ML18026A242

Forwards Response to Generic Ltr 91-06, Resolution of Generic Issues A-30, 'Adequacy of Safety-Related DC Power Supplies.'

ML18026A242
Person / Time
Site:	Susquehanna
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