperatortodetermine thecauseofthecondition andtoinitiatecorrective action.3.13Indication ofBassedandInoerableStatusofCircuitBreakersorOtherDisconnectin DevicesAlthoughindication ofbypassedandinoperable statusofcircuitbreakersorotherdisconnecting devicesisnotprovidedasapartoftheBypassIndication System,the24VdcSystemTroubleAlarminthecontrolroomisinitiated forthefollowing condition (whicharedisconnecting devicesinthesystem):Hainbatteryfuseopen.Batterychargeracinputcircuitbreakeropen.Batterychargerdcoutputcircuitbreakeropen,ordcdistribution panelfeederbreakeropen.
P RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.24VDCSUBSYSTEM PAGE10TABLE124VDCSstemReflashPanelIndicators 1L610(Typicalforpositiveandnegativebuses)l.24VDCSystemLowVoltage2.,24VDCSystemHighVoltage3.BatteryHonitor(indicates batterydegradation oropenbatteryfuses)4.BatteryChargerTroubleindicates (1)ACpowerfailure,(2)DCoutputbreakeropen,or(3)batterychargerfailureC:KWP51%00CSK24VDCSS
~PGO(18)10/24/919:168AI 124DCLOCALREHASHPANELWITHINDICATION 1L670MULTIPLEALARMINPUTSFROM%24VDCPOWERSYSTEMPERTABLE1DCSYSTEMAlARMINPUTSFROMOTHERREFLASHPANELS(8MILARTOABOVE)CONTROLROOMPANEL1C651ANNUNCIATOR
+24VDCSYSTEMTROUBLE1L670FIGURE1
INDICATOR UGHI'ERASHER PANELPOWERFAILUREPOSITIVEBUSLOWVOLTAGENEGATIVEBUSHIGHVOLTAGEBATlERYCHARGER41TROUBLE0NEGATIVEBUSLOWVOLTAGEBATTERYPOSITIVEMONITORBATIERYCHARGERWTROUBLE0POSITIVEBUSHIGHVOLTAGEBATlERYNEGATIVEMONITOR224VDCSYSTEMLOCALREHASHERPANELQYPICAOFIGURE2 IBATIERYBANK1D670I+24-24I96PCLQ>0+24VDCBA11ERYCHARGERDCBKRQvQ~-24VDCBA11ERYCHAI&ERDCBKRQvQA59y27P27y69NNSPARECOMPOUTPUTAMPPOSVOLTSNEG}VOLTSNEGSPAREMPUIEROUTPUTPROCESSRADIATION MONITORSSOURCERNG.MON'SINIERMRNG.MON'S1RIP.AUX,UNITSNOTE1+24VCOMMON-24V24VDCSYSTEMOYPICAQNOTE1:COMMONBUSGROUNDED SUSUEHANNAS.E.S.125VDCSYSTEMATTACHMENT IIPage1ENCLOSURE 1Thefollowing information isapplicable toeitherUnit1or2atSusquehanna SES.1.UnitSUSUEHANNAS.E.S.UNIT-1or2125VDCSYSTEM2.a0Thenumberofindependent redundant divisions ofClasslEorsafety-related DCpowerforthisplantisSeeRemark1(IncludeanyseparateClass1Eorsafety-related DC,suchasanyDCdedicated tothedieselgenerators).
b.Thenumberoffunctional safety-related divisions ofDCpowernecessary toattainsafeshutdownforthisunitisSeeRemark2.3.Doesthecontrolroomatthisunithavethefollowing
- separate, independently annunciated alarmsandindications foreachdivisionofDCpower?a~3.5.Alarms1.Batterydisconnect orcircuitbreakeropen?No2.Batterychargerdisconnect orcircuitbreakeropen(bothinputACandoutputDC)?NoDCsystemground?NoDCbusundervoltage?
NoDCbusovervoltage?
No6.Batterychargerfailure?No7.Batterydischarge?
Nob.Indications l.2.3.Batteryfloatchargecurrent?NoBatterycircuitoutputcurrent?NoBatterydischarge?
NoBusvoltage?No SUSUEHANNAS.E.S.125VDCSYSTENATTACHMENT II4.Page2c.Doestheunithavewrittenprocedures forresponsetotheabove'alarmsandindications?
NoI*,IDoesthisunithaveindication ofbypassedandinoperable'status ofcircuitbreakersorotherdevicesthatcanbeusedtodisconnect thebatteryandbatterychargerfromitsDCbus,andthebatterychargerfromitsACpowersourceduringmaintenance ortes'ting?
NoSeeremark¹35.Iftheanswertoanypartofquestion3or4isno,thenprovideinformation justifying theexistingdesignfeaturesofthefacility's safety-related DCsystems.*Seeendnote.Seeremark¹36.(I)Haveyouconducted areviewofmaintenance andtestingactivities tominimizethepotential forhumanerrorcausingmorethanoneDCdivisiontobeunavailablet
~esand(2)Doplantprocedures prohibitmaintenance ortestingonredundant DCdivisions atthesametime?~esIfthefacilityTechnical Specifications haveprovisions equivalent tothosefoundintheWestinghouse andCombustion Engineering StandardTechnical Specification formaintenance andsurveillance, thenquestion7maybeskippedandastatement tothateffectmaybeinsertedhere.7.Aremaintenance, surveillance andtestprocedures regarding stationbatteries conducted routinely atthispoint?Specifically:
a.Atleastonceper7daysarethefollowing verifiedtobewithinacceptable limits:I.2.3.4.5.Pilotcellelectrolyte level?YesSpecificgravityorchargingcurrent?YesFloatvoltage?YesTotalbusvoltageonfloatcharge?YesPhysicalcondition ofallcells?Yes
SUSUEHANNAS.E.S.125VDCSYSTEMATTACHMENT IIb.Page3Atleastonceper92days,orwithin7daysafterabatterydischarge, overcharge, orifthepilotcellreadingsareoutsidethe7-daysurveillance requirements arethefollowing verifiedtobewithinacceptable limits:l.2.3.4.5.6.Electrolyte levelofeachcell?YesTheaveragespecificgravityofallcells?YesThespecificgravityofeachcell?YesTheaverageelectrolyte temperature ofarepresentative numberofcells?YesThefloatvoltageofeachcell?YesVisually.inspectormeasureresistance ofterminals andconnectors (including theconnectors attheDCbus)?Yesc.Atleastevery18monthsarethefollowing verified:
2.3.5.Lowresistance ofeachconnection (bytest)?YesPhysicalcondition ofthebattery?YesBatterychargercapability todeliverratedampereoutputtotheDCbus?YesThecapability ofthebatterytodeliveritsdesigndutycycletotheDCbus'?YesEachindividual cellvoltageiswithinacceptable limitsduringtheservicetest?Yesd.Atleastevery60months,iscapacityofeachbatteryverifiedbyperformance ofadischarge test'?Yese.Atleastannually, isthebatterycapacityverifiedbyperformance discharge test,ifthebatteryshowssignsofdegradation orhasreached85Xoftheexpectedservicelife?Yes8.Doesthisplanthaveoperational featuressuchthatfollowing lossofonesafety-related DCpowersupplyorbus:a.Capability ismaintained forensuringcontinued andadequatereactorcooling?Yes SUSUEHANNAS.E.S.125VDCSYSTENATTACHMENT IIPage4b.Reactorcoolantsystemintegrity andisolation capability aremaintained7 Yesc.Operating procedures, instrumentation (including indicators andannunciators),
andcontrolfunctions areadequatetoinitiatesystemsasrequiredtomaintainadequatecorecooling7Yes9.Iftheanswertoanypartofquestion6,7,or8isno,thenprovideyourbasisfornotperforming themaintenance, surveillance andtestprocedures described and/orthebasesfornotincluding theoperational featurescited.*SeeNotebelow.*Note:Forquestions involving supporting typeinformation (question numbers5and9)insteadofdeveloping andsupplying theinformation inresponsetothisletter,youmaycommittofurtherevaluatetheneedforsuchprovisions duringtheperformance ofyourindividual plantexamination forsevereaccidentvulnerabilities (IPE).Ifyouselectthisoption,youarerequired, to:1)Sostateinresponsetothesequestions, and2)Committoexplicitly addressquestions 5and9inyourIPEsubmittal pertheguidelines outlinedinNUREG-1335 (section2.1.6,Subitem7),"Individual PlantExamination:
Submittal Guidance."
C:KIIP51I,docshadeqofsa.pgd (18)10/24/918:57am
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.125VDCSUBSYSTEM PAGE1REMARK1:TheUnit1Class1Edirectcurrent,(dc)systemconsistsoffourindependent 125voltdcsubsystems.
Thesefoursubsystems areidentified aschannelsA,B,C,andD.Eachsubsystem providesthecontrolpowerforitsassociated classlEacpowerloadgroupconsisting of:'.16kVswitchgear, 480Vloadcenters,andastandbydieselgenerator.
