ML103480005

Non-Concurrence Form Sections a, B, & C for TSTF-513

ML103480005
Person / Time
Site:	Technical Specifications Task Force
Issue date:	05/17/2010
From:	Peck M S NRC/RGN-IV/DRP/RPB-B
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Download: ML103480005 (10)

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Use ADAMS Template NRC-006 SummaryIncorporationofTSTF513 1intoplantspecificTechnicalSpecificationswouldresultinasignificantreductioninthemarginofsafetyatsomereactorfacilities.Theproposedchangewouldpermitlicenseestooperateforperiodsuptosevendayswithouttheminimumreactorcoolantsystem(RCS)leakdetectioncapabilityassumedintheLeakBefore Break(LBB)safetyanalysis.ApprovalofTSTF513wouldalsoestablishanewagencyprecedentbyallowinglicenseestocreditTechnicalSpecificationrequiredRCSleakdetectionequipmentas"operable"whenthatequipmentisnotcapableofperformingtheintendedsafetyfunctionasdescribedintheplantsafetyanalysis.CurrentRequirementsRegulatoryGuide1.45 2establishesthetypicallicensingbasiscommitmentforRCSleakdetectiontomeetGeneralDesignCriteria(GDC)30,"QualityofReactorCoolantPressureBoundary."RegulatoryGuide1.45,PositionC.5,establishedtherequirementthatcontainmentatmosphericgaseousradiationmonitorshavethecapabilityofdetectingaonegallonperminute(gpm)leakwhenusedforRCSleakagedetection.RegulatoryGuide1.45specifiesthat"realisticprimary"coolantradioactivitysourcetermbeusedwhendemonstratinggaseousmonitorleakdetectioncapability.ThegaseousmonitoristypicallyoneofthreeRCSleakdetectionsystemsrequiredbyTechnicalSpecification3.4.15,"RCSLeakageDetectionInstrumentation."

3AtWestinghousePWRs,thespecifiedsafetyfunctionofthesesystemsistoprovideplantoperatorswithanearlyindicationofpotentialpressureboundaryleakagebetweenthe72hourRCSinventorybalanceintervalrequiredbyTechnicalSpecificationSurveillance3.4.13,"RCSOperationalLeakage."ThemajorityofUSWestinghousePWRshavealsoincorporatedtheLBBpipefracturemechanicstechnologyintotheplantspecificdesignbases.4TheLBBtechnologyprovidedthebasisforreducingthenumberofRCSpipingsupports,resolutionofUnresolvedSafetyIssueA 2,"AsymmetricBlowdownLoadsonPWRPrimarySystems,"andGDC4,"EnvironmentalandDynamicEffectsDesignBases."5TheLBBNRCreviewcriterionspecifiesthatlicenseesarerequiredtomaintainRCSleakagedetectionsystemsequivalenttoRegulatoryGuide1.45tousetheLBBtechnology.

6TheLBBsafetyanalysisrequireslicenseestomaintainatleastoneRCSleakdetectionsystemwiththecapabilityofdetectingaonegpmleakinfourhoursavailableatalltimes.7TheintegrityofthiskeysafetyrequirementhasbeentypicallypreservedbyTechnicalSpecification3.4.15,"RCSLeakageDetectionInstrumentation."

8TechnicalSpecification3.4.15currentlyprohibitscontinuedreactoroperationwithoutatleastoneoperableRCSleakagedetectionsystem.Michael Peck Ma y 17, 201 0

