L-12-316, Request for Exemption for Post-Repair Testing Requirements of Containment Vessel Opening
| ML13018A349 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 01/18/2013 |
| From: | Lieb R FirstEnergy Nuclear Operating Co |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| L-12-316 | |
| Download: ML13018A349 (11) | |
Text
FENOC^ \ 5501NorthEtalaRoute2 OakHarbor,Qhio 43449 FirstEnergy Nuclear@eratingCampany RaynnndA.Ueb 4tg^321-7876 WcePresldent, Nuclear Fax:41*32t-7582 January18,2A13 L-12-316 10cFR 54,12 ATTN: Docurnent ControlDesk U.S.NuclearRegulatory Commission Washington, DC20555-0001
SUBJECT:
Davis-Besse NuclearPowerStation DocketNo.50-346,LicenseNo.NPF-3 Requestfor Exernption fromPost:Bepair TestingRequiremenls, of Containment Vegs3l Opening Pursuant to t0 CFR50.12,"specificExemptions," theFirstEnergy NuclearOperating Cornpany (FENOC) requestsan exemption fromcertainrequirements of 10 CFR50.55a,"CodesandStandards," Paragraph (bX2XixXJ),fortheDavis-Besse NuclearPowerStation.Therequested exemption wouldallowthe useof an alternate methodof containrnent testingfollowing associated activities withsteamgenerator replacement.
FENOCrequests approval of theexemption by January18,2014,in ordertosupport thescheduled refuelingoutagein the springof 2014.Therequestfor exemption is enclosed.
Thereare no regulatory commitments contained in thissubmittal.lf thereareany questions or additional informationis required,please contactMr.ThomasA. Lentz, Manager FleetLicensing, at (330)315-6810.
/frw Lieb
Davis-Besse NuclearPowerStation L-12-31 6
Page2
Enclosure:
Request{or Exemption from10CFR50.55a(bX2Xix)(J) Post-RepairTesting Regarding of Davis-BesseNuclear VesselOpening I PowerStationContainment NRCRegionlll Administrator NRCResident Inspector NRCProjectManagei SafetyBoard UtilityRadiological
Requestfor Exemption t
from10CFR50.55a(bX2XiX)(J)
Subject:
Requestfor Exemption Post-Regarding N;rclear RepairTestingof Davis-Besse VesselOpening PowerStationContainment Page.1of I 1.0 lntroduction 2.A Background 3.0 Proposed Exemption 4.0 Conclusions 5.0 References
Page2 of I 1 . 0 lntroduction ln accordance withtheprovisions of 10CFR50.12,"specificExemptions," the FirstEnergy Nuclear Operating Gompany (FENOC) is submitting a request for exemption fromcertainrequirements of 10 CFR50.55a,"CodesandStandards,"
Paragraph (bX2XixXJ). Therequested exemption wouldallowtheuseof an alter;ratemethodof containment testingin lieuof the 10 CFR50.55a{bX2XixXJ) required Appendix J TypeA leakagete-st, following activitr'es associated witha Davis-Besse NuclearPowerStation(DBNPS) steam generator replacernent.
Thealternate rnethodproposed is a restoration of the containment to itsoriginal design condition, including a 100 percent radiograph of the weld, followed bythe leaktestdescribed in theAmerican Societyof Mechanical Engineers (ASME)
BoilerandPressure Vessel(B&PV)Code,IWE-5223.a(a) (a bubbletest- direct pressure technique).
2.Q Backgrgqfr-d.
FENOCplansto replace theDBNPSsteamgenerators in thespringof 2014.
Thesereplacement activities require theopening of thecontainment vesselto provideaccessforthe removalof theoriginalsteamgenerators aswellas the installationof the replacement steamgenerators.Following replacement of thesemajorcomponents, thecontainment vesselwillbe restored to itsoriginal designrequirements.
