L-MT-17-015, Mitigating Strategies Flood Hazard Assessment (MSA) Submittal
| ML17087A343 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 03/28/2017 |
| From: | Gardner P Northern States Power Co, Xcel Energy |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| CAC MF7712, L-MT-17-015 | |
| Download: ML17087A343 (40) | |
Text
2807 West County Road 75 Monticello, MN 55362 800.895.4999 xcelenergy.com March 28, 2017 L-MT-17-015 10 CFR 50.54(f)
ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 Monticello Nuclear Generating Plant Docket No. 50-263 Renewed Facility Operating License No. DPR-22 Monticello Nuclear Generating Plant, Mitigating Strategies Flood Hazard Assessment (MSA)
Submittal (CAC No. MF7712)
References:
- 1) NRC Letter, Request for Information Pursuant to Title 10 of the Code of Federal Regulations 50.54(f) Regarding Recommendations 2.1, 2.3, and 9.3, of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident, dated March 12, 2012. (ADAMS Accession No. ML12056A046)
- 2) NSPM Letter to NRC, Monticello Nuclear Generating Plant: Response to Post-Fukushima Near-Term Task Force (NTTF) Recommendation 2.1, Flooding - Flood Hazard Reevaluation Report, L-MT-16-024, dated May 12, 2016. (ADAMS Accession No. ML16145A179)
- 3) NRC Letter, Coordination of Requests for Information Regarding Flooding Hazard Reevaluations and Mitigating Strategies for Beyond-Design-Basis External Events, dated September 1, 2015. (ADAMS Accession No. ML15174A257)
- 4) NRC Staff Requirements Memorandum, Staff Requirements - COMSECY-14-0037 - Integration of Mitigating Strategies for Beyond-Design-Basis External Events and the Reevaluation of Flooding Hazards," dated March 30, 2015. (ADAMS Accession No. ML15089A236)
- 5) Nuclear Energy Institute (NEI) guidance, NEI 12-06, Revision 2, Diverse and Flexible Coping Strategies (FLEX) Implementation Guide, dated December 2015. (ADAMS Accession No. ML16005A625)
Document Control Desk Page 2
- 6) Nuclear Regulatory Commission (NRC), JLD-ISG-2012-01, Compliance with Order EA-12-049, Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events, Revision 1, dated January 22, 2016. (ADAMS Accession No. ML15357A163)
- 7) NRC Letter to NSPM, Monticello Nuclear Generating Plant - Interim Staff Response to Reevaluated Flood Hazards Submitted in Response to 10 CFR 50.54(f) Information Request - Flood-Causing Mechanism Reevaluation (CAC No. MF7712), dated September 16, 2016. (ADAMS Accession No. ML16248A004)
- 8) NRC Letter, Supplemental Information Related to Request for Information Pursuant to Title 10 of the Code of Federal Regulations 50.54(f) Regarding Flooding Hazard Reevaluations for Recommendation 2.1 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident, dated March 1, 2013. (ADAMS Accession No. ML13044A561)
On March 12, 2012, the NRC issued Reference 1 to request information associated with Near-Term Task Force (NTTF) Recommendation 2.1 for Flooding. One of the Required Responses in Reference 1 directed licensees to submit a Flood Hazard Reevaluation Report (FHRR).
Northern States Power Company, a Minnesota corporation (NSPM), d/b/a Xcel Energy, submitted the FHRR for the Monticello Nuclear Generating Plant (MNGP), on May 12, 2016 (Reference 2). Per Reference 8, the NRC considers the reevaluated flood hazard to be beyond the current design/licensing basis of operating plants.
Concurrent with the FHRR, NSPM developed and implemented mitigating strategies in accordance with NRC Order EA-12-049, "Requirements for Mitigation Strategies for Beyond-Design-Basis External Events," for the MNGP. In Reference 4, the NRC affirmed that licensees need to address the reevaluated flooding hazards within their mitigating strategies for beyond-design-bases (BDB) external events, including the reevaluated flood hazards. This requirement was confirmed by the NRC in Reference 3. Guidance for performing Mitigating Strategies Assessments (MSAs) is contained in Appendix G of NEI 12-06, Revision 2 (Reference 5). The Reference 5 guidance was endorsed by the NRC in Reference 6.
In Reference 7, the NRC concluded that the reevaluated flood hazards information is suitable for the assessment of mitigating strategies developed in response to Order EA-12-049 for the MNGP.
The Enclosure to this letter provides the MNGP Mitgating Strategies Flood Hazard Assessment (MSA). The new flooding analyses were bounded by the plant design basis flood for all postulated flooding scenarios, with the exception of local intense precipitation (LIP). The MSA evaluated the FLEX strategy implementation during the LIP flooding event. The assessment concluded that the existing FLEX strategies can be successfully implemented as designed. No additional actions or procedural changes are required.
Document Control Desk Page 3 Please contact John Fields, at 763-271-6707, if additional information or clarification is required.
Summary of Commitments This letter makes no new commitments and no revisions to existing commitments.
I declare under penalty of perjury that the foregoing is true and correct.
Executed on March 1:9, 2017.
Peter A. Gardner Site Vice President, Monticello Nuclear Generating Plant Northern States Power Company-Minnesota Enclosure cc:
Administrator, Region Ill, USNRC Project Manager, Monticello Nuclear Generating Plant, USNRC Resident Inspector, Monticello Nuclear Generating Plant, USNRC
L-MT-17-015 NSPM 36 pages to follow ENCLOSURE MONTICELLO NUCLEAR GENERATING PLANT Monticello Mitigating Strategies Flood Hazard Assessment
XcelEnergy ContractNo.00048375
MonticelloMitigatingStrategies FloodHazardAssessment
CLIENTAPP.: N/A BLACK&VEATCH OverlandPark,KS
0 3/13/2017 IssuedforUse (RAR1809990002)
SDT N/A DVR180999 0019 SDT NO.
DATE DESCRIPTION DRN DES CHK APP FILENUMBER50.2000 REVIEWLEVELN/A THISDOCUMENTCONTAINS SAFETYRELATEDITEMS THISDOCUMENTCONTAINS SEISMICCATEGORYIITEMS YES NO YES NO CLIENTDOCUMENTREFERENCENUMBER TOTALSHEETS PROJECTDOCUMENTNUMBER N/A 36 180999.50.230003
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Page2of36 TableofContents
ListofAcronyms,Abbreviations,andDefinitions.........................................................................................3 Acronyms..................................................................................................................................................3 Definitions.................................................................................................................................................4 1.
ExecutiveSummary...............................................................................................................................5 2.
Background...........................................................................................................................................5 2.1 Purpose.........................................................................................................................................5 2.2 SiteDescription.............................................................................................................................6 3.
OverviewofFLEXStrategies.................................................................................................................7 4.
CharacterizationoftheMSFHI(NEI1206,Revision2,AppendixG,SectionG.2)..............................11 5.
BasisforMitigatingStrategiesAssessment(NEI1206,Revision2,AppendixG,SectionG.3)..........12 6.
AssessmentofCurrentFLEXStrategy(NEI1206,Revision2,AppendixG,SectionG.4.1)................14 6.1 LIPTimeline.................................................................................................................................14 6.2 RobustnessofPlantEquipment..................................................................................................22 6.2.1 PlantAccessDoors-EvaluationofPotentialWaterIntrusion...........................................22 6.2.2 PlantAccessDoors-StructuralEvaluationforLIPLoads...................................................23 6.3 OperatorActionsOutsideofthePlantStructures......................................................................24 6.4 FLEXPortableEquipmentStorage..............................................................................................24 6.5 DeploymentofPortableEquipment...........................................................................................24 6.5.1 DeploymentofPortableDieselPump(PDP).......................................................................25 6.5.2 Deploymentof120VACPortableGenerator......................................................................28 6.5.3 Deploymentof480VACPortableDieselGenerator...........................................................31 6.5.4 DebrisRemoval...................................................................................................................33 6.5.5 OperationofPortableEquipment......................................................................................34 6.6 ConclusionsandSummary..........................................................................................................34 7.
