ML17325B516

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LER 99-007-00:on 981020,calculations Showed That Divider Barrier Between Upper & Lower Containment Vols Were Overstressed.Engineers Are Currently Working on Analyses of Loads & Stress on Enclosures
ML17325B516
Person / Time
Site: Cook American Electric Power icon.png
Issue date: 04/01/1999
From: KOSLOFF D C
INDIANA MICHIGAN POWER CO.
To:
Shared Package
ML17325B513 List:
References
LER-99-007, LER-99-7, NUDOCS 9904070426
Download: ML17325B516 (1)


Text

NRCForm366U.S.NUCLEARREGULATORYCOMMISSION(6-1998)LICENSEEEVENTREPORT(LER)(Seereverseforrequirednumberofdigits/charactersforeachblock)APPROVEDBYOMBNO.3160%104EXPIRES06/30)2001ESTIMATEDBORDENPERRESPONSETOCOMPLYWITHTHISMANDATORYINFORMATIONCOILECAONREOVEST'.500HRS.REPORTEDlESSONSlEARNEDAREINCORPORATEDNTOTHELICENSINGPROCESSANDFEDSACKTOINDVSTRY,FORWARDCOMMENTSREGARIXNGSVRDENESTNATETOTHEINFORMATIONANORECORDSMANAGEMENTBRANCH(T4F55).V.S.NVCLEARREGVLATORYCOMMISSlON.WASHINGTON,DC20555400),ANOTOTHEPAPERWORKREDVCTIONPROJECT(51504)05),OFFICEOFMANAGEMENTANOSICGET.WASHINGTON.OC20505FACIUTYNAME(1)CookNuclearPlantUnit1DOCKETNUMBER(2)05000-315PAGE(2)1of1TITLE(4)CalculationsShowthattheDividerBarrierBetweenUpperandLowerContainmentVolumesMayBeOverstressedEVENTDATE(5)LERNUMBER(6)REPORTDATE(7)OTHERFACILITIESINVOLVED(8)MONTH10DAYYEAR201998YEAR1999SEQUENTIALNUMBER007REVISIONNUMBER00MONTHDAY0401YEAR1999AIINAMCookUnit2ILINAMDNUMBR05000-316DNUMOPERATINGMODE(9)re)(11)20.2201(b)50.73(a)(2)(viii)20.2203(a)(2)(v)50.73(a)(2)(i)THISREPORTISSUBMITTEDPURSUANTTOTHEREQUIREMENTSOF10CFRli:(CheckoneormoPOWERLEVEL(10)0020.2203(a)(1)20.2203(a)(2)(i)20.2203(a)(2)(ii)20.2203(a)(2)(iii)20.2203(a)(2)(iv)20.2203(a)(3)(i)20.2203(a)(3)(ii)20.2203(a)(4)50.36(c)(1)50.36(c)(2)LICENSEECONTACTFORTHISLER(12)50.73(a)(2)(ii)50.73(a)(2)(iii)50.73(a)(2)(iv)50.73(a)(2)(v)50.73(a)(2)(vii)50.73(a)(2)(x)73.71OTHERSpeofySIAbetraorbe)rwrornNRCForm366AMr:DonaldC.Kosloff,ComplianceEngineerTELEPHONENUMBER(IndudeAreaCode)616/465-5901,X2129COMPLETEONELINEFOREACHCOMPONENTFAILUREDESCRIBEDINTHISREPORT(13)CAUSESYSTEMCOMPONENTMANUFACTURERREPORTABLEToEPIXCAUSESYSTEMCOMPONENTMANUFACTURERREPORTABLETOEPIXSUPPLEMENTALREPORTEXPECTED(14)XYES(IfYes,completeEXPECTEDSUBMISSIONDATE)NOEXPECTEDSUBMISSIONDATE(15)MONTH08DAY201999Abstract(Limitto1400spaces,i.e.,approximately15single-spacedtypewrittenlines)(16)WhileworkingonapreliminarycalculationfortheUnit1steamgeneratorreplacementproject,itwasconcludedthatsomeofthestructuralloadcasesindicatedoverstressedconditionsinthesteamgeneratorenclosures.Basedonthesepreliminaiyanalyses,onOctober20,1998,withbothunitsinMode5,engineeringpersonneldeterminedthatapostulatedsteamlinebreakcouldresultincalculatedstressesexceedingthecodeallowablestressesfortheUnit1steamgeneratorenclosures.Thesereinforcedconcreteenclosuresarepartofthedividerbarrierbetweentheupperandlowercontainmentvolumes.Overstressedconditionsintheseenclosurescouldallowincreasedsteambypassflowaroundtheicecondenserswhichcouldresultinhigherthanexpectedcontainmentpressure.Whenthepotentialoverstressconditionswereidentified,itwasconcludedthattheconditionscouldbeduetosignificantconservatismsinthepreliminarycalculationandinitsinterpretation.Engineeringcontinuedtheirevaluationofthisissue.However,asevaluationscontinued,alackofinformationconfirminganacceptableconditionledtotheconclusionthattherewasnolongerareasonableexpectationthatthestructureswouldnotbeoverstressed.OnMarch2,1999,withbothunitsstillinMode5,theapparentoverstressconditionsweredeterminedtobereportableunder10CFR50.72(b)(2)(i)and50.73(a)(2)(ii).Basedonthisdetermination,anENSnotificationwasmadeonMarch2,1999,at1314hoursinaccordancewith10CFR50.72(b)(2)(i).Structuralengineersarecurrentlydevelopingappropriateanalysesoftheloadsandstressesontheenclosures.Theresultsoftheseanalyseswilldetermineifanoverstressedconditioncouldhaveoccurredand,ifso,thesafetysignificanceoftheoverstressedcondition.Appropriatecorrectiveactionwillbedevelopedbasedonanevaluationoftheanalyticalresults.9904070426990401PDRADQCK05000315S,PDR