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{{#Wiki_filter:ACCELERATEDDISRIBUTIONDEMONSTTIONSYSTEMREGULATORYINFORMATIONDISTRIBUTIONSYSTEM(RIDS)ACCESSIONNBR:9010050242DOC.DATE:90/09/20NOTARIZED:NOFACIL:50-244RobertEmmetGinnaNuclearPlant,Unit1,RochesterGAUTH.NAMEAUTHORAFFILIATIONMECREDY,R.C.RochesterGas6ElectricCorp.RECIP.NAMERECIPIENTAFFILIATIONJOHNSON,A.R.ProjectDirectorateI-3DOCKET05000244
{{#Wiki_filter:ACCELERATED DISRIBUTIONDEMONSTTIONSYSTEMREGULATORY INFORMATION DISTRIBUTION SYSTEM(RIDS)ACCESSION NBR:9010050242 DOC.DATE:
90/09/20NOTARIZED:
NOFACIL:50-244 RobertEmmetGinnaNuclearPlant,Unit1,Rochester GAUTH.NAMEAUTHORAFFILIATION MECREDY,R.C.
Rochester Gas6ElectricCorp.RECIP.NAME RECIPIENT AFFILIATION JOHNSON,A.R.
ProjectDirectorate I-3DOCKET05000244


==SUBJECT:==
==SUBJECT:==
ForwardsDesignAnalysis4525-1,"FaultCurrentAnalysisforPowerDistributionSys,"Rev1&DesignAnalysis4525-2.DISTRIBUTIONCODE:AOOIDCOPIESRECEIVED:LTR$ENCL$SIZE:TITLE:ORSubmittal:GeneralDistributionNOTES:LicenseExpdateinaccordancewith10CFR2,2.109(9/19/72).05000244RECIPIENTIDCODE/NAMEPDl-3LAJOHNSON,AINTERNAL:NRR/DET/ECMB9HNRR/DST8E2NRR/DST/SICB7ENUDOCS-ABSTRACTOGC/HDS2RES/DSIR/EIBEXTERNAL:NRCPDRCOPIESLTTRENCL11221111111'101111RECIPIENTIDCODE/NAMEPD1-3PDNRR/DOEA/OTSB11NRR/DST/SELB8DNRR/DST/SRXB8EGFILEOlNSICCOPIESLTTRENCL11111111101111NOTETOALL"RIDS"RECIPIENTS:PLEASEHELPUSTOREDUCEiVASK!CONTACTTHEDOCUMENTCONTROLDESK,ROOMPl-37(EXT.20079)TOELIMINATEYOURNAMEFROMDISTRIBUTIONLISTSFORDOCUMENTSYOUDON'TNEED!TOTALNUMBEROFCOPIESREQUIRED:LTTR17ENCL15  
ForwardsDesignAnalysis4525-1,"FaultCurrentAnalysisforPowerDistribution Sys,"Rev1&DesignAnalysis4525-2.DISTRIBUTION CODE:AOOIDCOPIESRECEIVED:LTR
\f$a IIIIIIIIIII/IIIIIIIIIIII~AirOall*///IjI//Ij/I//III/IIIg!p',ROCHESTERGASANDELECTRICCORPORATIONo89EASTAVENUE,ROCHESTERN.Y.14649-0001ROBERTC.MECREDYVicePresidentCinnaNuctearProductionSeptember20,1990TEt.EPHONEArtEAcooE7re546.2700U.S.NuclearRegulatoryCommissionDocumentControlDeskAttn:AllenR.JohnsonProjectDirectorateI-3Washington,D.C.20555
$ENCL$SIZE:TITLE:ORSubmittal:
GeneralDistribution NOTES:License Expdateinaccordance with10CFR2,2.109(9/19/72).
05000244RECIPIENT IDCODE/NAME PDl-3LAJOHNSON,A INTERNAL:
NRR/DET/ECMB 9HNRR/DST8E2NRR/DST/SICB 7ENUDOCS-ABSTRACT OGC/HDS2RES/DSIR/EIB EXTERNAL:
NRCPDRCOPIESLTTRENCL11221111111'101111RECIPIENT IDCODE/NAME PD1-3PDNRR/DOEA/OTSB11 NRR/DST/SELB 8DNRR/DST/SRXB 8EGFILEOlNSICCOPIESLTTRENCL11111111101111NOTETOALL"RIDS"RECIPIENTS:
PLEASEHELPUSTOREDUCEiVASK!CONTACTTHEDOCUMENTCONTROLDESK,ROOMPl-37(EXT.20079)TOELIMINATE YOURNAMEFROMDISTRIBUTION LISTSFORDOCUMENTS YOUDON'TNEED!TOTALNUMBEROFCOPIESREQUIRED:
LTTR17ENCL15  
\f$a IIIIIIIIIII/
IIIIIIIIIIII
~AirOall*///IjI//Ij/I//III/III g!p',ROCHESTER GASANDELECTRICCORPORATION o89EASTAVENUE,ROCHESTER N.Y.14649-0001 ROBERTC.MECREDYVicePresident CinnaNuctearProduction September 20,1990TEt.EPHONE ArtEAcooE7re546.2700U.S.NuclearRegulatory Commission DocumentControlDeskAttn:AllenR.JohnsonProjectDirectorate I-3Washington, D.C.20555