The125Vdcsubsystems alsoprovidedcpowerforsafetyfeaturevalveactuation, dieselgenerator auxiliaries, andplantalarmandindication circuits.
REMARK2:Fourseparateandindependent class1E125Vdcsubsystems supplycontrolpowerforeachoftheclass1Eloadgroups.Lossofanyoneofthesubsystems doesnotpreventtheminimumsafetyfunctionfrombeingperformed (i.e.,threeoutoffoursubsystems arenecessary toattainsafeshutdownforUnit1).REMARK3:1.0Thefollowing indications andalarmsforthe125VdcclasslEsubsystem areprovided.
Justification forthisdesignhasbeenpreviously providedinPLA-959totheNRCdatedll/6/81,regarding ControlRoommonitoring ofClass1Edcp'owersystems.
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.125VDCSUBSYSTEM PAGE2AlarmorIndication LocationLocalControlRoomNotesBusUndervoltage AlarmBusGroundAlarmBatteryMonitorAlarmBatteryChargerTroubleAlarmBusAmmeterBusVoltmeter BatteryChargerAmmeterBatteryChargerVoltmeter DCSystemTroubleAlarm1,21,21,2,41,2,5NOTES:1.SeeTable1andFigure2forspecificlocalalarmindication.
2.Thesearelocallyannunciated andactuatedcsubsystem troublealarm,seeTable1andFigurel.3.Hetersareprovidedlocally.SeeFigure3.Batterymonitorcomparesbatterycenterpointvoltagewithhighandlowthreshold reference pointsofthehighandlowvoltagecomparators.
Thedegradedcellconditions (suchasashortedcell)oranopencircuitcondition (suchasanopenfuse)aredetectedbythebatterymonitor.
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.125VDCSUBSYSTEM PAGE35.Batterychargertroublealarmindication isprovidedforbatterychargerACpowerfailure,DCoutputbreakeropen,batterychargerfailurealarmoperation, andbusovervoltage.
6.Oneannunciator windowforthe125Vdcsubsystem isprovided.
2.0 Themonitoring
schemeprovidedforthedcpowersubsystem isbasedonthedegreeofcontrolprovidedtothecontrolroomoperator.
Sincethedcpowersystemequipment cannotberemotelycontrolled, asingledcsystemtroubleannunciator windowforeachsubsystem isprovidedinthecontrolroom,consistent withthesystemlevelalarmcriteriasetforthinSectionBofR.G.1.47.TheSSESdesignisbasedonthegeneralcriteriathat,iftheoperatorcanperformsomecorrective actioninthecontrolroominresponsetoaspecificinput,thatinformation isspecifically provided.
Thedcpowersystemequipment cannotbecontrolled fromthecontrolroom.Annunciating specificinputsfromthe125Vdcsysteminthecontrolroomdoesnotenhancethecontrolroomoperators's abilitytodealwiththesituation anditwouldnotbeconsistent withSSESalarmdesignphilosophy.
However,iftheonlyresponserequiredistodispatchanoperatortoanarearemovedfromthecontrolroom,thentheonlyinformation requiredinthecontrolroomisgeneralinformation withonlythelevelofspecificity requiredtodirectthatoperatortotheproperlocation.
Thismethodisfasterandmorereliablesinceabnormalconditions areautomatically alarmed.Furthermore, thisapproachisconsistent withthehumanfactorsengineering goaltonotoverburdentheoperatorwithunnecessary information.
125Vdcsysteminstrumentation, locallyprovided, isinfullcompliance withtherequirement of,IEEE308-1974andRegulatory Guide1.47.TheDCsystemgeneraltroublealarmsandspecificlocalindicators inconjunction withtheroutineoperatorsurveillance providepositiveassurance thattheClass1Edcpowersystemaremaintained inasteadystatereadytoperformtherequiredsafetyfunction.
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.125VDCSUBSYSTEM PAGE43.0Following isthejustification foreachalarmandindication listedinGenericLetter91-06.3.1BatterDisconnect orCircuitBreaker0enAlarm:TheSusquehanna S.E.S.(SSES)125Vdcsubsystem utilizesfusesasthebatterydisconnect.
Thiscondition isdetectedbythebatterymonitor.Thebatterymonitorutilizesavariablethreshold circuittogetherwithtwocomparators (highandlow)todetectthelossofbatterycapability duetoanopencircuit(i.e.,anopenfuseordegradedcellcondition).
Avariablethreshold circuitacceptsthebatterychargervoltageanddevelopstwothreshold voltagesforusewiththecomparators.
Whenthemonitored voltagesgoaboveorbelowthethresholds, thebatterymonitoroutputrelaycontactsinitiatealocalbatterymonitoralarmwhichisreflashed tothecontrolroomasa125Vdcsystemtroublealarm.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.2BatterCharerDisconnect orCircuitBreaker0enBothInutACandOututDCAlarm3.2.1BatteryChargerACInputDisconnect orCircuitBreaker:SSESutilizesacircuitbreakerinthebatterychargerasadisconnect fortheacinputpowersupply.Anacpowerfailurealarmrelayisinstalled internaltothebatterychargertodetectlossofacinputpower.Thiscondition couldbecausedbyanopeninputcircuitbreakerorlossofthe480Vacpowersupplytothecharger.Theacpowerfailurealarmrelayinitiates abatterychargertroublealarmatthelocalreflasher panel,whichisreflashed tothecontrolroomasa125Vdcsystemtroublealarm.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.125VDCSUBSYSTEN PAGE53.2.2BatteryChargerDCOutputCircuitBreakerSSESutilizesacircuitbreakerinthebatterychargerasadisconnect forthedcoutputcircuit.Thecircuitbreakerisprovidedwithanauxiliary positionindicating switch.Aswitchcontactwhichisclosedwhenthecircuitbreakerisopenisusedtoinitiateabatterychargertroublealarmatthelocalreflasher panel.Adcsystemtroublealarmisreflashed tothecontrolroombythelocalreflasher panel.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.3DCSstemGroundAlarmThe125Vdcsubsystem isungrounded andisprovidedwithagrounddetection circuit.Itconsistsofarelayhavingacentertappedcoil.Thecoilisconnected acrossthepositiveandnegativebusanditscenterpointisgrounded.
Thegrounddetection relaycoilisnotactuatedduringnormaloperation ofthe125Vdcsubsystem whenagroundisnotpresent.Agroundoneitherthepositiveornegativebusofthe125Vdcsubsystem causesone-halfoftherelaycoiltobeshortcircuited, thusproviding sufficient voltagetotheremaining relaycoilhalftopickuptherelay.Anormallyopencontactoftherelayclosesandinitiates a125Vdcsystem.groundalarmatthelocalreflasher panel.Adcsystemtroublealarmisreflashed tothecontrolroomannunciator bythelocalreflasher panel.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.4DCBusUndervolta eAlarmThe125Vdcsubsystem isprovidedwithadcbusundervoltage relay.Therelayisconnected acrossthepositiveandnegativebusofthe125Vdcsubsystem.
Therelayisnormallyenergized andsettodropoutatthespecified setpoint.
A125Vdcbusundervoltage alarmatthelocalreflasher panelisinitiated aftertheundervoltage relaydropsout.
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.125VDCSUBSYSTEN PAGE6Thelocalreflasher panel,inturn,reflashesthealarmtothecontrolroomannunciator asadcsystemtroublealarm.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.5DCBusOvervolta eAlarmThe125Vdcsubsystem isprovidedwithanovervoltage relay.Therelayislocatedinsidethebatterychargercabinet.Itisconnected acrossthepositiveandnegative125Vdcbusofthebatterychargerandsettopickupatthespecified setpoint.
Anormallyopencontactoftheovervoltage relay,whenclosed,initiates abatterychargertroublealarmatthelocalreflasher panelwhichinturnwillreflashadcsystemtroubletothecontrolroomannunciator.
Sincethebattery,thebatterychargerandthedcloadcenterareincloseproximity ofeachother,thebatterychargervoltageisrepresentative ofthe125Vdcbusvoltage.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.6BatterCharerFailureAlarmThe125Vdcsubsystem batterychargerisprovidedwithabatterychargerfailurerelay.Thisrelaywilldetectthelossofthechargeroutputcurrentwiththeinputandoutputcircuitbreakersclosed.Thiscondition isindicative ofabatterychargerfailureanditinitiates abatterychargertroublealarmatthelocalreflasher panelwhichinturnwillreflashadcsystemtroublealarm'tothecontrolroomannunciator.
Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.125VDCSUBSYSTEM PAGE73.7BatterDischareAlarmThebatterycanonlydischarge, whenitsterminalvoltageislessthanthenominalopencircuitvoltage.Thisisindicative ofabatterychargerfailureorsystemcurrentinexcessofthechargercapability.
