ML17216A571

Proposed Changes to Tech Specs,Temporarily Modifying Plugging Limit Requirements to Permit Power Operation W/Some Steam Generator Tubes Exceeding Plugging Limits

ML17216A571
Person / Time
Site:	Saint Lucie
Issue date:	05/30/1986
From:	FLORIDA POWER & LIGHT CO.
To:
Shared Package
ML17216A569	List: ML17216A568 ML17216A571
References
NUDOCS 8606090226
Download: ML17216A571 (12)

Text

REACTORCOOLASYSTEMSURVEILLANCEREOUIRENENTSContinued5.Oefectmeansanimperfectionofsuchseveritythatitexceedstheplugginglimit.Atubecontainingadefectisdefective.Anytubewhichdoesnotpermitthepassageoftheeddy-currentinspectionprobeshallbedeemedadefectivetube.L.whichthetubeshallberemovedfromservicebecauseitmaybecomeunserviceablepriortothenextinspectionandisequalto40&fthenominaltubewallthickness.7.UnserviceabledescribestheconditionofatubeifitIstructuralintegrityintheeventofanOperatingBasisEarthquake,aloss-of-coolantaccident,orasteamlineorfeedwaterlinebreakasspecifiedin4.4.5.3.c,above,S.TubeInspectionmeansaninspectionofthesteamgeneratortubefromthepointofentry(hotlegside)completelyaroundtheU-bendtothetopsupportofthecoldleg.b.ThesteamgeneratorshallbedeterminedOPERABLEaftercompletingthecorrespondingactions(plugalltubesexceedingtheplugginglimitandalltubescontainingthrough-wa11cracks)requiredbyTable4.4-2.4.4.5.5Reportsa~Followingeachinserviceinspectionofsteamgeneratortubes,thenumberoftubespluggedineachsteamgeneratorshallbereportedtotheCoomissionwithin15days.b.ThecompleteresultsofthesteamgeneratortubeinserviceinspectionshallbeincludedintheAnnualOperatingReportfortheperiodinwhichthisinspectionwascompleted.Thisreportshallinclude:1.Numberandextentoftubesinspected.2.Locationandpercentofwall-thicknesspenetrationforeachindicationofanimperfection.3.Identificationoftubesplugged.ammo000338IPDR'ST.LUCIE-UNIT1860609022idp8PDRADOCK0p3/44-8~Cyc/e>llmr~g~s/o~~;~,ovMud~~~//q<p/~c4d.J/cp<o4~v~"8'p'C<4d<<)~uF.

~~Attachment2St.LucieUnit1DocketNos.50-335EmergencyLicenseAmendmentSteamGeneratorPluinLimitSAFETYEVALUATIONThreesteamgeneratortubeswereremovedfromtheAsteamgeneratorofSt.LucieUnit1(PSL-1)duringtheOctober-December1985outage.ThesewerethensenttoBRWforexaminationinordertobettercharacterizetheeddycurrent(ET)indicationsnotedduringthe1980and1985exams.ThesummaryofthelaboratoryworkanditscorrelationtothefieldETresultsareshownontheattachedtable.Thepresenceofgrainboundarydegradationintheformofintergrannularattack(IGA)withsomestresscorrosioncracking(SCC)causedareviewofallthe1985ETdata,andahistoricalreviewofapopulationofdefects,DistortedSupportSignals(DSS)andUndefinedSignals(UDS)aswellas1980-1985pluggedtubes.Additionally,asampleofgreaterthan50%ofdistortedsignalswerecomparedtothe1980datatoassessgrowth.UsingtheBdcWresultsasanindicatortheresultsofthe1985ETexamrevealedthepresenceofseventeenindicationshavingdepth,OOFo.TheseindicationshadtypicallybeenclassifiedaseitherDSSorUDS.WhiledirectcomparisonsofpreviousETdataaredifficultduetotheuseofdifferingequipmentandtechniques,thefollowingconclusionscanbereached:a)Thereisnosignificantchangeinindicationdepthorsignalamplitudebetweenthe1980and1985data.b)Indicationscanbeidentifiedincertaintubesasearlyas1981inthemajorityofcases.Asmallnumbercanbetrackedto1979.TheindustrydataonIGA/SCCdemonstratesthatthetubematerialbelowthesurfaceareaofuniformlydegradedIGA/SCCremainssoundanddoesnotsufferfromincipientdegradationinthegrainboundaries.TestshaveshownthattubeswithIGAwillsustainpressuredifferentialssubstantiallygreaterthanpredictedduringtheworstcasedesignbasisaccident(MSLB)priortoburst.Testinghasalsoshownthatthroughwallcracksof1inchinlengthleakbeforebreak.InordertoverifytheindustryresultsforPSL-l,samplesoftubingwereobtainedfromCEforthepurposeofleakratetesting.ThetestsrunatChattanoogausedthru-wallcracksof3/8",15/16",andIYi"inlengthfortheleak-before-breaktest.TheresultsdemonstratethattheleakageofthroughwallcracksofthesizeseenonPSL-1postMainSteamLineBreak(MSLB)are