==Subject:==
==Subject:==
Line 27: Line 40:


==DearMr.Johnson:==
==DearMr.Johnson:==
Peryourrequest,weareenclosingcopiesofDesignAnalysis4525-1"FaultCurrentAnalysisofPowerDistributionSystem"Rev1andDesignAnalysis4525-2"AdequacyofElectricSystemVoltages"Rev1foryourreview.Theseanalysesquantifytheeffectsassociatedwiththerecentlycompletedoffsitepowerreconfiguration(EWR'4525).EWR4525modifiedtheoffsitepowersystemsuchthattherewouldbeadedicated34.5/4.16kVtransformerassociatedwitheachofthetwoindependentoffsitetransmissionlines.Station204energizestransformer12AwhichisnowthenormalsourceofpowerforBus12AandsafetytrainAwhileStation13Aenergizestransformer12BwhichisnowthenormalsourceofpowerforBus12BandsafetytrainB(seefigure1).Thisnormalconfigurationisreferredtoasthe50/50modesinceeachindependentoffsitepowersourcesupplies1/2oftherequiredoffsitepower.Theoperatorsstillhavetheabilitytoputtheoffsitepowersystemineitherthe100/0mode(Transformer12Bsuppliesalloffsitepower)orthe0/100mode(Transformer12Asuppliesalloftheoffsitepower).ThenormalconfigurationpriortoEWR4525wastohavealloffsitepowersuppliedbytransformer12A.EWR4525hassignificantlyreducedthelikelihoodofasimultaneouslossofoffsitepowertobothsafetytrainsandhasimprovedsystemperformancesincetheelectricalloadisnownormallydividedbetweentwotransformers.TheprimaryobjectiveofDesignAnalysis4525-2istodemonstratethatthereconfiguredoffsitepowersupplywillbecapableofmaintainingadequatevoltagesforallrequiredoperatingconditions.Theresultsindicatedthatbothoffsitesourcesr5'ot00502429005'20PDR4DOCK05000244PPDCgooI Il'IF"~A,4'3 (circuit751fromStation204&767fromStation13A)arecapableofprovidingadequatevoltagesforallrequiredfunctions.Twospecialcasesarediscussedbelowwhichrepresentthelimitingcases:1.ThecomputersimulationsindicatedthatbothoffsitesourcesmayhavedifficultyinmaintainingadequatevoltagesduringthestartupofaReactorCoolantPump(RCP)forthespecialcasewhentheoffsitegridvoltagewasatitsminimumvalue(33kvforcircuit751and116kvforcircuit767).ThisissueiscurrentlybeingaddressedbymodifyingtheRCPnormalstartprocedures.TheoperatorshavebeeninstructedtoverifythatadequateprestartvoltagesexistpriortoattemptinganRCPstart.Wehavecalculatedcircuit767mayalsohaveasimilarproblemwhenattemptingaSteamGeneratorFeedwaterPump(SGFWP)Start.Thiscomputeranalysisiscurrentlybeingreevaluatedtodetermineifanyexcessiveconservatismispresentintheanalysisandifrequired,theSGFWPstartprocedurewillalsobemodified.ItshouldbenotedthatCircuit767hasnothadanydifficultytodateinstartingeithertheRCPortheSGFWP.2.TheworstcaseLossofCoolantAccident(LOCA)simulationassumestwodegradedoperatingconditions:operatingsolelyonline767,(100/0mode),andamin'imumgridvoltage(116kv).Theresultsshowallbusvoltagesabove414volts,indicatingthatallofthe1Epumpmotorswilloperateandthattheundervoltagerelayingonthesebusseswillnotdisconnectthemfromoffsitepower.However,thelowest480voltMCCvoltagewas405volts,whichislowerthanRG&E'sacceptancecriteria.TheonlyloadsontheMCCsrequiredtomitigatethisaccidentwouldbeMOVs.WebelievethattheMOVswilloperateproperlyatthisvoltage,however,toprovidegreaterassurancewehaverevisedouroperatinglimitstowhichtheoffsitegrid,voltageswillbecontrolledwhensafeguardsequipmentisrequired.Whentheoffsitesupplyisprovidedinthe100/0mode(767isthelonesource)thegridvoltagewillbemaintainednolowerthan118kv.Asimulationhasbeenrunatthisvoltagewhichprovidedresultswithinallacceptancecriteria.Historicaldatademonstratesthatthegridvoltageisatleast118kvover95%ofthetime.Forthenormaloperatingmode,inthe50/50configuration,thesimulationresultsshowthatallofthevoltagesarewithintheestablishedcriteria,evenattheminimumgridvoltageof116kv.Itshouldbenotedthatthispotentiallowvoltageconditionwasnotcreatedbythereconfigurationoftheoffsitepowersystemandinfact,thelikelihoodoftheconditionoccurringwassignifi-cantlyreduced.Theabilitytoruntheoffsitepowersysteminthe50/50modewasamajorobjectiveofthepowersystemreconfigura-tionproject(EWR4525).ItshouldalsobenotedthatthemostsevereLOCAsimulationforcircuit751(0/100modeandminimumsourcevoltage33kv)resultedinacceptablevoltages.
Peryourrequest,weareenclosing copiesofDesignAnalysis4525-1"FaultCurrentAnalysisofPowerDistribution System"Rev1andDesignAnalysis4525-2"Adequacy ofElectricSystemVoltages" Rev1foryourreview.Theseanalysesquantifytheeffectsassociated withtherecentlycompleted offsitepowerreconfiguration (EWR'4525).EWR4525modifiedtheoffsitepowersystemsuchthattherewouldbeadedicated 34.5/4.16kV transformer associated witheachofthetwoindependent offsitetransmission lines.Station204energizes transformer 12AwhichisnowthenormalsourceofpowerforBus12AandsafetytrainAwhileStation13Aenergizes transformer 12BwhichisnowthenormalsourceofpowerforBus12BandsafetytrainB(seefigure1).Thisnormalconfiguration isreferredtoasthe50/50modesinceeachindependent offsitepowersourcesupplies1/2oftherequiredoffsitepower.Theoperators stillhavetheabilitytoputtheoffsitepowersystemineitherthe100/0mode(Transformer 12Bsuppliesalloffsitepower)orthe0/100mode(Transformer 12Asuppliesalloftheoffsitepower).Thenormalconfiguration priortoEWR4525wastohavealloffsitepowersuppliedbytransformer 12A.EWR4525hassignificantly reducedthelikelihood ofasimultaneous lossofoffsitepowertobothsafetytrainsandhasimprovedsystemperformance sincetheelectrical loadisnownormallydividedbetweentwotransformers.
TheprimaryobjectiveofDesignAnalysis4525-1wastoverifythatthereconfigurationoftheoffsitepowersystemdidnotresultinexcessiveshortcircuitdutiesforeithertheneworexistingequipment.Theresultsindicated.thatthereconfigurationhadanegligibleimpactontheshortcircuitdutiesfortheexisting'quipmentandthatallofthenewequipmentwasspecifiedwithshortcircuitratingswellinexcessofthecalculatedduties.Theexistingequipmentwasfoundtohaveadequateshortcircuitcapacityforallcasesexceptforonecaseofdieselgeneratortesting,discussedbelow:Aspecialcaseinvolvingthedieselgeneratorwhenitisinitsmonthlytestconfigurationwascomputersimulatedanditwasdetermined.thatpotentialshortcircuitdutiescouldexceedacceptablelimits.Thisisalowprobabilityeventrequiringaphase-to-phasefaultoccurrenceduringatwohourtestperiod.Theconsequenceofsuchaneventisaneconomicconcernonly,notasafetyissue.Theeventcouldresultinashutdownoftheplantforrepairs.Safeguardsystemredundancycouldbereduced,however,theeventwouldnotrequiretheuseofthesafeguardssystemforplantshutdown.Thisconditionwasnotcreated.bythereconfigurationoftheoffsitepowersystemandvariousalternativestoresolvethisissuearecurrentlybeingevaluated.WeexpecttobeabletoinformyouofourintendedcorrectiveactionbyOctober30,1990.Verytrulyyours,RobertC.MecreTHM/122Att'achmentsxc:Mr.AllenR.Johnson(MailStop14D1)ProjectDirectorateI-3Washington,D.C.20555U.S.NuclearRegulatoryCommissionRegionI475AllendaleRoadKingofPrussia,PA19406GinnaSeniorResidentInspector  
Theprimaryobjective ofDesignAnalysis4525-2istodemonstrate thatthereconfigured offsitepowersupplywillbecapableofmaintaining adequatevoltagesforallrequiredoperating conditions.
~~~OI=I=SITEDISTRIBUTIONSYSTEMEV/R4525SIAIjASIA.204TOCSUTRAIISfOIIIIfft52I2II~I12IIXtie12BYNO12AEY12AX52NO12AYNC5252ftEMOVAQLELltIKTOVIGEtIERA)ORDUMMYBREAKERDUMMYBREAKER52525252525)52IOSIA.TOSTA.SIRV.SLRV.1ftAtIS.IRArIS.lII7pl6'..AlIIYfRAltl-Il-TOSTA.SERV.TRAtIS.g15TOSTA.SERV.TRAtlS.(ISTOSTA.TOSIA.SERV.SERV.TRAtlS.TRAtIS.pl4glSSAFCiYTRAltl"A"}}
Theresultsindicated thatbothoffsitesourcesr5'ot0050242 9005'20PDR4DOCK05000244PPDCgooI Il'IF"~A,4'3 (circuit751fromStation204&767fromStation13A)arecapableofproviding adequatevoltagesforallrequiredfunctions.
Twospecialcasesarediscussed belowwhichrepresent thelimitingcases:1.Thecomputersimulations indicated thatbothoffsitesourcesmayhavedifficulty inmaintaining adequatevoltagesduringthestartupofaReactorCoolantPump(RCP)forthespecialcasewhentheoffsitegridvoltagewasatitsminimumvalue(33kvforcircuit751and116kvforcircuit767).Thisissueiscurrently beingaddressed bymodifying theRCPnormalstartprocedures.
Theoperators havebeeninstructed toverifythatadequateprestartvoltagesexistpriortoattempting anRCPstart.Wehavecalculated circuit767mayalsohaveasimilarproblemwhenattempting aSteamGenerator Feedwater Pump(SGFWP)Start.Thiscomputeranalysisiscurrently beingreevaluated todetermine ifanyexcessive conservatism ispresentintheanalysisandifrequired, theSGFWPstartprocedure willalsobemodified.
ItshouldbenotedthatCircuit767hasnothadanydifficulty todateinstartingeithertheRCPortheSGFWP.2.TheworstcaseLossofCoolantAccident(LOCA)simulation assumestwodegradedoperating conditions:
operating solelyonline767,(100/0mode),andamin'imumgridvoltage(116kv).Theresultsshowallbusvoltagesabove414volts,indicating thatallofthe1Epumpmotorswilloperateandthattheundervoltage relayingonthesebusseswillnotdisconnect themfromoffsitepower.However,thelowest480voltMCCvoltagewas405volts,whichislowerthanRG&E'sacceptance criteria.
