ML18031A343

Final Deficiency Rept Re Termination Module Insulation Damage.Caused by Improper Assembly,Handling,Storage & Producibility of Termination Module.Methods,Planning Process & Operator Training Upgraded

ML18031A343
Person / Time
Site:	Susquehanna
Issue date:	01/08/1980
From:	PENNSYLVANIA POWER & LIGHT CO.
To:
Shared Package
ML18031A342	List: ML18031A341 ML18031A343
References
NUDOCS 8001150438
Download: ML18031A343 (7)

Text

ATTACEKNTPage1of6TERMINATIONMODULEFINALRESOLUTIONConductorInsulationDamageofT-HODSLocatedInTerminationCabinets.ThePowerGenerationControlComplex(PGCC)isdevelopedandsuppliedbyGeneralElectricundertheH-1NSSScontract.ThePGCCusesterminationcabinetstointerfacebetweenfieldcables.Mostcablesinterfaceonaterminationmodule(T-HOD)whichconsistsofanANconnectorforthecablefromthePGCCfloorsectionandaterminalboardfor.theincomingfieldcable(seeattachedFigs.3-4,3-5,and3-6).NCR3030wasissuedonSeptember28,1978toidentifydamagedconductorinsulationwithintheT-MODconnectinganANconnectorandtheterminalboard.ThedamageswerefirstobservedduringanimplementationofreworkofterminationcabinetITC-621attheSSESsite.Ofthe-total450T-MODunitsforSSESUnit1,127unitswerefoundtoexhibitoneormoreofthefollowingdefects:1)Severeindentationsontheinsulation(noexposedwire).2)Abrasion(scuffing)oftheinsulation(noexposedwire).3)'Nicksanddings'ntheinsulation;i.e.,minor1/32"to1/8"long)lateralandlongitudinalcuts(exposedwire).4)Severelongitudinalgouging.Hirewasexposed(1/8"to1/2"long)andthegougedinsulationindicatedsharpedgecuttinginbothdirections.GeneralElectric'sQAverificationprocedureforthemanufacturingprocesswasinsufficienttodetectthedamageinsulation.CauseItwasdeterminedbyGEthat95%ofthedamagedunitswereHi-DensityTerminationModules(21and48pinassemblieswhichusetwistedshieldedpairandtriplecables-20awgwirewithferruleterminationsontheshields).Duringthereassembly(i.e.,pininsertionandextractionusingthestandardAmphenoltoolingoftheterminationmodules)continualdifficultywasobserved.Theferruleedgeduringextraction,andthesharpinsertiontooledgeduringassembly,impactedonthedenselypackedwiresattheconnectorarea.Furtherdamage(3abrasionsoutof900con-ductors)wasobservedduringthereassemblyoperation.Theassembledunitswerethenre-inspectedandthethxeeaddeddefectswerenoted.

ATTACEBKHTPage2of6ItwascausedItwasofonemoduledamageother.alsonotedthatthesharpedgesoftheterminationmoduleframesindentationsonthewire.insulationofimproperlystackedunits.seenthatthiswascausedbythesharpedgeofthesteelframemodulelaidagainsttheunprotectedwirebundlesofanadjacentHandlingprecautionsarerequiredtopreventthistypeofsinceitcanpotentiallyoccuranytimetwomodulescontacteachInsummary,thepossiblecauseofinsulationdamagecanbeattributedto:1)2)3)ImproperAssembly-PinInsertion/ExtractionHandlingandStorageProducibility-Hi-Densitymodules-Conductorfreelength-FerruleconceptAnalsisoftheSafetImlicationsThesystemdesignwasreviewedandthefollowingwasconcludedfortheworstcondition.TheinsulationdamageoftheT-MODsvariesfrombarelyvisibletotheunaidedeyeto1/2"exposedbarewire.Althoughnoinsulationbreakdownwasobservedduringthehi-pottesting(standard2.2KVDC)ofindividualconductorstoconnectorshellandotherpinsofthesameconnector,thefrequencyofoccurrenceissuchthatifthedefectswereleftundetected/uncorrected,shortingofconductorsmustbeassumedpossible.SomeoftheaffectedsystemsareRHR,RCIC,andCorespray.LossofT-MODconductorsmaypreventthecircuitsfromperformingtheirdesignedsafetyrelatedfunctions.Suchaneventualitypresentsanunacceptableconditioneventhroughtheremayberedundantsubsystemsremainingunaffected.InadditionGeneralElectric'sQAprogramhadfailedtodetectanydefectsduringthemanufacturingprocess.ProjectEngineeringhasdeterminedthePGCCT-MODsdeficiencytobereportableunder10CFR50.55(e).CorrectiveActionSAllUnit1defectiveunitshavebeenreturnedtoGESanJoseforrework.Toprecludere-occurrenceonthereworkofUnit1T-NODS,thefollowingactionshavebeentakenbyGE:l.ImproperAssemblyThemethods,planningprocess,andoperatortraininghavebeenupgradedsincetheSusquehannaIT-MODSwerebuiltinthefirstquarterof1976.This,withtheproducibilitychanges,willminimizedifficultiesobservedduringthereassemblyoperationsforT-Mods.GeneralElectric'squalityprogramappliedtotheUnitIterminationmoduleswasdefectiveinonemajorarea.Thein-processinspectionsystemdidnotincludethephysicalinspectionofthepininsertionprocess.(Theassumptionthatcontinuityandinsulationtestingwoulddetectallfunctionallysignificantinsulationdamagehasnotbeenconfirmed).Addedin-processinspectionpointsandareviseddetailed.inspection.-planhavebeenaddedtotheassemblyoperationoftheT-Mods.

