ML18030A167

Final Deficiency Rept Re Cracks in Limitorque Limit Switch Rotors Originally Reported 800923.Caused by Misalignment in Holes in Limit Switch Rotor & Pinion Shaft.Cracked Rotors Will Be Replaced

ML18030A167
Person / Time
Site:	Susquehanna
Issue date:	11/19/1980
From:	CURTIS N W PENNSYLVANIA POWER & LIGHT CO.
To:	GRIEF B H NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
10CFR-050.55E, 10CFR-50.55E, PLA-575, NUDOCS 8011250293
Download: ML18030A167 (6)

Text

ACCESSIONNBR:FAGIL:5038750"388AUTHINANECURTIS',ri~RECIP~NAMEGRIEF,B,H,REGUIATORYINFORMATIONDISTRIBUTIONSYSTEM(RIDS)801.1280298~DDC.DATE:80/11/19NDTAIOED:NDDDCKEiT0SusquehannaSteamElectric.StationiUnitirPennsylva'58SusquehannaSteamElectricStation~Unit2iPennsylva0500038AUTHORAFF1IL1IATIONPennsylva'nia-Power8LIightCo;RECIPIENTAFFILIATIONRegion1r=-PhiladelphiaEOfficeoIftheDirector

SUBJECT:

Finaldeficiencyreptrecracksin1imitorquelimitswitchrotorsoriginallyreported800923perteammtglastwk,CausedbymisalignmentinholesinlimitswitchrotorLpinionshaft~Crackedrotorswi11berepla'ced-..DISTRIBUTIONCODE':B019SCOPIESRECEIVED:L1TR+ENCL<+TITLE:Cons'truct,ionDeficiencyRepoft(10CFR50.55EONOTES:SendI8E"3copiesFSAR8allamends,SendILK"3copiesFSAR8allamends.0500038705000388REC'IPIENTIDGODET/NAME>ACTION:A/DL1ICENSNG-04'USHBROOKgM~ObINTERNAL:AD/RCI/IEl17ASLBP/J~HARDEDO8STAFF'9HYD/GKOBR22LICQUALIBR12NRCPDR02PROC/TSTREV13L01OSDEV-21COPIESLiTTRENCL1-1111111111-11111111111RECIPIENTI'DCODE/NAME0YOUNGBLOODrB05STARKgR~07AEOD18D/DIRHUMFAC15EQUIPQUAl.lBR11ILK<09MPA20OELD21QABR14RUTHERFORDH~IECOPIESLTTRENCLl11111111111111EXTERNAL):ACRSNSIC1608161611LPDR03<Oi/2t'9go't2.TOTALNUMBEROFTCOP~IESREQUIRED;L'TTR~ENCL(

n1r TWONORTHNINTHSTREET,ALLENTOWN,PA.1EI01PHONEr(215)821-5151biit-ir',i~~g"'ORMANtlV.CJRTISVicePresibent-EngineeringttConstruction-Nuclear821-538INovember19,1980SMttiDV$4,pt,~pg~,USZVC~t"Trtr'IJJIIPPPEgygESkgiIttt(gf19406Mr.BoyceH.GrierDirector,RegionIU.S.NuclearRegulatoryCommission631ParkAvenueKingofPrussia,PennsylvaniaSUSQUEHANNASTEAMELECTRICSTATIONFINALREPORTOFADEFICIENCyRELATINGTOLIMITORQUELIMITSWITCHROTORSERs100450/100508FILES840-4/900-10PLA-575

Reference:

PLA-547datedSeptember23,1980

DearMr.Grier:

ThisletterservestoprovidetheCommissionwithafinalreportogadeficiencyrelatingtodefectiveLimitorauelimitstitchrotors.Theconditionwasoriginallyreportedintheabavereferencedletter.Theinformationcontainedhereinissubmittedir.conpliancetotheprovisionsof10CFR50.55(e).TheattachmenttothislettercontainsacKescriptionofthedefect,itsprobablecause,safetyimpactandsignificazcealongwithacorrectiveactionplan.Theconditionisbeingcontrolled@neerBechtelNonconformanceReport56020andactionforUnitIisscheduled=orcompletionbyApril,1981.WetrusttheCommissionwillfindtheinforrationforwardedbythislettertobesatisfactory.Verytrulyyours,N.W.CurtisVicePresident-Engineering6Construction-NuclearAttachmentFLW:mcbgoiV5i/013R50Ã9PENNSYLVANIAPOWER5LIGHTCOMPANY Mr.BoyceH.GrierNovember19,1980cc:Mr.VictorStello(15)Director-OfficeofXnspection6EnforcementU.S.NuclearRegulatoryCommissionWashington,D.C-20555Mr.-G.McDonald;DirectorOfficeofManagementInformation6ProgramControlU.S.NuclearRegulatoryCommissionWashington,D.C.20555Mr.RobertM.GalloU.S.NuclearRegulatoryCommissionP.O.Box52Shickshinny,Pennsylvania18655 SUBJECTLimitorqueLimitSwitchRotorsDESCRIPTIONOFPROBLEMThelimitswitchesontheLimitorqueValveoperatorsarevalvepositionswitches,whichareusedforthecontrolofthevalveoperatorandforindicationofvalveposition.Thelimitswitchassemblyconsistsoftwostationaryfingerswithamovingcontactbetweenthefingers.Themovingcontactispartofthelimitswitchrotorwhichisgeareddirectlytothevalveoperator.Thelimitswitchrotorismadeofaphenolicmaterialandispinnedtoametalpinionshaft.Asthevalveoperates,thelimitswitchrotorturns,rotatingthemovingcontact,therebyopeningorclosingthelimitswitchcontact.DuringthepreoperationalcheckoutoftheLimitorqueValveoperators,crackswerefoundinthelimitswitchrotorwhereitispinnedtothepinionshaft.~CAUSEInitially,itwasbelievedthattherotorcrackswerecausedbyamisalignmentintheholesinthelimitswitchrotorandthepinionshaft.Whenthepinwas'nsef:tedthroughtheholesduringmanufacturing,itwaspostulatedthatthecrackingcouldhaveoccurred.Limitorquewasrequestedtoreviewtherotorcrackingproblemanddetermineifitoccurredduringmanufacturing.Limitorquerespondedstatingt~itwasnotpossibleforthecrackingtohaveoccurredviaamisalignmentintheholes.Duringmanufacturing,therotorsweremoldedwitha3/32"diameterhole.Therotorwasplacedonanundrilledpinionshaft.A1/8"diameterholewasdrilledsimultaneouslythroughtherotorandpinionshaft,usingthe3/32"holesasaguide.Thepinwastheninserted.Misalignmentoftheholes,whichcouldcausetherotorcracking,hasnotbeenaproblemunderthismanufacturingprocess.Thecrackswereprobablycausedbyconstmctionpersonnelbumpingthelimitswitchrotor,whenthevalvecompartmentcoverwasremoved.Afieldinspectionofsixty(60)Unit2valveoperatorshasbeenperformed.TheUnit2'alveswereinspectedsincethereislessconstructionactivitiesassociatedwiththesevalves.Ofthesixtyvalvesinspected,onlyone(1)brokenrotorwasobserved.However,therehavebeennumerousbrokenrotorsidentifiedonUnit1valves.Thistendstoconfirmthatthecrackedrotorswerecausedbyconstructionpersonnel,1ANALYSISOFSAFETYIMPLICATIONSThelimitswitchesareusedforthecont"olofthevalveoperatorandforindicationastovalveposition.Adefe"tivelimitswitchrotorwouldresultinthefailureofavalvetooperateand/orincorrectindicationofthevalveposition.PPaLEngineering.hasdeterminedthatthefailureofalimitswitchrotorisareportabledeficiencyundertherecgxirementsof10CFR50.55(e).TheaffectedLimitorqueoperatorsareusedinmanysystemswhicharerequiredforthesafeshutdownofthe'plant.AttachmenttoPLA-575Page1of2 CORRECTIVEACTIONAninspectionofallsafetyrelatedvalvesonUnitland2willbeperformed.TheinspectionoftheUnit2valveswillbedoneafterallmajorconstructionactivitiesassociatedwiththevalveoperatoriscompleted.Crackedrotorswhichareidentifiedwillbereplaced,andtrackedbyBechtelNCR6020.CONCLUSIONOncetheinspectionoftheLimitorcpxeoperatorsisccxnpleteandallcrackedrotorsarereplaced,failureofthelimitswitchrotorisnotexpectedtooccurnorwilltheLimotorqueoperatorbepreventedfromperformingitsintendedfunction.Attachment,.toPLA-575Page2of2