TheonlyloadsontheMCCsrequiredtomitigatethisaccidentwouldbeMOVs.WebelievethattheMOVswilloperateproperlyatthisvoltage,however,toprovidegreaterassurance wehaverevisedouroperating limitstowhichtheoffsitegrid,voltageswillbecontrolled whensafeguards equipment isrequired.
Whentheoffsitesupplyisprovidedinthe100/0mode(767isthelonesource)thegridvoltagewillbemaintained nolowerthan118kv.Asimulation hasbeenrunatthisvoltagewhichprovidedresultswithinallacceptance criteria.
Historical datademonstrates thatthegridvoltageisatleast118kvover95%ofthetime.Forthenormaloperating mode,inthe50/50configuration, thesimulation resultsshowthatallofthevoltagesarewithintheestablished
: criteria, evenattheminimumgridvoltageof116kv.Itshouldbenotedthatthispotential lowvoltagecondition wasnotcreatedbythereconfiguration oftheoffsitepowersystemandinfact,thelikelihood ofthecondition occurring wassignifi-cantlyreduced.Theabilitytoruntheoffsitepowersysteminthe50/50modewasamajorobjective ofthepowersystemreconfigura-tionproject(EWR4525).ItshouldalsobenotedthatthemostsevereLOCAsimulation forcircuit751(0/100modeandminimumsourcevoltage33kv)resultedinacceptable voltages.
Theprimaryobjective ofDesignAnalysis4525-1wastoverifythatthereconfiguration oftheoffsitepowersystemdidnotresultinexcessive shortcircuitdutiesforeithertheneworexistingequipment.
Theresultsindicated.
thatthereconfiguration hadanegligible impactontheshortcircuitdutiesfortheexisting'quipment andthatallofthenewequipment wasspecified withshortcircuitratingswellinexcessofthecalculated duties.Theexistingequipment wasfoundtohaveadequateshortcircuitcapacityforallcasesexceptforonecaseofdieselgenerator testing,discussed below:Aspecialcaseinvolving thedieselgenerator whenitisinitsmonthlytestconfiguration wascomputersimulated anditwasdetermined.
thatpotential shortcircuitdutiescouldexceedacceptable limits.Thisisalowprobability eventrequiring aphase-to-phase faultoccurrence duringatwohourtestperiod.Theconsequence ofsuchaneventisaneconomicconcernonly,notasafetyissue.Theeventcouldresultinashutdownoftheplantforrepairs.Safeguard systemredundancy couldbereduced,however,theeventwouldnotrequiretheuseofthesafeguards systemforplantshutdown.
Thiscondition wasnotcreated.bythereconfiguration oftheoffsitepowersystemandvariousalternatives toresolvethisissuearecurrently beingevaluated.
Weexpecttobeabletoinformyouofourintendedcorrective actionbyOctober30,1990.Verytrulyyours,RobertC.MecreTHM/122Att'achments xc:Mr.AllenR.Johnson(MailStop14D1)ProjectDirectorate I-3Washington, D.C.20555U.S.NuclearRegulatory Commission RegionI475Allendale RoadKingofPrussia,PA19406GinnaSeniorResidentInspector  
~~~OI=I=SITE DISTRIBUTION SYSTEMEV/R4525SIAIjASIA.204TOCSUTRAIISfOIII Ifft52I2II~I12IIXtie12BYNO12AEY12AX52NO12AYNC5252ftEMOVAQLE LltIKTOVIGEtIERA)OR DUMMYBREAKERDUMMYBREAKER52525252525)52IOSIA.TOSTA.SIRV.SLRV.1ftAtIS.IRArIS.lII7pl6'..AlIIYfRAltl-Il-TOSTA.SERV.TRAtIS.g15TOSTA.SERV.TRAtlS.(ISTOSTA.TOSIA.SERV.SERV.TRAtlS.TRAtIS.pl4glSSAFCiYTRAltl"A"}}