Oncethecontainment vesselhasbeenrestored, a leakagetestin accordance with10CFR50.55a,Paragraph (bX2)(ix)(J), wouldbe required:
In general,a repair/replacement activitysuclTas replacinga large containment penetration,cuttinga largecanstruction openingin the containment pressure boundaryto replacesteam generators, reactor yesse/heads,prossurizers, or othermajorequiprnent; or othersimilar modificafion is considered a majorcontainment madification. When applyingIWE-5000to C/assMC pressure-retaining components, any major containment modification or repair/replacemont, musfbe followed by a TypeA fesfto provideassurance of bothcontainmont structural integrityandleaktightintegrity prior to returning to seruice,in accordance with 10 CFRpart 5A,AppendixJ, OptionA or OptionB on whichthe appticanf'sor licensee's Containment Leak-Rate TestingProgramis based.WhenapplyingtWE-5000,if a TypeA, B, or C Tesfis pefformed, lhe fesf pressure and acceptanco standardfor the fesfmustbe in accordance with10 CFRpart50,AppendixJ.
Page3 of 9 FENOCbelievesthat due to the natureof the repair,whichrestoresthe containmentvesselto ASI\4ErdQuirements, afi'effdstivepost-repairtest of containmentstructuraland leaktightintegritycan be peformedby an alternative leakagetest in accordance with IWE-5223.4(a), whichstates:
l IWE-5223.4Examination. Duringthepneumaticleakagefes[ theleak tighfness of brazedjointsand weldsaffectedby therepairlreplacement activityshatlbe verifiedby performingoneof the following:
(a)a bubbletest-direcfpressuro technique in accordance withSecfionV, Article10,Appendix l, or anyotherSecfibn V, Article10leaktestthatcan be peffarmed in conjunctionwith thepneumaticleakagefesf.
TheDBNPScontainment vesselis a cylindrical steelpressure vesselwith hemispherical domeandellipsoidal bottom.lt is completely enclosed by'a reinforcedconcrete shieldbuilding havinga cylindrical shapewitha shallow domeroof.An annularspaceis provided between thewallof thecontainment vessetandtheshieldbuilding, andclearance is alsoprovided between the containment vesselandthedomeof theshieldbuilding.
Withtheexception of theconcrete underthecontainment ves$el,thereareno structurattiesbetween thecontainment vesselandtheshieldbuilding abovethe foundation slab.Abovethisthereis virtually unlimited freedom fordifferential movement between thecontainment vesselandtheshieldbuilding.
Thevesselinsidediameteris 130feet,andthe netfreevolurneis approximately 2,834,000 ft3,Thecylindrical shellandbottomheadthickness, exclusive of reinforced areas,is 1 %inchwitha domethickness of 13f16inch.Theoriginal Construction Codeforthecontainment vesselwastheASMEB&PVCode, Section lll, ClassB, 1968Edition through Summer1969Addenda.
DBNPSis in itsFourth10-year inservice inspection whichbeganon interval, September 21,2A12.TheDBNPSCode of Record is ASME B&PVCode, SectionXl, Inservice Inspection of NuclearPowerPlantComponents, 2A07 Editionthrough2008Addenda.Thecontainment vesselis a SeismicClassl, ClassMCvessel.
Theduration of theproposed alternativewouldbethroughcompletion and approvalof all testingassociated with restorationof the containment opening cieatedto supportth-eDBNPSsteamgenerator replacement.
Page4 of I 3.0 P.rop.osedExemption ProposedAlternative Therequested exemption is fromlhe requirement to performtheTypeA integratedleakratetestspecified by 10CFR50.55a,Paragraph (bX2){ix)(J),
followingrestoration of thecontainment vesselpressureboundary,Thattestis to be replaced witha combination of a weldrepairthatrestores the containment to' itsoriginal designrequirernents, including 100 percent radiography of the weld, anda localized leakagebubbleteston thecontainment vesselrepairarea.