References..........................................................................................................................................35
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Page3of36 List of Acronyms, Abbreviations, and Definitions Acronyms AC-AlternatingCurrent BDB-BeyondDesignBasis CDB-CurrentDesignBasis cfs-cubicfeetpersecond DC-DirectCurrent EDG-EmergencyDieselGenerator EFT-EmergencyFiltrationTrain ELAP-ExtendedLossofallACPower EOP-EmergencyOperatingProcedure ERO-EmergencyResponseOrganization FHRR-FloodHazardReevaluationReport FLEXDB-FLEXDesignBasis(floodhazard)
HCVS-HardendedContainmentVentSystem HMR-HydroMetrologicalReport LIP-LocalIntensePrecipitation LUHS-LossofUltimateHeatSink MNGP-MonticelloNuclearGeneratingPlant MSA-MitigatingStrategiesFloodHazardAssessment MSFHI-MitigatingStrategiesFloodHazardInformation(fromtheFHRRandMSFHIletter)
NB-notbounded NGVD29NationalGeodeticVerticalDatumof1929 NEI-NuclearEnergyInstitute NRC-NuclearRegulatoryCommission NSPM-NorthernStatesPowerCompany,aMinnesotacorporation NSRC-NationalSAFERResponseCenter NTTF-NearTermTaskForce PAB-PlantAdministrationBuilding PDG-PortableDieselGenerator PDP-PortableDieselPump PMF-ProbableMaximumFlood psf-poundspersquarefoot RCIC-ReactorCoreIsolationCooling RHR-ResidualHeatRemoval RHRSW-RHRServiceWater RPV-ReactorPressureVessel SBO-StationBlackout SFP-SpentFuelPool SRV-SafetyReliefValve SSC-Structure,System,Component UHS-UltimateHeatSink USARUpdatedSafetyAnalysisReport VAC-VoltsAC VDC-VoltsDC WSE-WaterSurfaceElevation
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Page4of36 Definitions FLEXDesignBasisFloodHazard:thecontrollingfloodparametersusedtodeveloptheFLEXstrategies foraflood.
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- 1.
Executive Summary FLEXstrategiesweredevelopedtomitigateanextendedlossofallACpower(ELAP)andalossofnormal accesstotheultimateheatsinkresultingfrombeyonddesignbasesexternalevents;includingdesign bases flooding events. New flooding analyses were performed in support of developing the Flood Hazard Reevaluation Report (FHRR) for the Monticello Nuclear Generating Plant (MNGP). For all postulatedfloodingscenarios,excepttheLocal IntensePrecipitation(LIP),thenewfloodinganalyses wereboundedbytheplantdesignbasisflood.TheMitigatingStrategiesAssessment(MSA)evaluates FLEX strategies to ensure the strategies can successfully be implemented for the Local Intense Precipitationfloodingeventortodetermineifchangesarerequiredtothestrategies.Basedonthe evaluation herein, the FLEX strategies can be implemented without change for the Local Intense Precipitationevent.
- 2.
Background
2.1 Purpose OnMarch12,2012,theNRCissuedReference1torequestinformationassociatedwithNearTermTask Force(NTTF)Recommendation2.1forFlooding.OneoftheRequiredResponsesinReference1directed licensees to submit a Flood Hazard Reevaluation Report (FHRR). The NRC determined that the reevaluatedfloodhazardisbeyondthecurrentdesign/licensingbasisofoperatingplants.Reference2 wassubmittedinresponsetotherequestinReference1fortheMNGP.Subsequenttosubmittalofthe FHRR (Reference 2), the MNGP performed additional more refined flooding analysis for the LIP (Reference9).Reference9usessitespecificprecipitationinputsinlieuoftheapplicableHMRmethods fordeterminingprecipitationinputs,andincludesanunsteadyflowapproachtorefinetheevaluationof theimpactsofwateroutsideofvariousplantdoors.
Concurrent to the flood hazard reevaluation, the MNGP developed and implemented mitigating strategiesinaccordancewithNEI1206,DiverseandFlexibleCopingStrategies(FLEX)Implementation Guide,(earlierrevisionofReference4).
In Reference 3, the Commission affirmed that licensees need to address the reevaluated flooding hazardswithintheirmitigatingstrategiesforbeyonddesignbasis(BDB)externalevents,includingthe reevaluatedfloodhazards.ThispositionwasconfirmedinReference5.
Guidanceforperformingmitigatingstrategiesfloodhazardassessments(MSAs)isprovidedinAppendix GofNEI1206(Reference4).ForthepurposeoftheMSA,theNRCdeterminedthatthefloodhazard information provided in the FHRR is the Mitigating Strategies Flood Hazard Information (MSFHI).
AppendixGofNEI1206,describestheMSAforfloodingascontainingthefollowingelements:
SectionG.2-CharacterizationoftheMSFHI SectionG.3-BasisforMitigatingStrategiesAssessment(MSFHIFLEXDBComparison)
SectionG.4.1-AssessmentofCurrentFLEXStrategies(ifnecessary)
SectionG.4.2-AssessmentforModifyingFLEXStrategies(ifnecessary)
SectionG.4.3-AssessmentofAlternativeMitigatingStrategies(ifnecessary)
SectionG.4.4-AssessmentofTargetedHazardMitigatingStrategies(ifnecessary)
IfaSectionG.3assessmentshowsthattheFLEXDesignBasisfloodhazard(FLEXDB)completelybounds the reevaluated flood (in the MSFHI), only documentation for Sections G.2 and G.3 are required; assessmentsanddocumentationfortheremainingsections(G.4.1throughG.4.4)arenotnecessary.Ifa
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Page6of36 SectionG.3assessmentshowsthattheFLEXDBdoesnotcompletelyboundtheMSFHI,thenSections G.4.1throughG.4.4needtobeperformed.SectionsG.4.1throughG.4.4areperformedsequentially untilanacceptableresultisreceived.Forexample,iftheevaluationforSectionG.4.1demonstratesthat theexistingFLEXstrategiescanbeimplementedasdesigned,thentheMSAisconsideredcompleteand theresultsdocumented.
2.2 Site Description The site is located within the city limits of the Monticello, Minnesota, on the right bank of the MississippiRiver.Theplantsiteoccupiesanareaofapproximately2,150acres.Thetopographyofthe MNGPsiteischaracterizedbyrelativelylevelbluffs,whichrisesharplyabovetheriver.Threedistinct bluffsexistattheplantsiteatelevations920,930,and940ft.Bluffslocatedapproximatelyamilenorth andsouthofthesiteriseto950ft.Furthertothenorth,theterrainisrelativelylevelwithnumerous lakesandwoodedareas.Tothesouth,west,andeast,theterrainishillyanddottedwithnumerous smalllakes(Reference6).
TheMississippiRiverabutsthesitetothenorthandnorthwest.TheflowintheMississippiRiverinthe vicinityoftheplantisunregulatedandsubjecttolargevariationsthroughouttheyear.Normalriver levelisatelevation905ftandthemaximumriverfloodstagewasrecordedin1965atelevation916ft.
The1,000yearprojectedriverfloodstageisatelevation921ft(Reference6).
Thenaturalgradeofthepowerblockisatelevation930ftwithelevationsofthemajorityofcritical structureopeningsrangingfrom931ftto935ft.ThefloorelevationoftheIntakeStructureandScreen Houseisat919ft(Reference10).
ElevationsusedinthisevaluationareintheNGVD29datum.
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- 3.
Overview of FLEX Strategies FLEXcapabilityisdesignedtomitigatetheconsequencesofapostulatedbeyonddesignbasisexternal event coincident with an extended loss of all AC power (ELAP) and a loss of normal access to the ultimate heat sink. NEI 1206 (Reference 4) outlines an approach for adding diverse and flexible mitigationstrategiesorFLEXthatwillincreasedefenseindepthforbeyonddesignbasisscenariosto addressanELAPandlossofnormalaccesstotheultimateheatsink(LUHS)occurringsimultaneouslyat allunitsonasite.
PlantcopingcapabilityduringaFLEXscenarioisdividedintothreephases:
Phase1(shorttermphase)-DuringPhase1,theplantiscopingusinginstalledplantequipment.
Phase2(transitionphase)-DuringPhase2,copingisextendedusingportableequipmentthatis storedonsite.
Phase 3 (long term phase) - During Phase 3, coping is extended indefinitely using portable equipmentthatisstoredoffsiteandisdeployedtothesite.
Timedurationsfortheshorttermandtransitionphasearedefinedbasedonplantspecificorgeneric analyses,capabilitiesoftheportableonsiteequipment,andcapabilitiesforaccessingthesitetodeploy offsiteportableequipmentfollowingabeyonddesignbasesexternalevent.
FLEXstrategiesweredesignedandpreviouslyevaluatedforthedesignbasesfloodexternalevent(i.e.,
FLEXDB),whichfortheMNGPistheprobablemaximumflood(PMF)ontheMississippiRiver.ThePMF is a relatively slow developing event that provide several days to prepare for the event. The FLEX strategyforthePMFistoproactivelystageselectedFLEXequipmentwithinthefloodprotectedarea beforethedesignbasisfloodlevelisreached.
