ML15134A359
| ML15134A359 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 05/11/2015 |
| From: | Arizona Public Service Co |
| To: | Regner L M Plant Licensing Branch IV |
| Regner L M | |
| References | |
| Download: ML15134A359 (34) | |
Text
Pre-Submittal Meeting for Palo Verde Unit 1, 2, and 3 Updated Spent Fuel Pool Criticality AnalysisMay 11, 2015 Purpose*Present and discuss planned licensing changeschanges-Update spent fuel pool (SFP) criticality analysis-Add neutron absorbing inserts to SFP racks2 Objectives*Updated criticality analysis will-Provide basis for replacing non-conservative Technical Specification (TS) caused by missed poweruprateimpactpower uprate impact-Include Next Generation Fuel (NGF) *Account for reactivity effects of integral fuel burnable absorber (IFBA)Maintainfullcoreoffloadcapability-Maintain full core offload capability3 Borated Aluminum Inserts*Additional reactivity hold down is planned tomeet10CFR5068andmaintainfullto meet 10 CFR 50.68 and maintain full core offload capabilityThlhdliiittld-Thermal hydraulic, seismic, structural, and pool cooling calculations will be updated as needed-Add a coupon surveillance program to monitor material performance4 TS Changes*TS 3.7.17 -Spent Fuel Assembly Storage -Incorporate new burnup and enrichment curves-Display information with the polynomial explicitly stated-Include diagrams of approved arrays5 TS Changes*TS 3.7.15 -Fuel Storage Pool Boron-Currently 2150 ppm-May increase in response to accident conditions analysis6 TS Changes*TS 4.3 -Fuel Storage-Incorporate new arrays-Update boron concentration-Reduce radially averaged enrichment from 4.8 wt% to 4.65 wt%7 New TS*5.5.21 -Spent Fuel Storage Rack Neutron AbsorberMonitoringprogramAbsorber Monitoring program -Will consider upcoming NRC Generic Letter "MonitoringofNeutronAbsorbingMaterialsinMonitoring of Neutron-Absorbing Materials in Spent Fuel Pools"RecentDresdenOE-Recent Dresden OE-License extension-Plant decommissioning8 Implementation *Prior to NGF implementation in each unit*Considering installing inserts under 10CFR505910 CFR 50.59Cidiliditif*Considering a license condition for a specified period of time to transition betweenTSbetween TS9 Methodology*Based onISG201001"StaffGuidanceRegardingthe-ISG-2010-01, "Staff Guidance Regarding the Nuclear Criticality Safety Analysis for Spent Fuel Pools"-NEI 12-16, "Guidance for Performing Criticality Analyses of Fuel Storage at Light-Water ReactorPowerPlants"Revision1Reactor Power Plants, Revision 1-EPRI Depletion Benchmark Reports-Multiple NUREGsp10 Recent Licensing Actions*Methodology similar to:-ComanchePeak-Comanche Peak-Prairie Island-Turkey Point*Insert material similar to:-LaSallePhBtt-Peach Bottom-Quad Cities*Criticalitycodeusagesimilarto:Criticality code usage similar to:-Millstone 211 ISG Item 1 -Fuel Assembly Selection*Palo Verde will demonstrate that variations indesignareadequatelyaccountedforinin design are adequately accounted for in a single, limiting, fuel assembly designCEStddFl-CE Standard Fuel-CE Value Added Pellet-Westinghouse NGF (8 LUAs)-AREVAAdvancedCE-16HTP(8LTAs)AREVA Advanced CE16 HTP (8 LTAs)12 ISG Item 2 -Depletion Analysis *Depletion parameters will impact the isotopicinventoryofburnedfuelisotopic inventory of burned fuel*Major depletion inputs-Fuel type-Axial burnup -Moderator temperature-Reactor powerSolubleboron-Soluble boron-Burnable absorbers13 ISG Item 2.a -Depletion Uncertainty*The EPRI methodology will be used to demonstratethe5%depletionuncertaintydemonstrate the 5% depletion uncertainty is conservative for Palo Verde*Fission product uncertainty explicitly considered14 ISG Item 2.b -Reactor Parameters*Limiting axial moderator temperature profiles derivedpastpresentandanticipatedprofilesderived past, present, and anticipated profiles-Same methodology employed at Comanche Peakgypy*Analysis performed at 4070 MWth*Licensee controls include verification of radial diibidTldpower distribution and T-cold15 ISG Item 2.c -Burnable Absorbers*Palo Verde has used the following integral burnable absorbers-B4C rods in CE STD Fuel-Erbia in CE STD Fuel and Value Added Pellet-IntegralFuelBurnableAbsorber(IFBA)inNGFIntegral Fuel Burnable Absorber (IFBA) in NGF -Gadolinia in AREVA Fuel *AnalysiswillnotcreditErbiaBCorGadolinia*Analysis will not credit Erbia, B4C, or Gadolinia*NGF fuel modeled with IFBA in all 236 pins for depletion analysis onlypyy-Pool