Therepair/replacement nondestructive examination (NDE)activities, specifically thepre-service examination andpost-repair/replacement testingrequirements, associated withtemporary removal andreinstallation of the DBNPScontainment vesselopeningwilltie performed in accordance withthe requirements of the 2047Edition through2008Addenda of ASMESectionXl. ASMESection Xl, Paragraph IWA-4411, "Welding, Brazing, Fabrication,andInstallation," states thatweldingandinstallation activitiesshallbe performed in accordance withthe Owner'sRequirements and,exceptas modified by lWA4411(a)through(i),in accordance withtheoriginal Construction Codeof theitem.
Fabrication andinstallation activities(thatis,cuttingandwelding) willbe performed in accordance withtheoriginal Construction CodeClassB of ASME Sectionlll, or reconciled to a latereditionof theASMEGodein accordance with the requirements of tWA-4000, "RepairlReplacement Activities."Therestoration of theconstruction openingandassociated weldwillreturnthe structural integrity of thecontainment vesselto itsoriginal design requirernents, Priorto performing therepairweld,thesurfaces to be weldedwillbe prepared in accordance withtheapproved ASME Repair/Replacement Plan. The weld will be performed byqualified personnel in accordance withASME-Section lX, "Qualification Standard forWeldingandBrazing Procedures, Welders, Brazers, andWeldingandBrazing Operatois," requirements. Post weld examinations will be performed onthecontainment vesselrepair,whichwillinclude a 100 percent radiography in accordance withtheConstruction Code.In addition, a general visualexamination willbe performed during,or upon completion of, the pressure test,
Page5 of I Thereapplication of containment vesselcoatings willbe perforrned following completion of radiography andpriorto theperformancti of the localized leakage bubbletest. Therefore, thecontainment vessel opening will have been restored to itsoriginaldesignrequirernents andwillhavebeenexarnined to ensureweld integrity.Thecombination of thesechecksensurethestructural integrity requirement of 10CFR50.55a(bX2Xix)(J) hasbeen met.
Structuralintegrityandthe leaktight integrityof therepairwillthenbe ensuredby the proposed localizedleakagebubbletest. Thecontainment vesselopening repairweldwillbe bubbletestedafterpressurizing theentirecontainment to between 0.96Pa and1.10Pa, whereP. is thedesignbasisloss-of-coolant accident containment peakpressure (Pr),whichis 38.0poundspersquareinch gauge(psig).Thebubbletestof therepairweldwillbeperformed aftera hold timeof at least15minutes.Thetestacceptance criteriawillbe zerodetectable leakage, whichwillbe determined bytheabsence of bubbleformation usinga leakdetection rnedium in accordance withtestprocedures.
A VT-2inspection willbe performed withthetestpressure heldat or above38.0 psig.Thistestpressure willstructurallytestthecontainment vesselrepairweld.
Anyleakageidentified willbe corrected, andthetestwillbe re-performed. The nondestructive examination (NDE) personnel performing the l/T.-2 visual inspection willbe certifiedin accordance withtherequirements of AN$I/ASNT CP-189, "ASNTStandard for Qualification andCertification of Nondestructive TestingPersonnel." Theleakage testshallbeperformed priorto entryintoMode 4 followingrestoration of thecontainment vesselboundary.
As noted,thisbubbletestwillensurezeroleakage at therepairarea,in lieuof a TypeA testthatmeasures andpermitsa specified amountof totalcontainment leakage; in otherwords,thiszeroleakageacceptance criterion is morestringent thanthatof a TypeA test.
Zeroleakage acceptance criteriaforthebubbletestwillensurethatthe containment vessel leakage rateis notalteredbythesteamgenerator replacement andthepressurization activity, of theentirecontainment vesselto theaccidentpressure willconfirmthe integrity of the containment vesselafterthe repair.
Thecombination of therepairto originat designrequirements, including 100 percenlradiography, andthe localized leakage bubbletestonthepressure boundary weldareaof thecontainment vessel,willprovidea moreeffective examination thantheTypeAtestrequired by 10CFR50.55a(b)(2)(ix)(J) dueto thezeroleakage acceptance criteriathat willbe applied.
