ML17331B238

Application for Exigent Amend to License DPR-58,revising TS 4.4.5, SGs to Incorporate Acceptance Criterion for SG Tube Degradation in Tubesheet Region Known as F*.Westinghouse Repts WCAP-13970 & WCAP-13971 encl.WCAP-13970 Withheld

ML17331B238
Person / Time
Site:	Cook
Issue date:	02/15/1994
From:	FITZPATRICK E INDIANA MICHIGAN POWER CO. (FORMERLY INDIANA & MICHIG
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML17331B239	List: ML17331B238 ML17331B240 ML17331B241 ML17331B242
References
AEP:NRC:1166K, NUDOCS 9402250130
Download: ML17331B238 (16)

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.-,ACCELERATED DISf/'TIONDEMONSATIONSYSTEMREGULATORY INFORMATION DISTRIBUTION SYSTEM(RIDS)ACCESSION NBR:9402250130 DOC.DATE:

94/02/15NOTARIZED:

YESDOCKETFACIL:50-315 DonaldC.CookNuclearPowerPlant,Unit1,IndianaM05000315AUTH.NAMEAUTHORAFFILIATION FITZPATRICK,E.

IndianaMichiganPowerCo.(formerly Indiana6MichiganEleRECIP.NAME RECIPIENT AFFILIATION DocumentControlBranch(Document ControlDesk)R

SUBJECT:

Application forexigentamendtolicenseDPR-58,revising TSI4.4.5,"SGs"toincorporate acceptance criterion forSGtubedegradation intubesheet regionknownasF*.Westinghuse DreptsWCAP-13970 6WCAP-13971 encl.WCAP-13970 withheld.

SDISTRIBUTION CODE:AP01DCOPIESRECEIVED:LTR ENCLSIZE:TITLE:Proprietary ReviewDistribution

-PreOperating License6Operating R/NOTES:ghJCIPP~31'IlA>P4ICA'Pl3$40-RECIPIENT IDCODE/NAME PD3-1LAHICKMAN,J INTERNAL:

QD~OREGFILE01EXTERNALNRCPDRCOPIESLTTRENCL11331i1110IhrP)RECIPIENT IDCODE/NAME PD3-,1PDOGC/HDS2COPIESLTTRENCL1110DDDNOTETOALL"RIDS"RECIPIENTS:

PLEASEHELPUSlOREDUCEWASTE!CONTACTTHEDOCUMENTCONTROLDESK,ROOMPl-37(EXT.20079)TOELIMINATE YOURNAMEFROMDISTRIBUTION LISTSFORDOCUMENTS YOUDON'TNEED!TOTALNUMBEROFCOPIESREQUIRED:

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/*0I'1e~FjfIIcI Indianainlchlgan Po'warCompanyP.O.Box16631Coiumbus, OH43216AEP:NRC:1166KDonaldC.CookNuclearPlantUnit1DocketNo.50-315LicenseNo.DPR-58TECHNICAL SPECIFICATION CHANGESTOINCORPORATE MSTEAMGENERATOR TUBEPLUGGINGCRITERION U.S.NuclearRegulatory Commission DocumentControlDeskWashington, D.C.20555Attn:T.E.MurleyFebruary15,1994

DearDr.Murley:

Thisletteranditsattachments constitute anapplication foranexigentamendment totheTechnical Specifications (T/Ss)forDonaldC.CookNuclearPlantUnit1.Specifically, wearerequesting achangetoT/S4.4.5(SteamGenerators) toincorporate anacceptance criterion forsteamgenerator tubedegradation inthetubesheet regionknownasM.Thiscriterion hasbeenlicensedandsuccessfully implemented atanumberofoperating plants.Asdiscussed withyourstaffonFebruary9,1994,thereasonforrequesting thisonanexigentbasisisthatthechangeisassociated withsteamgenerator repairsduringthecurrentUnit1refueling outage.Therepairsarecurrently scheduled tobeginMarch6,1994.Therefore, werequestapprovalofthisamendment requestbyMarch4,inordertoavoidoutagedelays.Attachment 1containsadescription oftheproposedT/Schangesaswellasthe10CFR50.92nosignificant hazardsevaluation.

