ML17213A498

Technical Evaluation of Adequacy of Station Electric Distribution Sys Voltages for St Lucie Nuclear Power Plant, Unit 1.

ML17213A498
Person / Time
Site:	Saint Lucie
Issue date:	10/05/1981
From:	SELAN J C LAWRENCE LIVERMORE NATIONAL LABORATORY
To:	Office of Nuclear Reactor Regulation
Shared Package
ML17213A497	List: ML17213A496 ML17213A498
References
CON-FIN-A-0250, CON-FIN-A-250 UCID-19110, NUDOCS 8209280487
Download: ML17213A498 (14)

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• ,'~,*=~lPTECHNICAL EVALUATION OFTHEADEQUACY.

OFSTATIONELECTRICDISTRIBUTION SYSTEMVOLTAGES:

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ivS~*'aABSTRACTThisreportdocuments thetechnical evaluation oftheadequacyofthestationelectric'istribution systemvoltagesfortheSt.LucieNuclearPowerPlant,Unit.1..Theevaluation istodetermine if,theonsitedistribution system,inconjunction withtheoffsitepower.sources, hassufficient capacitytoautomatically startandoperateallClasslEloadswithintheequipment voltageratingsundercertainconditions established bytheNuclearRegulatory Commission.

Thevoltageanalysissubmirted hasadequately demonstrated thecapacityandcapability oftheelectrical distribution systemtosupplyadequatevoltagetotheClass1Eequipment underworstcaseoperating conditions.

FOREWORDThisreportissuppliedaspartoftheSelectedElectrical, Instrumentation, andControlSystemsIssuesProgrambeingconducted fortheU.S.NuclearRegulatory Commission,'ffice ofNuclearReactorRegulation, DivisionofOperating

Reactors, byLawrenceLivermore National'aboratory.

TheU.S.NuclearRegulatory Commission fundedtheworkundertheauthorization entitled"Electrical, Instrumentation andControlSystemSupport",

BGR201904031,FINA-0250.-111-TABLEOFCONTENTS~pael.INTRODUCTION

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......~.~...~24ANALYSIS4.14.24'.14'.243AnalysisConditions

.AnalysisResultsOvervoltage Undervoltage AnalysisVerification

~~~4~4~4~4~465~EVALUATION 66~CONCLUSION 7REFERENCES

~~~~~~~~~~~~~~~i8ILLUSTRATIONS FIGURE1St.Lucie-Unit1Electrical One-LineDiagram~~~~Pae~~3TABLE1St.Lucie-Unit1Class1EEquipment VoltageRatings'andAnalyzedHorstCaseTerminalVoltages~~.~..~~5 TECHNICAL EVALUATION OFTHEADEQUACYOFSTATIONELECTRICDISTRIBUTION SYSTEMVOLTAGESFORTHEST.LUCIENUCLEARPOWERPLANTUNIT1(DocketNo.50-335)JamesC.SelanLawrenceLivermore NationalLaboratory, Nevada1~INTRODUCTION TheNuclearRegulatory Commission (NRC)byaletterdatedAugust8,1979[Ref.1],expandeditsgenericreviewoftheadequacyofthestationelectricdistribution systemsforalloperating nuclearpowerfacilities.

Thisreviewistodetermine iftheonsitedistribution system,inconjunction withtheoffsitepowersources,hassufficient capacityandcapability toautomatically startandoperateallrequiredsafetyloadswithintheequipment voltageratings.Inaddition, theNRCrequested eachlicenseetofollowsuggested guidelines andtomeetcertainrequirements intheanalysis.