Abatterychargerfailurealarmisprovidedanditsoperation isdiscussed inSection3.6.'Whensystemcurrentexceedsbatterychargercapability, adcsystemundervoltage condition willoccur,andwillbedetectedbythedcbusundervoltage relay.(SeeSection3.4.)Chargerfailureandbusundervoltage initiatealarmsatthelocalreflasher panelwhichinturnwillreflashadcsystemtroublealarmtothecontrolroomannunciator.
Thisisconsistent withthegeneraldesignphilosophy asdiscussed inSection2.0.3.8BatterFloatChareCurrentIndication Undernormalconditions, thebatteryfloatchargecurrentisverysmallcomparedtobatterydischarge current.measurement ofthiscurrentrequiresaverysensitive ammeter.Shuntbypassesareemployedtoprotecttheammetermovementfromthemuchlargerbatterydischarge currentpossibleinthiscircuit.Theseshuntsmustbemanuallyremovedwhenreadingnormalsmallfloatchargecurrent.Thusthisreadingcannotbecontinuous andnoautomatic indication oralarmscanbegiven.Sincetheintentofindicating "BatteryFloatChargeCurrent"istodetermine thebatterycondition, themethodusedtoaccomplish thispurposeshouldnotbeimportant.
Thebusundervoltage, busground,batterymonitorandbatterychargerfailurealarms(previously described) providecontinuous monitoring todetectdegradation ofbatterycapability.
Thesealarmswillreflashthedcsystemtroublealarminthecontrolroom,andanoperatorisdispatched locallytodetermine thecauseofthecondition andinitiatecorrective action.
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.125VDCSUBSYSTEM PAGE8Specificindication isprovidedonthelocalreflasher panel.Thisresponseisexactlywhatwouldbeachievedifanimproperstateofbatterycurrentwereindicated onanammeterinthecontrolroom.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.9BatterCircuitOututCurrentIndication.
Innormalcondition whenthebatterychargerissupplying the125Vdcpower,thebatterycircuit(batteryandthebatterycharger)outputcurrentisindicated byanammeterlocatedatthebatterycharger.Inthecondition ofabatterychargerfailure,thebatterysuppliesthedcpower.Inthiscondition thebatterycircuitoutputcurrentisindicated byanammeterlocatedatthedcloadcenter.Asindicated inSection3.8,theintentofindicating "batterycurrent"istodetermine thebatterycondition, andtherefore themethodusedtoaccomplish thispurposeshouldnotbeimportant.
3.10BatterDischareIndication Aspreviously discussed inSection3.7,abatterydischarge willoccurasaresultofabatterychargerfailureorsystemcurrentinexcesstobatterychargercapability.
Sincetheseconditions areautomatically alarmedinthecontrolroom(viathesystemtroublealarm),anoperatorwillbedispatched locallytodetermine thecauseofthecondition andinitiatecorrective action.Thisresponseisexactlywhatwouldbeachievedifbatterydischarge currentwasindicated onanammeterinthecontrolroom.
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.125VDCSUBSYSTEM PAGE93.11BusVoltaeIndication Thebattery,thebatterychargerandthedcloadcenterof125Vdcsubsystem arelocatedincloseproximity ofeachother.Thebatterychargerandthedcloadcenterareeachprovidedwithavoltmeter.
Thepurposeofabusvoltmeter atthecontrolroomwouldbetoenabletheoperatortodispatchsomeonetotakecorrective actionlocallytocorrectabnormalbusvoltage.AtSSESthebusundervoltage ismonitored directlyandthebusovervoltage conditions aremonitored atthebatterychargeroutput.Thebusundervoltage andthebatterychargeroutputovervoltage conditions areannunciated as125Vdcsystemlowvoltageorbatterychargertroubleatthelocalreflasher panel.Adcsystemtroublealarmisreflashed tothecontrolroomannunciator bythelocalreflasher panel.Thisdesignautomatically alertsthecontrolroomoperatortounusualvoltageconditions withoutunnecessarily requiring hisperiodicattention andanalysis.
Asaresult,125Vdcbusvoltageindication isnotprovidedinthecontrolroomandhasbeenprovidedonthefrontoftheloadcenterwhereitprovidesusefulinformation duringsurveillance andmaintenance activities.
Avoltmeter islocatedonthefrontofthebatterychargerpanel.Withthechargeroutputcircuitbreakerclosed,thechargeroutputandthebusvoltagesareessentially thesameduetothecloseproximity ofthechargertotheloadcenter.Allabnormalvoltageconditions ofthebatterychargerareannunciated atthelocalreflasher panelwhichisreflashed tothecontrolroomasadcsystemtroublealarm.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.12,AlarmResonseProcedure Controlroomalarmresponseprocedures fora125Vdcsystemtroublealarmdirecttheoperatortorespondtothelocalreflasher paneltodetermine thecondition whichcausedthealarm.
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.125VDCSUBSYSTEH PAGE10Localalarmresponseprocedures forthereflasher panelareprovidedtodirecttheoperatortodetermine thecauseofthecondition andtoinitiatecorrective action.3.13Indication ofBassedandInoerableStatusofCircuitBreakersorOtherOisconnectin DevicesAlthoughindication ofbypassedandinoperable statusofcircuitbreakersorotherdisconnecting devicesisnotprovidedasapartoftheBypassIndication System,the125VdcSystemTroubleAlarminthecontrolroomisinitiated forthefollowing condition (whicharedisconnecting devicesinthesystem):Hainbatteryfuseopen.Batterychargeracinputcircuitbreakeropen.Batterychargerdcoutputcircuitbreakeropenor125Vdcloadcenterinputbreakeropen.125Vdcloadcenterfeederbreakerto125Vdcdistribution panelsopen.r(Theundervoltage relayatthedistribution panelsinitiates thedistribution panellowvoltagealarmatthelocalreflasher panelwhichisreflashed tothecontrolroom125Vdcsystemtroublealarm.)
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.125VDCSUBSYSTEN PAGE11TABLE1125VDCSstemReflashPanelAlarms1L6101.125VDCSystemLowVoltage2.125VDCSystemGround3.BatteryMonitor(indicates batterydegradation oropenbatteryfuses)4.BatteryChargerTroubleindicates (1)ACpowerfailure,(2)DCoutputbreakeropen,(3)batterychargerfailure,or(4)busovervoltage 5.125VDCDistribution Panel1D614LowVoltage6.125VDCDistribution Panel1D615LowVoltageC:XWP51XDDCSX125VDCSS.PGD (18)10/24/919:00am CHANNELA125VDCLOCALREHASHPANELWITHINDICATION 1L610MULTIPLEAIARMINPUTSFROM125VDCCHANNELAPOWERSYSTEMPERTABK1DCSYSTEMALARMINPUTSFROMOTHERREFLASHPANELS(SIMILARTOABOVE)CONTROLROOMPANEL1C651ANNUNCIATOR 125VDCSYSTEMTROUBLE1L610FIGURE1 INDICATOR UGHTREFLASHER PANELPOWERFAILURENAMEPlATE 125VDCSYSTEMLOWVOLTAGEBATTERYCHARGERSPARE125VDCSYSTEMGROUND125VDCDISTPANEL10614LOWVOLTAGESPAREBATTERYMONITOR125VDCPANEL1D615LOWVOLTAGESPARE125VDCSYSTEMLOCALREFlASHER PANELOYPfCADFIGURE2 59BATTERYCHARGERAMMETERVOLTMETER BATTERYBANKFUSEBATTERYMONITORAMMETERQVOLTMETER 27SYSTEMGROUNDINDICATORS DCLOADCENTERLOADSLOADSSEETABLE1FORALARMS125VDCSYSTEMQYPICADFIGURE3 SUSUEHANNAS.E.S.250DCSYSTEMATTACHMENT IIIPage1ENCLOSURE 1Thefollowing information isapplicable toeitherUnit1orUnit2atSusquehanna SES.1.UnitSusuehannaS.E.S.Unit-1or2250VDC2.,Thenumberofindependent redundant divisions ofClass1Eorsafety-related dcpowerforthisplantis~2two.(IncludeanyseparateClasslEorsafety-related dc,suchasanydcdedicated to,thedieselgenerators.)
b.Thenumberoffunctional safety-related divisions ofdcpowernecessary toattainsafeshutdownforthisunitis~1one3.Doesthecontrolroomatthisunithavethefollowing
- separate, independently annunciated alarmsandindications foreachdivisionofdcpower?a.Alarms1.Batterydisconnect orcircuitbreakeropen?No2.Batterychargerdisconnect orcircuitbreakeropen(bothinputacandoutputdc)?No3.dcsystemground?No4.dcbusundervoltage?
No5.dcbusovervoltage?
No6.Batterychargerfailure?No SUSUEHANNAS.E.S.250DCSYSTENATTACHNENT III7.Batterydischarge?
NoPage2b.Indications 1.Batteryfloatchargecurrent?No2.Batterycircuitoutputcurrent?No3.Batterydischarge?
No4.Busvoltage?Noc.Doestheunithavewrittenprocedures forresponsetotheabovealarmsandindications?