Revision as of 13:16, 29 June 2018

Forwards Rev 1 to Design Analysis EWR 4525-1, Fault Current Analysis of Power Distribution Sys & Rev 1 to Design Analysis EWR 4525-2, Adequacy of Electric Sys.... NRC Will Be Notified of Util Intended Corrective Action by 901030
ML17262A174
Person / Time
Site: Ginna Constellation icon.png
Issue date: 09/20/1990
From: MECREDY R C
ROCHESTER GAS & ELECTRIC CORP.
To: JOHNSON A R
Office of Nuclear Reactor Regulation
Shared Package
ML17262A175 List:
References
NUDOCS 9010050242
Download: ML17262A174 (7)


Text

ACCELERATED DISRIBUTIONDEMONSTTIONSYSTEMREGULATORY INFORMATION DISTRIBUTION SYSTEM(RIDS)ACCESSION NBR:9010050242 DOC.DATE:

90/09/20NOTARIZED:

NOFACIL:50-244 RobertEmmetGinnaNuclearPlant,Unit1,Rochester GAUTH.NAMEAUTHORAFFILIATION MECREDY,R.C.

Rochester Gas6ElectricCorp.RECIP.NAME RECIPIENT AFFILIATION JOHNSON,A.R.

ProjectDirectorate I-3DOCKET05000244

SUBJECT:

ForwardsDesignAnalysis4525-1,"FaultCurrentAnalysisforPowerDistribution Sys,"Rev1&DesignAnalysis4525-2.DISTRIBUTION CODE:AOOIDCOPIESRECEIVED:LTR

$ENCL$SIZE:TITLE:ORSubmittal:

GeneralDistribution NOTES:License Expdateinaccordance with10CFR2,2.109(9/19/72).

05000244RECIPIENT IDCODE/NAME PDl-3LAJOHNSON,A INTERNAL:

NRR/DET/ECMB 9HNRR/DST8E2NRR/DST/SICB 7ENUDOCS-ABSTRACT OGC/HDS2RES/DSIR/EIB EXTERNAL:

NRCPDRCOPIESLTTRENCL11221111111'101111RECIPIENT IDCODE/NAME PD1-3PDNRR/DOEA/OTSB11 NRR/DST/SELB 8DNRR/DST/SRXB 8EGFILEOlNSICCOPIESLTTRENCL11111111101111NOTETOALL"RIDS"RECIPIENTS:

PLEASEHELPUSTOREDUCEiVASK!CONTACTTHEDOCUMENTCONTROLDESK,ROOMPl-37(EXT.20079)TOELIMINATE YOURNAMEFROMDISTRIBUTION LISTSFORDOCUMENTS YOUDON'TNEED!TOTALNUMBEROFCOPIESREQUIRED:

LTTR17ENCL15

\f$a IIIIIIIIIII/

IIIIIIIIIIII

~AirOall*///IjI//Ij/I//III/III g!p',ROCHESTER GASANDELECTRICCORPORATION o89EASTAVENUE,ROCHESTER N.Y.14649-0001 ROBERTC.MECREDYVicePresident CinnaNuctearProduction September 20,1990TEt.EPHONE ArtEAcooE7re546.2700U.S.NuclearRegulatory Commission DocumentControlDeskAttn:AllenR.JohnsonProjectDirectorate I-3Washington, D.C.20555