model assumes no burnable absorbers16 ISG Item 2.d -Rodded Operation*Palo Verde does not operate with control rodsinsertedrods inserted-Guide tube wear program*End of cycle check will ensure that fuel assembliesexperiencedaninsignificantassemblies experienced an insignificant amount of rodded operation at hot full powerp17 ISG Item 3 -Criticality Analysis*SCALE 6.1.2 will be used in the analysis-KENO V.a solves the eigenvalue (keff) problem in 3D using the Monte Carlo method-238 Group ENDF/B-VII will be used as the library-Millstone LAR used SCALE 6.0 with the KENO V.a module and 238 Group ENDF/B-VII library18 ISG Item 3.a -Axial Burnup Profile*Bounding axial burnup profiles selected frompastpresentandanticipatedfrom past, present, and anticipated profilesClifilitlildhk-Cycle specific licensee controls include checks on cutback regions (blanket), fuel design, and moderator temperature-Same methodology used at Comanche Peak and Prairie Island19 ISG Item 3.b -Rack Model*Dimensions and tolerance of racks are traceabletodesigndocumentstraceable to design documentsBoratedaluminuminsertB10areal*Borated aluminum insert B-10 areal density conservatively modeled at quantitylessthanminimumcertifiedarealquantity less than minimum certified areal density20 ISG Item 3.c -Interfaces*All interfaces are evaluated and all interfacesareanacceptable2x2arrayinterfaces are an acceptable 2x2 array-Palo Verde has only one rack design-No gaps modeled between rack modules21 ISG Item 3.d -Normal Conditions*Analysis demonstrates that keff 0.95 at lessthantheTSrequiredboronless than the TS required boron concentration for:Fuelmovement-Fuel movement-Fuel inspection and reconstitutionForeignObjectSearchandRetrieval-Foreign Object Search and Retrieval-Limiting normal condition to initiate accident identifiedidentified22 ISG Item 3.e -Accident Conditions*Analysis demonstrates that keff 0.95 at lessthantheTSrequiredboronless than the TS required boron concentration forMisloadedordroppedsinglefreshfuel-Misloaded or dropped single fresh fuel assembly into, outside of, or on top of spent fuel racks-Multiple misloaded fuel assemblies-Loss of SFP cooling-Seismic events23 ISG Item 3.e (contd.)*Limiting dilution event reduces pool boron from2150ppmto1900ppmfrom 2150 ppm to 1900 ppm TRMrequiresboronconcentrationtobe*TRM requires boron concentration to be maintained at 4000 ppm24 ISG Item 4 -Code Validation*Will perform criticality code validation in accordancewithNUREG/CR-6698accordance with NUREG/CR-6698-Data carefully considered to identify trends consistentwithNUREG1475consistent with NUREG-1475-HTC experiments will be included*Fission products will be explicitly accounted for-No lumped fission products will be used25 Palo Verde Arrays*6 arrays will be analyzed*Palo Verde expects to submit between 3 and6ofthefollowingarraysforapprovaland 6 of the following arrays for approvalFildiifltid*Final designs specify location and orientation of borated aluminum inserts26 Palo Verde Arrays*Infinite array of 2 fresh fuel assemblies (Fr)withtwoblockedlocationsandno(Fr) with two blocked locations and no inserts27 Palo Verde Arrays*Infinite array of 2 fresh fuel assemblies (Fr)withtwotrashcans(TC)andtwo(Fr) with two trash cans (TC) and two inserts28 Palo Verde Arrays*Infinite array of 3 low reactivity fuel assemblies(Lo)and1high(Hi)reactivityassemblies (Lo) and 1 high (Hi) reactivity fuel assembly with 2 inserts29 Palo Verde Arrays*Infinite array of 2 high reactivity fuel assemblies(Hi)andonelowreactivityfuelassemblies (Hi) and one low reactivity fuel assembly (Lo) with one blocked cell and oneinsertone insert30 Palo Verde Arrays*Infinite array of 4 low reactivity fuel assemblies(Lo)withoneinsertassemblies (Lo) with one insert31 Palo Verde Arrays*Infinite array of 4 depleted fuel assemblies (De)withnoinserts(De) with no inserts32 Margin Maintenance*Palo Verde will monitor the margin identifiedintheanalysisidentified in the analysis*CyclespecificchecksofkeyinputCycle specific checks of key input parameters*0.005 k additional margin reserved by Palo VerdeBurnupandenrichmentcurveswillbefor-Burnup and enrichment curves will be for keff= 0.9933 Conclusion*Palo Verde is proposing an acceptable methodology for performing SFP criticality gypgyanalysisllldbdl*Permanently installed borated aluminum inserts will be credited in the analysis*Submit LAR by Nov 2015*Request NRC approval in 18 -24 months34