PastContainmentGaseousRadiationMonitorOperabilityIssues In2003,theNRCidentifiedthatgaseousradiationmonitorsusedforRCSleakagedetectionattheByronandBraidwoodplantswerenotcapableofperformingthespecifiedsafetyfunction.9TheAgencyconcludedthatbetween223and839hourswouldbeneededbeforethesegasmonitorscoulddetectaonegpmRCSleakusinga"realistic"primarycoolantradioactivitysourceterm.In2003,theNRCalsoconcludedthattheCallawaygaseousmonitorwasinoperablebecausegreaterthan500hourswereneededbeforethedetectorcoulddetectaonegpmleakatcurrentRCSactivitylevels.10TheNRCsubsequentlyidentifiedthatthegaseousmonitorsatWolfCreek, 11DiabloCanyon, 12andMcguire13 werealsoinoperable.Ineachofthesecases,theNRCconcludedthatthegaseousmonitorswereinoperableforTechnicalSpecification3.4.15compliancebecausetheleakdetectorswerenotcapableofdetectingaRCSleakinareasonableperiodoftime,consistentwitheithertheplantlicensingbasisorsafetyanalysis.TheinspectorsfoundthegaseousmonitordesignresponseandsensitivitywasbasedonanassumedRCSsourcetermequivalenttoabout0.1percentfailednuclearfuel.ThisassumedRCSsourcetermwasseveralordersofmagnitudegreaterthan"realistic"coolantradioactivityspecifiedbyRegulatoryGuide1.45.TheNRCinspectorsconcludedthatnoneofthesereactorshadeveroperatedwiththeRCSsourcetermassumedinthemonitordesignandthatcurrentperformancestandardswouldlikelyresultinareactorshutdownlongbefore0.1percentfuelfailurewouldoccur.ApplyingNRCoperabilityguidance, 14agencyinspectorsconcludedthatmonitorswereinoperablybecausetheywerenotabletofunctionasacreditableleakdetectorsatcurrentRCSconditions.InspectorsalsoconcludedthatthehighRCSsourcetermsspecifiedinthedesignandFSARswereaconditionrequiredforoperabilitybecausetheseconditionswereexplicitlyrelieduponbylicenseestodemonstrateRCSleakdetectionfunction.In2005,theNRCissuedInformationNotice2005 24 15toalertlicenseesthattheRCSactivityassumedinthecontainmentradiationatmosphericmonitordesigncalculationsmaybenonconservative.Theagencyconcludedthatindividualgaseousmonitorresponseandsensitivityweredependantonplantspecificfactors,includingplacementofdetectorinletinrelationtoRCSpiping,RCSsourceterm,ifargoninjectionwasused,containmentsize,containmentventilationflowanddistribution(mixing).InformationNotice2005 24alsoreinforcedthefactthatatmosphericmonitoroperabilitywasdependantonthecapabilityofthemonitortoperformthespecifiedsafetyfunctiontodetectaRCSleak.ChangesProvidedbyTSTF513TSTF513providestwochangesthatwouldresultinasignificantreductioninthemarginofsafetyforsomereactorfacilities.First,TSTF513includesa"clarification"totheBasisofTechnicalSpecification3.4.15""However,thegaseousorparticulatecontainmentatmosphereradioactivitymonitorisOPERABLEwhenitiscapableofdetectinga1gpmincreaseinunidentifiedLEAKAGEwithin1hourgivenanRCSactivityequivalentofthatassumedinthedesigncalculationsforthemonitors."ThisstatementwouldallowlicenseestocreditatmosphericradiationmonitorsasoperableRCSleakdetectorsindependentofthecapabilityofthesecomponentstodetectanactualRCSleak.TSTF513wouldallowsomePWRs(includingByron,Braidwood,Callaway,WolfCreek,DiabloCanyon,&McGuire)tooperatewithaTechnicalSpecification"operable"leakdetectorthatwouldlikelyneverhavethenecessaryRCSsourcetermtobefunctional.

ProposedTSTF513wouldresultinasignificantreductioninthemarginofsafetyatsomereactorfacilitiesbecausethechangewouldreducetheminimumrequiredfunctionalRCSleakdetectioncapabilityfromonetonone.TSTF513providesanewlimitingconditionforoperation,"ConditionD."Thisconditionallowsreactoroperationforuptosevendayswithonlythegaseousmonitor.GiventhattheBasis"clarification"wouldnolongerrequirethegaseousmonitortobecapableofdetectingaRCSleaktobe"operable,"thisConditionwouldeffectivelypermitcontinuedreactoroperationforsevendays(atsomefacilities)withoutanyRCSleakdetectioncapability.ReactoroperationwithoutatleastoneRCSleakdetectionsystem(withaonegpmwithinfourhourcapability)wouldplacetheplantoutsidetheboundsoftheNRCLBBsafetyanalysisassumstions.