~CIlItI'C<<C,4'r,C.~4,,(.UIr~CI'lfCI<<W4"4I'4WI'<<'<<(('=lfn.wfl4aC('r,4c'((rg(<<"t'(I'W'r<<I<<fh,,If'"'I(~<<I*('<<(~X wellbelowthoseassumedintheSafetyEvaluation.TheseresultsareconservativeinthatthemaximumcracklengthseenatPSL-1isapproximatley.6".InadditionbursttestsrunonCEtubingfor3"long,fullycircumferentialIGAverifythatIGAat70FocouldwithstandovertwicetheMSLBpressuredifferentialpriortobursting.TheseresultsarealsoconservativeascomparedtoSt.LucieUnitl.Therefore,itcanbeconcludedthatPSL-1cancontinuetobesafelyoperatedduetothefollowing:1)TheIGA/SCCcanbedetectedandsizedthroughETmeans.Inaddition,theresultsofthehistoricaldatareviewdemonstratethattheattackhasoccurredearlyintheoperatinglifeoftheplant,andhasnotgrownsignificantlyduringthelatestcycle.ThatthecorrosionoccurredearlyintheoperatinglifeofSt.LucieUnit1isfurtherevidencedintheimprovementinsteamgeneratorwaterchemistrybeginningin1978.Furthermore,sincelate1982,theSt.LucieUnitshavebeenoperatingwithaverystringentsecondarywaterchemistrycontrolprogrambasedupontheEPRISteamGeneratorOwner'sGroup(SGOG)PWRSecondaryWaterChemistryGuidelines.Thisconclusioncanalsobesupportedbytheimprovementinsecondarywaterchemistrysincethe"adoptionofEPRIWaterChemistryGuidelines.2)BothFPLandindustrytestsdemonstratethatthroughwallcrackswillleakbeforebreak,andthatIGAaffectedtubeswillresistburstinguntilapressuremuchgreaterthanthePSLdesignbasisisreached.Therefore,apotentialproblemwillbedetectedpriortoitbecomingasafetyconcern,andthattheexistingconditionwillnotleadtoexceedingthedesignbasis.:cacMCI1:1 IIA 5/23/86PSL//11985R)STCUTIESTEAMCENERATCRMTAREVIBV"A"Gen.LineRow62829610612913715516286696977113960090110011070908502935657361515051610166595107065062921091091003238802580559Total13Total0 411v1lfI'J'(hl St.LucieUnit1EddCurrent-MetallorahCorrelationLocationSludgePile(120/12-2)1.3"ATSSludgePile(79/91-2)1.4"ATS4.4"ATStlEggCrate(59/95-4)02EggCrate(59/95-5)03EggCrate(120/12-7)FPLField41XUDS57%DSS29X82%Lab40X20X50%notseen25%80X8xl50%60X50%30X90XAr.tua10~eth30X16%42X52%13%72XOefect~AearaeceIG/TGSCCParallelA~i~I~~~~kslongestover1axiallengthacross360oftubecirc.0%ostover90IGAPATCH"axial"circ.1/2"xl/2naIGAPATCH"axial"circ..8"xl/2uaIGAPATCH(0.7axiax0.3circ.)IGAPATCH(04axiaIx0.3circ)IGA/TGSCCPARALLELaxialcracksinlanarea0.6"longestover2inchesaxialacross0.1"oftubecirc.