Subject:

OffsitePowerSystemAnalysesR.E.GinnaNuclearPowerPlantDocketNo.50-244

DearMr.Johnson:

Peryourrequest,weareenclosing copiesofDesignAnalysis4525-1"FaultCurrentAnalysisofPowerDistribution System"Rev1andDesignAnalysis4525-2"Adequacy ofElectricSystemVoltages" Rev1foryourreview.Theseanalysesquantifytheeffectsassociated withtherecentlycompleted offsitepowerreconfiguration (EWR'4525).EWR4525modifiedtheoffsitepowersystemsuchthattherewouldbeadedicated 34.5/4.16kV transformer associated witheachofthetwoindependent offsitetransmission lines.Station204energizes transformer 12AwhichisnowthenormalsourceofpowerforBus12AandsafetytrainAwhileStation13Aenergizes transformer 12BwhichisnowthenormalsourceofpowerforBus12BandsafetytrainB(seefigure1).Thisnormalconfiguration isreferredtoasthe50/50modesinceeachindependent offsitepowersourcesupplies1/2oftherequiredoffsitepower.Theoperators stillhavetheabilitytoputtheoffsitepowersystemineitherthe100/0mode(Transformer 12Bsuppliesalloffsitepower)orthe0/100mode(Transformer 12Asuppliesalloftheoffsitepower).Thenormalconfiguration priortoEWR4525wastohavealloffsitepowersuppliedbytransformer 12A.EWR4525hassignificantly reducedthelikelihood ofasimultaneous lossofoffsitepowertobothsafetytrainsandhasimprovedsystemperformance sincetheelectrical loadisnownormallydividedbetweentwotransformers.

Theprimaryobjective ofDesignAnalysis4525-2istodemonstrate thatthereconfigured offsitepowersupplywillbecapableofmaintaining adequatevoltagesforallrequiredoperating conditions.

Theresultsindicated thatbothoffsitesourcesr5'ot0050242 9005'20PDR4DOCK05000244PPDCgooI Il'IF"~A,4'3 (circuit751fromStation204&767fromStation13A)arecapableofproviding adequatevoltagesforallrequiredfunctions.

Twospecialcasesarediscussed belowwhichrepresent thelimitingcases:1.Thecomputersimulations indicated thatbothoffsitesourcesmayhavedifficulty inmaintaining adequatevoltagesduringthestartupofaReactorCoolantPump(RCP)forthespecialcasewhentheoffsitegridvoltagewasatitsminimumvalue(33kvforcircuit751and116kvforcircuit767).Thisissueiscurrently beingaddressed bymodifying theRCPnormalstartprocedures.

Theoperators havebeeninstructed toverifythatadequateprestartvoltagesexistpriortoattempting anRCPstart.Wehavecalculated circuit767mayalsohaveasimilarproblemwhenattempting aSteamGenerator Feedwater Pump(SGFWP)Start.Thiscomputeranalysisiscurrently beingreevaluated todetermine ifanyexcessive conservatism ispresentintheanalysisandifrequired, theSGFWPstartprocedure willalsobemodified.

ItshouldbenotedthatCircuit767hasnothadanydifficulty todateinstartingeithertheRCPortheSGFWP.2.TheworstcaseLossofCoolantAccident(LOCA)simulation assumestwodegradedoperating conditions:

operating solelyonline767,(100/0mode),andamin'imumgridvoltage(116kv).Theresultsshowallbusvoltagesabove414volts,indicating thatallofthe1Epumpmotorswilloperateandthattheundervoltage relayingonthesebusseswillnotdisconnect themfromoffsitepower.However,thelowest480voltMCCvoltagewas405volts,whichislowerthanRG&E'sacceptance criteria.