NoDoesthisunithaveindication ofbypassedandinoperable statusofcircuitbreakersorotherdevicesthatcanbeusedtodisconnect thebatteryandbatterychargerfromitsdcbusandthebatterychargerfromitsacpowersourceduringmaintenance ortesting?NoSeeremark¹15.Iftheanswertoanypartofquestion3or4isno,thenprovideinformation justifying theexistingdesignfeaturesofthefacility's safety-related dcsystems.*Seenotebelow.SeeRemark¹16.(1)Haveyouconducted areviewofmaintenance andtestingactivities tominimizethepotential forhumanerrorcausingmorethanonedcdivisiontobeunavai1ablet
~esand(2)doplantprocedures prohibitmaintenance ortestingonredundant dcdivisions atthesametime?~es(Seeresponsefromthesite)IfthefacilityTechnical Specifications haveprovisions equivalent tothosefoundintheWestinghouse andCombustion Engineering StandardTechnical Specifications formaintenance andsurveillance, thenquestion7maybeskippedandastatement tothateffectmaybeinsertedhere.
SUSUEHANNAS.E.S.250OCSYSTENATTACHMENT IIIPage37.Aremaintenance, surveillance andtestprocedures regarding stationbatteries conducted routinely atthisplant?Specifically:
a.Atleastonceper7daysarethefollowing verifiedtobewithinacceptable limits:1.Pilotcellelectrolyte level?Yes2.Specifygravityorchargingcurrent?Yes3.Floatvoltage?Yes4.Totalbusvoltageonfloatcharge?Yes5.Physicalcondition ofallcells?Yesb.Atleastonceper92days,orwithin7daysafterabatterydischarge; overcharge, orifthepilotcellreadings, areoutsidethe7-daysurveillance requirements arethefollowing verifiedtobewithinacceptable limits:l.Electrolyte levelofeachcell?Yes2.Theaveragespecificgravityofallcells?Yes3.Thespecificgravityofeachcell?Yes4.Theaverageelectrolyte temperature ofarepresentative numberofcells?Yes5.Thefloatvoltageofeachcell?Yes6.Visuallyinspectormeasureresistance ofterminals andconnectors (including theconnectors atthedcbus)?Yes SUSUEHANNAS.E.S.250DCSYSTEMATTACHMENT IIIc.Atleastevery18monthsarethefollowing verified:
Page41.Lowresistance ofeachconnection (bytest)?Yes2.Physicalcondition ofthebattery?Yes3.Batterychargercapability todeliverratedampereoutputtothedcbus?Yes4.Thecapability ofthebatterytodeliveritsdesigndutycycletothedcbus?Yes5.Eachindividual cellvoltageiswithinacceptable limitsduringtheservicetest?Yesd.Atleastevery60months,iscapacityofeachbatteryverifiedbyperformance ofadischarge test?Yese.Atleastannually, isthebatterycapacityverifiedbyperformance discharge test,ifthebatteryshowssignsofdegradation orhasreached85Koftheexpectedservicelife?Yes8.Doesthisplanthaveoperational featuressuchthatfollowing lossofonesafety-related dcpowersupplyorbus:a.Capability ismaintained forensuringcontinued andadequatereactorcooling?Yesb.Reactorcoolantsystemintegrity andisolation capability aremaintained?
Yesc.Operating procedures, instrumentation (including indicators andannunciators),
andcontrolfunctions areadequatetoinitiatesystemsasrequiredtomaintainadequatecorecooling?Yes9.Iftheanswertoanypartofquestion6,7or8isno,thenprovideyourbasisfornotperforming themaintenance, surveillance andtest SUSUEHANNAS.E.S.250DCSYSTEMATTACHNENT IIIPage5procedures described and/orthebasesfornotincluding theoperational featurescited.*Seenotebelow.*Note:Forquestions involving supporting typeinformation (question numbers5and9)insteadofdeveloping andsupplying theinformation inresponsetothisletter,youmaycommittofurtherevaluatetheneedforsuchprovisions duringtheperformance ofyourindividual plantexamination forsevereaccidentvulnerabilities (IPE).Ifyouselectthisoption,youarerequiredto:(1)Sostateinresponsetothesequestions, and(2)Committoexplicitly addressquestions 5and9inyourIPEsubmittal pertheguidelines outlinedinNUREG-1335 (Section2.1.6,Subitem7),"Individual PlantExamination:
Submittal Guidance."
c:~sp51~docsQR106001.PGD (18)10/24/919:06am RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.250VDCSUBSYSTEM PAGE1REMARK1:1.0Thefollowing indications andalarmsforthe250VdcclasslEsubsystem areprovided.
Justification forthisdesignhasbeenpreviously providedinPLA-959totheNRCdated11/6/81,regarding ControlRoommonitoring ofClass1Edcpowersystems.AlarmorIndication BusUndervoltage AlarmBusGroundAlarmBatteryMonitorAlarmBatteryChargerTroubleAlarmBusAmmeterBusVoltmeter BatteryChargerAmmeterBatteryChargerVoltmeter DCSystemTroubleAlarmLocalLocationControlRoomNotes1,21,21,2,41,2,5NOTES:1.SeeTable1andFigure2forspecificlocalalarmindication.
2.Thesearelocallyindicated andactuatedcsubsystem troublealarm,seeTable1andFigurel.3.Metersareprovidedlocally.SeeFigure3.
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.250VDCSUBSYSTEM PAGE24.Batterymonitorcomparesbatterycenterpointvoltagewithhighandlowthreshold reference pointsofthehighandlowvoltagecomparators.
Thedeg}adedcellconditions (suchasashortedcell)oranopencircuitcondition (suchasanopenfuse)aredetectedbythebatterymonitor.5.Batterychargertroublealarmindication isprovidedforbatterychargerACpowerfailure,DCoutputbreakeropen,batterychargerfailurealarmoperation, andbusovervoltage.
6.Oneannunciator windowforeach250Vdcsubsystem isprovided.
2.0 Themonitoring
schemeprovidedforthedcpowersubsystem isbasedonthedegreeofcontrolprovidedtothecontrolroomoperator.
Sincethedcpowersystemequipment cannotberemotelycontrolled, asingledcsystemtroubleannunciator windowforeachsubsystem isprovidedinthecontrolroom,consistent withthesystemlevelalarmcriteriasetforthinSectionBofR.G.1.47.TheSSESdesignisbasedonthegeneralcriteriathat,iftheoperatorcanperformsomecorrective actioninthecontrolroominresponsetoaspecificinput,thatinformation isspecifically provided.
Thedcpowersystemequipment cannotbecontrolled fromthecontrolroom.Annunciating specificinputsfromthe250Vdcsysteminthecontrolroomdoesnotenhancethecontrolroomoperators's abilitytodealwiththesituation anditwouldnotbeconsistent withSSESalarmdesignphilosophy.
However,iftheonlyresponserequiredistodispatchanoperator, toanarearemovedfromthecontrolroom,thentheonlyinformation requiredinthecontrolroomisgeneralinformation withonlythelevelofspecificity requiredtodirectthatoperatortotheproperlocation.
Thismethodisfasterandmorereliablesinceabnormalconditions areautomatically alarmed.Furthermore, thisapproachisconsistent withthehumanfactorsengineering goaltonotoverburdentheoperatorwithunnecessary information.
250Vdcsysteminstrumentation, locallyprovided, isinfullcompliance withtherequirement ofIEEE308-1974andRegulatory Guide1.47.
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.250VDCSUBSYSTEM PAGE3TheDCsystemgeneraltroublealarmsandspecificlocalindicators inconjunction withtheroutineoperatorsurveillance providepositiveassurance thattheClasslEdcpowersystemaremaintained inasteadystatereadytoperformtherequiredsafetyfunction.
3.0 Following
isthejustification foreachalarmandindication listedinGenericLetter91-06.3.1BatterDisconnect orCircuitBreaker0enAlarm:TheSusquehanna S.E.S.(SSES)250Vdcsubsystem utilizesfusesasthebatterydisconnect.
Thiscondition isdetectedbythebatterymonitor.Thebatterymonitorutilizesavariablethreshold circuittogetherwithtwocomparators (highandlow)todetectthelossofbatterycapability duetoanopencircuit(i.e.,anopenfuseordegradedcellcondition).
Avariablethreshold circuitacceptsthebatterychargervoltageanddevelopstwothreshold voltagesforusewiththecomparators.