FortheLIP,thissamewarningtimedoesnotexist.TheassessmentofFLEXstrategyimplementationfor theLIPneedstoaccountforthelackofwarningtime.ForevaluationofthepotentialimpactfromaLIP totheFLEXstrategiesitisusefultounderstandthetimelineforimplementationofthestrategies.For theLIP,similartootherexternalevents,itisassumedthattheELAPoccursattime=0.Asshownin Table 6.11 this time period also corresponds with the highest rainfall period; which would be reasonablethatthelossofoffsitepoweroccursduringthemostseveretimeoftheevent.Inaddition, as the LIP event is a 6 hour6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> event, assuming that the ELAP occurs at time = 0 places the maximum subsequentFLEXstrategyimplementationtimecoincidentwiththeLIPevent.
ThetimelineforimplementationofFLEXstrategiesisshowninTable31.(Reference7)
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Page8of36 Table31-TimelineforImplementationofFLEXStrategies Action Item Elapsed Time Action ELAP EventTime Constraint (Y/N)
Remarks/Applicability
0 BeyondDesignBasis ExternalEventHappens NA Plant@100%power.
1 PerC.4 B.09.02.A, Station Blackout ImmediateOperator Actions NA VerifyHPCIandRCICstartat47 inches.Dispatchoperatorto investigateEmergencyDiesel Generator.
2 1hr EmergencyClassification SG1.1DeclareELAP Y
Inordertoensurethatfollowon actionsarecompletedconsistent withthetimelinesidentified,a timelydecisionmustbemade thattheStationBlackout(SBO) conditionisanExtendedLossof ACPower(ELAP).
3 2hr DCloadshedcomplete Y
Thisisanecessaryactionto ensuresafetyrelatedbattery powercanbeextendedthrough Phase1.
4 PerC.4 B.09.02.A, Station Blackout DepressurizeReactor usingSRVstoarange thatwillsupport continuedoperationof RCIC N
Reactordepressurizationwillbe securedinarangethatwillenable continuedRCICoperation 5
6hr Offsitestaffing resourcesbegintoarrive.
NA NAbecausenotatimeconstraint; includedforreference.
6 68hours LargeDebrisRemoval N
Willbeperformedbyaugmented personnel.
7 PerC.5
- 1200, Primary Containment Control InitiateuseofHardened ContainmentVent System Y
TheHardenedContainmentVent System(HCVS)mustbeopened pertheEOPs.Theventis poweredbyavailablebatteryand suppliedwithNitrogenfromthe AlternateNitrogenSystem.
8 8hr Foremergencyheatload, providemakeuptoSFP Y
ProvidemakeuptotheSFPusing portableFLEXpump.
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Page9of36 Table31-TimelineforImplementationofFLEXStrategies Action Item Elapsed Time Action ELAP EventTime Constraint (Y/N)
Remarks/Applicability 9
After8but before9.4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> SupplementAlternate Nitrogen Y
Provideadditionalnitrogensupply totheAlternateNitrogenSystem tosupportcontinuedSRVand HardenedContainmentVent Systemoperation.
10 810hr Portabledieseldriven FLEXpumpstagedfor use N
TheFLEXPortableDieselPump (PDP)willbestagedafterhour8 andbeforeendofhour10.
OperationofPDPisnotneeded untilstartofhour11.
11 After10hr ProvideBatteryRoom ventilation Y
Necessaryforcontinued qualificationandoperationof batteriesandequipment.Portable FLEXfanswillbeavailableand poweredbytheFLEX120VAC generatorandwillprovide cooling.
12 After10hr ProvideRCICroom cooling N
Necessaryforcontinued qualificationandoperationof RCICequipment.PortableFLEX fanswillbeavailableandpowered bytheFLEX120VACgenerator andwillprovidecooling.
13 After10hr ProvideMainControl Roomcooling N
NecessaryforcontinuedMain ControlRoomhabitability.
PortableFLEXfanswillbe availableandpoweredbythe FLEX120VACgeneratorandwill providecooling.
14 11hror before Batteriesarebeing repoweredusing portableFLEX480VAC DieselGenerator Y
NecessaryforcontinuedDC power.
15 After22hrs Refuelportable equipment Y
Phase2portableequipmentwill requirerefuelingnoearlierthan 22hrs.
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Page10of36 Table31-TimelineforImplementationofFLEXStrategies Action Item Elapsed Time Action ELAP EventTime Constraint (Y/N)
Remarks/Applicability 16 2572hrs Supplementonsite equipmentwith equipmentfromthe NationalSAFERResponse Center(NSRC)
Y TheNationalSAFERResponse Center(NSRC)equipmentwill provideareliablebackuptothe onsiteportableequipmentfor extendedoperation.Itwillrestore powertoa4160VACbusand restorewatermakeupfromthe UHSperthedirectionofthefully staffedERO.
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- 4.
Characterization of the MSFHI (NEI 1206, Revision 2, Appendix G, Section G.2)
TheNRChascompletedtheInterimStaffResponsetoReevaluatedFloodHazards(Reference8)tothe floodhazardsinformationsubmittedintheMNGPFHRR.TheNRCstaffhasconcludedthatthelicensee's reevaluatedfloodhazardinformationissuitablefortheassessmentofmitigatingstrategiesdevelopedin responsetoOrderEA12049.Thesummaryofthereevaluatedfloodhazard(i.e.,MSFHI)parameters wasprovidedinReference8.Thefollowingfloodcausingmechanismswereconsideredaspartofthe FHRR:
LocalIntensePrecipitation StreamsandRivers FailureofDamsandOnsiteWaterControl/StorageStructures StormSurge Seiche Tsunami IceInducedFlooding ChannelMigrations/Diversions Table2intheEnclosuretoReference8indicatesthatthefollowingarethefloodhazardsforuseinthe MSA.
Mechanism StillwaterElevation Waves/Runup ReevaluatedFlood Hazard LocalIntense Precipitation 935.8ftNGVD29 Minimal 935.8ftNGVD29
Note1toTable2intheEnclosuretoReference8statesthat:thelicenseeisexpectedtodevelopflood eventdurationparametersandapplicablefloodassociatedeffectstoconducttheMSA.Thestaffwill evaluatethefloodeventdurationparameters(includingwarningtimeandperiodofinundation)and floodassociatedeffectsduringitsreviewoftheMSA.
Subsequent to submittal of the FHRR (Reference 2), the MNGP performed additional more refined floodinganalysisfortheLIP(Reference9).Reference9usessitespecificprecipitationinputsinlieuof the applicable HMR methods for determining precipitation inputs, and includes an unsteady flow approach to better quantify the impacts of water outside of various plant doors. The results from Reference9areconsistentwiththefloodhazardsinTable2intheEnclosuretoReference8.
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- 5.
Basis for Mitigating Strategies Assessment (NEI 1206, Revision 2, Appendix G, Section G.3)
FLEXstrategiesweredevelopedtomitigateanextendedlossofallACpowerresultingfromanexternal event; including design bases flooding events. As described in the FHRR (Reference 2), Section 3, Comparison of Current Design Basis and Reevaluated Flood Hazard, the only nonbounded flood mechanismistheLIP.TheLIPisconsiderednonboundedbecauseitisnotincludedintheMNGPCDB.
As described above, subsequent to submittal of the FHRR (Reference 2), the MNGP performed additional more refined flooding analysis for the LIP (Reference 9). Reference 9 uses site specific precipitation inputs in lieu of the applicable HMR methods for determining precipitation inputs, and includesanunsteadyflowapproachtobetterquantifytheimpactsofwateroutsideofvariousplant doors.Table51summarizestheresultsofthefloodhazardreevaluationfortherevisedLIPcalculation (Reference9).Withtheexceptionofthechangeinmethodologyfordeterminingprecipitationinputs andtheuseofanunsteadyflowapproach,allassumptions,inputs,andmethodsarethesameasthose describedinSection2.1ofReference2.
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Page13of36 Table51-LocalIntensePrecipitation FloodScenarioParameter Plant Design Basis Flood FLEXDB Flood Hazard MSFHI MSFHIBounded (B)orNot Bounded(NB) byFLEXDB FloodLeveland AssociatedEffects
- 1. MaximumStillwaterElevation(ftNGVD29)
LIPwasnotspecificallyaddressedintheUSAR.
FLEXstrategiesdidnotincludeLIPasitisnotwithin theMNGPdesignbasis 935.72 NB
- 2. MaximumWaveRunupElevation(ftNGVD29)
SeeNote2 N/A
- 3. MaximumHydrodynamic/DebrisLoading(psf)
SeeNote3 N/A
- 4. EffectsofSedimentDeposition/Erosion SeeNote4 N/A
- 5. ConcurrentSiteConditions SeeNote5 N/A
- 6. EffectsonGroundwater SeeNote6 N/A FloodEvent Duration
- 7. WarningTime(hours)
SeeNote7 N/A
- 8. PeriodofSitePreparation(hours)
SeeNote8 N/A
- 9. PeriodofInundation(hours)
SeeNote9 NB
- 10. PeriodofRecession(hours)
SeeNote10 NB Other
- 11. PlantModeofOperations SeeNote11 N/A
- 12. OtherFactors SeeNote12 N/A Additionalnotes,N/Ajustifications(whyaparticularparameterisjudgednottoaffectthesite),andexplanationsregarding thebounded/nonboundeddetermination.
