ML21126A315

Proposed License Amendment Request to Battery Surveillance Requirements - Response to Request for Additional Information

ML21126A315
Person / Time
Site:	North Anna
Issue date:	05/06/2021
From:	Mark D. Sartain Virginia Electric & Power Co (VEPCO)
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
21-137
Download: ML21126A315 (8)

Text

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VIRGINIAELECTRIC AND POWER COMPANY l

RICHMOND,VIRGINIA 23261 I

May6,2021 ATTN:Document Control Desk U.S.NuclearRegulatory Commission Serial No.: 21-137 NRA/ENC: RO l

DC20555-0001 Washington, Docket Nos.:50-338 /

50-339 I I

License Nos.:NPF-4 l NPF-7 j I

V l NORTH ANNAPOWER STATION UNITS 1AND 2 I

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System dated Byletter (ADAMS)

December Accession 17,2020(Agencywide No.ML20352A394),

Documents Access andManagement Virginia Electric andPower Company l

(DominionEnergy Virginia) requested changes totheTechnical Specifications (TS) for i AnnaPower North Station (NAPS) Units 1and2.Specifically,the proposed amendment I NAPSTS 3.8.4, revises "Electrical PowerSystems, DC Sources -

Operating," l Surveillance Requirements foreachsafety-related (SRs) battery 3.8.4.2 that and3.8.4.5 specifya total byadding connection newacceptance criteria resistance value as l

f established byNorth Annacalculations. j Theinter-cell connection resistance valueof1.5E-4 Ohmcurrently specified inTS 3.8.4 i if isnon-conservative all, ora considerable number, ofthe connections are postulated to E beattheTSlimit value, sincethe acceptable totalbattery connection resistance value l wouldbeexceeded.

connection resistance Thenewacceptance iswithinpre-established criteriawillconfirm andensures limits that that thetotal thebatteries battery will

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their perform specified safetyfunction bymaintaining required battery terminal voltage under designed load conditions. ,

I Byemaildated March 26,2021, NRCstaff indicated that additional information was I necessary response tocomplete theirreview additional oftherequested information changes. TheNRCrequested byMay7,2021. TheEnterprise a l totheirrequest for (RAl)

Project (EPID)

Identifier referenced forthisrequestisL-2020-LLA-0275.

Dominion Energy Virginia's response totheNRCsRAIiscontained intheEnclosure to this letter. g i

Serial No.: 21-137 Docket Nos.: 50-338/339 Page2 of3 Please contact Erica N.Combsat804-273-3386 if youhave anyquestions regarding this submittal.

Sincerely,

.a -

MarkD.Sartain Vice President -

Nuclear Engineering & Fleet Support COMMONWEALTH OFVIRGINIA )

)

COUNTY OFHENRICO )

Theforegoing document was acknowledged before inand for theCounty rne, andCommonwealth aforesaid, today byMr.Mark D.Sartain,whoisVice President Nuclear Engineering andFleet Support, ofVirginia Electric andPower Company. Hehasaffirmed beforemethat he is duly authorized toexecute andfiletheforegoing document inbehalfofthat company,andthat thestatements inthedocument are truetothe best ofhis knowledge andbelief.

Acknowledged methis before fo dayof , 2021.

MyCommission Expires: 0N PDu a i Commonwealth ofVirginia Reg. # 7518653 MyCommission ExpiresDecember 31,2023 N taryP ic

Enclosure:

' , Response toNRCRequest for AdditionalInformation Commitments madebythis letter:None

References:

1 Letter from Dominion Energy VirginiatoNRC,"North AnnaPower Station Units 1and 2, Proposed License Amendment Request to ChangeBattery Surveillance Requirements," dated December 17,2020. [ADAMS Accession No.ML20352A394)

Serial No.:

21-137 Docket Nos.:

50-338/339 Page3of3 cc: Regional Administrator, Region II U. S.Nuclear Regulatory Commission Marquis OneTower 245Peachtree Center Avenue, NE,Suite 1200 Atlanta,Georgia 30303-1257 Mr.G.E.Miller Senior ProjectManager -

NorthAnnaPowerStation U.S.Nuclear Regulatory Commission Mail Stop 09E-3 OneWhite North Flint 11555 Rockville Pike Rockville, Maryland 20852-2738 Mr.Marcus Harris OldDominion Electric Cooperative Innsbrook Corporate Center 4201Dominion Boulevard, Suite 300 Glen Allen, Virginia 23060 NRCSenior Resident Inspector North AnnaPower Station

Serial No.:

21-137 Docket 50-338/339 Nos.:

ENCLOSURE Virginia andPowerCompany Electric Virginia)

