ML080990538

Response to NRC Request for Additional Information Regarding Nine Mile, Unit 2, Two Inoperable Control Room Air Conditioning Subsystems

ML080990538
Person / Time
Site:	Nine Mile Point
Issue date:	04/07/2008
From:	Polson K Constellation Energy Group
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
TAC MD6352
Download: ML080990538 (10)

Text

Keith J.Polson Vice President-Nine Mile Point Constellation Energye Nine Mile Point Nuclear StationP.O.Box63 Lycoming, New York 13093 315.349.5200 315.349.1321 Fax April 7,2008 u.S.NuclearRegulatoryCommissionWashington,DC20555-0001 ATTENTION:

SUBJECT:

DocumentControlDeskNineMilePointNuclearStation Unit No.2;DocketNo.50-410ResponsetoNRCRequestforAdditionalInformationRegardingNineMilePointNuclearStation,Unit No.2,TwoInoperableControlRoomAirConditioningSubsystems(TACNo.MD6352)

REFERENCES:

(a)Letterfrom K.J.Polson(NMPNS)toDocumentControlDesk(NRC),datedJuly30,2007,ApplicationforTechnicalSpecificationChangeTSTF-477,Revision3,"AddActionforTwoInoperableControlRoomACSubsystems"totheTechnicalSpecificationsUsingConsolidatedLineItemImprovementProcess(b)LetterfromM.J.David(NRC)to K.J.Polson(NMPNS),datedFebruary07,2008,RequestforAdditionalInformationRegardingNineMilePointNuclearStation,Unit No.2,TwoInoperableControlRoomAirConditioningSubsystems(TACNo.MD6352)Pursuantto10CFR50.90,NineMilePointNuclearStation,LLC,(NMPNS)requested,inReference(a), approval ofanamendmenttotheNineMilePointUnit2RenewedOperatingLicenseNPF-69toreviseTechnicalSpecification3.7.3,"ControlRoomEnvelope AirConditioning(AC)System"byaddinganactionstatementfortwoinoperablecontrolroomACsubsystems.Thepurpose ofthisletteristoprovideresponsestotherequestforadditionalinformation (RAI)transmittedtoNMPNSinReference(b).ResponsetotheRAIisprovidedinAttachment1.ThisresponsedoesnotaffecttheNoSignificantHazardsDeterminationanalysisprovidedbyNMPNSinReference(a).Pursuantto10CFR50.91(b)(1),NMPNShasprovidedacopy ofthisresponse,withattachments,totheappropriatestaterepresentative.

DocumentControlDeskApril7, 2008Page2Thislettercontainsnoregulatory commitments

.Shouldyouhaveanyquestions regarding theinformationinthissubmittal

,pleasecontactT.F.Syrell

,LicensingDirector,at(315)349-5219.Verytrulyyours

,STATEOFNEW YORK TO WIT: COUNTY OF OSWEGO I , Keith J.Polson,beingdulysworn,statethatIamVicePresident-NineMilePoint

,andthatIamdulyauthorizedtoexecuteandfilethisresponseon behalf ofNineMilePointNuclearStation,LLC.

To the best ofmyknowledgeand belief ,thestatementscontainedinthisdocumentaretrueandcorrect.Totheextentthatthesestatementsarenotbasedonmypersonalknowledge

,theyarebaseduponinformationprovidedbyotherNineMilePointemployeesand/orconsultants.SuchinformationhasbeenreviewedinaccordancewithcompanypracticeandIbelieve ittobereliable.Subscribedand sw0r:tme,aNotaryPublicinandfortheState ofNewYorkandCounty of

,thisday of-Afrll ,2008.WITNESSmyHandandNotarialSeal:

My Commission Expires: KJP/GB DocumentControlDeskApril7,2008Page3

Attachment:

1.ResponsetoNRCRequestforAdditionalInformationRegardingNineMilePointNuclearStation,Unit No.2,TwoInoperableControlRoom Air Conditioning Subsystemscc:S.J.Collins,NRCRegionalAdministrator,RegionIR.V.Guzman,NRCProjectManagerSeniorNRCResidentInspector J.P.Spath,NYSERDA ATTACHMENT 1 RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION REGARDING NINE MILE POINT NUCLEAR STATION, UNIT NO.2, TWO INOPERABLE CONTROL ROOM AIR CONDITIONING SUBSYSTEMSNineMile Point Nuclear Station, LLC April7,2008 Attachment 1 Response to NRC Request for Additional Information Regarding Nine Mile Point Nuclear Station, Unit No.2, Two Inoperable Control Room Air Conditioning SubsystemsThisattachmentprovidesNineMilePointNuclearStation,LLC(NMPNS)responsestotherequestforadditionalinformationdocumentedintheNRCletterdatedFebruary07,2008.EachNRCquestionis restated(initalics),followedbytheNMPNSresponse.QuestionI TSTF-477, Revision 3,Section3.0,assumesacontrolroom ACsystemthatconsists oftwoindependent,redundantsubsystems, providingcoolingandheating ofrecirculatedcontrolroomair.TheLARstates,"Duetothedesign ofthesystem,whenbothsubsystemsareinoperable,thecapability fortheControlRoomEnvelope ACSystemtoperformitsdesignfunctionmaystillexistbyhavingsufficientcomponentsoperablefrombothsubsystemstomeetitssafetyfunction."I.aExplainthedesign ofthesystemincludinginterfacingandsupportsystems(e.g.,power,instrumentationandcontrols,chilledwater,andservicewater).Includeadiscussion ofindependenceand redundancy.

NMPNS ResponseControlRoomEnvelope AirConditioning(AC)SystemDesignTheControlRoomEnvelopeACSystemisdesignedtoprovideanenvironmentthatensureshabitability oftheareasserviced,consistentwithpersonalcomfort,andoptimumperformance ofequipmentwithintemperaturelimitssetforthintheUpdatedSafetyAnalysisReport(USAR).Thesystemequipmenthassufficientsurpluscoolingcapacitytomaintaintheseconditionsduringnormalandaccidentconditionsandconcurrentequipmentsinglefailurescenariosandisdesignedtomaintaincontrolroomenvelopetemperaturefora30daycontinuousoccupancyfollowingisolation ofthecontrolroomenvelope.TheenvelopeincludestheMainControlRoomareas(elevation 306')andtheRelayRoomareas(elevation 288'6")oftheControlBuilding.TheControlRoomEnvelopeACSystemportion oftheControlBuildingheating,ventilationandairconditioning(HVAC)consists oftwo(2)independent,redundantsubsystemsthatprovidecooling ofrecirculatedandoutsideair.Allcomponentsareredundanttomaintainfunctionintegrityduringadesignbasisaccident(DBA).Asingleactivefailure ofacomponent oftheControlRoomEnvelopeACSystem,assumingaloss ofoffsitepower,doesnotimpairtheability ofthesystemtoperformitsdesignfunction.AllcomponentsareCategoryI,poweredfromClassIEbuses,andareSafetyClass3.Thesubsystemsreceiveelectricalpowerfromtwooffsitesourcesduringnormaloperationandfromredundantstandbyemergencydieselgenerators ifoffsitepowerislost.Eachredundantsubsystemincludestwo100%capacityairconditioningunits(ACUs).EachACUincludesanairfilterassembly,coolingcoil,andfan.ACsubsystemAconsists of 2HVC*ACUIAdesignedtoservicetheControlRoomareaventilation,el.

306',and2HVC*ACU2AdesignedtoservicetheRelayRoomareaventilation,el.

288'6".ThissubsystemispoweredfromtheDivision1powersource,andreceivesitscoolingwatertotheACUcoilsfromtheAchilledwatersubsystem.TheredundantBsubsystemiscomprised of 2HVC*ACUIB(ControlRoom)andHVC*ACU2B(RelayRoom)poweredfromtheDivision2powersource,andreceivescoolingwaterfromtheBchilledwatersubsystem.AlsoincludedwithineachACsubsystemareductwork,dampersandinstrumentationandcontrolstoprovideforcontrolroomenvelopetemperaturecontrol.Eachcontrolbuildingchilledwatersubsystemincludesawaterchiller,chilledwaterpump,expansiontank,controls,pipingandvalves.

lof6 Attachment 1 ResponsetoNRC Request for Additional Information RegardingNineMile Point Nuclear Station, Unit No.2, Two Inoperable Control Room Air Conditioning SubsystemsControlBuildingChilledWaterSystemTheControlBuildingChilledWaterSystemprovideschilledwaterduringnormal,plantshutdown,andDBAconditionstotheMainControlRoomEnvelopeACSystem(MainControlRoomand Relay Room).Thesystemisaclosedlooppipingsystemconsisting oftwoindependent,redundant chilledwaterloopsortrains.Eachtrainiscapable ofmeetingtotalchilledwaterdemand.Eachtrainis designedtoCategoryIcriteriaandconformstothesingle-failurecriterion.Eachtrainreceiveselectrical powerfromtwooffsitesourcesduringnormaloperationandfromredundantstandbyemergencydieselgenerators ifoffsitepowerislost.EachControlBuildingchilledwatersubsystemortrainisasafety-related,seismically-qualified,fullyredundantsystem,andisdesignedtoassurean uninterruptible supply of watertotheACUs.