- 1. None
- 2. ConsiderationofwindgeneratedwaveactionfortheLIPeventisnotexplicitlyrequiredinNUREG/CR7046,ANS2.8or the50.54(f)letter.Furthermore,waverunupisconsiderednegligibleduetolimitedflooddepthsandfetch.
- 3. Hydrodynamicloadingwasnotconsideredplausibleduetosurfacewaterflowdirectionisnottowardsthebuildings.
Debrisimpactloadingwasnotconsideredplausibleduetolimitedvelocitiesandflooddepths.
- 4. Duetolimitedvelocities,andshortdurationofflooding,sedimentdepositionanderosionisnotconsideredtohavean effectontheLIPfloodlevels.
- 5. High winds and hail could coincide with the LIP event. Section 6 evaluates performing actions to implement FLEX strategiesthatrequiregoingoutsidetheplant.Environmentalconditionswouldbeconsideredpriortopersonnelbeing directedtomovebetweenlocations.
- 6. DuetorelativelyshortdurationoftheLIPevent,surchargetogroundwaterisnotconsidered.
- 7. Warningtimeisnotcreditedinthefloodprotectionstrategy(sinceonlypermanent/passivemeasuresareusedfortheLIP flood)and,therefore,wasnotconsideredaspartoftheanalysis.
- 8. SSCsimportanttosafetyareprotectedbymeansofpermanent/passivemeasuresand,therefore,sitepreparationwas notconsideredaspartoftheanalysis.
- 9. Theperiodofinundationvariesthroughoutthesite;thetimethatthewatersurfaceelevationexceedstheheightof openingforplantaccessdoorsisprovidedinTable6.12.
- 10. Thetimeforwatertorecedefromthesitevariesbysitelocation.Oncethefloodwatersrecedebelowfinishedfloor elevationitwouldtakeapproximately2to4hoursforfloodwaterstocompletelyrecedefromareasneartheplantaccess doors.Figures6.11through6.13showwatersurfaceelevationsthroughoutthesiteat1hour,2hours,and4hours, respectively.
- 11. Therearenolimitationsonplantmodesofoperationpriorto,orduring,theLIPevent.
- 12. Therearenootherfactorsapplicabletothisfloodcausingmechanism.
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- 6.
Assessment of Current FLEX Strategy (NEI 1206, Revision 2, Appendix G, Section G.4.1)
TheassessmentoftheabilitytoimplementtheFLEXstrategiesduringaLIPfocusesonthefollowing:
RobustnessofPlantEquipment(Section6.2).
The robustness of plant equipment is evaluated to confirm that SSCs are capable of withstandingtheLIP.
Actionsperformedbyplantpersonnel(Section6.3).
Potentialimpactstotimingofoperatoractionsareevaluated.
FLEXPortableEquipmentStorage(Section6.4).
ThelocationoftheFLEXStorageBuildingsisevaluatedforpotentialimpactfromtheLIP.
DeploymentofPortableEquipment(Section6.5).
ThedeploymentofFLEXportableequipmentduringandfollowingtheLIPeventisevaluated.
ConsiderationsintheevaluationincludedeploymentoftheFLEXequipmentfromthestorage buildingtothestaginglocation;accesstoconnectionpoints,deploymentofcablesandhoses; andqualificationsoftheportableequipment.
6.1 LIP Timeline Section6.1identifiestheassumptionwithbasesforthetimingoftheELAPconcurrentwiththeLIPper Reference4,AppendixG.Inaddition,Section6.1describestheimpactsfromtheLIPthatwillbeused forevaluationoftheFLEXstrategies.
Asdescribedabove,FLEXstrategieswereinitiallydesignedforthedesignbasesfloodexternalevent, which for the MNGP is the probable maximum flood (PMF) on the Mississippi River. The PMF is a relatively slow developing event that provides several days to prepare for the event. For the LIP, warningtimeisnotcredited.Thus,theassessmentofFLEXstrategyimplementationfortheLIPneedsto accountforanabsenceofwarningtime.
The LIP event is not expected to cause an ELAP. For the LIP, similar to other external events, it is assumedthattheELAPoccursattime=0.AsshowninTable6.11thistimeperiodalsocorresponds withthetimeperiodofthehighestprecipitationrate.Itisreasonabletoassumethatthelossofoffsite poweroccursduringthemostseveretimeoftheLIPevent.Inaddition,astheLIPeventisa6hour event, assuming that the ELAP occurs at time = 0 places the maximum subsequent FLEX strategy implementationtimecoincidentwiththeLIPevent.
The updated LIP calculation for the MNGP is provided in Reference 9; which describes the inputs, assumptions,methodology,andresults.Thetimelinesforthecumulativeprecipitationandprecipitation rates during the LIP are shown in Table 6.11. The precipitation rate is determined by dividing the changeincumulativeprecipitationbythechangeintimeduration.
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Page15of36
Table6.11,PrecipitationCumulativePrecipitationandRates Time Duration Cumulative Precipitation(inches)
PrecipitationRate (inches/hour) 5min 4.5 54 15min 7.2 16.2 30min 10.2 12.0 1hr 13.2 6.0 6hr 20.6 1.5
Figures6.11,6.12,and6.13showwaterdepthsatvarioustimesduringtheLIPevent.Waterlevels showninFigures6.11through6.13areextractedfromtheReference9analysisresults.Figure6.11 showsthewaterdepthsat1hourintotheevent,Figure6.12showsthewaterdepthsat2hoursinto theevent,andFigure6.13showsthewaterdepthsat4hoursintotheevent.
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Page16of36 Figure6.11,WaterDepthsDuringLIPatOneHour
MonticelloMitigatingStrategiesFloodHazardAssessment Rev.0
Page17of36 Figure6.12,WaterDepthsDuringLIPatTwoHours
Flow_ Dept11_2Hr (ft)
L]o.o.25 L]o.2s-o.s L]o.s-o.1s Oo.75-
- c:::J 1.0 - 1.25 O
t.2s-t.s 1.5-1.75 1.75-2 2.0-2.25 2.25-2.5 2.5 - 2.75 2.75-3
- ~0-3.25 3.25 -J.S l.0-3.75 3.75 -4
- 25
- --2*-***
- *****.15
- . 75-5
- *. 0
MonticelloMitigatingStrategiesFloodHazardAssessment Rev.0
Page18of36 Figure6.13,WaterDepthsDuringLIPatFourHours
Flow_Depth_4Hr (ft) c:JM.2S c:Jo.2s-o5 c:Jo.s - o.7s c:Jo.75-1 c:JI.0-125 c:J 1,25-15 1.5-1.75 1.75-2 2.0 - 2.25 2.25 - 25 2.5 - 2.75 2.75-3 3.0 - 3.25 3.25-a 3.5-3.75 3.75-*
- . o.*.. 25
- . 25-4.5
- 5-4.75
- . 75 - 5
- 5.o
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Page19of36
Anadditionalconsiderationisthepotentialforwateringresstotheplantstructures.AsshowninTable 6.12,themaximumwatersurfaceelevationsaroundtheplantstructurescanbeupto1.00ftabovethe elevationforsomeoftheplantaccessdoorsillsorinverts.Table6.12includesthemaximumwater depthateachdoor,thedooropeningwidth,doorgaporifthedoorisassumedtobeopen,thepeak waterinflowrateandtotalinflowvolumeandtimedurationthatthewaterelevationexceedsthedoor opening.Themaximumwaterdepthsoccuratdifferenttimesallduringthefirsthouroftheevent.The locationsoftheplantaccessdoorsareshownonFigure6.14.
Table6.12WaterDepthatPlantAccessDoors OpeningLocation Opening Invert/SillLevel (ft)
Estimated Maximum WSE (ft)
Maximum WaterDepthat Opening Door Opening Width (ft)
Gapat Bottomof Door(in.)
(Note1)
PeakInflow Total Estimated Inflow Volume (ft3)
Total Estimated Inflow Time (min)
(ft)
(in.)
