ML17328A584

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LER 90-002-00:on 900108,two MSIVs Exhibited Closing Time in Excess of Tech Spec 3.7.1.5 Limit of 5 S.On 900109 & 10, Confirmed That Excessive Condensation Collected on Vent Side.Caused by Inadequate insulation.W/900209 Ltr
ML17328A584
Person / Time
Site: Cook American Electric Power icon.png
Issue date: 02/09/1990
From: BLIND A A, DROSTE J B
INDIANA MICHIGAN POWER CO. (FORMERLY INDIANA & MICHIG
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-90-002, LER-90-2, NUDOCS 9002280017
Download: ML17328A584 (12)


Text

ACCELERATEDD1BUTl0NDE}d04STATIONSYSI'EMREGULATOINFORMATION DISTRIBUTION SYSTEM(RIDS)ACCESSION NBR:9002280017

'OC.DATE:

90/02/09NOTARIZED:

NODOCKETIFACIL:50-316 DonaldC.CookNuclearPowerPlant,Unit2,Indiana&05000316AUTH.NAME'UTHORAFFILiATION DROSTE,J.B.

IndianaMichiganPowerCo.(formerly Indiana&MichiganEleBLIND,A.A.

IndianaMichiganPowerCo.(formerly Indiana&MichiganEleRECIP.NAME RECIPIENT AFFILIATION

SUBJECT:

LER90-002-00:on 900110,MSIV inoperability duetocondensate accumulation onventsideofoperating piston.W/8ltr.DZSTRZBOTZON CODE:ZE22TCOPZESRECEZVED:LTR jENCL[SZSE:TITLE:50.73/50.9 LicenseeEventReport(LER),Incidenti Rpt,etc.NOTES:RECIPIENT XDCODE/NAME PD3-1LAGIITTER,J.

INTERNAL:

ACNWAEOD/DSP/TPAB DEDRONRR/DET/EMEB9H3 NRR/DLPQ/LHFB11 NRR/DOEA/OEABll NRR/DST/SELB 8DNRRQ~R/LB8DlEGFXL02RGN3FILE01COPIESLTTRENCL111122111111111111111111~RECIPIENT IDCODE/NAME PD3-1PDAEOD/DOAAEOD/ROAB/DSP NRR/DET/ECMB 9HNRR/DET/ESGB 8DNRR/DLPQ/LPEB10 NRR/DREP/PRPB11 NRR/DST/SICB 7ENRR/DST/SRXB 8ERES/DSIR/EIB COPIESLTTRENCL11112211111122111111hDS44111111NOIR'IOALL'RICS"KXIPIBGSEXTERNALEG&GWILLIAMSESLPDRNSICMAYS,GNUDOCSFULLTXTLSTLOBBYWARDNRCPDRNSICMURPHYgGA111111RIDSDDSPIZASEHELPUSIOREVXZ%RKE!CGKPACT'IHEDOCXMWZCOWEDDESK-,LXSTSFORDOCUMEMIS YOUDC%ITNEED!FULLTEXTCONVERSION REQUIREDTOTALNUMBEROFCOPXESREQUIRED:

LTTR35ENCI35 IndianaMichiganPowerCompanyCookNuclearPlantP.O.Box"58.Bndgman.

Ml'91066164655901INDIANANICHIGANPOWERFebruary9,1990UnitedStatesNuclearRegulatory Commission

.Document ControlDeskRockville, Maryland20852Operating LicenseDPR-74DocketNo.50-316DocumentControlManager:Inaccordance, withthecriteriaestablished by10CFR50.73entitledLicenseeEvent,ReortinSystem,thefollowing reportisbeingsubmitted:

90-002-00 Sincerely, A.A.BlindPlantManagerAAB:clwAttachment ccD.H.Williams, Jr.A.B.Davis,RegionIIIM.P.AlexichP.A.BarrettJ.E.BorggrenR.F.KroegerNRCResidentInspector J.G.Giitter,NRCR.C.CallenG.Charnoff, Esg.DottieSherman,ANILibraryD.HahnINPOS.J.Brewer/B.P.

Lauzau@00224<00/7

+00209PDRADOCI0<00031bPDr:

NRCFORM366(689)U.S.NUCLEARREGULATORY COMMISSION LICENSEEEVENTREPORTILER)APPROVEDOMBNO.31504104EXPIRES:4/30/92ESTIMATED BURDENPERRESPONSETOCOMPLYWTHTHISINFORMATION COLLFCTION REQUEST:50.0HRS,FORWARDCOMMENTSAEGARDING BURDENESTIMATETOTHERECORDSANDREPORTSMANAGEMENT BRANCH(P630),V.S.NUCLEARREGULATOAY COMMISSION, WASHINGTON, DC20555.ANDTOTHEPAPERWORK REDUCTION PROJECT(31500104).

