ML17249A179

Responds to 790808 Ltr Re Adequacy of Station Electric Distribution Sys Voltages.Submits Sys Model & Acceptance Criteria for Use W/Proprietary Code PTI-PSS/E to Verify Offsite Power Capability.Final Rept Submitted in 60 Days

ML17249A179
Person / Time
Site:	Ginna, Sterling
Issue date:	10/08/1979
From:	SADDOCK H G ROCHESTER GAS & ELECTRIC CORP.
To:	ZIEMANN D L Office of Nuclear Reactor Regulation
References
TASK-08-01.A, TASK-RR NUDOCS 7910120205
Download: ML17249A179 (13)

Text

REGULATORYINFORMATIONDISTRIBUTIONSYSTEM(RIDS)ACCESSIONNBR:7910120205C.DATE:79/10/08NOTARIZNODOCKET0FACIL:50-244RobertEmmetGonnaNuclearPlant>Unit1>RochesterG05000244STN-50-485SterlingPowerProspectNuclear>Unit1>Rochester05000485AUTH.NAMEAUTHORAFFILIATIONSADDOCK>H.G.RochesterGas8cElectricCorp.RECIP.NAMERECIPIENTAFFILIATIONZIEMANN>D.L.OperatingReactorsBranch2

SUBJECT:

Respondsto790808ltrreadequacyofstationdistributionsosvoltages.Submitssosmodel/Criteriaforusew/proprietqrgcodePTi-PSS/Eoffsitepowercapability.Finalreptsubmittedcleetricacceptancetoverifyin60days.DISTRIBUTIONCODE:A015SCOPIESRECEIVED:LTRQENCL+SIZE:TITLE:OnsiteEmergencyPowerSystemsNOTES:'.//8PHKF-2WS8ECIR'IENTIDCODE/NAMEACTION:05BC488N4>LA/INTERNAL:0EGFILE12f47DO15OELD17AUXILSYSBR20ENGRBR22PLANTSYSBR24PWRSYSBR26TONDI>D28HANNON>J30EEBEXTERNAL:03LPDR31ACRSrnifTzCOPIESLTTRENCL7711111111111111111111616RECIPIENTIDCODE/NAMELA4~~~<>LaudA>02.NRCPDR13I8(E16MPA18INCSYSBR21REACSFTYBR23ADVREACBR25WAMBACHT27MCDONALD>D2'PBRINKMAN8HANAUER04NSICCOPIESLTTRENCL1,0'1221111111111111111C../YaF~8~S'7"4A/2)8RSg2-E'4RA/7.Q~(~J"(!SV58TOTALNUMBERQFCOPIESREQUIRED:LTTR~ENCL/>Is]

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Subject:

AdeguacyofStationElectricDistributionSystemsVoltages

DearMr.Ziemann:

Inaccordancewiththeletter,datedAugust8,1979fromWilliamGammilltoAllPowerReactorLicenseesregardingtheabovesubject,RG&EhaspreparedasystemmodelandacceptancecriteriaforusewiththeproprietarycodePTI-PSS/E,toexhaus-tivelyverifyoffsitepowercapabilityinaccordancewithGDC17.BasedonEnclosure2,GuidelinesforVoltageDropCalculationsoftheAugust,8letter,andusingthemodeldescribedinEnclosure1ofthisletter,RG&Eisevaluatingtheinplantvoltageeffectsofpossiblegridvariationsincombinationwithallpossibleplant:operatingmodes.Sincethenumberofcombinationsrepresent-ingpossiblesystemtransientstatestobeanalyzedisapproxi-mately100,theseanalysesarestillbeingperformed.Thefinalresultsoftheseanalyseswillbetransmittedsixtydaysfromthedateofthisletter.Subseguenttothecompletionofthesystemtransient,loadflowanalyses,theresultswillbecomparedwithsyst:emhistorical.dataandcurrenttest,results.Astatusreportonthisportionofthestudywillbetransmittedtoyouninetydaysfromthedateofthisletter.Inanalysesperformedthusfar,noviolationsorpotentialviolationsofGDC17havebeenidentified.Verytrulyyours,HarryG.SaddockT9I0120coLOcS Enclosure1TheelectricaldistributionsystemattheR.E.GinnaNuclearPlantisbeingreviewedtodetermineifthepotentialexistsforeventsorconditionsthatwouldbeinviolationofGeneralDesignCriteria(GDC)17.Thisreviewisbeingaccomplishedbyperform-ingacomputeranalysisassessingtheelectricsystem'scapa-bilitytoadequatelysupplyallsafetyloads.Followingtheanalysis,alleventsorconditionsthatcouldresultinthelossofbothoffsitesourceswillbeidentified.Theanalysisisbasedonaninteractivecomputerloadflowprogramthatmodelstheentireelectricaldistributionsystemrepresentingallplantoperatingmodesaswellasallanticipatedelectricaltransientconditions.Theloadflowsolutionsthenprovidethebusvoltagesandthepowerflowsoneachbusforthevariouscasesstudied.Theresultsofthisanalysis,particularlythevoltagelevelsonthesafetybuses,arethenevaluatedtodeter-mineifapotentialexistsforlowvoltagetransientsthatwouldcausespurioustrippingfromanoffsitesource.Thiswouldindicatethat,thesystemitselflackssufficientcapacitytoautomaticallystartandoperateallreguiredsafetyloadsforthoseoperatingmodeswherelowordegradedvoltagespotentiallyexist.Finally,allresults,conclusions,futuremodificationsorchangestooperatinglimitsresultingfromthisreportwillbesummarized.