Intheunlikelyeventbothchilledwatertrainsfail,servicewatercanbeutilizedforemergencycooling.l.b.Whatisthesafetyfunction oftheNMP2controlroomenvelopeACsystem?

NMPNS ResponseThedesignbases oftheNineMilePoint,Unit2(NMP2)ControlRoomEnvelopeACSystemistoprovideanenvironmentthatensureshabitability oftheareasservedconsistentwith personnel comfortandoptimumperformance ofequipment.Theseincludemaintainingtemperaturelimitsfora30daycontinuousoccupancyfollowingisolation ofthecontrolroomenvelopeunderbothnormalandaccident conditions.ControlRoomEnvelopeACSystemisdesignedsuchthatasinglesubsystemprovidestherequiredtemperaturecontrolto maintainasuitablecontrolroomenvelopeenvironmentfora sustained occupancy of37persons.Thedesignconditionsforthecontrolroomenvelopeenvironmentare75°Fand50%relativehumidity.WithrespecttoTechnicalSpecificationsSection3.7.3,thesafetyfunction oftheControlRoomEnvelopeACSystemconsists ofensuringthattheControlRoomEnvelopetemperaturewillnot exceed equipmentOPERABILITYlimits

(::=;90°F)forthe30daycontinuousoccupancyfollowingisolation oftheControlRoomEnvelope.TheControlRoomEnvelopeACSystemsafetyfunctionis maintainedwhenControlRoomACcomponentsequivalenttooneControlRoomEnvelopesubsystemare OPERABLE (TechnicalSpecificationsBases3.7.3).l.c.Provideexplanations ofhowthecapability forthesystemtoperformitssafetyfunctionmaystillexistwhenbothsubsystemsareinoperable,assumingrepresentativecomponentandsubsystem failures.NMPNS ResponseTheControlRoomEnvelopeACSystemsafetyfunctionismaintainedwhentheControlRoomEnvelopeACsystemcomponentsequivalenttoone (l)controlroomenvelopeACsubsystemareoperable.

20f6 Attachment 1 ResponsetoNRC Request for Additional Information RegardingNineMile Point Nuclear Station, Unit No.2, Two Inoperable Control Room Air Conditioning SubsystemsDescribedinresponsetoQuestion l.aabove,theControlRoomEnvelopeACSystemconsists of twoindependent,redundantACsubsystems.Eachsubsystemconsists of two AirConditioningUnits(oneACUservicingtheMainControlRoomareaeL 306',andoneACUservicingthe RelayRoomeL 288'6"),twoindependentredundantControlBuildingChilledWatersubsystemswhichprovidescoolingwatertothecoolingcoils ofthetworedundantcontrolroomACsubsystems,ductwork,dampers,andinstrwnentationandcontrolstoprovidecontrolroomenvelopetemperaturecontroLEachChilledWatersubsystemisdivisionallypoweredconsistentwiththeircorrespondingACU.Duetothedesigncharacteristics oftheControlRoomEnvelopeACSystem,thereexistsseveralsystemoperatingconfigurationswithbothcontrolroomenvelopeACsubsystemsthatcanmaintainsafety function.Option1:Operation ofbothACUsinonesubsystem (2HVC*ACUlAservicingtheMainControlRoom,and2HVC*ACU2AservicingtheRelayRoom)with"A"ChilledWatersubsystems operable.Option2:Operation ofbothACUsinthealternatesubsystem(2HVC*