(cfs)
(gpm)
IntakeStructureDoor (Door209)-interior betweenScreenHouse andIntakeStructure 919.50 920.02 0.52 6.24 3
3/4 0.77 346 707 30 1/2 0.51 229 472 30 Open 3.23 1,450 1,520 30 WestRollUpDoor TurbineBldgAddition (Door119) 931.25 931.11 n/a n/a n/a n/a TurbineBuilding Door119Open (Notes2and3) n/a n/a EastRollUpDoor TurbineBldgAddition (Door120) 931.25 931.53 0.28 3.36 n/a n/a TurbineBuilding Door120Open (Notes2and3) n/a n/a TurbineBldgDoor(Door 30) 931.00 931.53 0.53 6.36 3
1 1.04 467 2,242 66 3/4 0.78 350 1,681 66 RailcarEntry-Turbine Bldg(Door24) 935.00 935.72 0.72 8.64 16 1
6.5 2,918 17,700 86 1/4 1.6 719 4,425 86 RailcarEntry-Reactor Bldg(Doors45and46) 935.00 935.23 0.23 2.76 17 1/8 0.48 216 617 36 1/16 0.24 108 309 36 EmergencyDiesel Generator-East (Door8) 931.00 931.11 0.11 1.32 3
1/4 0.12 54 33 7
EmergencyDiesel Generator-West (Door7) 931.00 931.11 0.11 1.32 3
1/4 0.12 54 33 7
PABStairwayDoor (AdjacenttoDoor341) 932.83 933.09 0.26 3.12 4
1/2 0.48 216 177 9
5/16 0.30 135 111 9
13.8KVRoom (Door1) 931.00 931.52 0.52 6.24 6
1/2 1.03 463 2,253 67 1/4 0.51 229 1,127 67 OffGasStack (Door193) 932.50 933.50 1.00 12.00 5
1/4 0.59 265 2,720 101 1/8 0.30 135 1,360 101 FuelOilTransferPump House (Door483) 931.00 931.11 0.11 1.32 2.5 1/4 0.10 45 28 7
1/8 0.05 23 14 7
Open 0.26 117 52 7
FlexBuilding#1 (FLEXStorageBldg)
EastRollUpDoor 920 919.81 0
0 n/a n/a Flex#1East RollUpDoor Open n/a n/a FlexBuilding#1 (FLEXStorageBldg)
WestRollUp/Man Door 920 920.04 0.04 0.48 n/a n/a Flex#1West RollUp/Man DoorOpen n/a n/a
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Page20of36 Table6.12WaterDepthatPlantAccessDoors OpeningLocation Opening Invert/SillLevel (ft)
Estimated Maximum WSE (ft)
Maximum WaterDepthat Opening Door Opening Width (ft)
Gapat Bottomof Door(in.)
(Note1)
PeakInflow Total Estimated Inflow Volume (ft3)
Total Estimated Inflow Time (min)
(ft)
(in.)
(cfs)
(gpm)
FlexBuilding#2 (Warehouse#6)
NorthDoor 931.94 932.56 0.62 7.44 n/a n/a Flex#2North DoorOpen n/a n/a FlexBuilding#2 (Warehouse#6)
CenterDoor 931.71 932.56 0.85 10.20 n/a n/a Flex#2Center DoorOpen n/a n/a FlexBuilding#2 (Warehouse#6)
SouthDoor 931.71 932.56 0.85 10.20 n/a n/a Flex#2South DoorOpen n/a n/a Notes:
- 1. Wheremorethanonegapforadoorisshown,thesmallergapisbasedonsitemeasurements.Thelargergapisanassumedvaluethatisconservativerelative tothemeasuredgap.
- 2. Doors119and120canbeopenorclosedandareassumedtobeopenforthisevaluation.
- 3. Doors119and120areexteriordoorsfromtheoutsidetotheTurbineBuildingAddition.Door30isbetweentheTurbineBuildingAdditionandtheTurbine Building.Door30iscreditedwithprecludingwateringressinlieuofDoors119and120.
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Page21of36 Figure6.14,PlantAccessDoorLocations
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Page22of36 6.2 Robustness of Plant Equipment Section 6.2 evaluates the robustness of plant equipment per Reference 4, Appendix G, in order to demonstratethattheexistingFLEXstrategiescanbeimplementedfortheLIP.
TheMNGPislicensedforaPMFfromtheMississippiRiverwithafloodwaterelevationupto939.2ft (USARReference6).Proceduralactionsareimplementedbasedonriverwaterelevationprojectionsto provide flood protection for a PMF. Flood preparation measures for a PMF are implemented per proceduresA.6and830002(References10and11,respectively).Specificmeasuresaretakenaspartof References10and11forpreparationforafloodfromtheMississippiRiver.Theseprotectivemeasures includeconstructionofaleveeandbinwallextensionsaroundthepowerblockandsealingpenetrations intheIntakeStructureinordertokeepwateroutoftheplant.Implementationofthesepreparation measures can take several days. Based on the time duration of the PMF there is sufficient time to implementtheprotectivemeasures.
For a LIP event the levee and bin wall extensions would not be constructed due to an absence of warningtimeandbecause,ifconstructed,theleveeandbinwallextensionscouldexacerbatetheLIP eventbyprecludingwaterdrainagefromthesite.WiththeexceptionofDoor209,penetrationsinthe Intake Structure will not see water during the LIP. During the LIP flood, the predicted water levels exceedthresholdelevationsofseveralpathwaysasthedoorsarenotprotected.
TheevaluationoftherobustnessofplantfloodprotectionfeaturesduringaLIPconsiders(1)theimpact ofwaterintrusionatdoorsthatwouldnotbeprotected,and(2)thestructuralimpactsofthehydraulic loadstodoorsthatwouldnotbeprotected.
6.2.1 Plant Access Doors - Evaluation of Potential Water Intrusion AsshowninTable6.12,theLIPfloodlevelsexceedtheelevationofseveraldoorsill/inverts.Theimpact ofinleakagebythedoorsinTable6.12isassessedbyconsideringthelocationintheplantstructures wherethewatercouldaccumulate.
EDGBuilding Thepeakwaterelevationoutsidethedoorsis931.11orapproximately1.3inches.Theequipmentinthe EDG Building can tolerate a water depth up to 16 inches. In addition, there are 9 in. curbs which separatethetwoEDGroomsfromeachotherandseparatetheEDGBuildingfromtheTurbineBuilding.
At a water level of 9 in. in the EDG Building, the water would overtop the curbs and flow into the TurbineBuilding.Therefore,evenifitisassumedthatthewaterlevelintheEDGBuildingequalizedwith thewaterleveloutsidethedoors,SSCsimportanttosafetyintheEDGBuildingwouldnotbeadversely affectedbytheLIP.
TurbineBuilding LeakagepastDoors1,24,30,and209couldaccumulateintheTurbineBuilding.LeakagepastDoor1 can accumulate in either the Turbine Building or the PAB Basement, thus, it is included in the determination of total water accumulation in both structures. The available volume in the Turbine Buildingtoaccommodateinleakageis140,874ft3.TurbineBuildingAdditionDoors119and120can eitherbeopenorclosed,thus,Doors119and120arenotcreditedwithprecludingwateringress.Door 30iscreditedinlieuofDoors119and120.UsingtheconservativedoorgapsizesforDoors1,24,30, and209(assumingthatDoor209isopen)thetotalwatervolumethatcouldaccumulateintheTurbine
MonticelloMitigatingStrategiesFloodHazardAssessment Rev.0
Page23of36 Buildingis2,253+17,700+2,242+1,520=23,715ft3.Thus,SSCsimportanttosafetyintheTurbine BuildingwillnotbeadverselyaffectedbytheLIP.
PABBasement LeakagepastthePABStairwayDoorandDoor1,couldaccumulateinthePABBasement.Theavailable volumeinthePABBasementtoaccommodateinleakageis3,047ft3.Itisnotedthatthevolumeof 3,047 ft3 is based on a conservative water height of 4 inches as compared to a limiting component heightof4.75inches.UsingtheconservativedoorgapsizesforthePABStairwayDoorandDoor1the totalwatervolumethatcouldaccumulateinthePABBasementis177+2,253=2,430ft3.Iftherealistic doorgapsizeisusedforDoor1,thetotalwatervolumethatcouldaccumulateinthePABBasementis 177+1,127=1,304ft3.Thisismuchlessthantheacceptancecriteriaof3,047ft3.Thus,SSCsimportant tosafetyinthePABwillnotbeadverselyaffectedbytheLIP.2,430ft3ofwaterinthePABBasementis equivalentto3.2inchesofwaterdepth.
FuelOilPumpHouse TheavailablevolumeintheFuelOilPumpHousetoaccommodateinleakagepastDoor483is80ft3.
Usingaconservativedoorgapwiththedoorclosedtheinleakageis28ft3.Furthermore,conservatively assumingthatDoor483isopenthetotalwatervolumethatcouldaccumulateinthepumphouseis52 ft3.Thus,SSCsimportanttosafetyintheFuelOilPumpHousewillnotbeadverselyaffectedbytheLIP.
