ML19022A243

Presentation Material for 1/22/19 Pre-Submittal Meeting Fillet Weld Preheat Alternative Request

ML19022A243
Person / Time
Site:	Millstone
Issue date:	01/22/2019
From:	Dominion Energy Nuclear Connecticut
To:	Plant Licensing Branch 1
Guzman R
References
Download: ML19022A243 (8)

Text

Millstone Power Station Unit 3 Proposed Alternative Request IR-3-39 Fillet Weld Alternative to ASME Code Section XI, IWA-4221 (C)

Pre-Submittal Meeting January 22nd, 2019 1

DominionEnergyrequestsanalternativetoASMESectionXI,IWA 4221(c)requirementsforfilletweldsfabricatedduringtheBReactor PlantComponentCoolingWater(CCP)heatexchanger(HX) replacementprojectinRefuelingOutage17.

RequestwillbesubmittedfortwoASMECodeClass3,24inchSlipon Flangeinnerdiameter(ID)filletwelds(FW12andFW30)made withoutASMEIIICoderequired200oFpreheatorpostweldheat treatment(PWHT)toremaininservicewithoutrepairorreplacement.

Background&Request January 22nd, 2019 2

• TherequestfollowstheprecedentestablishedbyEntergyforRiverBend Unit1(ADAMSAccessionNo.ML13239A074)andwasapprovedbythe NRConJan28,2014(ADAMSAccessionNo.ML13353A608).

• Millstonerequestwilldemonstrateanacceptablelevelofqualityand safetyper10CFR50.55a(z)(1).

• KeytechnicaldifferencesbetweenRiverBendandMillstonerequests arelistedintheTablebelow:

Precedent January 22nd, 2019 3

River Bend Millstone Bimetallic StainlesstoCarbonSteelWelds CarbonSteelWelds ShieldMetalArc Weld(SMAW)E309Lcoatedelectrode Gas TungstenArcWeld(GTAW)withER70S2barewire CastSA216GrWCBbasemetal WroughtSA105basemetal Variousbasemetalthicknesses2to5in.

1.81thick Variouschemicalcompositions Singlechemicalcomposition AutomatedMicrohardness Map ManualMicrohardness Traverse AutomatedBallIndentureTesting Tensile,Bend,andImpactTestingonoriginalWeldPQR

TheIDfilletweldsarenotnecessarytomaintainstructuralintegrity.

ThefullyCodecompliantoutsidediameter(OD)filletweldsarecapableof accommodatingalldesignloadsandmaintainingstructuralintegrityshould theIDweldfail.

Visualandmagneticparticle(MT)examinationsperformedon productionweldsFW12andFW30didnotresultinanyrecordable indications.

TheoriginalWeldingProcedureQualificationTestingdemonstratedthat GTAWweldsmadeusingthisprocess,fillermetal,andparametershave acceptablestrength,ductility,andtoughnessthroughtheweldand HAZ.

WeldingwasperformedperASMEsectionIXon11/2thickP1material withidenticalcarboncontent.

WeldingwasperformedwithoutelevatedPreheatorPWHT.

EvaluationofProductionWelds January 22nd, 2019 4

• IdenticalSliponFlangeJoint,SameMaterialandWeldJointDetails

• SameWeldingProcedureandSequence

• Areaslaidoutandwelded(singlepass&multipass)torepresent:

ActualproductionIDfilletweldswithout200oF preheat Codecompliantfilletwelds Twocrosssectionstakenforeachcondition(singlepass&multipass)

Microsections werepolished,etched,andexaminedat400x

• Microhardnesstraverseacrossfourregionsrepresenting:

HeatAffectedZone(HAZ)onbasemetalside(finegrained)

HAZonweldside(coursegrained)

Weldmetalnearthefusionline Weldmetalattheweldthroat(centerline)

MockupTesting January 22nd, 2019 5

MultipassGTAWfilletweldson1.81thickSA105lowCarbonmaterial withoutthe200oF preheatproducecomparablemicrostructuresand lowerhardness(oftheweldandHAZ)withrespecttoequivalentcode compliantsinglepassfilletweldsmadewith200oF preheatandon material11/2thickwithoutpreheat.

Nocrackingwasobservedinanymockupweldcrosssectionsor detectedbytheMTexaminationoftheactualfieldwelds.

CrackingoftheIDfilletfieldweldandheataffectedzonesisunlikely because:

Averylowhydrogenweldingprocesswasutilized, Themultipass GTAWweldandHAZasdepositedwithout200oFpreheat haveacceptablemechanicalpropertiesandexcellenttoughness,and OperationalstressintheIDfilletweldzoneislowandpredominantly compressive.

MockupTestingResults January 22nd, 2019 6

Thecombinationoflowcarboncontentandmultipass weldingis moreeffectivethan200oF preheatinreducingHAZhardnessand preventingcracksusceptiblemicrostructures.

Theactualconditionsusedforthesewelds(basematerial, thickness,carboncontent,multipass,andweldingprocess variables)havebeenshowntoproduceweldswithanacceptable levelofqualityandsafetywhencomparedtosimilarASMEIII Codecompliantwelds.

FW12&FW30madewithoutASMEIIICoderequired200oF preheatontheMPS3BCCPHXhaveacceptablepropertiesfor continuedusewithoutrepairorreplacement.

Conclusions January 22nd, 2019 7

• NRCPreSubmittalMeetingon01/22/2019

• SiteFacilitySafetyReviewCommitteeReviewtargetedfor midFebruary2019

• AlternativeRequestSubmittaltotheNRCexpectedbyend ofFebruary2019 Schedule January 22nd, 2019 8