Page6 of I FENOCbelieves thatan exemption frornthe requlrements of 10 CFR50.56a(b)(2)(ix)(J) to perform theproposed alternative ensures the continued abilityof thecontainment vesselto providean acceptable levelof qualityand'safety afterthesteamgenerator replacement activitiesand,therefore, willnotpresent an undueriskto publichealthandsafety,andis consistent with the common defenseandsecurity.ln addition, nolawexiststhatprecludes the activities coveredbythisexemption request.
Specia/Circumsfances DBNPShassuccessfully completed twocontainment vgsselrestorations following lwo separatereactorvesselclosureheadreplacements, Perthe DBNPSContainment Leakage RateTestingProgram, thetests performed in the 2003refueling outageandthe 2011mid-cycle outageindicated thatthe Containment Systemis performing wellwithinleakagelimitsas greaterthan50%
marginremained of the0.375%weightperdayleakagelimitin bothcases.
Greater thanB0%marginremained following therestoration of thecontainment vesselduringthe2011mid-cycle outage.
TheTypeA testmethodrequires additionaltime,manpower, dose,andtest instrumentation installation. TheTypeA testtakeslongerto performandvirtually stopsotherworkfromtakingplaceinsidecontainment for an extended period.In addition, theTypeA testdoesnotprovideas muchassurance of thequalityof therepairweldbecause it couldallowsomeleakage throughtherepairweldand stillbe considered an acceptable test.
A 100percentradiograph of theweldalongwitha localized leaktestprovides an accurate anddirectmethodof ensuring thestructural and leaktight integrityof the repairweld.Thelocalized bubbletestis considered a superior testfor determining leakageat the repairedareaas compared to a TypeA test. The combination of a 100percentweldradiography (rneeting theconstruction code radiography acceptance criteria)andthe localized leakBgebubbletestof the repairweld(whileat designpressure) willconfirmtheintegrity of thecontainment vessel.Therefore, FENOCbelieves thatapplication of the proposed alternative testingwouldachieve theunderlying purpose of therule,andthatthisrequest therefore meetsthespecialcircumstances described in 10CFR50.12(aXzXii).
Precedents A similarASMECodealternative wassoughtby Entergyfor fheWaterford 3 refueling outagein thefallof 2012(Reference 1). Theproposed Code alternative wasapprovedby the NRCbasedon theconclusion thatthe proposed atternative willprovideadequate assurance of structural integrity{Reference 2)-
Page7 of I Anothersimilaralternative wasrequested by Tennessee ValleyAuthority(TVA) on November 17,20A5,forWattsBarNuclearPlant,Unit1 (Reference 3). The NRCapproved therequestonAugust30,2006(Reference 4).
4.A Conclusions 10 CFR50.12statesthatthe NRCffi?v,uponapplication by anyinterested personor uponits owninitiative, grantexemptions fromthe requirements of 10 CFRPart50when(1)theexemptions areauthorized by law,willnotpresent an undueriskto publichealthandsafety,andareconsistent withthecommon defenseandsecurity; and(2)whenspecialcircumstances, as definedin 10 CFR50.12(a)(2) arepresent.Therequested exemption to allowthe
' design combination of a weldrepairthatrestores thecontainment itsoriginal to requirements, including 100percent radiography of theweld,andanASME ArticleIWE-5223.4(a) directleakage test(bubble test)at theDBNPSsatisfies theserequirements as described below.
1, Authorized by Law No lawexiststhatprecludes theactivitiescoveredbythisexemption request.,Thisexemption wouldperrnitrestoration of thecontainment to its original designrequi.rements paired withthe performance of a localized leakagebubbletest. lt is a one-timealternative forthe 10 CFR50.55a(bX2Xix)(J) required Appendix J TypeA testfollowing repair/replacement activities associated withthe DBNPScontainment vesselaffectedbythe replacement of thesteamgenerators. As stated above,10 CFR50.12allowstheNRCto grantexemptions fromthe requirernents of 10 CFRPart50.