Whenthemonitored voltagesgoaboveorbelowthethresholds, thebatterymonitoroutputrelaycontactsinitiatealocalbatterymonitoralarmwhichisreflashed tothecontrolroomasa250Vdcsystemtroublealarm.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.2BatterCharerDisconnect orCircuitBreaker0enBothInutACandOututDCAlarm3.2.1BatteryChargerACInputDisconnect orCircuitBreaker:SSESutilizesacircuitbreakerinthebatterychargerasadisconnect fortheacinputpowersupply.Anacpowerfailurealarmrelayisinstalled internaltothebatterychargertodetectlossofacinputpower.Thiscondition couldbecausedbyanopeninputcircuitbreakerorlossofthe480Vacpowersupplytothecharger.Theacpowerfailurealarmrelayinitiates abatterychargertroublealarmatthelocalreflasher panel,whichisreflashed to
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.250VDCSUBSYSTEM PAGE4thecontrolroomasa250Vdcsystemtroublealarm.Thisisconsistent withthegeneraldesignphilosophy discussed insection2.0.3.2.2BatteryChargerDCOutputCircuitBreakerSSESutilizesacircuitbreakerinthebatterychargerasadisconnect forthedcoutputcircuit.Thecircuitbreakerisprovidedwithanauxiliary positionindicating switch.Aswitchcontactwhichisclosedwhenthecircuitbreakerisopenisusedtoinitiateabatterychargertroublealarmatthelocalreflasher panel.Adcsystemtroublealarmisreflashed tothecontrolroombythelocalreflasher panel.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.3DCSstemGroundAlarmThe250Vdcsubsystem isungrounded andisprovidedwithagrounddetection circuit.Itconsistsofarelayhavingacentertappedcoil.Thecoilisconnected acrossthepositiveandnegativebusanditscenterpointisgrounded.
Thegrounddetection relaycoilisnotactuatedduringnormaloperation ofthe250Vdcsubsystem whenagroundisnotpresent.Agroundoneitherthepositiveornegativebusofthe250Vdcsubsystem causesone-halfoftherelaycoiltobeshortcircuited, thusproviding sufficient voltagetotheremaining relaycoilhalftopickuptherelay.Anormallyopencontactoftherelayclosesandinitiates a250Vdcsystemgroundalarmatthelocalreflasher panel.Adcsystemtroublealarmisreflashed tothecontrolroomannunciator bythelocalreflasher panel.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.,3.4DCBusUndervolta eAlarmThe250Vdcsubsystem isprovidedwithadcbusundervoltage relay.Therelayisconnected acrossthepositiveandnegative RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.250VDCSUBSYSTEM PAGE5busofthe250Vdcsubsystem.
Therelayisnormallyenergized andsettodropoutatthespecified setpoint.
A250Vdcbusundervoltage alarmatthelocalreflasher panelisinitiated aftertheundervoltage relaydropsout.Thelocalreflasher panel,inturn,reflashes thealarmtothecontrolroomannunciator asadcsystemtroublealarm.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.5DCBusOvervolta eAlarmThe250Vdcsubsystem isprovidedwithanovervoltage relay.Therelayislocatedinsidethebatterychargercabinet.Itisconnected acrossthepositiveandnegative250Vdcbusofthebatterychargerandsettopickupatthespecified setpoint.
Anormallyopencontactoftheovervoltage relay,whenclosed,initiates abatterychargertroublealarmatthelocalreflasher panelwhichinturnwillreflashadcsystemtroubletothecontrolroomannunciator.
Sincethebattery,'he batterychargerand,thedcloadcenterareincloseproximity ofeachother,thebatterychargervoltageisrepresentative of250Vdcbusvoltage.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.6BatterCharerFailureAlarmThe250Vdcsubsystem batterychargerisprovidedwithabatterychargerfailurerelay.Thisrelaywilldetectthelossofthechargeroutputcurrentwiththeinputandoutputcircuitbreakersclosed.Thiscondition isindicative ofabatterychargerfailureanditinitiates abatterychargertroublealarmatthelocalreflasher panelwhichinturnwillreflashadcsystemtroublealarmtothecontrolroomannunciator.
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.250VDCSUBSYSTEM PAGE6Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.7BatterDischareAlarmThebatterycanonlydischarge whenitsterminalvoltageislessthanthenominalopen.circuitvoltage.Thisisindicative ofabatterychargerfailureorsystemcurrentinexcessofthe,chargercapability.
Abatterychargerfailurealarmisprovidedanditsoperation isdiscussed inSection3.6.Whensystemcurrentexceedsbatterycharger'apability, adcsystemundervoltage condition willoccur,andwillbedetectedbythedcbusundervoltage relay.(SeeSection3.4)Chargerfailureandbusundervoltage initiatealarmsatthelocalreflasher panelwhichinturnwillreflashadcsystemtroublealarmtothecontrolroomannunciator.
Thisisconsistent withthegeneraldesignphilosophy asdiscussed inSection2.0.3.8BatterFloatChareCurrentIndication Undernormalconditions, thebatteryfloatchargecurrentisverysmallcomparedtobatterydischarge current.Measurement ofthiscurrentrequiresaverysensitive ammeter.Shuntbypassesareemployedtoprotecttheammetermovementfromthemuchlargerbatterydischarge currentpossibleinthiscircuit.Theseshuntsmustbemanuallyremovedwhenreadingnormalsmallfloatchargecurrent.Thusthisreadingcannotbecontinuous andnoautomatic indication oralarmscanbegiven.Sincetheintentofindicating "BatteryFloatChargeCurrent"istodetermine thebatterycondition, themethodusedtoaccomplish thispurposeshouldnotbeimportant.
Thebusundervoltage, busground,batterymonitorandbatterychargerfailurealarms(previously described) providecontinuous monitoring todetectdegradation ofbatterycapability.
Thesealarmswillreflashthedcsystemtroublealarminthecontrol RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.250VDCSUBSYSTEM PAGE7room,andanoperatorisdispatched locallytode'termine thecauseofthecondition andinitiatecorrective action.Specificindication isprovidedonthelocalreflasher panel.Thisresponseisexactlywhatwouldbeachievedifanimproperstateofbatterycurrentwereindicated onanammeterinthecontrolroom.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.9BatterCircuitOututCurrentIndication Innormalcondition whenthebatterychargerissupplying the250Vdcpower,thebatterycircuit(batteryandthebatterycharger)outputcurrentisindicated byanammeterlocatedatthebatterycharger.Inthecondition ofabatterychargerfailure,thebatterysuppliesthedcpower.Inthiscondition, thebatterycircuitoutputcurrentisindicated byanammeterlocatedatthedcloadcenter.Asindicated inSection3.8,theintentofindicating "batterycurrent"istodetermine thebatterycondition, andtherefore themethodusedtoaccomplish thispurposeshouldnotbeimportant.
3.10BatterOischareIndication Aspreviously discussed inSection3.7,abatterydischarge willoccurasaresultofabatterychargerfailureorsystemcurrentinexcesstobatterychargercapability.
Sincetheseconditions areautomatically alarmedinthecontrolroom(viathesystemtroublealarm),anoperatorwillbedispatched locallytodetermine thecauseofthecondition andinitiatecorrective action.Thisresponseisexactlywhatwouldbeachievedifbatterydischarge currentwasindicated onanammeterinthe RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.250VDCSUBSYSTEM PAGE8controlroom.3.11BusVoltaeIndication Thebattery,thebatterychargerandthedcloadcenterof250Vdcsubsystem arelocatedincloseproximity ofeachother.Thebatterychargerandthedcloadcenterareeachprovidedwithavoltmeter.
Thepurposeofabusvoltmeter atthecontrolroomwouldbetoenabletheoperatortodispatchsomeonetotakecorrective actionlocallytocorrectabnormalbusvoltage.AtSSESthebusundervoltage ismonitored directlyand'thebusovervoltage conditions aremonitored atthebatterychargeroutput.Thebusundervoltage andthebatterychargeroutputovervoltage
.conditions areannunciated as250Vdcsystemlowvoltageorbatterychargertroubleatthelocalreflasher panel.Adcsystemtroublealarmisreflashed tothecontrolroomannunciator bythelocalreflasher panel.Thisdesignautomatically alertsthecontrolroomoperatortounusualvoltageconditions withoutunnecessarily requiring hisperiodicattention andanalysis.
Asaresult,250Vdcbusvoltageindication isnotprovidedinthecontrolroomandhasbeenprovidedonthefrontoftheloadcenterwhereitprovidesusefulinformation duringsurveillance andmaintenance activities.
Avoltmeter islocatedonthefrontofthebatterychargerpanel.Withthechargeroutputcircuitbreakerclosed,thechargeroutputandthebusvoltagesareessentially thesameduetothecloseproximity ofthechargertotheloadcenter.Allabnormalvoltageconditions ofthebatterychargerareannunciated atthelocalreflasher panelwhichisreflashed tothecontrolroomasadcsystemtroublealarm.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.250VDCSUBSYSTEM PAGE93.12AlarmResonseProcedure Controlroomalarmresponseprocedures fora250Vdcsystemtroublealarmdirecttheoperatortorespondtothelocalreflasher paneltodetermine thecondition whichcausedthealarm.Localalarmresponseprocedures forthereflasher panelareprovidedtodirecttheoperatortodetermine thecauseofthecondition andtoinitiatecorrective action.3.13Indication ofBassedandInoerableStatusofCircuitBreakersorOtheDisconnectin DevicesAlthoughindication ofbypassedandinoperable statusofcircuitbreaker's orotherdisconnecting devicesisnotprovidedasapartoftheBypassIndication System,the250VdcSystemTroubleAlarminthecontrolroomisinitiated forthefollowing condition (whicharedisconnecting devicesinthesystem):Mainbatteryfuseopen.Batterychargeracinputcircuitbreakeropen.Batterychargerdcoutputcircuitbreakeropen,or250Vdcloadcenterbreakeropen.250Vdcloadcenterfeederbreakerto250Vdcmotorcontrolcentersopen.(Eachoftheloadcenterfeederbreakerstothe250VdcMCC'sisprovidedwithanauxiliary positionindicating switchwhichinitiates analarmonthelocalreflasher panelwhenthecircuitbreakerisopen.A250Vdcsystemtroublealarmisreflashed tothecontrolroombythelocalreflasher panel.)