Attachment 2containstheexistingT/Spagesmarkedtoreflectthechanges.Attachment 3containstheproposedrevisedT/Spages.Attachment 4containsWestinghouse ElectricCorporation's reportWCAP-13970, entitled"WTubePluggingCriterion forTubeswithDegradation intheTubesheet RollExpansion RegionofCookNuclearPlantUnit1SteamGenerators."

Thisreportsupportsthe10CFR50.92evaluation contained inAttachment 1.Thereportisconsidered proprietary toWestinghouse ElectricCorporation.

Assuch,anaffidavit forwithholding frompublicdisclosure isprovidedinAttachment 4.Anon-proprietary versionoftheWCAP(WCAP-13971) isprovidedinAttachment 5.)81~.689402250130 940215PDRADOCK05000315,PDR~pg.00pic,PDpi~~g5~c.(pealf-y.V

.~~V.

Dr.T~E.Hurley2AEP:NRC:1166K Webelievetheproposedchangeswillnotresultin(1)asignificant changeinthetypesofanyeffluentthatmaybereleasedoffsite,or(2)asignificant increaseinindividual orcumulative occupational radiation exposure.

TheseproposedchangeshavebeenreviewedbythePlantNuclearSafetyReviewCommittee andbytheNuclearSafetyandDesignReviewCommittee.

Incompliance withtherequirements of10CFR50.91(b)(l),

copiesofthisletteranditsattachments havebeentransmitted totheMichiganPublicServiceCommission andtotheMichiganDepartment ofPublicHealth.Thisletterissubmitted pursuantto10CFR50.30(b),

and,assuch,anoathstatement isattached.

Sincerely, E.EDFitztrickVicePresident drAttachments cc:A.A.BlindG.CharnoffJ.B.Martin-RegionIIINFEMSectionChiefNRCResidentInspector

-BridgmanJ.R.Padgett STATEOFOHIO)COUNTYOFFRANKLIN)

E.E.Fitzpatrick, beingdulysworn,deposesandsaysthatheistheVicePresident oflicenseeIndianaMichiganPowerCompany,thathehasreadtheforgoingTECHNICAL SPECIFICATION CHANGESTOINCORPORATE WSTEAMGENERATOR TUBEPLUGGINGCRITERION andknowsthecontentsthereof;andthatsaidcontentsaretruetothebestofhisknowledge andbelief.Subscribed andsworntobeforemethis~~dayof19~.NOTARYPUBLICRlrhD.HILLlfoTARYPUBS.'lt'TATE OFpH[pN

ATTACHMENT 1TOAEP:NRC:1166KDESCRIPTION ANDJUSTIFICATION OFCHANGES10CFR50.92ANALYSISFORCHANGESTOTHEDONALDC.COOKNUCLEARPLANTUNIT1TECHNICAL SPECIFICATIONS ATTACHMENT 1TOAEP:NRC:1166K Page1I.INTRODUCTION Thisamendment requestproposesachangetoTechnical Specification (TS)4.4.5(SteamGenerators) toincorporate arevisedacceptance criterion forsteamgenerator tubeswithdegradation inthetubesheet rollexpansion region.Thiscriterion forsteamgenerator tubeacceptance wasdeveloped byWestinghouse ElectricCorporation andisknownasW("F-Star"

).Thiscriterion wasdeveloped toavoidunnecessary pluggingofsteamgenerator tubes.TheexistingT/Stuberepairing andpluggingcriteriaapplythroughout thetubelength,butdonottakeintoaccountthereinforcing effectofthetubesheet ontheexternalsurfaceofthetubeintherollexpansion region.Thepresenceofthetubesheet willconstrain thetubeandwillcomplement itsintegrity inthatregionbyessentially precluding tubedeformation beyonditsexpandedoutsidediameter.