- 2. No UndueRiskto PublicHealthandSafety Theunderlying purposes of 10CFR50.55a(bX2XixXJ) areto ensurethat containment structuralandleaktight integrityis maintained so a$to limit efflu_ent release to values bounded by theanalyses of radiological consequences of designbasisaccidents. Basedon theabove,no new accidentprecursors arecreatedby the proposed alternative testing.lt is a one-time alternativeforthe 10CFR50.55a(b)(2Xix)(J) required Appendix J TypeA testfollowingrepair/replacement activities associated the with DBNPScontainment vesselaffectedbythe replacements of thesteam generators. Also,basedon theabove,theconsequences of postulated accidents arenotincreased. Therefore, thereis no undueriskto public healthandsafety.
Page B of g
- 3. Consistent WithCornmon DefenseandSecurity Theproposed exemption is a one-timealternative forthe 10CFR50.55a(bX2Xix)(J) required Appendix J TypeA testfollowing repair/replacement activities associated withthe.DBNP$containment vesselaffectedby the replacements of thestearngenerators. This alternative testhasno relationto securityissues.Therefore, thecornrnon defenseandsecurityis notimpacted by thisexemption.
- 4. Specia I Circurnstances Specialcircumstances includq, in part,thespecialcircumstances defined in 10CFR50.1z(aX2Xii), whichstates,"Application of theregufation in the particular circumstances wouldnotservetheunderlying purpose of the ruleor is notnecessary to achieve the underlying purposeof therule."
Theunderlying purpose of 10CFR50.55a(bX2XixXJ) is to ensurethat containment andleaktight structural integrityis maintained to limiteffluent releaseto valuesboundedby theanalyses of radiological consequences of designbasisaccidents.Theintentof the ruleis notcomprornised by FENOC's proposed actionbecause thecontainment structural integrity will be restored, andleakratesfromthe regionsaffectedbythe repairwill be zero.
Theproposed actionwillappropriately permitthe performance of a localized leakagebubbletest. lt is a one-time alternative for the 10CFR50.55a(b)(2)(ix)(J) required Appendix J TypeA testfollowing repairlreplacement activities associated withreplacement of thesteam generators. Therefore, sincetheunderlying purposes of 10CFR50.55a(b)(2)(ix)(J) areachieved, thespecialcircumstances required by 10CFR50.12(aX2Xii) forthegranting of an exemption from 10CFR50.55a(bX2Xix)(J) exist As demonstrated above,FENOCbelieves thisexemption requestis in accordance withthecriteria of 10 CFF50.12.Specifically, therequested exemption is authorized by law,willnotpresentan undueriskto thepublichealth andsafety,andis consistent withthecommondefenseandsecurity.Also, specialcircumstances arepresent as previously described.
PageI of I 5.0 References 1, Entergyletterto NRCdatedJuly27,2A11,"Request to forAlternative ASMEIWE-5221 RegardingPostRepairTestingof Wate#ord3'sSteel Containment VesselOpening" (ADAMS Accession No.ML112150195).
- 2. NRCletterto Entergy datedJanuary 4,2A12,"Watedord SteamElectric Station,Unit3 - Request to ASMEIWE-5221 forAlternative Regarding Post-RepairTestingof SteelContainment Vessel Opening(TAC No, ME6795) (ADAMS AccessionNo.M1113330137).
- 3. TVAletterto NRCdatedNovember 17,2005,'WattsBarNuclearPlant WBN), Unit1 - OneTimeRequestfor RelieffromAmericanSocietyof Mechanical Engineers (ASME), Xl CodeRequirements Section - Tests FollowingRepair,Modification,or Replacernent(lWE-5221)"(ADAMS Accession No.ML053260493).
4, NRCletterto TVAdatedAugust30,2006,"WattsBarNuclearPlant,Unit 1 - OneTimeRequestfor RelieffromAmericanSocietyof Mechanical Engineers SectionXl CodeRequirements - TestsFollowing Repair, Modification, or Replacement (lWE-5221) (TAC No.MCB920)" (ADAMS Accession No.ML0615901 11).