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.250VDCSUBSYSTEM PAGE10TABLE1250VDCSstemReflashPanelIndicators Ticall.250VDCSystemLowVoltage2.250VDCSystemGround3.BatteryMonitor(indicates batterydegradation oropenbatteryfuses)4.BatteryChargerTroubleindicates (1)ACpowerfailure,(2)DCoutputbreakeropen,(3)batterychargerfailure,or(4)busovervoltage (Division Ihas2chargers, DivisionIIhas1charger)5.LoadCenterIncomingBreakersTrip6.RCIC&Isolation ValveControlCenter1D254trouble7.TurbineBldg.ControlCenter1D155trouble8.ComputerUPSSupplyBreakerTripC:XMP51%00CSX250VDCSS.PGD (18)10/24/919:08am CHANNELA250VDCLOCALRERASHPANELWITHINDICATION 1L650MULTIPLEALARMINPUISFROM250VDCCHANNELAPOWERSYStEMPERTABLE1DCSYSTEMALARMINPUTSFROMOTHERREFLASHPANELS(SIMILARTOABOVE)CONTROLROOMPANEL1C651ANNUNCIATOR 250VDCSYSTEMTROUBLE1L650FIGURE1 INDICATOR UGHTREFLASHER PANELPOWERFAILURESYSTEMLOWVOLTAGEBATTERYCHAIWERATROUBLERCIC&ISOVLVSCONTROLCENTER1D254TROUBLE250VDCSYSTEMGROUNDBATTERYCHARGERBTROUBLETURBBU)GCONTROLCENTER1D155TROUBLEBATTERYMONITORLCINCOMINGBKR7245212/22 TRIPCOMPUTERUPSSUPPLYBKRTRIP250VDCSYStEMLOCALREFLASHER PANELOYPICAOFIGURE2 59BATTERYCHARGERAMMETERVOLTMETER BATTERYBANKFUSEBATTERYMONITORAMMETERQVOLTMETER 27SYSTEMGROUNDINDICATORS DCLOADCENTERLOADSLOADSSEETABLE1FORALARMS250VDCSYSTEMOYPICAQFIGURE3
SUSUEHANNAS.E.S.UNIT-1ANDUNIT2DG-E125VDCSYSTEMATTACHMENT IVPage1ENCLOSURE 1Thefollowing information isapplicable toeitherUnitatSusquehanna SES.UnitSusuehannaS.E.S.CommontoUnit1&2DG-E125VDCSYSTEM'a~Thenumberofindependent redundant divisions ofClass1Eorsafety-related dcpowerforthisplantisseeRemarkl.(IncludeanyseparateClass1Eorsafety-related dc,suchasanydcdedicated tothedieselgenerators.)
b.Thenumberoffunctional safety-related divisions ofdcpowernecessary toattainsafeshutdownforthisunitisseeRemark1.3.Doesthecontrolroomatthisunithavethefollowing
- separate, independently annunciated alarmsandindications foreachdivisionofdcpower?a.alarms1.Batterydisconnect orcircuitbreakeropen?No2.Batterychargerdisconnect orcircuitbreakeropen(bothinputacandoutputdc)?No3.dcsystemground?No4.dcbusundervoltage?
No5.dcbusovervoltage?
No6.Batterychargerfailure?No7.Batterydischarge?
No 0
SUSUEHANNAS.E.S.UNIT-1ANDUNIT2DG-E125VDCSYSTEMb.Indications ATTACHMENT IVPage21.Batteryfloatchargecurrent?No2.Batterycircuitoutputcurrent?No3.Batterydischarge?
No4.Busvoltage?Noc.Doestheunithavewrittenprocedures forresponsetotheabovealarmsandindications?
NoDoesthisunithaveindication ofbypassedandinoperable statusofcircuitbreakersorotherdevicesthatcanbeusedtodisconnect thebatteryandbatterychargerfromitsdcbusandthebatterychargerfromitsacpowersourceduringmaintenance ortesting?NoSeeRemark25.Iftheanswertoanypartofquestion3or4isno,thenprovideinformation justifying theexistingdesignfeaturesofthefacility's safety-related dcsystems.*Seenotebelow.SeeRemark26.(I)Haveyouconducted areviewofmaintenance andtestingactivities tominimizethepotential forhumanerrorcausingmorethanonedcdivisiontobeunavailablet
~esand(2)doplantprocedures prohibitmaintenance ortestingonredundant dcdivisions atthesamatime?~esIfthefacilityTechnical Specifications haveprovisions equivalent tothosefoundintheWestinghouse andCombustion Engineering StandardTechnical Specifications formaintenance andsurveillance, thenquestion7maybeskippedandastatement tothateffectmaybeinsertedhere.
SUSUEHANNAS.E.S.UNIT-1ANDUNIT2DG-E125VDCSYSTEMATTACHMENT IVPage37.Aremaintenance, surveillance andtestprocedures.
regarding stationbatteries conducted routinely atthisplant?'pecifically:
a.Atleast,onceper7daysarethefollowing verifiedtobewithinacceptable limits:1.Pilotcellelectrolyte level?Yes2.Specifygravityorchargingcurrent?Yes3.Floatvoltage?Yes4.Totalbusvoltageonfloatcharge?Yes5.Physicalcondition ofallcells?Yesb.Atleastonceper92days,orwithin7daysafterabatterydischarge, overcharge, orifthepilotcellreadingsareoutsidethe7-daysurveillance requirements arethefollowing verifiedtobewithinacceptable limits:l.Electrolyte levelofeachcell?Yes2.Theaveragespecificgravityofallcells?Yes3.Thespecificgravityofeachcell?Yes4.Theaverageelectrolyte temperature ofarepresentative numberofcells?Yes5.Thefloatvoltageofeachcell?Yes6.Visuallyinspectormeasureresistance ofterminals andconnectors (including theconnectors atthedcbus)?Yes SUSUEHANNAS.E.S.UNIT-1ANDUNIT2DG-'E125VDCSYSTEMc.Atleastevery18monthsarethefollowing verified:
ATTACHMENT IVPage41.Lowresistance ofeachconnection (bytest)?Yes2.Physicalcondition ofthebattery?Yes3.Batterychargercapability todeliverratedampereoutputtothedcbus?YestThecapability ofthebattery-todeliveritsdesigndutycycletothedcbus?Yes5.Eachindividual cellvoltageiswithinacceptable limitsduringtheservicetest?Yesd.Atleastevery60months,iscapacityofeachbatteryverifiedbyperformance ofadischarge test?Yese.Atleastannually, isthebatterycapacityverifiedbyperformance discharge test,ifthebatteryshowssignsofdegradation orhasreached85Xoftheexpectedservicelife?Yes8.Doesthisplanthaveoperational featuressuchthatfollowing lossofonesafety-related dcpowersupplyorbus:a.Capability ismaintained forensuringcontinued andadequatereactorcooling?Yesb.Reactorcoolantsystemintegrity andisolation capability aremaintained?
Yesfc.Operating procedures, instrumentation (including indicators andannunciators),
andcontrolfunctions areadequatetoinitiatesystemsasrequiredtomaintainadequatecore,cooling?
Yes SUSUEHANNAS.E.S.UNIT-1ANDUNIT2DG-E125VDCSYSTEMATTACHMENT IVPage59Iftheanswertoanypartofquestion6,7or8isno,thenprovideyourbasisfornotperforming themaintenance, surveillance andtestprocedures described and/orthebasesfornotincluding theoperational featurescited.*Seenotebelow.*Note:Forquestions involving supporting typeinformation (question numbers5and9)insteadofdeveloping andsupplying theinformation inresponsetothisletter,youmaycommittofurtherevaluatetheneedforsuchprovisions duringtheperformance ofyourindividual plantexamination forsevereaccidentvulnerabilities (IPE).Ifyouselectthisoption,youarerequiredto:(1)Sostateinresponsetothesequestions, and(2)Committoexplicitly addressquestions 5and9inyourIPEsubmittal pertheguidelines outlinedinNUREG-1335 (Section2.1.6,Subitem7),"Individual PlantExamination:
Submittal Guidance."
c:Xup51hdocshdg-e125v.pgd (18)10/24/91 8:48am RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.UNIT1ANDUNIT2DG-E125VDCSUBSYSTEM PAGE1REMARK1:DieselGenerator Eisaninstalled sparedieselgenerator capableofsubstituting asanemergency powersourceforanyoneoftheexistingemergency dieselgenerators (A,B,C,D).TheDieselGenerator E125Vdcpowersubsystem isidentified asChannelHandisdedicated toproviding dcpowertoESWvalvesforDieselGenerator Ecooling,DieselGenerator Econtrols, andDieselGenerator E4.16kVSwitchgear.