Theresistance tobothtuberuptureandtubecollapseissignificantly strengthened bythetubesheet.

Inaddition, theproximity ofthetubesheet significantly affectstheleakbehaviorofthroughwalltubecracksinthisregion,i.e.,nosignificant leakagerelativetoplantT/Slimitsistobeexpected.

TheWmethodology anddetermination oftheWdistanceareincludedinWCAP13970,entitled"WTubePluggingCriterion forTubesWithDegradation intheTubesheet RollExpansion RegionoftheDonaldC.CookUnit1SteamGenerators."

Thisreport,preparedbyWestinghouse ElectricCorporation, iscontained inAttachment 4.Anon-proprietary versionofthereportisincludedinAttachment 5.II.ESCRIPTION OFTHECHANGESTheproposedchangesarethosenecessary toincorporate theWtubesheet regionpluggingcriterion intotheT/Ss.Thespecificchangesareasfollows:Arequirement isaddedtoinspect(intherollexpandedregion)alltubeswhichhavehadtheWcriteriaapplied.Therollexpandedregionofthesetubesmaybeexcludedfromtherequirements ofT/S4.4.5.2.b.l.

Definitions forWdistanceandanWtubeareadded.Wdistanceisthedistancefromthebottomofthehardrolltransition towardthebottomofthetubesheet thathasbeenconservatively determined tobe1.11inches(notincluding eddycurrentuncertainty).

An,&tubeisatubewithdegradation, belowtheWdistance, equaltoorgreaterthan40$,andnotdegraded(i.e.,noindications ofcracking) withintheWdistance.

Thedefinition of"Repair/Plugging Limit"(T/S4.4.5.4.a.6) ismodifiedtonotethatthe408repair/plugging limitdoesnotapplytotheportionofthetubeinthetubesheet belowtheWdistanceforWtubes.

ATTACHMENT 1TOAEP:NRC:1166K Page2Arequirement isaddedtoreporttotheNRCtheresultsofinspections performed underT/S4.4.5.2foralltubesthathavedefectsbelowtheWdistanceandwerenotplugged.III.10CFR5092EVALUATION Theamendment hasbeenproposedtoaddresseddycurrentindications oftubedegradation whichcanoccurintherollexpandedportionofthetubeswithinthetubesheet inthesteamgenerators attheCookNuclearPlantUnit1.Thesesteamgenerators werefabricated witha2.75inchpartialdepthrollexpansion inthetubesheet.

Interpretation ofeddycurrentdatafromtheCookNuclearPlantUnit1andsimilarplantshasshownapotential forprimarywaterstresscorrosion cracking(PWSCC)withintherollexpandedportionofthetubeinthetubesheet.

Itcanbeshownthattubepluggingorsleevingisnotrequiredinmanysuchcasestomaintainsteamgenerator tubeintegrity.

UsingexistingT/Stubepluggingcriteriaforthelengthoftubewithinthetubesheet, manyofthetubeswithpotential indications wouldhavetoberepairedorremovedfromservice.Theproposedamendment wouldprecludeoccupational radiation exposurethatwouldotherwise beincurredbyplantworkersinvolvedintubepluggingorsleevingoperations.

Theproposedamendment wouldalsoavoidlossofmargininreactorcoolantsystemflowandtherefore assistinassuringthatminimumflowratesaremaintained inexcessofthatrequiredforoperation atfullpower.Reduction intheamountoftubepluggingorsleevingrequiredcanreducethelengthofplantoutagesandreducethetimethatthesteamgenerator isopentothecontainment environment duringanoutage.Thepossibility oftuberepairbysleevingshouldnotbeconsidered areasontoexcludeuseofthisproposedtubesheet pluggingcriterion, butshouldbeconsidered oneoftheoptionsusedtoaddressdegradation intheexpandedregionofthetube.Thedisadvantages oftubeplugsnotedabovealsoapplytosomeextenttosleeves.Theproposedamendment addresses theactionrequiredwhendegradation hasbeendetectedinthemechanically expandedportionofsteamgenerator tubeswithinthesteamgenerator tubesheet.