Theserequirements aredetailedinSection5ofthisreport.BylettersdatedNovember9,1979[Ref.2],September 12,1980[Ref.3],February10,1981[Ref.4],andJuLy23,1981[Ref.5],FloridaPower&LightCompany(FPL),thelicensee, submitted theiranalysisandconclusion regarding theadequacyoftheelectrical distribution system'svoltagesatSt.Lucie,Unit1.Thepurposeofthisreportistoevaluatethelicensee's submittal withrespecttotheNRCcriteriaandpresentthereviewer's conclusion ontheadequacyofthestationelectricdistribution systemstomaintainthevoltagewithinthedesignlimitsoftherequiredClass1Eequipment fortheworstcasestartingandloadconditions'.

DESIGNBASISCRITERIAThedesignbasiscriteriathatwereappliedindetermining theadequacyofstationelectricdistribution systemvoltagestostartandoperateallrequiredsafetyloadswithintheirrequiredvoltageratingsareasfollows:

(1)GeneralDesignCriterion 17(GDC17),"Electric PowerSystems,"

ofAppendixA,"GeneralDesignCriteriaforNuclearPowerPlants,"intheCodeofFederalRegulations, Title10,Part50(10CFR50)[Ref.6]~(2)GeneralDesignCriterion 13(GDC13),"Instrumentation andControl,"

ofAppendixA,"GeneralDesignCriteriaforNuclearPowerPlants,"intheCodeofFederalReulations, Title10,Part50(10CFR50)Ref.6(3)ANSIC84.1-1977, "VoltageRatingsforElectricPowerSystemsandEquipment"

[Ref.7].(4)IEEEStd308-1974, "Class1EPowerSystemsforNuclearPowerGenerating Stations"

[Ref.8]~(5)"Guidelines forVoltageDropCalculations,"

Enclosure 2,toNRCletterdatedAugust8,1979[Ref.1].3.SYSTEMDESCRIPTION Anelectrical one-linediagramofSt.Lucie,Unit1,isshowninFigure1.Theelectrical distribution systemisdesignedsuchthatduringnormalstartupandshutdownconditions, theauxiliary loadsaresuppliedbythestartuptransformer.

Whentheunitisabove170MWepoweroutput,theauxiliary loadsaresuppliedbytheunitauxiliary transformer.

Thetwostartuptransformers aresuppliedfroma240KVswitchyard wheretheoutputoftheunitgenerator isconnected throughamaintransformer bank.Thetwostartuptransformers havenoelectrical intertieconnections betweenthemwitheachtransformer supplying itsowntrainofauxiliary loads.Aunittriporasafetyinjection signal(SIS)willinitiateautomatic transferoftheonsitedistributon systemfromtheunitauxiliary transformer tothes'tartuptransformer.

Boththestartuptransformers andunitauxiliary trans-formershavetwosecondary

windings, withoneat6.9KVandthesecondat4160volts.Therearethree4160-volt andthree480-voltClass1Ebuses.TheClass1Eequipment isprotected fromundervoltage conditions byanundervoltage relaylocatedoneach4160-volt Class'lEbus.Theinversetimerelayhasavoltagesetpointof88.34Xof4160volts(3675volts)withatimedialsettingof1.Therelaywillactuateat79.5Xof4160voltsin'pproximately 3seconds.=

Thevoltagesetpointatthe4160-volt levelisequiva-lentto83%of480voltsattheClass1E480-voltmotorcontrolcenterbuses.Thelicenseestatesthatadesignmodification isplannedtoaddundervoltage relaysonthe480-voltClass1Ebuses[Ref.2].Thelicenseehasnotprovidedanyfurtherdesigninformation ontheplannedmodification.

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4~ANALYSIS4.1ANALYSISCONDITIONS FPLanalyzedtheonsitedistribution systemvoltageswiththestartuptransformer asthesupplying sourceunderminimumandmaximumexpectedgridvoltagesof230KVand244KV,respectively.

Inconjunction withtheaboveconditions, threeloadingcaseswereanalyzedtodetermine thevoltageattheterminals oftheClasslEequipment.

InCase1,thenormalrunningloadsweretransferred tothestartuptransformer following aunittripfromfullloadcoincident withaminimumexpectedgridvoltage.Theloadingconditions ofCase2arethesameasCase1,butwiththeadditionofloadsassociated withanaccident.