16ApprovalofTSTF513wouldalsoestablishanewagencyprecedentbypermittinglicenseestocreditnonfunctionalequipmentas"operable."Thispositioniscontrarytocurrentagencyoperabilityguidance.17Thisguidancespecifiesthat:Asystem,subsystem,train,component,ordeviceshallbeOPERABLEorhaveOPERABILITYwhenitiscapableofperformingitsspecifiedsafetyfunction(s)andwhenallnecessaryattendantinstrumentation,controls,normaloremergencyelectricalpower,coolingandsealwater,lubrication,andotherauxiliaryequipmentthatarerequiredforthesystem,subsystem,train,component,ordevicetoperformitsspecifiedsafetyfunction(s)arealsocapableofperformingtheirrelatedsupportfunction(s).TSTF513FailedtoProvideAdequateTechnicalJustificationfortheUseofContainmentAtmosphereGrabSamplesforRCSLeakDetectionTSTF513justifiedthesevendayLimitingConditionforOperationD,inpart,byrequiringlicenseestoanalyzecontainmentatmospheregrabsamplesonceevery12hours.UseofatmospheregrabsamplesisnotanNRCapprovedmethodforRCSleakdetection 18andtheTSTFdidnotprovideanadequatetechnicaljustificationthatgrabsampleswereeffectiveforRCSleakagedetection.Containmentgrabsamplesaretypicallytakenfromtheuppercontainmentdeck.ThecriticalpipingaffectedbytheLBBanalysisisremotelylocatedinthelowercontainment,withintheconfinesofthebiologicalshieldandcranewalls.ForRCSgrabsamplestobeeffectivetoidentifyRCSleakage,thecoolantsourcetermandleakratemustbesufficienttoraisegaseousorparticulateradiationlevelsaboveminimumdetectionlimitsatthelocationthegrabsampleistaken.Forgaseousgrabsamples,licenseestypicallyfillafourlitersamplebottlebyamechanicalairpump.Xe 133isatypicaldominantRCSgaseousnuclide.RCSXe 133concentrationsareoftenlessthan7x10 4µCi/ml.A60gallonleak(onegpmoveranhour)wouldreleaseabout2.2x10 5ml(or160µCi)intocontainmentfromtheRCS.Givenalarge,dryPWRcontainmenthasabout2.5x10 6Ft 3(7.1x10 10ml)freespace,theresultingincreaseinXe 133inthecontainmentatmospherewouldbeabout2.21x10 9µCi/ml,assuminginstantaneouscontainmentairmixing.ThisXe 133valueislowerthanthe1x10 8µCi/mllevelofdetectionuseforanalyzinggrabsamples.19Actualexpectedradionuclideconcentrationsattheuppercontainmentdeckcouldbesignificantlylessduetomixingresidenttimeinthecontainment:[N samplepoint]/dt=d[N leak]/dt/[ContainmentVolume]*d[mixing]/dtWhereNisradionuclideconcentration,dtistimedifferentialandd[mixing]/dtcorrespondstothetimedependdiffusion/forcedconvectionoftheRCSleaklocationtosamplepoint.Giventhatcontainmentcoolerscirculateabout110,000scfm,aboutathirdradionuclideconcentrationwouldbeseenattheuppercontainmentdeckafteronehourwhencomparedtotheinstantaneousmixingcase(dependingonplantspecificparameters).

Forparticulategrabsamples,licenseestypicallycountafilterafterpassingabout30ft 3ofthecontainmentatmosphere.AmajorcontributortoRCSparticulateconcentrationisCo 58orCs 138.AtypicalRCSconcentrationforCo 58orCs 138isabout2x10 3µCi/ml.Applyingthesameapproachusedforthegaseousgrabsample,60gallonsofRCSwouldresultinabout6.3x10 9µCi/mlincontainmentassuminginstantaneousmixing.ThisCo 58valueisalsolowerthanthe1x10 8µCi/mllevelofdetectionusedforgrabsamples.20Actualradionuclideparticulateconcentrationsattheuppercontainmentdeckwouldalsobelessduetomixingresidenttimeinthecontainment:d[N samplepoint]/dt=d[Nleak]/dt/[ContainmentVolume]*d[mixing]/dt-d[N plateout]/dtInadditiontothetransportterms,additionalcontainmentatmosphericparticulateswouldbelostduetoplateoutonthecoolersurfacesinthelowercontainmentsurfacesandinthecontainmentcoolingcoolercoils.ProposedAlternative1. RecommendthattheAgencynotapproveTSTF513,Revision2.2. Recommendadditionalrenegotiationwithindustryto:- Removethe"clarification"toTechnicalSpecification3.4.15Basiswhichprovidesforcreditingnonfunctionalequipmentasoperable.RemovalofthischangewouldstillpermittheuseofradiationmonitorsforRCSleakdetectionatthoseplantswherethisequipmentremainsfunctionalgivenplantspecificdesignfeaturesandRCSsourceterms.- SpecifythatatmosphericgrabsampleanalysisresultsarerequiredtobecompletedeveryfourhourswhileoperatinginConditionD.ThischangewouldprovideconsistencywiththeLBBsafetyanalysis.- IncludedprovisionsintheTechnicalSpecificationBasistoensurelicenseescompleteaplantspecificanalysis,includingtheapplicablerangesofRCSsourcetermsandcontainmentdesignandequipmentalignmentsandtransporttimes,demonstratingcontainmentatmosphericgrabsampleshavethecapabilitytodetectaonegpmRCSleakwithinfourhours.- EnsuretherevisedbasisforTechnicalSpecification3.4.15includesallapplicablesafetyanalysis(LBB).3. CorrecterroronAttachment1,page1.Attachment1states:"Newcondition[D]RequiredActionrequireanalyzinggrabsamplesofthecontainmentatmosphereorperforminganRCSwaterinventorybalanceevery12hoursandrestoringanothermonitorwithin7days."NewCondition[D]doesnotrequirewaterinventorybalanceevery12hours.