Thisequipment isalllocatedinaseparateDieselGenerator Ebuilding.
TheDieselGenerator E125VdcSubsystem isrequiredonlywhenthisdieselgenerator issubstituting foroneoftheexistingdieselgenerators.
Itisinadditionto,independent andisolatedfromtheotherfourClasslE125VdcSubsystems.
Lossofanyoneofthe125VdcSubsystems doesnotpreventtheminimumsafetyfunctionfrombeingperformed.
REMARK2:1.0Thefollowing indications andalarmsfortheDG-E125VdcclasslEsubsystem areprovided.
Justification forthisdesignisconsistent withthedesignphilosophy regarding ControlRoommonitoring ofClass1Edcpowersystemsaspreviously providedinPLA-959totheNRCdated11/6/81.
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.UNIT1ANDUNIT2DG-E125VDCSUBSYSTEM PAGE2AlarmorIndication LocalLocationControlRoomNotesBusUndervoltage AlarmBusGroundAlarmBatteryMonitorAlarmBatteryChargerTroubleAlarmBusAmmeter1,21,21,2,41,2,5BusVoltmeter BatteryChargerAmmeterBatteryChargerVoltmeter DCSystemTroubleAlarmNOTES:1.SeeTable1forspecificlocalalarmannunciation.
2.ThesealarmsarelocallyprovidedonDG-Eannunciator/reflasher panelOC577E.Adcsubsystem troublealarm.isreflashed tothecontrolroombythisannunciator.
SeeTable1,Figure1.3.Hetersareprovidedlocally.SeeFigure2.4.Batterymonitorcomparesbatterycenterpointvoltagewithhighandlowthreshold reference points,,of thehighandlowvoltagecomparators.
Thedegradedcellconditions (such"asashortedcell)oranopencircuitcondition (suchasanopenfuse)aredetectedbythebatterymonitor.
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.UNIT1ANDUNIT2DG-E125VDCSUBSYSTEM PAGE35.Batterychargertroublealarmindication isprovidedforbatterychargerACpowerfailure,DCoutputbreakeropen,batterychargerfailurealarmoperation, batterychargerhigh/lowvoltageandbatterychargerhighvoltage(shutdown).
6.Oneannunciator windowfortheDG-E125Vdcsubsystem isprovided.
2.0 Themonitoring
schemeprovidedforthedcpowersubsystem isbasedonthedegreeofcontrolprovidedtothecontrolroomoperator.
Sincethedcpowersystemequipment cannotberemotelycontrolled, asingledcsystemtroubleannunciator windowforeachsubsystem isprovidedinthecontrolroom,consistent withthesystemlevelalarmcriteriasetforthinSectionBofR.G.1.47.TheSSESdesignisbasedonthegeneralcriteriathat,iftheoperatorcanperformsomecorrective actioninthecontrolroominresponsetoaspecificinput,thatinformation isspecifically provided.
Thedcpowersystemequipment cannotbecontrolled fromthecontrolroom.Annunciating specificinputsfromthe125Vdcsysteminthecontrolroomdoesnotenhancethecontrolroomoperators's abilitytodealwiththesituation anditwouldnotbeconsistent withSSESalarmdesignphilosophy.
However,.if theonlyresponserequiredistodispatchanoperatortoanarearemovedfromthecontrolroom,thentheonlyinformation requiredinthecontrolroomisgeneralinformation withonlythelevelofspecificity re'quired todirectthatoperatortotheproperlocation.
Thismethodisfasterandmorereliablesinceabnormalconditions areautomatically alarmed.Furthermore, thisapproachisconsistent withthehumanfactorsengineering goaltonotoverburdentheoperatorwithunnecessary information.
125Vdcsysteminstrumentation, locallyprovided, isinfullcompliance withtherequirement ofIEEE308-1974andRegulatory Guide1.47.eTheDCsystemgeneraltroublealarmsandspecificlocalindicators inconjunction withtheroutineoperatorsurveillance providepositiveassurance thattheClass1Edcpowersystemaremaintained inasteadystatereadytoperformtherequiredsafetyfunction.
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.UNIT1ANDUNIT2DG-E125VDCSUBSYSTEM PAGE43.0Following isthejustification foreachalarmandindication listedinGenericLetter91-06.3.1BatterDisconnect orCircuitBreaker0enAlarm:TheSusquehanna S.E.S.(SSES)DG-E125Vdcsubsystem utilizesafuseddisconnect asthebatterydisconnect.
Thiscondition isdetectedbythebatterymonitor.Thebatterymonitorutilizesavariablethreshold circuittogetherwithtwocomparators (highandlow)todetectthelossofbatterycapability duetoanopencircuit(i.e.,anopenfuseor,degradedcellcondition).
Avariablethreshold circuitacceptsthebattery'chargervoltageanddevelopstwothreshold voltagesforusewiththecomparators.
Whenthemonitored voltagesgoaboveorbelowthethresholds, thebatterymonitoroutputrelaycontactsinitiatealocalbatterymonitorannunciator whichisreflashed tothecontrolroomasaDG-E125Vdcsystemtroublealarm.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.2BatterCharerDisconnect orCircuitBreaker0enBothInutACandOututDCAlarm3.2.1BatteryChargerACInputDisconnect orCircuitBreaker:SSESutilizesacircuitbreakerinthebatterychargerasadisconnect fortheacinputpowersupply.Anacpowerfailurealarmrelayisinstalled internaltothebatterychargertodetectlossofacinputpower.Thiscondition couldbecausedbyanopeninputcircuitbreakerorlossofthe480Vacpowersupplytothecharger.Theacpowerfailurealarmrelayinitiates abatterychargertroublealarmatthelocalannunciator panel,whichisreflashed tothecontrolroomasaDG-E125Vdcsystemtroublealarm.Thisisconsistent withthegeneraldesignphilosophy discussed insection2.0.
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.UNIT1ANDUNIT2DG-E125VDCSUBSYSTEM PAGE53.2.2BatteryChargerDCOutputCircuitBreakerSSESutilizesacircuitbreakerinthebatterychargerasadisconnect forthedcoutputcircuit.Thecircuitbreakerisprovidedwithanauxiliary positionindicating switch.Aswitchcontactwhichisclosedwhenthecircuitbreakerisopenisusedtoinitiateabatterychargertroublealarmatthelocalannunciator panel.ADG-Edcsystemtroublealarmisreflashed tothecontrolroombythelocalannunciator
'anel.Thisisconsistent withthe,generaldesignphilosophy discussed inSection2.0.3.3DCSstemGroundAlarm'heDG-E125Vdcsubsystem isungrounded andisprovidedwithagrounddetection circuit.Itconsistsofarelayhavingacentertappedcoil.Thecoilisconnected acrossthepositiveandnegativebusanditscenterpointisgrounded.
Thegrounddetection relaycoilisnotactuatedduringnormaloperation ofthe125Vdcsubsystem whenagroundisnotpresent.Agroundoneitherthepositiveornegativebusofthe125Vdcsubsystem causesone-halfoftherelaycoiltobeshortcircuited, thusproviding sufficient voltagetotheremaining relaycoilhalftopickuptherelay.Anormallyopencontactoftherelayclosesandinitiates a125Vdcsystemgroundalarmatthelocalannunciator panel.ADG-Edcsystemtroublealarmisreflashed tothecontrolroomannunciator bythelocalannunciator panel.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.4DCBusUndervolta eAlarmTheDG-E125Vdcsubsystem isprovidedwithabatterychargerundervoltage relay.Therelayisconnected acrossthepositiveandnegativebusofthe125Vdcbatterycharger.Therelayisnormallyenergized andsettodropoutatthespecified setpoint.
Abatterychargertroublealarmatthelocalannunciator panelis
RESPONSETOGENERICLETTER91-06SUSUEMANNAS.E.S.UNIT1ANDUNIT2DG-E125VDCSUBSYSTEPAGE6initiated aftertheundervoltage relaydropsout.Thelocalannunciator panel,inturn,reflashes thealarmtothecontrolroomannunciator asaDG-Edcsystemtroublealarm.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.Inadditiontothebatterychargerundervoltage relay,abusundervoltage relayisprovidedtodetectalossofbusvoltage.ThemostprobablecauseofaDCsystemundervoltage condition isaresultofabatterychargerproblem,whichwillbedetectedbythebatterycharger,failurealarmrelay(seeSection3.6).Thechargerfailurerelayinitiates abatterychargertroublealarmatthelocalannunciator panel,whichinturn,reflashes aDG-Edcsystemtroublealarmtothecontrolroomannunciator.
Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.5DCBusOvervolta eAlarmTheDG-E125Vdcsubsystem isprovidedwithanovervoltage relay.Therelayislocatedinsidethebatterychargercabinet.Itisconnected acrossthepositiveandnegative125Vdcbusofthebatterychargerandsettopickupatthespecified setpoint.
Anormallyopencontactoftheovervoltage relay,whenclosed,initiates abatterychargertroublealarmatthelocalannunciator panelwhichinturnwillreflashaDG-Edcsystemtroublealarmtothecontrolroomannunciator.
Sincethebattery,thebatterychargerandthedcloadcenterareincloseproximity ofeachother,thebatterychargervoltageisrepresentative oftheDG-E125Vdcbusvoltage.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.UNITIANDUNIT2DG-E125VDCSUBSYSTEM PAGE73.6BatterCharerFailureAlarmTheDG-E125Vdcsubsystem batterychargerisprovidedwithabatterychargerfailurerelay.Thisrelaywilldetectthelossofthechargeroutputcurrentwiththeinputandoutputcircuitbreakersclosed.Thiscondition isindicative ofabatterychargerfailureanditinitiates abatterychargertroublealarmatthelocalannunciator panelwhichinturnwillreflashaDG-Edcsystemtroublealarmtothecontrolroomannunciator.
Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.7BatterDischareAlarmThebatterycanonlydischarge whenitsterminalvoltageislessthanthenominalopencircuitvoltage.Thisisindicative ofabatterychargerfailureorsystemcurrentinexcessofthechargercapability.
Abatterycharger,failurealarmisprovidedanditsoperation isdiscussed inSection3.6.Whensystemcurrentexceedsbatterychargercapability, adcsystemundervoltage condition willoccur,andwillbedetectedbythebatterychargerundervoltage relay(seeSection3.4).Chargerfailureandbatterychargerundervoltage initiatealarmsatthelocalannunciatorpanelwhichinturnwillreflashaDG-Edcsystemtroublealarmtothecontrolroomannunciator.
Thisisconsistent withthegeneraldesignphilosophy asdiscussed inSection2.0.3.8BatterFloatChareCurrentIndication Undernormalconditions, thebatteryfloatchargecurrentisverysmallcomparedtobatterydischarge current.Measurement ofthiscurrentrequiresaverysensitive ammeter.Shuntbypassesareemployedtoprotecttheammetermovementfromthemuchlargerbatterydischarge currentpossibleinthiscircuit.'hese shu'ntsmustbemanuallyremovedwhenreadingnormalsmallfloatchargecurrent.Thusthisreadingcannotbecontinuous andnoautomatic RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.UNIT1ANDUNIT2DG-E125VDCSUBSYSTEM PAGE8indication oralarmscanbegiven.Sincetheintentofindicating "BatteryFloatChargeCurrent"istodetermine thebatterycondition, themethodusedtoaccomplish thispurposeshouldnotbeimportant.
Thebatterychargerundervoltage, busground,batterym'onitorandbatterychargerfailurealarms(previously described) providecontinuous monitoring todetectdegradation ofbatterycapability.
ThesealarmswillreflashtheDG-Edcsystemtroublealarminthecontrolroom,andanoperatorisdispatched locallytodetermine thecauseofthecondition andinitiatecorrective action.Specificindication isprovidedonthelocalannunciator panel.Thisresponseisexactlywhatwouldbeachievedifanimproperstateofbatterycurrentwereindicated onanammeterinthecontrolroom.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.9BatterCircuitOututCurrentIndication Innormalcondition whenthebatterychargerissupplying the125Vdcpower,thebatterycircuit(batteryandthebatterycharger)outputcurrentisindicated byanammeterlocatedatthebatterycharger.Inthecondition ofabatterychargerfailure,thebatterysuppliesthedcpower.Inthiscondition thebatterycircuitoutputcurrentisindicated byanammeterlocatedatthedcswitchboard.
Asindicated inSection3.8,theintentofindicating "batterycurrent"istodetermine thebatterycondition, andtherefore themethodusedtoaccomplish thispurposeshouldnotbeimportant.
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.UNIT1ANDUNIT2DG-E125VDCSUBSYSTEM PAGE93.10BatterDischareIndication Aspreviously discussed inSection3.7,abatterydischarge willoccurasaresultofabatterychargerfailureorsystemcurrentinexcesstobatterychargercapability.
Sincetheseconditions areautomatically alarmedinthecontrolroom(viathesystemtroublealarm),anoperator'will bedispatched locallytodetermine thecauseofthecondition andinitiatecorrective action.Thisresponseisexactlywhatwouldbeachievedifbatterydischarge currentwasindicated onanammeterinthecontrolroom.3.11BusVoltaeIndication Thebattery,thebatterychargerandthedcswitchboard oftheDG-E125Vdcsubsystem arelocatedincloseproximity ofeachother.Thebatterychargerandthedcswitchboard areeachprovidedwithavoltmeter.
Thepurposeofabusvoltmeter atthecontrolroomwouldbetoenabletheoperatortodispatchsomeonetotakecorrective actionlocallytocorrectabnormalbusvoltage.Thiscondition willoccurwhenabatterychargerproblemispresent.Undervoltage andovervoltage conditions aremonitored atthebatterycharger,andareannunciated asbatterychargertroubleatthelocalannunciator panel.ADG-Edcsystemtroublealarmisreflashed tothecontrolroomannunciator bythelocalannunciator panel.Thisdesignautomatically alertsthecontrolroomoperatortounusualvoltageconditions withoutunnecessarily requiring hisperiodicattention andanalysis.
Asaresult,125Vdcbusvoltageindication isnotprovidedinthecontrolroomandhasbeenprovidedonthefrontofthedcswitchboard whereitprovidesusefulinformation duringsurveillance andmaintenance activities.
Avoltmeter islocatedonthefrontofthebatterychargerpanel.Withthechargeroutputcircuitbreakerclosed,thechargeroutputandthebusvoltagesareessentially thesameduetotheclose RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.UNIT1ANDUNIT2DG-E125VDCSUBSYSTEM PAGE10proximity ofthechargertotheloadcenter.Allabnormalvoltageconditions ofthebatterychargerareannunciated atthelocalannunciator panelwhichisreflashed tothecontrolroomasaDG-Edcsystemtroublealarm.Thisisconsistent withthegeneraldesignphilosophy discussed inSection2.0.3.12AlarmResonseProcedure Controlroomalarmresponseprocedures foraDG-E125Vdcsystemtroublealarmdirecttheoperatortorespondtothelocalannunciator paneltodetermine thecondition whichcausedthealarm.Localalarmresponseprocedures fortheannunciator panelareprovidedtodirecttheoperatortodetermine thecauseofthecondition andtoinitiatecorrective action.3.13Indication ofBassedandInoerableStatusofCircuitBreakersorOtherDisconnectin DevicesAlthoughindication ofbypassedandinoperable statusofcircuitbreakersorotherdisconnecting devicesisnotprovidedasapartoftheBypassIndication System,the125VdcSystemTroubleAlarminthecontrolroomisinitiated forthefollowing condition (whicharedisconnecting devicesinthesystem):Hainbatteryfuseddisconnect open.Batterychargeracinputcircuitbreakeropen.Batterychargerdcoutputcircuitbreakeropenor125Vdcswitchboard breakeropen.
RESPONSETOGENERICLETTER91-06SUSUEHANNAS.E.S.UNIT1ANDUNIT2DG-E125VDCSUBSYSTEM PAGE11TABLE1125VDG-EDCSstemAnnunciator PanelAlarmsl.125VDCSystemLowVoltage2.125VDCSystemGround3.BatteryHonitor(indicates batterydegradation oropenbatteryfuses)4.BatteryChargerTroubleindicates (1)ACpowerfailure,(2)DCoutputbreakeropen,(3),battery chargerfailure,(4)batterychargerhigh/lowvoltage,or(5)batterycharger'igh voltage(shutdown).
C:XQP51%00CS~RGL91-06.PGD (18)10/24/918:35am DG-EBLDGPANELOC577EMULTIPLEALARMINPUTSFROMDG-E125VDCPOWERSYSTEMPERTABlE1CONTROLROOMPANELOC653ANNUNCIATOR DG-EBLDGPANELOC577EDCSYSTEMTROUBLEFIGURE1 7/5959BATTERYCHARGERAMMETERVOLTMETERBATTERYBANKFUSEBATTERYMONITORAMMETERVOLTMETER 27SYSTEMGROUNDINDICATORS DCSWITCHBOARD LOADSLOADSSEETABLE1FORALARMSDG-E125VDCSYSTEMFIGURE2