FinallyinCase3,theloadingconditions werethesameasCase1exceptthegridwasatthemaximumexpectedvalue.Inadditiontotheaboveconditions, thefollowing assumptions werealsomade:(1)Normalloadsusedweremeasuredvalueswiththep~antatfullload.(2)Powerfactorofrunningloadswasassumedas0.85.(3)HeasurednormalrunningloadsincludedseveralClasslEloads.(4)Startingpowerfactorforthe4KVmotorswasassumedas0.22.Startingcurrentwastakenfromnameplate data.(5)Startingpowerfactorforthe480-voltmotoroperatedvalveswasassumedtobe0.60.Thestartingcurrentwastakenfromplantstartuptestdata.(6)Allcurrentswereassumedtoremainconstant.

4.2ANALYSISRESULTSTheworstcaseClasslEequipment terminalvoltagesfromtheanalysessubmitted occurunderthefollowing conditions:

Normalrunningloadsbeingsupplied.bythestartuptransformer (unittripwithloadtransfertothestartuptransformer) andgridatthemaximumexpectedvoltageof244KV.4.2'Undervolta eUnittripfromfullloadwithtransferofthenormalrunningloadstothestartuptransformer concurrent withanaccidentcondition andthegridattheminimumexpectedvoltage,of230KV.TheaboveworstcaseClass1Eequipment terminalvoltagesareshowninTablel.

TABLE1ST.LUCIE-UNIT1CLASSlEEQUIPMENT VOLTAGERATINGSANDANALYZEDWORSTCASETERMINALVOLTAGES(inXofEquipment NominalVoltageRating)MinimumRatedAnalyzedRatedAnalyzedEuipmentNominalVoltageRating(100X)SteadyStateSteady-StateTransient Motors4000StartOperate1101065759099.493~5460(')StartOperate110104.3759092.982Starters(

PickupDropoutOperate12062'(c)11079'(c)81.18589OtherEquipment(d)

(a)460-voltmotorscanoperateat75Xterminalvoltageforoneminutewithoutdamage.Also,460-voltMOV'.scanoperateindefinitely at80Xterminalvoltage.(b)Motorcontrolcentercontactors aresuppliedfrom480/120-volt transformers.

Startersizes1-2and3-4aresuppliedby50VAand500VAsizetransformers, respectively.

(c)Thesevaluesobtainedfromtestsperformed.

(d)ClasslEinstruments arefedfrominverters.

4~3ANALYSISVERIFICATION FPLobtainedtestdatabyusingstandardplanttestmethodologies'his includedusingvoltmeters tomeasurethesecondary voltagesofthepotential transformers forthe4160-volt switchgear and480-voltloadcenters.Thebusamperesandthe480-voltMCCvoltageswerereadfromthecabinet's panelboardmeters.Thereadingstakenwereonaperphasebasis.Thesereadingswerethenaveragedandtheirrespective transformer ratioswereusedtocalculate actualbusvoltagesandamperes.Theverification resultsshowsthattheanalytical valueswerewithin2Xoftheactualplantdataobtained[Ref.4).5~EVALUATION TheNRCgenericletter[Ref.1}statedseveralrequirements thattheplantmustmeetinthevoltageanalysis.

Theserequirements andanevaluation ofthelicensee's submittals areasfollows:(1)Withtheminimumexpectedgridvoltageandmaximumloadcondition, eachoffsitesourceanddistribution systemconnection mustbecapableofstartingandcontinuously operating allClasslEequipment withintheequipment's voltageratings.Thevoltageanalysisresultssubmitted byFPLdemonstrate thattheoffsitesources,incon)unction withtheonsitedistribution system,havethecapacityandcapability toautomatically startandcontinuously operatetheClasslEequipment withthedesignratingsfortheworstcaseconditions.