ReactorBuilding LeakagepastDoors45/46and193couldaccumulateintheReactorBuilding.Theavailablevolumeof theReactorBuildingtoaccommodateinleakageis6,713ft3.Usingtheconservativedoorgapsizefor Door45/46andDoor193thetotalwatervolumethatcouldaccumulateintheReactorBuildingis617+
2,720=3,337ft3.Thisismuchlessthantheallowablevolumeof6,713ft3.Thus,SSCsimportantto safetyintheReactorBuildingwouldnotbeadverselyaffectedbytheLIP.
IntakeStructure LeakagebyDoor209wouldaccumulateintheTurbineBuilding,andisaddressedinthediscussionfor theTurbineBuilding,above.
OffGasStack LeakagebyDoor193intotheOffGasStackwouldaccumulateintheReactorBuilding.Thisisincludedin theabovediscussionoftheReactorBuilding.TherearenoSSCsimportanttosafetyintheOffGasStack thatcouldbeaffectedbywateraccumulationduringtheLIP.
6.2.2 Plant Access Doors - Structural Evaluation for LIP Loads ConsiderationwasalsogiventohydrodynamicanddebrisimpactsduringtheLIPevent.Themaximum floodlevelpredictedduringtheLIPeventis935.72ft.TheLIPeventdoesnotincludeanydebrisimpact oranyappreciablehydrodynamiceffectsduetothedirectionofallflowbeingawayfromthebuilding.
As described above, there are several doors that will be subjected to water loading without flood protection. Reference 12 performed a structural evaluation comparing existing allowable pressure, differentialpressure,orcapacityqualificationsforeachdoorwiththeresultantLIPloading.Theresults of the evaluation indicate that the existing allowable pressure, differential pressure, or capacity qualificationsboundtheresultantLIPloading.
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Page24of36 6.3 Operator Actions Outside of the Plant Structures Section6.3evaluatesperformingoperatoractionsoutsideofplantstructuresduringtheLIP.Following unittrip,anoperatorgoestotheGasHousetosupportthepurgeofhydrogeninthemaingenerator.
AccessingthegashouserequiresashorttransitoutsidetheTurbineBuilding;neartheTurbineBuilding RailwayDoor24.ThisistheonlyoperatoractionoutsideofplantstructuresduringtheLIP.
TheMNGPFLEXValidationdocument(Reference13)indicatesthatthereisa5hourtimeconstraintfor performingthisaction.Theabilitytopurgethemaingeneratorwithinthetimeconstraintwasvalidated inReference13,ValidationPlanNo.1009;whichshowedthattheactioncouldbecompletedwithin14 minutes.Thevalidationplanassumedthattheactionsdidnotstartuntilafterthefirsthour.
Precipitation rates as a function of time are shown in Table 6.11, above. During the first hour the precipitationratesareveryhighandmaymakeitdifficultfortheoperatortogobetweentheTurbine BuildingandtheGasHouse.Afterthefirsthour,theprecipitationratehasdecreasedto1.5inchesper hourandtheoperatorcanmakethetransittoperformtheactionsintheGasHouse.Table6.12shows thatthepeakwatersurfaceelevationnearDoor24is8.6inchesandthewaterelevationisabovethe doorelevationfor86minutes.Afterthattime,thewaterhasrecededfromthisareaandisnolonger abovethedoorsill.Thus,waterelevationsduringtheLIPwillnotprecludetheoperatorfrombeingable tomakethetransittotheGasHousetoperformtheactions.
Assumingtheoperatordoesnotstarttheactionsuntilafterthewaterhasrecededfromthevicinityof Door24isconsistentwiththevalidationplanassumption.Usingthevalidatedtimeof14minutesto perform the actions, there is more than sufficient time to complete the actions to purge the main generatorwithinthe5hourtimeconstraint.
6.4 FLEX Portable Equipment Storage Section6.4evaluatesthestorageofFLEXportableequipmentperReference4,AppendixG,inorderto demonstratethattheexistingFLEXstrategiescanbeimplementedfortheLIP.
Twostoragebuildingsareprovided;Warehouse#6andtheFLEXStorageBuilding;shownonFigures6.5 1through6.53.OnecompletesetofportableequipmentisstoredineachFLEXstoragebuilding.The portableequipmenttobedeployedandthedeploymentstrategyaredeterminedduringtheinitialtime of the event using procedure C.54101, FLEX Site Assessment (Reference 14). The LIP calculation determines the peak water level that could be reached inside Warehouse #6 and the FLEX Storage Buildingassumingthattheexteriordoorsareopen.ThepeakwaterlevelinsideWarehouse#6is10.2 in.andinsidetheFLEXStorageBuildingis0.48in.ThesewaterlevelswillnotadverselyaffecttheFLEX portable equipment in the storage buildings, the associated equipment such as hoses, or the deploymentvehicle.Thus,fortheLIP,bothsetsofFLEXportableequipmentwillbeavailableproviding redundancyandflexibility.
6.5 Deployment of Portable Equipment Section 6.5 evaluates FLEX equipment deployment, including validation performed of deployment activities,perReference4,AppendixG,inordertodemonstratethattheexistingFLEXstrategiescanbe implementedfortheLIP.
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Page25of36 Table 31, above, identifies the time critical actions that need to be completed for successful implementationoftheFLEXstrategies.Actionsthatrequiredeploymentofportableequipmentandthe associatedtimingare:
StagethedieseldrivenFLEXpumpforusewithin810hours.ThisisforReactorPressureVessel (RPV)makeupandSFPmakeup(nonemergencycase).ProvidemakeuptoSpentFuelPool(SFP) within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> for the case where the reactor fuel assemblies are offloaded into the SFP; referredtoastheemergencyheatloadcase.
Provide Battery Room, RCIC Room and Main Control Room cooling within 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> using portablefanspoweredfromportableFLEX120VACgenerators.
RepowerBatteryChargerswithin11hoursusingportableFLEX480VACgenerators.
Eachoftheseisdescribedinmoredetailbelow.EquipmentdeploymentlocationsareshownonFigures 6.51,6.52and6.53.
Refueling of portable equipment is not included as part of this evaluation. As shown in Table 31, refuelingofportableequipmentisrequirednoearlierthan22hours;whichiswellaftertheLIPeventis over.
6.5.1 Deployment of Portable Diesel Pump (PDP)
6.5.1.1 Function Thefunctionoftheportabledieselpump(PDP)istoprovidemakeuptotheReactorPressureVessel (RPV)andtheSpentFuelPool(SFP).AsshowninTable31,forprovidingmakeuptotheRPVandthe SFP,thePDPisstagedafterhour8andbeforetheendofhour10aftereventinitiation.Forthecase duringanoutagewherethefuelhasbeenremovedfromtheRPVandplacedintheSFP(emergencyheat loadcase)itmaybenecessarytoprovidemakeuptotheSFPwithin8.3hours;i.e.,minimumtimefor theliquidintheSFPtostarttoboil(Reference7).TheLIPeventisoverbythistimeandasshownon Figures6.51,thewaterlevelshaverecededandwillnotaffectPDPdeploymentoroperation.
6.5.1.2 PumpStagingandHoseRoutingLocation ProcedureC.54201(Reference15)showspossiblePDPstaginglocationsandhoserouting.Onlyone PDPisdeployed.ThesuctionforthePDPcanbetakenfromtheIntakeortheDischargeCanal.ThePDP staging location depends on the selected suction source. Figure 6.51 shows potential PDP staging locationsanddeploymentroutessixhoursintotheLIPevent.Themajorityofthedeploymentroutes arerelativelydrywiththeexceptionofthesouthsideoftheWarehouse#6.Adjacenttothesouthside ofWarehouse#6isaswalewithdeeperwater.AsshownonFigure6.51southoftheswale,thewater depthislessthan9inchesandwillnotprecludedeployment.
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Page26of36 Figure6.51PDPDeploymentRoutesandStagingLocations (waterelevationsshownareat4hours)
Flow_Depth_4Hr (ft) c:Jo.o.25 c:Jo25-0.5 c:Jo.5-o7s c:Jo.75-*
01.0-125 1.25-1.5 1.5-1.75 1.75-2 2.0-2.25 2.25-2.5 2.5-2.75 2.75-3 3.0-3.25 3.25-3.5 3.5-3.75 3.75-*
- .o-*.25 425-*.s
- .5-4.75
- . 75-5
- 5 o
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Page27of36
6.5.1.3 ConnectionLocations ThePDPcanbeconnectedtooneofthefollowinglocationstoprovidemakeuptotheRPVandSFP:
- 1. RHRSW68viaTurbineBuildingNorthRoute
- 2. FireSystemat12CoolingTower
- 3. ARHRDischargePipe
- 4. RHRSW68viaPABSouthRoute
TheRHRSW68connectionisatthe931ftlevelintheTurbineBuilding.Thisconnectionpointisabove theaccumulatedwaterelevationintheTurbineBuilding.Thus,theLIPwillnotaffectaccesstothis connectionpoint.