Energy (Dominion AnnaPower North Station Unit 1 andUnit 2

Serial No.:21-137 Docket Nos.:

50-338/339 Enclosure Page1of4 RESPONSE TONRCREQUEST FORADDITIONAL INFORMATION REGARDING PROPOSED LICENSE AMENDMENT REQUEST TO CHANGE BATTERY SURVEILLANCE REQUIREMENTS Byletter dated December 17, 2020(Agencywide Documents Access andManagement System (ADAMS) Accession No. ML ML20352A394), Virginia ElectricandPower Company (Dominion EnergyVirginia) requested changes tothe Technical Specifications (TS) for North AnnaPower Station (NAPS) Units 1and2. Specifically, theproposed amendment revises NAPSTS 3.8.4, "Electrical PowerSystems, DC Sources -

Operating," Surveillance Requirements (SRs) 3.8.4.2 and3.8.4.5 byadding new acceptance criteriaforeachsafety-related battery that specify a total connection resistance value asestablished byNorth Anna calculations.

Theinter-cell connection resistance value of1.5E-4 Ohm specified inTS 3.8.4 isnon-conservative ifall,ora considerable number, oftheconnections arepostulated tobeat theTS limit value, since theacceptable totalbattery connection resistance value would beexceeded. Thenewacceptance criteria willconfirm that the total battery connection '

resistance iswithinpre-established limits andensures that the batteries will perform their specified safety function bymaintaining required battery terminal voltage under designed load conditions.

Ina March 26,2021 e-mail from Mr.EdMiller (NRC Senior Project Manager) toMs.Erica I

Combs(Dominion Energy Virginia Corporate Licensing), theNRC technical staff requested additional information regarding theproposed changes byMay7,2021. The Enterprise ProjectIdentifier (EPID) referenced for this request isL-2020-LLA-0275.

Dominion's response totheNRCrequest for additional information (RAI) isprovided below.

RAl Question No.1 W:

Theregulations at10CFR50.36, "Technicalspecifications," establish therequirements related tothe content oftheTS.Pursuant to10CFR50.36(c), TSarerequired toinclude items infivespecificcategories related tostation operation:

(1)Safety limits,limiting safety system settings, andlimiting control settings, (2)Limiting conditions for operation (LCOs),

Serial No.: 21-137 Docket Nos.: 50-338/339 Enclosure Page2 of4 (3) Surveillance requirements (SRs),

(4)Design features; and (5) Administrative controls.

Theproposed changes inthis LARrelate tothe SRcategory.

10CFRPart 50.36(c)(3), "Surveillance requirements," requires surveillance relating to test,calibration, orinspection toassurethat thenecessary quality ofsystems and components ismaintained,that facility operationwill bewithin safety limits, andthat the conditions limiting for operationwill bemet.

E519115185L.

IntheLAR,Section 3.2, Technical Analysis, the licensee states:

AlorthAnnavoltage profile calculations for the Class 1Ebatteries provide a basis for themaximum allowable total connection resistance values (to include the i nter-cell, inter-jar, and cable termination connectors) that would ensure proper operation of the 125V D C Vital Bus in Design Basis Accident andSBO[station blackout) scenarios. The inter-rack and inter-tier cable resistance is not included within the basis of total connection resistance values. Theperiodic tests measure fromthecell post to thecable termination for thecable termination connectors. Theinter-rack and inter-tiercables areseparately included inthecalculation analysis, and any configuration change that would impact these cables would require an update tothe analysis.

Pleaseprovide asummary ofassumptions, design basis andmargins considered for total circuit resistances including battery internal resistance, battery system connection resistance,external conductor andconductor connection resistances.

Besponse:

CalculationsEE-0857, "NAPSStation Battery 1-Ill Voltage Profile Calculation" andEE-0858,"NAPSStation Battery 1-ll Voltage Profile Calculation," provide thebasis for the Intercell total Connection Resistance (ICR) ofall North Anna125VDCVital BusStation Batteries.Analyses inboth calculations wereperformed using theElectrical Transient Analyzer Program (ETAP) software. TheEnersys/Exide 2GN-23 stationary batteries wereoriginally installed under Design Change DC85-29 andconsist of60cells residing in30jarssecured tofour battery racks.

SerialNo.:21-137 Docket Nos.:50-338/339 Enclosure Page3of4 Calculation EE-0857, Revision 0 provides anallowable maximum ICRof2,502 micro-Ohmsbased ontheresults ofETAPvoltage drop analysis forthe125VDCdistribution system ofthe 1-Ill 125VDCVital Bus. This analysis isconsidered bounding for batteries 1-I,2-I, and2-Ill based onbattery duty cycle loading (amp-hours removed) andcontrol circuit lengths.