ACUlBservicingtheMainControlRoom,and2HVC*ACU2BservicingtheRelayRoom)with"B" Chilled Watersubsystemsoperable.Option3:Operation of 2HVC*ACUlA(MainControlRoom)fromonesubsystem,andoperation of2HVC*AC2B(RelayRoom)fromthealternateACsubsystem,withbothChilledWatersubsystemsoperable.Option4:Operation of2HVC*ACUlB(MainControlRoom)fromoneACsubsystem,andoperationon2HVC*ACU2A(RelayRoom)fromthealternateACsubsystem,withboth Chilled Watersubsystemsoperable.AsillustratedinOptions3and4above,thedesignandoperatingconfigurationcapabilities oftheControlRoomEnvelopeACSystempermitsanACUfromeachsubsystemtobeinoperable(onefromtheControlRoomareaandonefromtheRelayRoomarea),andstillmaintainControlRoomEnvelopeACSystemssafetyfunction.SufficientACUs,andsupportingsubsystems,andrepresentativecomponentsremainavailablewhichareequivalenttohavingonecontrolroomenvelopeACsubsystemfullyoperable.TechnicalSpecification(TS)3.7.3hastakencreditfortheseconfigurations.1.dDoprocedurescurrentlyexisttoguide plant staffinregainingsystemsafetyjitnction?

NMPNS Response The plant'sCorrectiveActionProgramandestablishedproceduralguidanceandcontrolsgoverntheidentification,tracking,andtimelyresolution ofinoperableordegradedequipment/componentsremovedfromservice,includingTSConditionentry,trackingandrequiredcompletiontimes.Administrativeproceduresprovideriskmanagementandintegratedworkmanagementtoolsnecessarytoregaintooperablestatus,degradedsystemconditionsandsystem/componentsafetyfunctions,inatimelymanner.

30f6 Attachment 1 ResponsetoNRC Request for Additional Information Regarding Nine Mile Point Nuclear Station, Unit No.2, Two Inoperable Control Room Air Conditioning SubsystemsQuestion2Pleaseexplainthemeaning of the following statem entinSection 2.2 oftheLAR ,"Theability of theControlRoomEnvelopeACSystemtomaintaincontrolroomenvelopetemperaturewithinlimitsisanimplicitassumption ofthesafetyanalysisevaluatedintheUpdatedSafetyAnalysisReport(USAR)

Chapter 6,EngineeringSafetyFeatures

,andChapter 15 ,AccidentAnal ysis." NMPNS Response USAR Chapter 6, Engineered Safety Features, providesthedesignbases, system designs, system operational procedures

, design evaluations, testing and inspections, and instrumentation requirements associated with various engineeredsafetyfeaturesystems associatedwithNine Mile Point Unit 2.USAR Chapter 15 examines postulatedfailuresand their consequences, and evaluates the plant's built in capabilitiestocontroland accommodatesuchfailuresandevents.

Both USARchaptersdiscussthevariousdesignfunctions oftheControl Room Envelope.Includedisthe Control Room Envelope AC System'sfunctionto maintain acceptable temperature and humidity conditions duringbothnormaland accident conditions.

However, the specific defined temperature limitvaluesarenot discussedinthese chapters (valuesarelistedin USAR Chapter9),but these values remain an implicit assumption in bothchaptersanalysesand would be maintainedsuchthat safety-related control room envelope equipment would remain operable duringnormaland emergency conditions.Question3TheTS 3.7.3inAttachment (2)oftheLARcontainstheexpressions,"Twocontrolroomenvelope ACsubsystemsinoperablewithsafetyfunctionmaintained..."and"Twocontrolroomenvelope ACsubsystemsinoperablewithsafetyfunctionnotmaintained..."Pleaseexplainthemeaning of bothexpressionsandtheprocess fordeterminingwhichisapplicableinagivencircumstance.

NMPNS Response Response to Question Lc provides operating conditions or situationsthatmeet existingTS3.7.3, Condition A,"Two control room envelope AC subsystems inoperable with safety function maintained

..."Duetothedesign oftheControl Room EnvelopeACSystem, ifoneACUis inoperable in each of the redundant subsystems and both inoperableACUsarenot servicingthesamearea (Control Room or Relay room)representative components remain available which are equivalenttohavingone control room envelope AC subsystem fully operable,andsafety function canstillbemet.

Conversely, iftwoACUsare inoperable,onefromeachAC subsystem ,andboth inoperable ACUs servicethesamearea(Main Control Room or Relay Room),heatload removal capabilities wouldbelosttothatarea.Thus,theplant wouldenterthe condition of two controlroomAC subsystems inoperablewithsafetyfunctionnot maintained

.40f6 Attachment 1 ResponsetoNRC Request for Additional Information Regarding Nine Mile Point Nuclear Station, Unit No.2, Two Inoperable Control Room Air Conditioning SubsystemsQuestion4 Regarding proposed ACTION B.for TS3.7.3inAttachment (2)oftheLAR:4.aWhatspecificsafetyfunction(s)is/aremeantbytheexpression

"...withsafetyfunctionnotmaintained...