TheFireSystemconnectionat12CoolingTowerislocatedoutside.AsshowninSection6.1,theLIPis essentiallyoverafter6hoursandthewatershavereceded.ThePDPisdeployedaftersixhoursandthis connectionpointshouldbeavailable.
The connection to the A RHR Discharge Pipe is at the 896 ft elevation in the Reactor Building. As discussedinSection6.2.1,above,watervolumethatcouldaccumulateintheReactorBuildingisasmall fractionoftheavailablevolume.Thus,thisconnectionpointwillnotbeaffectedbytheaccumulated watervolumeintheReactorBuilding.Thus,theLIPwillnotaffectaccesstothisconnectionpoint.
6.5.1.4 TimeValidation MNGPvalidatedtheabilitytodeployandstagethePDPwithinthetimeconstraintsinReference13, ValidationPlanNo.1006.Thevalidationplanassumedastarttimeof8hoursandshowedthatthePDP canbestagedwithintheavailabletimeconstraint.The8hoursisbasedonanassumedarrivaltimefor supplementalpersonnelat6hoursandincludes2hoursfordebrisremoval.FortheLIPevent,debris removalisexpectedtobeminimalanddeploymentshouldbeabletostartearlierthan8hours.The validationalsousedthemostlimitingstaginglocationandhoseroutingoptions.The8hourassumed starttimeisaftertheLIPeventisoverandwaterhasrecededfromthedeploymentpaths.Thus,theLIP willnotaffectthetimevalidationfordeployingthePDP.
FortheSFPemergencyheatloadcase,itmaybenecessarytoprovidemakeuptotheSFPwithin8.3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />;i.e.,minimumtimefortheliquidintheSFPtostarttoboil.Thisconfigurationcouldexistduring an outage. During this condition there are additional supplemental personnel already at the site to supporttheoutage.Usingavailablepersonnel,thedeploymentandstagingwouldoccurmuchsooner than8hours,butwellafterthemostseveretimeperiodsfortheLIP.Inaddition,makeupwouldonly needtobeprovidedtotheSFPinlieuofboththeRPVandtheSFP,whichsimplifiesdeploymentand operation.Basedontheseconsiderations,theLIPwillnotaffecttheabilitytoprovidemakeuptothe SFPwithinthetimeconstraint.
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Page28of36
6.5.2 Deployment of 120 VAC Portable Generator
6.5.2.1 Function Thefunctionofthe120VACportablegeneratoristopowerportablefanstoprovideforcedventilation fortheBatteryRoom,RCICRoomandMainControlRoom.AsshowninTable31,thefansareoperating toprovideforcedventilationfortheseareasbeforetheendofhour10aftereventinitiation.TheLIP eventisoverbythistimeandasshownonFigure6.52,thewaterlevelshaverecededandwillnot affectdeploymentoroperationofthe120VACportablegenerator.
6.5.2.2 GeneratorStagingandCableRoutingLocation ProcedureC.54406(Reference16)showspossiblestaginglocationsforthe120VACportablegenerator.
One 120 VAC portable generator is deployed. Figure 6.52 shows potential staging locations and deploymentroutesforthe120VACportablegeneratorsixhoursintotheLIPevent.Themajorityofthe deployment routes are relatively dry with the exception of the south side of the Warehouse #6.
AdjacenttothesouthsideofWarehouse#6isaswalewithdeeperwater.AsshownonFigure6.52 southoftheswale,thewaterdepthislessthan9inchesandwillnotprecludedeployment.
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Page29of36 Figure6.52120VACGeneratorDeploymentRoutesandStagingLocations (waterelevationsshownareat4hours)
N E
w s
Flow_Oepth_4Hr (ft) o~2*
c:Jo25-0.5 c:Jo.s-0.75 c:Jo.75-1 CJ1.D-1.25 1.25 - 1.5 1.5-1.75 175-2 2.0-2.25 2.25-2.5 25-2.75 2.75 * )
- .*. 3.25 3.25-3.$
3.5-3.75 3.75-*
- -o-*.25
- 25-*.5
- **. 7 *...
- 50
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Page30of36
6.5.2.3 ConnectionLocations The 120 VAC Generator is used to provide power to portable fans to provide cooling for Battery Chargers,theRCICRoom,andtheMainControlRoom.
ToprovidecoolingtotheDivisionIBatteryChargers,aportablefanisplacedoutsidetheDivisionI250V BatteryRoomatelevation928ftinthePAB(Reference17).WaterthatentersthePABduringtheLIP accumulates at the 928 ft elevation. As discussed in Section 6.2.1, the water depth at the 928 ft elevationinthePABisapproximately3in.Aportablefancanbestagedabovethiselevationsuchit wouldnotbeaffectedbytheLIP.Itisnotedthattheplacementoftheportablefanisbasedonwhich batterycharger(s)ispowered-RefertoSection6.5.3.IfthebatterychargersintheEFTarepowered, thenthisfanisnotnecessary.
ToprovidecoolingtotheDivision2BatteryChargers,aportablefanisplacedoutsidetheDivisionII 250V Battery Room at elevation 932 ft in the EFT Building (Reference 18). This is above the LIP maximum surface elevation and water does not enter the EFT Building during a LIP. Therefore, operationofthisfanwillnotbeaffectedbytheLIP.
To provide cooling to the RCIC Room, the portable fan is placed at elevation 935 ft in the Reactor BuildingandflexibleductingisloweredtotheRCICRoom(Reference19).Thepowercordfromthe120 VACGeneratortotheportablefanisroutedthroughDoors45/46.AsshowninTable6.12,thewater level has receded below the elevation of Doors 45/46 within 36 minutes. This is well before the portablefan,ductwork,andpowercordwouldbestaged.Therefore,operationofthisfanwillnotbe affectedbytheLIP.
ToprovidecoolingtotheMainControlRoom,aportablefanisplacedoutsidethePABentranceand flexibleductworkisroutedtotheMainControlRoom(Reference17).TheelevationofthePABentrance isabovethemaximumwatersurfaceelevationfortheLIP.Therefore,operationofthisfanwillnotbe affectedbytheLIP.
6.5.2.4 TimeValidation MNGPvalidatedtheabilitytodeployandstagethe120VACGeneratorwithinthetimeconstraintsin Reference13,ValidationPlanNo.1008.Thevalidationshowedthatthetotaltimetoestablishcooling was36minutescomparedtoasuccesscriteriaof1hour.Thevalidationalsousedthemostlimiting staging location, fan placement, duct routing, and cable routing options. The ability to initiate the actionstodeploythe120VACGeneratorneedtoconsideranassumedarrivaltimeforsupplemental personnelat6hoursandtimefordebrisremoval;2hourshasbeenusedforotherFLEXscenariosfor debrisremoval.FortheLIPevent,debrisremovalisexpectedtobeminimalanddeploymentshouldbe abletostartearlierthan8hours.The8hourassumedstarttimeisaftertheLIPeventisoverandwater has receded from the deployment paths. With the conservative 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> start time, cooling will be establishedwithintheavailabletimeconstraint.Thus,theLIPwillnotaffectthetimevalidationfor deployingthePDP.
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Page31of36 6.5.3 Deployment of 480 VAC Portable Diesel Generator
6.5.3.1 Function The function of the 480 VAC Portable Diesel Generator (PDG) is to repower the Battery Chargers to chargetheBatteries.AsshowninTable31,theBatteryChargersareenergizednolaterthan11hours aftereventinitiation.TheLIPeventisoverbythistimeandasshownonFigure6.53,thewaterlevels haverecededandwillnotaffectdeploymentoroperationofthePDG.
6.5.3.2 GeneratorStagingandCableRoutingLocation Procedure (Reference 14) shows possible staging locations for the 480 VAC PDG. Only one PDG is deployed.Figure6.53showspotentialstaginglocationsanddeploymentroutesforthePDGsixhours intotheLIPevent.Themajorityofthedeploymentroutesarerelativelydrywiththeexceptionofthe southsideoftheWarehouse#6.AdjacenttothesouthsideofWarehouse#6isaswalewithdeeper water.AsshownonFigure6.53southoftheswale,thewaterdepthis9inchesorlessandwillnot precludedeployment.
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Page32of36 Figure6.53PDGDeploymentRoutesandStagingLocations (waterelevationsshownareat4hours)
Flow_Dopt~_4Hr (ft)
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- 2 2.0-225 2-25 -2.5 2.5-2.75 2.75-3
- 0-3.25 3.25 -3.5 3.5-3.75 3.75 - 4
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Page33of36 6.5.3.3 ConnectionLocations The PDG can be connected to one of the following locations to power battery chargers or other components(Reference20).