Calculation EE-0858, Revision 0,provides anallowable maximum ICRof902micro-Ohms based o n the results of ETAP voltage drop a nalysis forthe125VDCdistribution system ofthe1-ll 125VDC Vital Bus.Addendum G tothis calculation provides an allowable maximum ICRof1,502 micro-Ohms based onthe results ofETAPvoltage drop analysis forthe2-II 125VDCVital Bus. Theanalysis ofthe2-II 125VDCVital Busis considered bounding for batteries 1-IV and 2-IV based onbattery duty cycle loading.

A value of8.5micro-Ohms forinter-jarconnectors and9.5micro-Ohms for inter-cell connectors wasassumed present inthemanufacturer suppliedperformance data based onmanufacturer data anda review ofstation battery resistance readings. Perthe manufacturer, Enersys, six toeight cellsareconnected inseries toderive discharge curves for endcell voltage. Therefore theimpact ofconnection plates isincluded inthe data supplied. Thevalues assumed werebased onanaverage ofmeasured resistances from all station batteries andcompared toaverage resistance readings supplied by Enersys. Thevalues assumed wereconservatively lower than the values supplied by Enersys. Theresistance ofconnector endplates wasincluded as part oftheoverall battery system connection resistance andwasnot included aspart of the assumed inter-cellandinter-jar connection resistance.

Overall analyzed battery system connection plate resistance doesnot include the effects ofinstalled battery connector cables, only connected inter-cell, inter-jar, and end connector plates. Theeffects ofcables areconsidered asa separate elementof the North Anna125VDCbattery ETAPmodel(s). During performance ofperiodic teststhat measure battery resistance, theconnection cables arenot included in field measurements. Forcells attheendofeachrack, measurements aretaken fromthe battery post tothebolted lugconnecting thebattery cable. Thetotal sumofinter-cell, inter-jar, andendconnector plateresistance iscompared toavalue bound bythe analysis performed inCalculations EE-0857 andEE-0858.

Cable temperatures wereassumed tobeoperating ata maximumrating of750Cto conservatively increase theresistance ofall cables. Forcables within theNorth Anna battery rooms, thehighest expected roomtemperature is29.40C, allowing thecables 45.60C oftemperature rise during operation. This wasconsidered conservative when comparing theevaluated 750Campacity ofthe250MCM Aluminum cables that connect

Serial No.: 21-137 Docket Nos.: 50-338/339 Enclosure Page4 of4 thebattery bank totheir respective distribution panel tothehighest continuous current produced in the ETAP model(s).

Battery cables are maintained asscheduled cables with pullticketlengths referenced via Dominion's Plant Data Management System (PDMS) for North Anna.Each125VDC battery iscomposed of 4 racks for all 60cells. Scheduled inter-rackcables connect cell 12tocell 13andcell48 to cell49.An unscheduled inter-tier cableconnects cell 30to cell 31.Cell 31resides on the rack directly below cell 30andisconnected bya setof fourparallel 2/0Copper cables supplied bythemanufacturer, with theexception of Battery 1-III,which hasfour parallel 4/0Aluminum conductors asprovided fromthe manufacturer during theoriginal installation ofthe2GN-23batteries. Thebattery I analyzed inCalculation EE-0857 includes theuseofthe4/0Aluminum cables, which j bounds the useof2/0Copper onall other batteries.

Battery Internal Resistance isa part oftheincluded ETAP battery library for theGNseries [

ofbatteries. Itseffectsarepresent inthewayETAP calculates terminal voltage based j onapplication ofIEEE 485Annex Ctomanufacturer performance data.

Margin for overall battery connection resistance isnotincluded inthe analyses performed inCalculations Calculation EE-0857 EE-0857 andEE-0858.

toallow for increases Instead, a small margin load toDCpowered loads over time isincluded andinclude in j a

theimpacts ofthepotential increases inload onvoltage drop. Calculation EE-0858 creditsa small margin load for the2-II, 1-IV, and2-IV 125VDCVital Bus Distribution Systems butdoesnotinclude anyfor 1-II duetothe voltage analysisresults during 1-ll i Station Battery's duty cycle. Themargin loads aretracked byCorporate Electrical/I&C Analysis inconjunction with theNorth Station Anna Electrical Load Listandany required g calculation updates. I TheETAPbattery model analyzes thetotal connection plate resistanceinseries with the batterycables toinclude their effects onvoltage drop within theNorth Anna125VDC l batterymodel between the modeled battery source andthemain distribution panel. The maximum allowable resistance from the calculations hasbeenused asthebasis for this d License Amendment Request. j I

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