ATTACHMENT3NOSIGNIFICANTHAZARDSCONSIDERATIONDETERMINATIONThestandardsusedtoarriveatadeterminationthatarequestforamendmentinvolvesnosignificanthazardsconsiderationareincludedintheCommission'sregulations,10CFR50.92,whichstatesthatnosignificanthazardsconsiderationsareinvolvediftheoperationofthefacilityinaccordancewiththeproposedamendmentwouldnot(1)involveasignificantincreaseintheprobabilityorconsequencesofanaccidentpreviouslyevaluated;or(2)createthepossibilityofanewordifferentkindofaccidentfromanyaccidentpreviouslyevaluated;or(3)involveasignificantreductioninamarginofsafety.Eachstandardisdiscussedasfollows:(1)Operationofthefacilityinaccordancewiththeproposedamendmentwouldnotinvolveasignificantincreaseintheprobabilityorconsequencesofanaccidentpreviouslyevaluated.Theeventsofconcernforthisamendmentarethosewhichcouldpotentiallyleadtoasteamgeneratortuberuptureduringnormaloperationoraccidentconditions.RecentmetallurgicalanalysesoftubesamplesremovedfromaSt.LucieUnit1steamgeneratorduringthelate-1985refuelingoutageandanextensivereviewofeddy-currentdatafor100Foofthetubesinbothsteamgeneratorsindicatesthattheconditionofthetubeshasbeencharacterizedwithahighdegreeofconfidenceandthatthephenomenonofconcern(intergranularattack,orIGA)hasnotprogressedsignificantlyduringthelatestcycle.Furthermore,theeffectivetimeperiodoftheamendmentislimitedto30days.Thus,theuseofthemodifiedspecificationunderthesecircumstancesdoesnotinvolveasignificantincreaseintheprobabilityofoccurrenceofasteamgeneratortuberuptureeventoranyothereventpreviouslyevaluated.Inaddition,recentresultsofFPLandindustryleakratetestingindicatethatthrough-wallcrackswill"leakbeforebreak,"andthatIGA-affectedtubeswillmaintainintegritytoapressuregreaterthanthedesignbasispressureapplicableinthissituationtotheSt.LucieUnit1steamgenerators;therefore,theconsequencesofpreviouslyevaluatedaccidentsarenotsignificantlyincreasedbythisamendment.(2)Useofthemodifiedspecificationwouldnotcreatethepossibilityofanewordifferentkindofaccidentfromanyaccidentpreviouslyevaluated.TheevaluationperformedbyCE,ofsteamgeneratortubeswithgreaterdegradationthanthatpresentatPSL1,ensuresthatthismodificationwillnotcreatethepossibilityofanewordifferentkindofaccidentfromanyaccidentpreviouslyevaluated.

'L4Vg,(~lK'laUIA 4~Q~~(3)Useofthemodifiedspecificationwouldnotinvolveasignificantreductioninamarginofsafety.Industry'datahasdemonstratedthattubematerialbelowtheareaofuniformlydegradedIGAremainssound,andtestshaveshownthattubeswithIGAwillsustain,differentialpressuressubstantiallygreaterthanthosepredictedduringdesignbasisaccidents.ThelimitingstressconditionfortubesarethoserequirementsofRegulatoryGuide1.121whichcallsfortubingtobeabletowithstandthreetimesnormaloperatingdifferentialpressurewithoutbursting.Sixteenoftheseventeendefectsmeetthisrequirement.Theseventeenthhasasafetyfactorofapproximately2.75.TestsspecifictoFPLhavebeenconductedtoverifythattheleak-before-breakconceptappliestotheSt.LucieUnit1steamgeneratorsandthatpotentialproblemswillbedetectedbeforetheybecomesignificantsafetyconcerns.Thus,useofthemodifiedspecification,especiallyoveralimited30-daytimeperiod,doesnotinvolveasignificantreductioninamarginofsafetyinthattheASMESectionIIICodelimits(NB-3225)arenotsurpassed,andthattherequirementsofRegulatoryGuide1.121aremetbyalldefectswiththeexceptionofonewhichhasaslightlyreducedmarginofsafety.Basedonourcompilationofareliableandconservativeeddy-currentdatabase,ourdeterminationthatIGAisprogressingataslowrateofgrowth,theapplicabilityoftheleak-before-breakconcept,andtheshort-terminterimnatureofthemodifiedspecification(asdescribedabove),wehavedeterminedthattheamendmentrequestdoesnot(1)involveasignificantincreaseintheprobabilityorconsequencesofanaccidentpreviouslyevaluated,(2)createtheprobabilityofanewordifferentkindofaccidentfromanyaccidentpreviouslyevaluated,or(3)involveasignificantreductioninamarginofsafety;andthereforedoesnotinvolveasignificanthazardsconsideration.

~/~~~\J4eI(~'AII