ML18024A058

Susquehanna Units 1 and 2 - Letter Attaching a Final Report of a Deficiency in Carriage Bolt Fasteners Used on 480 Volt Motor Control Center Bus Splices

ML18024A058
Person / Time
Site:	Susquehanna
Issue date:	09/18/1978
From:	Curtis N W Pennsylvania Power & Light Co
To:	Grier B H NRC Region 1
References
Download: ML18024A058 (12)

Text

0REGULATQRY INFORMATION DISTRIBUTION SYSTEM(RIDS)DISTRIBUTION FORINCOMINGMATERIAL-3388REC:GRIERBH,NRCORG:CURTISNWPAPWR5LIGHTDOCDATE:'09/i8/78 DATERCVD:09/22/78DOCTYPE:LETTERNOTARIZED:

NOCOPlESRECEIVED

SUBJECT:

LTRiENCLFORWARDING FINALCONSTRUCTION DEF1CIENCY REPTCONCERNING DEFICIENCY INCARRIAGEBOLTFASTNERSUSEDON480VOLTMOTORCONTROLCENTERBUSSPLICES.PLANTNAME:SUSQUEHANNA' UNITiREVIEWERINITIAL:XJMSUSQUEHANNA

-UNIT2DISTRIBUTERINITIAL~@~

DITRIBUTIQN QFTHISMATERIALISASFOLLOWS+4~++++++++<<+++++

NOTES:SENDISE3CYSFSAR5ALLAMDTSCONSTRUCTION DEFICIENCY REPORT(iOCFR50.

55E)(DlSTRIBUTION CODEBOi9)FQRACTION:INTERNAL:

EXTERNAL:

ASSTDlRVASSALLO+4~W/ENCL

~RGd&MINER~~W/ENCLREGFIL-/ENCLW/2ENCL'QSSICK 0STAFF+4W/ENCL DIRECTORDPM4+W/ENCL QAB>>W/ENCL ADFQRENG+4W/ENCL ADFORPLANTSYSTEMS~~W/ENCL STANDARDS DEV.<~W/ENCLFERDDREISER/IE+%W/ENCL LPDRSWILI<ESBARRE.F'A~~W/ENCL TERA~~W/ENCL NSIC~~~W/ENCL ACRSCAT3>+W/ibENCLBRCIIIEFLWRN3BC<<W/ENCL LICASSTLWR03LA>+W/ENCL NRCPDR~>W/ENCL OELD44W/ENCL MIPC+~W/ENCLDEPUTYDIADPM~<W/ENCL DIRECTORDSS+4W/ENCL ADFORREACSFTY+4W/ENCL ADFORSYS8.PROJ>>W/ENCL l~SEYFRIT/IE44W/ENCL DISTRIBUTION:

LTR41ENCL4iSIZE:2P+7P4%4%%%%4M%%%%%%%W-e$44443%%dF4&%%%%%%%%%CONTROLNBR:780860144 AAlayTHEEND 1A TWONORTHNINTHSTREET,ALLENTOWN, PA.18101PHONE:(215)821-5151NORMANW.CURTISVicePresident.

Engineering 8Construction 821-5381September 18,1978Mr.BoyceH.GrierDirector, RegionIU.S.NuclearRegulatory Catmission 631ParkAvenueKLngofPrussia,Pennsylvania 17406c>3~rl'k~raPlC/IPlrn~arrl'CQ7RmCAcn~CDSUSQU12iANNA, STE2%EL'ECTRIC STATIONFINALREPORTOFADEFICIEb~

INCARRIAGEBOLTFASTEZKRS USH3ON480VOLTMOTORCONTROLCEDERBUSSPLICESDOCK"TNOS:50-387/50-388 LICENSENOS:CPPR-101/CPPR-102 ERs100450/100508

'ILE840-4'PTA-'290

earMr.Grier:Attached'is aDefinitive Reportofthesubjectdeficiency asreqLDxedby10CFR50.55 (e).OnAugust8,1978,J.D.Green,PP&LResidentNuclearQualityAssurance

Engineer, advisedMr.R.Gallo,ReactorInspector, NRCRegionI,thatPP&Lwas2ntheprocessofevaluating thergxz~bility ofthesubjectdeficiency.