?NMPNS Response The response to Question l.b above provided the definition of safety function maintained withrespecttoTS3.7.3.Conversetothisdefinition,the meaning of"safetyfunctionnot maintained" denotestheredoesnotexist operable components in both control room envelope AC subsystems to support system safetyfunction(heatloadremoval capabilities) in either or both the Main Control Room and Relay Room areas.4.bWhatisthebasis forthe90°Flimit proposedfornewREQUIRED ACTION B.l?NMPNS ResponseThebasesforthe proposed90°Fvalueare providedintheNMP2 USAR, Chapter9.4,Air Conditioning, Heating, Cooling, and Ventilation Systems.USAR Subparagraph 9.4.1.1, Design Bases, references USAR Table 9.4-1,"EnvironmentalandSystem Design Parameters for HV AC Systems," which includes the Control Building, elevation 306'"Control Room,"andControl Building", elevation 288'6""Relay Room." BothareasintheTableare designatedbyNotes(1)and(3) respectively, whichstateall related equipment located in boththecontrol roomandrelayroomis qualifiedtoan ambient temperature of120°F withinthepanel.The maximum ambient temperature in boththecontrolroomandrelayroomis90°F, which providesamargintoaccountforinternal temperature rise within safety-related control roomandrelayroompanels.4.cDoes"RestoreonecontrolroomenvelopeACsubsystemtoOPERABLE status," as proposedfornewREQUIRED ACTIONB.2,alsoinclude"Twocontrolroomenvelope AC subsystemsinoperablewithsafetyfunctionmaintained,"asstatedincurrentCONDITIONA?

NMPNS ResponseThenew proposed recommended Required ActionB.2was draftedtotakea conservative approach when both control roomenvelopeACsubsystemsare inoperablewithsafetyfunctionnot maintainedandis consistent with TSTF-447, Revision3.Thenew Required ActionB.2isnotmeantto include"Two control room envelopeACsubsystems inoperablewithsafetyfunction maintained."Question5RegardingcurrentNMP2TS 3.7.2,"ControlRoomEnvelopeFiltration(CREF)System:

"5.aWhatcomponentsaresharedbetweencontrolroomenvelope ACsubsystemsandCREF subsystems

?50f6 Attachment 1 ResponsetoNRC Request for Additional Information RegardingNineMile Point Nuclear Station, Unit No.2, Two Inoperable Control Room Air Conditioning Subsystems NMPNS ResponseSharedcomponentsbetweenTS 3.7.2,"ControlRoomEnvelopeFiltration(CREF)System,"andTS 3.7.3includethefanportion(andassociatedductwork)ofthefour100%capacityControlRoomEnvelopeACSystemACUs.5.bWhat sharedcomponentsinTS 3.7.2andTS 3.7.3arerequiredtoremainoperablewithtwocontrolroomenvelopeACsubsystemsinoperable:*Withsafetyfunctionmaintained?*Withsafetyfunctionnotmaintained?

NMPNS ResponseTheControlRoomEnvelopeFiltrationSystem(TS 3.7.2)isconsideredoperablewhentheindividualcomponentsnecessarytocontroloperatorexposureareoperableinbothredundantsubsystems.ACREFsubsystemisconsideredoperablewhentheassociatedACUs(fanportiononly)areoperable(onefortheControlRoomareaandonefortheRelayRoomarea),includingtheassociatedductwork.Duringnormaloperation,theCREFSystemrequiresthesetwofanstobeincontinuousoperationtomaintaincontrolroomenvelopepositivepressure (2: 0.125incheswatergaugepositivepressurewithrespecttooutsideatmosphere)topreventunfilteredinleakage.Operabilityrequirements of TS 3.7.2areindependentof,andarenotimpactedbytheoperabilityconditionsassociatedwithTS 3.7.3.WhetherbothcontrolroomACsubsystemsareinoperablewith/withoutsafetyfunctionmaintained,theCREFSystemreliesonthefanportiononly(andassociatedductwork)ofthetwoairconditioningunitstomaintainanoperablecondition.5.cWhatwouldbetheimpactonTS3.7.2 iftheNRC staffweretoapprovethe requestedchangesto TS 3.7.3?NMPNS ResponseTheNRCapproval oftheproposedamendmenttoTS 3.7.3,"ControlRoomEnvelope Air Conditioning(AC)System,"willhavenoimpact orrequiredchangestoTS 3.7.2,"ControlRoomEnvelopeFiltration(CREF)System." 6of6