- 1. RepowerD52,Charger,D3A(13)andD54,SwingCharger,D3A,D3B(13)Battery
- 2. RepowerD10,125VDCChargerfor#11Battery
- 3. RepowerD70,Charger,D16B,andD90,ChargerSwingD6A
- 4. RepowerD20,125VDCChargerfor#12Battery
TheconnectionsforBatteryChargersD70andD90arelocatedintheDivisionII250VDCBatteryRoom; whichislocatedat932ftelevationintheEFTBuilding.WaterdoesnotentertheEFTBuildingduringa LIP.Thus,theLIPwillnotaffectmakingthisconnection.
TheconnectionsforBatteryChargersD52andD54arelocatedintheDivisionI250VDCBatteryRoom.
TheconnectionforBatteryChargerD10isintheDivisionI125VDCBatteryRoom.Theconnectionfor BatteryChargerD20isintheDivisionII125VDCBatteryRoom.Alloftheseconnectionsarelocatedat the928ftelevationinthePAB.WaterthatentersthePABduringtheLIPaccumulatesatthe928ft elevation. As discussed in Section 6.2.1, the water depth at the 928 ft elevation in the PAB is approximately3in.TheconnectionstotheBatteryChargersareabovetheaccumulatedwaterdepth.
Itisnotedthat,duetowateraccumulationatthePAB928ftelevationitmaybedesirabletomakethe connectionintheEFTwhichisunaffectedbytheLIP.
6.5.3.4 TimeValidation MNGPvalidatedtheabilitytodeployandstagethePDGwithinthetimeconstraintsinReference13, ValidationPlanNo.1005.Thevalidationplanassumedastarttimeof8hoursandshowedthatthePDG canbestagedwithintheavailabletimeconstraint;i.e.,atotaldeploymentoftimeof9hour35minutes compared to time constraint of 11 hours1.273148e-4 days <br />0.00306 hours <br />1.818783e-5 weeks <br />4.1855e-6 months <br />. The 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> is based on an assumed arrival time for supplementalpersonnelat6hoursandincludes2hoursfordebrisremoval.FortheLIPevent,debris removal is expected to be minimal and deployment should be able to start earlier than 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />.
Furthermore,the8hourassumedstarttimeisaftertheLIPeventisoverandwaterhasrecededfrom thedeploymentpaths.Thevalidationalsousedthemostlimitingstaginglocationandcablerouting options.Thus,theLIPwillnotaffectthetimevalidationfordeployingthePDG.
6.5.4 Debris Removal InsupportofimplementationofFLEXstrategies,debrisremovalisassessedinReference21.Fordebris removal,theplantmaintainsafrontendloaderandaFreightlinertruckwithaplow;oneisstoredat eachFLEXBuildinglocation.
Regardingtimingofdebrisremoval(foranyexternalevent),Reference21states:
Basedonthetypeofdebrisexpecteditisreasonabletoconsiderthatadeploymentpathcan beclearedwithintwohours.Minordebrissuchasbuildingmaterials,treelimbs,andfencing canberemovedwithina2hourperiodbyuseoftheFreightlinertruckwithchainsandplow alongoneofthemanydeploymentpathoptionsleadingtothemainsecurityentranceaswell.
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Page34of36 For the LIP event significant debris is not expected. The deployment paths from Warehouse #6 are paved and level; thus erosion is not expected. Portions of the deployment path the FLEX Storage BuildingtotheProtectedAreaarenotpavedandareasaresloped.Theseunpavedslopedareascould experienceerosionduetotheLIP.ThesepathswouldbeassessedaspartofReference14.Anydebris removalandminorerosionrepairduetotheLIParewellwithinthecapabilityofeitherthefrontend loaderortheFreightlinertruck.
6.5.5 Operation of Portable Equipment Theevaluationoftheoperationofportableequipmentconsiderstheequipmentqualificationsandthe conditions for the personnel operating the equipment. Per Sections 6.5.1 through 6.5.3, above, the portableequipmentisexpectedtobeavailableatapproximately10hours.PerTable6.11,at6hours, theLIPeventisessentiallyover.Theheaviestprecipitationhaspassed;however,therecouldbesome lingeringrelativelylightprecipitation.Intheeventthattheportableequipmentisstagedandavailable prior to 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />, then per Table 6.11, the precipitation rate is approximately 1.4 inches/hour. The equipmentandpersonnelsupportingtheequipmentareevaluatedbasedonthishigherprecipitation rate.
The procurement specifications (Reference 22) for the portable equipment include the following requirementfortheequipment:
Theengineandgeneratorshallalsobecapableofstartingandcontinuousoperationregardless of external weather conditions (e.g., rain, snow, sleet, ice, wind, high solar radiation, high humidity,etc.).Supportsystemenclosuresshallprovideprotectionfromtheseelementsand shallbepermanentlyaffixedtotheunit(e.g.,NEMA4Xcabinetforcontrols).
When necessary to check on the portable equipment, personnel would use protective clothing as necessary.
6.6 Conclusions and Summary TheaboveevaluationdemonstratesthatthecurrentFLEXstrategiescanbeimplementedduringaLIP withoutchanges.Therefore,consistentwithNEI1206(Reference4),SectionG.4.1,theexistingFLEX strategiescanbeimplementedfortheLIPasdesignedandnofurtheractionsarenecessary.
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Page35of36
- 7.
References
- 1. U.S.NuclearRegulatoryCommissionLetter,RequestforInformationPursuanttoTitle10ofthe CodeofFederalRegulations50.54(f)RegardingRecommendations2.1,2.3,and9.3,oftheNear Term Task Force Review of Insights from the Fukushima Daiichi Accident; dated March 12, 2012.
- 2. NSPM Letter LM16024 to the U.S. Nuclear Regulatory Commission, Monticello Nuclear GeneratingPlant,Units1and2,ResponsetoMarch12,2012RequestforInformationEnclosure 2,Recommendation2.1,Flooding,RequiredResponse2,FloodingHazardReevaluationReport, datedMay12,2016,(ADAMSAccessionNo.ML16145A233).
- 3. U.S. Nuclear Regulatory Commission Letter, Coordination of Requests for Information Regarding Flooding Hazard Reevaluations and Mitigating Strategies for BeyondDesignBasis ExternalEvents,datedSeptember1,2015.
- 4. NuclearEnergyInstitute(NEI),ReportNEI1206,Rev2,DiverseandFlexibleCopingStrategies (FLEX)ImplementationGuide,datedDecember2015.
- 5. U.S.NuclearRegulatoryCommission,RevisiontoJLDISG201201,Revision1,Compliancewith Order EA12049, Order Modifying Licenses with Regard to Requirements for Mitigating StrategiesforBeyondDesignBasisExternalEvents,datedJanuary22,2016,(ADAMSAccession No.ML15357A163).
- 6. NSPM,MonticelloUpdatedSafetyAnalysisReport,Section2.2,SiteDescription,Revision26, andSection2.4,Hydrology,Revision32.
- 7. NSPM, FLEX, Diverse and Flexible Coping Strategies Coping Strategies (FLEX) Program Document,Revision1.
- 8. U.S. Nuclear Regulatory Commission, Letter to Peter A. Gardner, Northern States Power Company-Minnesota,
Subject:
MonticelloNuclearGeneratorPlant-InterimStaffResponse toReevaluatedFloodHazardsSubmittedinResponseto10CFR50.54(f)InformationRequest-FloodCausing Mechanism Reevaluation (CAC Nos. MF7712), Dated September 16, 2016, (ADAMSAccessionNo.ML16248A003).
- 9. Black&Veatch,LocalIntensePMP&Hydrology,Calculation180999.51.1005,Revision4.
- 10. NSPM,ProcedureA.6,ActsofNature,Revision55.
- 11. NSPM,Procedure830002,ExternalFloodingProtection,ImplementationtoSupportA.6,Acts ofNature,Revision7.
MonticelloMitigatingStrategiesFloodHazardAssessment Rev.0
Page36of36
- 12. Black & Veatch, Evaluation of Structural Elements - Flood, Calculation 180999.51.1010, Revision1.
- 13. NSPM,MNGPFLEXValidation,datedMay13,2015.
- 14. NSPM,OpsManC.54101,FLEXSiteAssessment,Revision1.
- 15. NSPM,ProcedureC.54201,FLEXPortableDieselPumpStagingandHoseConnection,Revision 0.
- 16. NSPM,ProcedureC.54406,Stage120VPortableDieselGenerator,Revision0.
- 18. NSPM,ProcedureC.54503,EFTVentilationduringFLEXConditions,Revision0.
- 19. NSPM,ProcedureC.54501,ReactorBuildingVentilationduringFLEXConditions,Revision0.
- 20. NSPM,ProcedureC.54402,StageandConnectFLEX480VPortableDieselGenerator,Revision 0.
- 21. Black & Veatch, Monticello Debris Removal Assessment, Evaluation 178599.50.210003, Revision0.