Coincident withPP&L'sverbaladvisorytotheCottmission, BechtelQualityAssurance issuedYEAR-1-27 (Managanent Corrective ActionReport)requesting thatBechtelProject.Engineering makeadetermination regarding thereporta-bilityofthedeficiency.

Thedetermination, affixtrting thereportability ofthedeficiency, wasmadeonAugust23,1978ardisthebasisfortheattachedfinalreport.The.defective mater2alisbeingcontrolled andwillbecorrected.

andclosedoutunder'heprovisions ofthe'echtel QualityProgram.Pleaseadviseshouldyourequireotherinformation.

Verytrulyyours,N.W..Curtis VicePresident-Engineering

&Construt~n ARS.mcbAttachment 7gOP+Oi44'ENNSYLVANIA POWERILLIGHTCOMPANY Mr.BoyceH.GrierSeptenber 18,1978ccrcMr.J.G.Davis(15)stingDirector-Office ofInspection 6Enforcement U.S.NuclearRegulatory Qmnission Washington, D.C.20555Mr.G.McDonaM,Director(1)OfficeofManaganent Information 6ProgramControlU.S.NuclearRegulatory Cpu.ssion Washix~n, D.C.20555Mr.RobertM.GalloU.S.NuclearRegulatory Caanission P;O.Box52Shickshiany, Pennsylvaxua 18655 FINALREPORTADEFICIENCY INCARRIAGEBOLTFASTENERS USH3ON480VOLTMOXORC(MHDLCENTERTHESUSQUEHANNA.

STEM1KZCTRICSTATIOND.P.ParsonsSSESElectrical GroupSupvr.CP,~c~~I07$A.M.e-Supervising Engineer-Design-Suscpxehanna A.R.Manager-Nuclear QualityAssurance PENNSYLVANIA, PONER&LIGHTCCMPANYALLENKNNgPENNSYLVANIA SEPT1M3ER 18,1978 CARRIAGEBOLTDEFICIENCY GH480VMYIQRCONXBDLCENZERBUSSPLICES-P.O.8856-E-118 ACSUSQUl5iANNA.

STEAMEf.ECTRIC STATIONUNITS1&2 TABLEOFCONTENTSIntroduction Description oftheDeficiency AnalysisofSafetyImplications Corrective ActionConclusions Pg.1Pgs.1,.2Pgs~2g3Pgse3g4Pg.4 Thisreportispresented inaccordance withtherequirenents ofTitle10,CodeofFederalRegulationsg Part50'ection 50.55(e).Adeficiency inecpignent suppliedbyCutler-Hanrner, Inc.wasdiscovered, duringconstruction activities beingperformed attheSuscpehanna SteamElectricStation(SSES).PP&L'sA/instructor (Bechte1) ginthecourseofinstalling carriageboltswhichareusedtosplicebussectionsattheshippingsplitsof480voltnntorcontrolcenterunits,notedtheoccurrence ofseveralcasesofthreadfai1ures(stripped threads)whiletorcpiagthebolts.Thefailuresandtheircausewereassessedfartheirimpactonthesafetyof~'peration oftheplant.Baseduponanevaluation ofthesafetyimplications, BechtelEngineering hasconcluded thatthecondition isreportable under10CFR50.55(e) because,wereittohaveremaineduncorrected, thecondition couldhaveadverseaffectsonthesafeoperation oftheplant.DEK5GPTION GFTHEDEFICIENCY ThedesignofSuscpehanna Units1a2providesfor28safetyrelated.480Vabatorcontrolcenters.Duringtheinstallation ofthese480Vmntorcontrolcentersections, itwasnotedthatthe3/8"carriageboltssuppliedfor I~efastening the480Vbusspliceplateswereexperiencing randomthreadfailureswhentorquedtoappxmxnately 18ft./lbs.

1Investigation oftheseboltfailuresrevealedthefollowing facts:l.The3/8"diametercarriageboltssuppliedhyCutler-Hztaer foruseinthe480Vbussplicesweresuppliedasamixedpacketwith1/4"thickand.3/8"thicknuts.2.Theinstruction manualfurnished byCutler-Hamaer fortheinstallation ofthe480VMX'sdidnotspecifythepropercanbination offasteners tobeusedforthebussplices;therebypermitting 3/8"carriageboltstobematedwith1/4"or3/8"thicknuts.Inadd.tiOn,,

theinstruction manualdidnotprovidevaluesfortoxquingthe3/8"carriagebolts.3.Alloftheholtthreadfailureswhichweredetectedoccurredwhena1/4"thicknutwasuti1izedincanbination witha3/8"diametercarriagebolt.Cutler-Hanaier wasapprisedoftheaboveinformation, andtheyadvisedthatthecorrectsplicefastenerwasa3/8"carriageboltwithafull3/8"thicknuttorchedto18ft./lbs.