Existingtuberepairorpluggingcriteriadonottakeintoaccounttheeffectofthetubesheet ontheexternalsurfaceofthetube.Thepresenceofthetubesheet willenhancetheintegrity ofpotentially degradedtubesinthatregionbyprecluding tubedeformation beyondtheexpandedoutsidediameter.

Structural (burst)integrity oftubeswithsignificant throughwall axialpenetration lengthisprovidedintherollexpandedarea.Anaxiallengthofrollexpansion equaltotheWlengthatthetopoftherollexpansion ofthetubeintothetubesheet providessufficient structural integrity toprecludepulloutofthetubeduetopressureeffects,evenafter

ATTACHMENT 1TOAEP:NRC:1166K Page3assumingthatthetubehasexperienced acompletecircumferential separation atorbelowthebottomoftheF+distance.

Thissameaxiallengthofrollexpansion ofthetubeintothetubesheet providesabarriertoleakageduringallplantconditions forthroughwallcrackingofthetubeintheexpandedregionbelowW.Theproposedchangedesignates aportionofthetubeforwhichtubedegradation ofadefinedtypedoesnotnecessitate remedialactionexceptasdictatedforcompliance withtubeleakagelimitsassetforthintheT/Ss.Asnotedabove,theareasubjecttothischangeisintheexpandedportionofthetubewithinthetubesheet ofthesteamgenerators.

TheWlengthhasbeendetermined tobe1.11inches.Soundrollexpansion of1.11incheswillsatisfyallapplicable recommendations ofRegulatory Guide1.121,withregardtotubeburstcapability.

Conformance oftheproposedamendments tothestandards foradetermination ofnosignificant hazardasdefinedin10CFR50.92(threefactortest)isshowninthefollowing:

1)Operation ofDonaldC.CookNuclearPlantUnit1inaccordance withtheproposedlicenseamendment doesnotinvolveasignificant increaseintheprobability orconsequences ofanaccidentpreviously evaluated.

Thesupporting technical andsafetyevaluations ofthesubjectcriterion demonstrate thatthepresenceofthetubesheet willenhancethetubeintegrity intheregionofthehardrollbyprecluding tubedeformation beyonditsinitialexpandedoutsidediameter.

Theresistance tobothtuberuptureandtubecollapseisstrengthened bythepresenceofthetubesheet inthatregion.Theresultofhardrolling ofthetubeintothetubesheet isaninterference fitbetweenthetubeandthetubesheet.

Tuberupturecannotoccurbecausethecontactbetweenthetubeandtubesheet doesnotpermitsufficient movementoftubematerial.

Theradialpreloaddeveloped bytherollingprocesswillsecureapostulated separated tubeendwithinthetubesheet duringallplantconditions.

Inasimilarmanner,thetubesheet doesnotpermitsufficient movementoftubematerialtopermitbucklingcollapseofthetubeduringpostulated LOCAloadings.

Thetypeofdegradation forwhich,theWcriterion hasbeendeveloped (cracking withacircumferential orientation) cantheoretically leadtoapostulated tuberuptureeventprovidedthatthepostulated through-wall circumferential crackexistsnearthetopofthetubesheet.

Anevaluation including analysisandtestinghasbeendonetodetermine theresistive strengthofrollexpandedtubeswithinthetubesheet.

Thisevaluation providesthebasisfortheacceptance criteriafortubedegradation subjecttotheWcriterion.

ATTACHMENT 1TOAEP:NRC:1166K Page4TheWlengthofrollexpansion issufficient toprecludetubepulloutfromtubedegradation locatedbelowtheWdistance, regardless oftheextentofthetubedegradation.