TheonlyloadsontheMCCsrequiredtomitigatethisaccidentwouldbeMOVs.WebelievethattheMOVswilloperateproperlyatthisvoltage,however,toprovidegreaterassurance wehaverevisedouroperating limitstowhichtheoffsitegrid,voltageswillbecontrolled whensafeguards equipment isrequired.

Whentheoffsitesupplyisprovidedinthe100/0mode(767isthelonesource)thegridvoltagewillbemaintained nolowerthan118kv.Asimulation hasbeenrunatthisvoltagewhichprovidedresultswithinallacceptance criteria.

Historical datademonstrates thatthegridvoltageisatleast118kvover95%ofthetime.Forthenormaloperating mode,inthe50/50configuration, thesimulation resultsshowthatallofthevoltagesarewithintheestablished

criteria, evenattheminimumgridvoltageof116kv.Itshouldbenotedthatthispotential lowvoltagecondition wasnotcreatedbythereconfiguration oftheoffsitepowersystemandinfact,thelikelihood ofthecondition occurring wassignifi-cantlyreduced.Theabilitytoruntheoffsitepowersysteminthe50/50modewasamajorobjective ofthepowersystemreconfigura-tionproject(EWR4525).ItshouldalsobenotedthatthemostsevereLOCAsimulation forcircuit751(0/100modeandminimumsourcevoltage33kv)resultedinacceptable voltages.

Theprimaryobjective ofDesignAnalysis4525-1wastoverifythatthereconfiguration oftheoffsitepowersystemdidnotresultinexcessive shortcircuitdutiesforeithertheneworexistingequipment.

Theresultsindicated.

thatthereconfiguration hadanegligible impactontheshortcircuitdutiesfortheexisting'quipment andthatallofthenewequipment wasspecified withshortcircuitratingswellinexcessofthecalculated duties.Theexistingequipment wasfoundtohaveadequateshortcircuitcapacityforallcasesexceptforonecaseofdieselgenerator testing,discussed below:Aspecialcaseinvolving thedieselgenerator whenitisinitsmonthlytestconfiguration wascomputersimulated anditwasdetermined.

thatpotential shortcircuitdutiescouldexceedacceptable limits.Thisisalowprobability eventrequiring aphase-to-phase faultoccurrence duringatwohourtestperiod.Theconsequence ofsuchaneventisaneconomicconcernonly,notasafetyissue.Theeventcouldresultinashutdownoftheplantforrepairs.Safeguard systemredundancy couldbereduced,however,theeventwouldnotrequiretheuseofthesafeguards systemforplantshutdown.

Thiscondition wasnotcreated.bythereconfiguration oftheoffsitepowersystemandvariousalternatives toresolvethisissuearecurrently beingevaluated.

Weexpecttobeabletoinformyouofourintendedcorrective actionbyOctober30,1990.Verytrulyyours,RobertC.MecreTHM/122Att'achments xc:Mr.AllenR.Johnson(MailStop14D1)ProjectDirectorate I-3Washington, D.C.20555U.S.NuclearRegulatory Commission RegionI475Allendale RoadKingofPrussia,PA19406GinnaSeniorResidentInspector

~~~OI=I=SITE DISTRIBUTION SYSTEMEV/R4525SIAIjASIA.204TOCSUTRAIISfOIII Ifft52I2II~I12IIXtie12BYNO12AEY12AX52NO12AYNC5252ftEMOVAQLE LltIKTOVIGEtIERA)OR DUMMYBREAKERDUMMYBREAKER52525252525)52IOSIA.TOSTA.SIRV.SLRV.1ftAtIS.IRArIS.lII7pl6'..AlIIYfRAltl-Il-TOSTA.SERV.TRAtIS.g15TOSTA.SERV.TRAtlS.(ISTOSTA.TOSIA.SERV.SERV.TRAtlS.TRAtIS.pl4glSSAFCiYTRAltl"A"