LoadFlowA~nalslsTheelectricaldistributionsystematGinnaStationisshownonFigureI,thesinglelinediagram.Theoffsitesourcesaretwo34.5Kv'circuits,designated767and751.Theimmediatelyavailablesourceofoffsitepoweris767circuit.whichistiedtotheRG&E115Kvgrid,designated13A.The751circuitisnormallyenergizedandavailablebymeansofamanualtransferfromthemaincontrolroom.When767circuitisoutofservice,751circuitistheimmediatelyavailableoffsitesource.Thegridisoperatedat117Kvto122Kvnormallywiththeplant"online"and113Kvto122Kvwiththeplant"offline".ThesafeguardsorIEdistributionsystemisdividedintotworedundantandcompletelyindependent,trains,AandB.AsdescribedintheGinnaStationFSAR,eachtrainisdesignedtomitigatetheconsequencesoftheworstcaseaccident.TrainAandBareeachmadeupoftwosafeguards480voltbuses,trainAconsistsofbuses14and18whiletrainBconsistsofbuses16and17.ThesesafeguardsbusesarelabledasIEonthesinglelinediagram,FigureI.

1"hi1I Presently,eachIEbuscontainstwoindependentundervoltage(lossofvoltage)systems,27and27B.Eachundervoltagemonitorissetatapproximately65%ofnominalvoltage.Nospurioustrippinghasbeenindicatedinanalysesperformedtodateandnonehasbeenexperiencedoverthepasttenoperatingyears.Theexistingundervoltagesystemisbeingupgradedandthelossofvoltagesystemssetpointwillberaisedto77%.Inadditionasecondlevel,inversetimesystemwillbeinstalledoneachbuswiththesetpointsshownonfigureII.Thisfigureshowsthemaximumproposedvoltageandtimevaluesthatwillbepartofthetechnicalspecifications.Themaximumsecondlevelandthenewlossofvoltagesetpointsaresummarizedbelow:UndervoltageUndervoltageRelay~Sstem~setointMax.TimedelasetointLossofvoltage368volts<8.5secondsDegradedvoltage414volts<1600secondsSincetheabovevaluesaremaximumvalues,theactualrelaysettingswillbedeterminedbythisanalysisandtheoperatinglimitswillbeimposedonthenewunder-voltagesystem.

0 Foradditionaldetailsofthenewlossofvoltageandsecondlevelsystems,refertoreferences1and2.OperatingModes:Allthe"on-line","off-line",load,offsitevoltagelevelsandtransientconditionsarebeingevaluatedintheloadflowprogram.Theoperatingmodesandcondi-tionsaredescribedbelow.a)ThePlant"online"withIEnormalbusloadsandwiththe115kVgridastheoffsitesourcewhichassumesminimum,nominal,andmaximumvoltagelevels.b)ThePlant"online"withheavyplantloading.Thisreflectsallsafetyloadsinservicewiththegridastheoffsitesourcewhichassumesminimum,,nominal,andmaximumvoltagelevels.c)Theplant"online"withnormalloadsand751circuitastheoffsitesources.d)Theplant"online"withheavyIEbusloadsand751circuitastheoffsitesource.

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e)TransientConditionsMotorstartingeither4Kvor480voltsafetyrelatedmotors.Planttripwheretheauxiliaryplantloadsaretransferredontooneofthetwooffsitesources.Start-upconditions.f)"Offline"lightandheavyloadsrepresentingcoldshutdownconditionswiththegridand/orthe34.5Kvsourceatminimum,normalandmaximumlevels.TheacceptancecriteriafordeterminingcompliancetoGDC-17areasfollows:Continuoussafeguardvoltagelevelshigherthen484voltsandlowerthan414voltsmustbereviewedforeitherreductionofequipmentdesignlifeand/ordegrada-tioninequipmentcapabilitytoperformrequiredsafetyfunctions,andforapotentialspurioustrippingoftheoffsitesource.

Theacceptancecriteriafordeterminingabnormalvoltagelevelsare:Anyoftheinplantbusvoltagesthathavebeencalculatedtobeatorbelowthelossofvoltagesetpointof368voltsareabnormalandwillviolateGDC-17.Anyoftheinplantbusvoltagesthathavebeencalculatedtobeatorbelowthesecondlevelsetpointof414voltsareabnormalandpotentiallyviolateGDC-17.3.Anyoftheinplantbusvoltagesthathavebeencalculatedtobeequaltoorgreaterthantheuppertenpercentdesignlimitofthe440voltsbasemotorsor484voltsareabnormalandpotentiallyviolateofGDC-17.Busvoltagesthatarebetween414and484voltsontheSafeguardbusesaredefinedasnormalandthoseoperatingmodesorconditionsdonotinanywaycompromisetheoffsitesourceandthereforemeettheintentofGDC-17.

Safeguardsvoltagelevelsthatdipbelow414voltsduringatransientconditionbutnearertoahigherlevelmustbereviewedforpossiblespurioustripping.Thedegradeundervoltagetrippoint,willbesetat414voltswithalongtimedelay.Thelossofvoltagesetpointwillbeat368voltswithaninstantaneoustripatthatlevel.