TheexistingT/Sleakageraterequirements andaccidentanalysisassumptions remainunchanged intheunlikelyeventthatsignificant leakagefromthisregiondoesoccur.Asnotedabove,tuberuptureandpulloutisnotexpectedfortubesusingtheWcriterion.

Anyleakageoutofthetubefromwithinthetubesheet atanyelevation inthetubesheet isfullyboundedbytheexistingsteamgenerator tuberuptureanalysisincludedintheCookNuclearPlantFSAR.Forplantswithpartialdepthrollexpansion likeCookNuclearPlantUnit1,apostulated tubeseparation withinthetubenearthetopoftherollexpansion (withsubsequent limitedtubeaxialdisplacement) wouldnotbeexpectedtoresultincoolantreleaseratesequaltothoseassumedintheFSARforasteamgenerator tuberuptureeventduetothelimitedgapbetweenthetubeandtubesheet (approximately

0.0 13inchdiametral

gap).Theproposedpluggingcriterion doesnotadversely impactanyotherpreviously evaluated designbasisaccident.

Leakagetestingofrollexpandedtubesindicates thatforrolllengthsapproximately equaltotheWdistance, anypostulated faultedcondition primarytosecondary leakagefromWtubeswouldbeinsignificant.

2)Theproposedlicenseamendment doesnotcreatethepossibility ofanewordifferent kindofaccidentfromanyaccidentpreviously evaluated.

Implementation oftheproposedWcriterion doesnotintroduce anysignificant changestotheplantdesignbasis.Useofthecriterion doesnotprovideamechanism toinitiateanaccidentoutsideoftheregionoftheexpandedportionofthetube.Anyhypothetical accidentasaresultofanytubedegradation intheexpandedportionofthetubewouldbeboundedbytheexistingtuberuptureaccidentanalysis.

Tubebundlestructural integrity willbemaintained.

Tubebundleleaktightness willbemaintained suchthatanypostulated accidentleakagefromWtubeswillbenegligible withregardtooffsitedoses.3)Theproposedlicenseamendment doesnotinvolveasignificant reduction inamarginofsafety.TheuseoftheWcriterion hasbeendemonstrated tomaintainthe,integrity ofthetubebundlecommensurate withtherequirements ofRegGuide1.121(intended forindications inthefreespanoftubes)andtheprimarytosecondary pressureboundaryundernormalandpostulated accidentconditions.

Acceptable tubedegradation fortheWcriterion isanydegradation indication inthetubesheet region,morethanthedistancebelowthebottomofthetransition betweentherollexpansion andtheunexpanded tube.Thesafetyfactorsusedintheverification ofthestrengthofthedegradedtubeareconsistent withthesafetyfactorsintheASMEBoilerandPressureVesselCodeusedinsteamgenerator design.TheWdistancehasbeenverifiedbytestingtobegreaterthanthelengthofrollexpansion requiredtoprecludebothtubepulloutand

ATTACHMENT 1TOAEP:NRC:1166K Page5significant leakageduringnormalandpostulated accidentconditions.

Resistance totubepulloutisbasedupontheprimarytosecondary pressuredifferential asitactsonthesurfaceareaofthetube,whichincludesthetubewallcross-section, inadditiontotheinnerdiameterbasedareaofthetube.Theleaktestingacceptance criteriaarebasedontheprimarytosecondary leakagelimitintheT/Ssandtheleakageassumptions usedintheFSARaccidentanalyses.

Implementation ofthetubesheet pluggingcriterion willdecreasethenumberoftubeswhichmustbetakenoutofservicewithtubeplugsorrepairedwithsleeves.BothplugsandsleevesreducetheRCSflowmargin;thus,implementation oftheWcriterion willmaintainthemarginofflowthatwouldotherwise bereducedintheeventofincreased pluggingorsleeving.

Basedontheabove,itisconcluded thattheproposedchangedoesnotresultinasignificant reduction inmarginwithrespecttoplantsafetyasdefinedintheFSARortheT/SBases.