ML15134A359

5/11/2015, Meeting Slide Regarding Pre-Submittal Meeting for Palo Verde Unit 1, 2, and 3 Updated Spent Fuel Pool Criticality Analysis

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 changes changes-Update spent fuel pool (SFP) criticality analysis

-Add neutron absorbing inserts to SFP racks 2

Objectives

• Updated criticality analysis will

-Provide basis for replacing non-conservative Technical Specification (TS) caused by missed poweruprateimpact power uprate impact-Include Next Generation Fuel (NGF)

• Account for reactivity effects of integral fuel burnable absorber (IFBA)Maintainfullcoreoffloadcapability

-Maintain full core offload capability 3

Borated Aluminum Inserts

• Additional reactivity hold down is planned tomeet10CFR5068andmaintainfull to meet 10 CFR 50.68 and maintain full core offload capabilityThlhdliiittld

-Th erma l h y drau lic, se i sm ic, s t ruc tura l , an d pool cooling calculations will be updated as

needed-Add a coupon surveillance program to monitor material performance 4

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 arrays 5

TS Changes

• TS 3.7.15 -Fuel Storage Pool Boron

-Currently 2150 ppm

-May increase in response to accident conditions analysis 6

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 AbsorberMonitoringprogram Absorber Monitoring program -Will consider upcoming NRC Generic Letter "MonitoringofNeutronAbsorbingMaterialsin Monitoring of Neutron-Absorbing Materials in Spent Fuel Pools" RecentDresdenOE

-R ecent Dresden OE-License extension

-Plant decommissioning 8

Implementation

• Prior to NGF implementation in each unit

• Considering installing inserts under 10CFR5059 10 CFR 50.59Cidiliditif

• C ons id er i ng a li cense con diti on f or a specified period of time to transition betweenTS between TS 9 Methodology

• Based on ISG 201001"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

-Multi ple NUREGs p 10 Recent Licensing Actions

• Methodology similar to:

-ComanchePeak

-Comanche Peak-Prairie Island

-Turkey Point

• Insert material similar to:

-LaSallePhBtt-P eac h B o tt om-Quad Cities

• Criticalitycode usagesimilarto:

Criticality code u sage similar to:-Millstone 2 11 ISG Item 1 -Fuel Assembly Selection

• Palo Verde will demonstrate that variations indesignareadequatelyaccountedforin in design are adequately accounted for in a single, limiting, fuel assembly designCEStddFl-CE St an d ar d F ue l-CE Value Added Pellet

-Westinghouse NGF (8 LUAs)

-AREVAAdvancedCE

-16HTP(8LTAs)AREVA Advanced CE 16 HTP (8 LTAs)12 ISG Item 2 -Depletion Analysis

• Depletion parameters will impact the isotopicinventoryofburnedfuel isotopic inventory of burned fuel*Major depletion inputs

-Fuel type-Axial burnup

-Moderator temperature

-Reactor powerSolubleboron

-Soluble boron-Burnable absorbers 13 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 considered 14 ISG Item 2.b -Reactor Parameters

• Limiting axial moderator temperature profiles derivedpastpresentandanticipatedprofilesderived past , present , and anticipated profiles-Same methodolo gy em p lo yed at Comanche Peakgypy*Analysis performed at 4070 MWth

• Licensee controls include verification of radial diibidT ld power di str ib ut i on an d T-co ld 15 ISG Item 2.c -Burnable Absorbers

• Palo Verde has used the following integral burnable absorbers-B 4C 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 , B 4 C , or Gadolinia*NGF fuel modeled with IFBA in all 236 pins for de pletion anal y sis onl ypyy-Pool model assumes no burnable absorbers 16 ISG Item 2.d -Rodded Operation

• Palo Verde does not operate with control rods inserted rods inserted-Guide tube wear program

• End of cycle check will ensure that fuel assembliesexperiencedaninsignificant assemblies experienced an insignificant amount of rodded operation at hot full p owe r p 17 ISG Item 3 -Criticality Analysis

• SCALE 6.1.2 will be used in the analysis

-KENO V.a solves the eigenvalue (k eff) 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 library 18 ISG Item 3.a -Axial Burnup Profile

• Bounding axial burnup profiles selected frompastpresentandanticipated from past , present , and anticipated profilesClifilitlildhk

-C yc l e spec ifi c li censee con t ro l s i nc l u d e c h ec k s on cutback regions (blanket), fuel design, and moderator temperature

-Same methodology used at Comanche Peak and Prairie Island 19 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 quantitylessthanminimumcertifiedareal quantity less than minimum certified areal density 20 ISG Item 3.c -Interfaces

• All interfaces are evaluated and all interfacesareanacceptable2x2array interfaces are an acceptable 2x2 array-Palo Verde has only one rack design

-No gaps modeled between rack modules 21 ISG Item 3.d -Normal Conditions

• Analysis demonstrates that k eff 0.95 at lessthantheTSrequiredboron less 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 identified identified 22 ISG Item 3.e -Accident Conditions

• Analysis demonstrates that k eff 0.95 at lessthantheTSrequiredboron less 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 events 23 ISG Item 3.e (contd.)

• Limiting dilution event reduces pool boron from2150ppmto1900ppm from 2150 ppm to 1900 ppm TRMrequiresboronconcentrationtobe

• TRM requires boron concentration to be maintained at 4000 ppm 24 ISG Item 4 -Code Validation

• Will perform criticality code validation in accordancewithNUREG/CR

-6698 accordance with NUREG/CR-6698-Data carefully considered to identify trends consistentwithNUREG 1475 consistent with NUREG-1475-HTC experiments will be included

• Fission products will be explicitly accounted for

-No lumped fission products will be used 25 Palo Verde Arrays

• 6 arrays will be analyzed

• Palo Verde expects to submit between 3 and6ofthefollowingarraysforapproval and 6 of the following arrays for approvalFildiifltid

• Fi na l d es i gns spec if y l oca ti on an d orientation of borated aluminum inserts 26 Palo Verde Arrays

• Infinite array of 2 fresh fuel assemblies (Fr)withtwoblockedlocationsandno (Fr) with two blocked locations and no inserts 27 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)reactivity assemblies (Lo) and 1 high (Hi) reactivity fuel assembly with 2 inserts29 Palo Verde Arrays

• Infinite array of 2 high reactivity fuel assemblies(Hi)andonelowreactivityfuel assemblies (Hi) and one low reactivity fuel assembly (Lo) with one blocked cell and oneinsert one insert 30 Palo Verde Arrays

• Infinite array of 4 low reactivity fuel assemblies(Lo)withoneinsert assemblies (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 identifiedintheanalysis identified 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 k eff= 0.99 33 Conclusion

• Palo Verde is proposing an acceptable methodolo gy for p erformin g SFP criticalit y gypgy analysisllldbdl*Permanent l y insta ll e d borate d a l uminum inserts will be credited in the analysis

• Submit LAR by Nov 2015

• Request NRC approval in 18 -24 months 34