(2)Withthemaximumexpectedoffsitegridvoltageandminimumloadcondition, eachoffsitesourceanddistribution systemconnection mustbecapableofcontinuously operating therequiredClasslEequipment withoutexceeding theequip-ment'svoltageratings.Thevoltageanalysisresultssubmitted, byFPLdemonstrate thatthe:Class 1Eequipment uppervoltagedesignratingwillnotbeexceeded.

(3)Theanalysismustshowthattherewillbenospurioussepara-tionfromtheoffsitepowersourcetotheClass1Ebusesbythevoltageprotection relayswhenthegridiswithinthenormalexpectedlimitsandtheloadingconditions established bytheNRCarebeingmet.

~.~LLNLwillverifyinaseparatereport(TACNo.10052)thattherequirements ofthispositionaremet.FinaldesignandTechnical Specifications areforthcoming.

FPLdidnotsubmitanalytical dataonstartingalargenon-Class 1EloadaftertheClass1EbusesOrefullyloaded.Thelicenseestatesthatstartingalargenon-Class lEloadwouldactuatetheunder-voltageprotection relayundertheworstcasecondition.

Thelargestnon-Class 1Emotoristhecondensate.

pumpwhichwouldbenormallyoperating.

Thepumpwouldhavetobemanuallytripped.Thelicenseestatesthatananalysisoftheplant'scondition wouldbemadebeforeanattempted restartofthepump.FPLdidnotsubmitanywrittenplantprocedures addressing thepumprestart.(4)Testresultsarerequiredtoverifythevoltageanalysescalculations submitted.

FPLverifiedtheirvoltageanalysisbytestandthepercenterrordifference of2Xconfirmtheanalytical resultsareacceptable.

(5)Reviewtheplant'selectrical powersystemstodetermine ifanyeventsorconditions couldresultinthesimultaneous lossofbothoffsitecircuitstotheonsitedistribution system.(compliance withGDC17.)FPLreviewedtheelectricpowersystemsandfoundthatnosingleeventorcondition couldresultinthesimultaneous orconsequential lossofbothrequiredcircuitstotheonsitedistribution system,thusnoviolation ofGDC17exists.6~CONCLUSIONS Basedontheinformation providedbyFloridaPowerandLightCompanyonSt.Lucie,Unit1'selectrical distribution system,itisconcluded that:(1)Voltageswithinthedesignratingsofthe.Class1Eequipment aresuppliedfromtheoffsitesourcesunderworstcasecondi-tions.(2)Theverification testperformed verifiestheanalysisresults.(3)AseparatereportwillbemadebyLLNL(TACNo.10052-DegradedGrid)toverifythatspurioustripswillnotoccurduringvoltagetransients uponfinaldesignandTechnical Specification submittal.,

fortheproposedundervoltage protection scheme.

(4),FPLhasdetermined thatnopotential foreitherasimul-taneousorconsequential lossoftheoffsitesourcesexists.(5)Addtional detailsoftheplantprocedures forassessing plantconditions priortotherestartofthecondensate pumpshouldbesubmitted.

REFERENCES 1.NRCletter(W.Gammill)toallPowerReactorLicensees, datedAugust8,1979.2.FPLletter(R.E.Uhrig)toNRC(W.Gammill),

datedNovember9,1979.3.FPLletter(R.E.Uhrig)toNRC(D.G.Eisenhut),

datedSeptember 12,1980.4.FPLletter(R.E.Uhrig)toNRC(D.G.Eisenhut),

datedFebruary10,1981.5.FPLletter(R.E.Uhrig)toNRC(D.G.Eisenhut),

datedJuly23,1981.6.CodeofFederalReulations, Title10,Part50(10CFR50),GeneralDesignCriterion 13and17ofAppendixAforNuclearPowerPlants.7.ANSI'C84.1-1977, "VoltageRatingsforElectricPowerSystemsandEquipment."

8.IEEESTD.308-1971, "Class1EPowerSystemforNuclearPowerGenerating Stations."

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