ATTACE4EIQ'Page30I62.HandlingandStorageOperatortraininginthehandlingofT-Modswithproperphysicalseparationand,stackingwillreduceobservedproblemsinthisarea.Inaddition,theT-Mods,whencomplete,willbestyrofoamwrappedandtapedtoprecludestorageandshippingdamage.(Thispracticewasimplementedinearly1977.)3~ProducibilityOntheUnitIreworkoftheT-Nods,severalproducibilitychangeswhichhavebeenimplementedonsubsequentprojectswillbeapplied:a.Tensolitewirewhichislesssusceptible,toabrasionand'dinging'illbeappliedtoreworkedT-Mods.b.AnalternatemethodofshieldingwhichdoesnotrequiretheferruleconceptwillbeappliedtoreworkedT-mods.c.LongerfreeconductorlengthforeaseofassemblywillbeappliedtoreworkedT-Nods.ConclusionTherepair/reworkandre-testoftheT-NODSforSSESUnit1hasbeenaccomplishedperGEproceduresandcriteria.Thedeficiencyhasnowbeencorrectedandthepotentialsafetyhazardhasbeeneliminated.TheSSESUnit1reworkedT-Nodsh'avebeenshippedandinstalledatthejobsite.AportionoftheUnit2T-NodsweremanufacturedinthesametimeperiodastheUnit1T-Mods.InspectionwillbeperformedatSSESperaGEdocumentFDIMDBC.DefectiveunitswillbereturnedtoGEforrepairbeforefuelload.GEfabricationpersonneltraining,.inspectionandrevisedfabricationtechniqueshasprecludedreoccurrenceofsimilarproblemsontheremainingUnit2T-Nods.TheinspectionstobeconductedinaccordancewithFDIMDBCincludea100$visualinspectionofterminalstripsforcracked.,brokenormissingbarriersandconductorinsulationfornicks,abrasionandcuts.Theexistenceofanyoftheseconditionsiscauseforrefection.SK:po2873 QAYAREDO50455OASISbAXPdtGAY0L%th'3.08420ATTACKZNTPage4of6l,r)~taTKNWOVLKGAYCtarviaDAf5nERBAYDtIihR~i'>~lJOARRCRCONIECTOR~TE$TATlONARYQAttltlERSFUXRFlATKt4PPCltTFCSTAgee04,AssembledTarnationCo%~(Doomremovodlotch~-~~reels~iai~p~'pie~eI~~O~iii'".S~~a'~iver~.a:'Sr

'sA"208420ATTACHMEHTPage5ofI~~~~y~y~~CCNNECTO'asmuoM~~817 HED0.10468'TTACHi~ITPage6of6v~~vIrv'(IPrvfILLSCASLC0000~~o~i'000~~~~~~1~~~o'~~~~~~~~~~V~~~~~~~~~~0lPt>.~~~I~~~~~~~4VNCTlOMSOX

'I