ThecarriageboltthreaRfailurehasbeendetatznined tohavebeencausedbytheundersized (1/4"thick)"jam"nuts.MALYSISOFSM.f"TYIMPLICATIONS The480VmotorcontrolsystandesignwasreviewedandthefollawLing wasconcluded fortheworstcondition, including apostulated seismicevent:Thedeficiency, whichinvolvesthe.actualstripping ofthreadsonsomeofthecarriagebolts,isconcealed bywashersandthenutsusedtofastenthebolts.Ifundetected, oruncorrected, thiscondition couldpermittingsurfaces, ofthebusandthebusspliceplatestobelooselyjoinedatapointwhichwasdesignedtoc;cry600amperesofloadcurrent.

Underload,suchlooseconnections coulddeveloparcingandoverheating whichcouldresultinafireorbusfai1ureandthelossoftheactorcontrolcenter.Inthosecaseswhereactualthreadstrippirxy hadnotocnowed,theundersized nutsmayhave,nonetheless, causedsufficient overstress onthecarriageboltsthatanincipient failureofthethreadscouldexist.Mdedforcesfranaseismiceventcouldcauseoverstressed

.boltstofail,loosening thebusjoint.Sucheventscouldresultinthesituation described inthepreceeding paragraph.

Sincethreadstripping orincipient threadstripping ofthesecarriageboltsisarareeventandcouldoccurinanyora11ofthesafeguaxds

~torcontxolcenters,thepossibility ofacaravanmodefai1ureexists.The.simultaneous lossofredundant motorcontrolcenterfeeds,whichservevitalsafetyrelatedloads,couldresultinasafetyhazardtotheoperation oftheplant.CORRECTIVE ACTIONTAKERTOCGFIRQLTHEDEFICIENT ITEMBechtelQualityContxolissuedNonconformance ReportN'o.2855on8/2/78toidentifyandcontxolthe480VYdX."s(twenty)present1y onsiteforthecarriageboltdeficiency beingreported.

BechtelQKgenerated Managanent Corrective ActionRequestNo.1-27datedAugust.7, 1978inordertoobtaindocumented evidenceofBechte1Project Engineering's evaluation ofthecauseofthecondition, thecorrective actionrequired, andthecondition's r@artability under10CPR50.55(e)

.CORRECTIVE ACTIONKORESOLVETHEDEFICIENCY Cuttler-Hamoer willreplaceallcarriageboltsandnutsusedforsplicinglinksatshippingsplitsonMCCswith3/8"boltsand3/8"thickness nutsforallMCCsalreadyinstalled, wil1replace1/4"nutswithfull-nuts (3/8")forKCsthatarenotyetinstalled, andwillutilized3/8"thicknutsforMZscurrent1y beingmanufactured.

(Thiswasdocumented ina~franCutler-HanaertoBechteldated8/28/78.)

Cutler-Hamner hasupdatedthe480VIKCinstruction booktoixmludetherecpiredtorquevalues(18ft./lbs.)

andhastransmitted arevisedinstruction manualtotheBechtelfieldforces.~CONCLUSIONS Withthereplacement ofall3/8"carriageboltsandnutsonallthebussplicesofallmotorcontrolcentersalreadydelivered totheSSESsitewithcorrect3/8"boltsand3/8"thicknuts,withthecorrecttorquingofthesefasteners to18ft.lbs.,andwithallfuturemotorcontxolcentersbeingsuppliedwithcorrecthardware, therequirements ofSpecification 8856-E-118 Revision6,Paragraph 9.2.1willhavebeenmet;thedeficiency willhavebeencorrected; andthepotential safetyhazardwi11havebeene1iminated.

TheBechtelgenerated Nonconformance Report(NCRNo.2855)willnotbecloseduntilthereisQualityControlverification thatthe480VMCCsbusspliceshavebeencompleted inaccordance withthedesignandvendorrequirements andtheatterx3ant inspections havebeenacccmplished.