References

1. Revised Models for Adoption of TSTF-513, Revision 2, "Revise PWR Operability Requirements and Actions For RCS Leakage Instrumentation" For Publication In The Federal Register (TAC Nos. ME0988)

2. Regulatory Guide 1.45, "Guidance on Monitoring and Responding to Reactor Coolant System Leakage, Revision 0

3. NUREG-0800, U.S. Nuclear Regulatory Commission Standard Review Plan, Section 5.2.5, "Reactor Coolant Pressure Boundary Leaka ge Detection," Revision 2

4. IAEA-TECDOC-710, "Applicability of the leak before break concept Report of the IAEA Extrabudgetary Programme on the Safety of WWER-440 Model 230 Nuclear Power Plants," Status report on a generic safety issue (www-pub.iaea.org/MTCD/publications/PDF/te_

710_web.pdf) 5. NUREG-1061, Volume 3, "Report of the U.S. Nuclear Regulatory Commission Piping Review Committed, Evaluation of Potential for Pipe Breaks, November," 1984

6. NUREG-0800, U.S. Nuclear Regulatory Commission Standard Review Plan, 3.6.3, "Leak-Before Brea k Evaluation Procedures," Revis ion, 1 7. Generic Letter 84-04, "Safety Evaluation of Westinghouse Topical Reports Dealing with Elimination of Postulated Pipe Breaks In PWR Primary Main Loops"

8. NUREG 1430

9. Letter to J.L. Skolds, Exelon Nuclear, February 20, 2003, from L. Raghavan, NRR, "Resolution of Allegation NRR-2002-A0022"

10. Callaway Plant - NRC Integrated Inspection Report 05000483/2003005,October 16, 2003 (ADAEMS ML032890770)

11. Wolf Creek Generating Station - NRC Integrated Inspection Report 05000482/2004004 November 9, 2004 (ADAMS ML0431402790)

12. Diablo Canyon Power Plant - NRC Integrated Inspection Report 05000275/2008004 AND 05000323/2008004 November 3, 2008, (ADAMS ML0830801130)

13. Mcguire Nuclear Station - NRC Integrated Inspection Report 05000369/2005002 And 05000370/2005002 And Independent Spent Fuel Storage Installation Inspection Report 0720038/20050001 (ADAMS ML051190140)

14. RIS 2005-20, Revision to NRC Inspection Manual Part 9900 Technical Guidance, "Operability Determinations & Functionality As sessments for Resolution of Degraded or Nonconforming Conditions Adverse to Quality or Safety". Revision 1

15. NRC INFORMATION NOTICE 2005-24, "Nonconservatism in Leakage Detection Sensitivity," August 3, 2005

16. Generic Letter 84-04, "Safety Evaluation of Westinghouse Topical Reports Dealing with Elimination of Postulated Pipe Breaks In PWR Primary Main Loops"

17. Ibid 13

18. Ibid 2, 3, & 5

19. Discussion with Diablo Canyon Chemistry Supervisor on May 13, 2010

20. Ibid 15