OFFICEOFMANAGEMENT ANDBUDGET,WASHINGTON, OC20503.FACILITYNAME(I)D.C.CookPlant-Unit2DOCKETNUMBER(2)PAE050003161OF1"PTITLE<<IMainSteamIsolation" ValveInoperaiity-DuetoConensateAccumulation onVentSideofOperating PistonEVENTDATK(5)LERNUMBER(41REPORTDATE,(7)OTHERFACILI'TIES INVOLVED(4)MONTHDAYYEARYEARSEQUENTIAL NVMSEtlreIIEVISION NVMSEIIMONTHOAYYEARFACILITYNAMESCookPlant-Unit1DOCKETNUMBER(SI 05000315011090900020002099005000OPERATINGMODEIS)3POWERLEVELppp20.402(SI 20.4051~I(lI(ll20406(~)(1)(lll20.405(~I(II(IIl)20.406(el(II(NI 20.405(~l(l)(vlX20.405(c) 50.34(cl(l I50.34(cl(2)60.73(el(2)(I)60.73(e)(2)(S) 50.73(el(2)Ill))LICENSEECONTACTFOATHISLER(12I50.73(el(2)(lv) 50.73(el(2llv)'0.73(el(2)(vSI

.50.73lel(2)(vSI)(AI

'0.73(e)12)(el)I I(5)50,73(~I(2I(eITHISREPORTISSUBMITTED PURSUANTT0THEREQUIREMENTS OF10CFR('):(Cntceontormortotrntlottowrnd)

(1173.7)(S)73.71(c)OTHKR(SptcrryinAprtrtctStrowtndinTerI,HRCForm3ddAINAMEJ.B.Droste--Technical Engineering Superintendent AREACODETELEPHONE NUMBER616465-5901COMPLETEONE(.INEFOAEACHCOMPONENT FAILUREDKSCRIBED INTHISREPORT(13)CAUSESYSTEM\'COMPONENT MANUFACTVREREPORTABLE TONPRDSCAUSESYSTEMCOMPONENT MANUFACTVRERBSBVTVX999.Y'Prr.,~4.NXrr.r..SUPPLEMENTAL REPORTEXPECTED(14)YEStttytr,comprtrtFXPECFEDSVSMISSION DAFEIXABS'TAACT tLimrtrott00Iptctt,r,t.,tpprorimtttiy trttttntin(littoterryptwrirttn tmttt(14)FXPECTED'UbMISSION DATE(ISIMONTHDAYYEAROnJanuary8,1990withUnit2inMode3-(HotStandby)surveillance testingoftheMainSteamIsolation Valves(MSIV's)wasconducted.

TwoMSIV'sexhibited aclosingtimeinexcessoftheTechnical Specification 3.7.1.5limitoffiveseconds.Thiscondit'ion isbelieved.tohave,existedduringpoweroperation.

Additional MSIVtestingonJanuary9,and10,1990confirmed thatexcessive condensation wascollecting ontheventsideoftheMSIVoperating piston.Whenthedumpvalveswereopenedtovent-offsteamfromtheMSIVoperating piston,theaccumulated condensate wouldflashtosteamandresultinincreased MSIVclosuretimes.Following anefforttoblowouttheMSIVcondensate draintubes,aseriesoftestswereperformed atvarioustimeintervals.

todetermine ifthecondensate problemhadbeenresolvedandverifyMSIVoperability.

Withthefailureof2-MRV-220 onJanuary11,1990,at0916hours,itwasevidentthatthecondensate p'roblemwasstillpresent.AllMSIV'sweredeclaredinoperable.and anUnusualEventwasdeclared.

AcooldowntoMode5(ColdShutdown) wasstarted.Repairactivities includeddisassembly oftheMSIV'stoenlargethecondensate draintubeportandtheequalizing steamnipple.Additional insulation wasplacedontheMSIV's,ventpipingandvalves.NRCForm366(669)

NRCFORM366A(6J)9)V.S.NUCLEARREGULATORY COMMISSION LICENSEEEVENTREPORT(LER)TEXTCONTINUATION" APPROVEDOMBNO.31500)OSEXPIRES:S/30/92ESTIMATED BURDENPERRESPONSETOCOMPLYWTHTHISINFORMATION COLLECTION REQUEST:50.0HRS.FORWARDCOMMENTSREGARDING BURDENESTIMATETOTHERECORDSANDREPORTSMANAGEMENT BRANCH(P430).U.S.NUCLEARREGULATORY COMMISSION, WASHINGTON, OC20555.ANDTOTHEPAPFRWORK REDUCTION PROJECT(3(500104).

OFFICEOFMANAGEMENT ANDBUDGET.WASHINGTON, OC20503.FACILITYNAME(1)DOCKETNUMBER(2)YEARLERNUMBER(6)SEQVENTIAL NVMEERREVISIONNVMSERPAGE(3)-D.C.CookPlant-Unit2TEXT///morespeceiereqvirN/.

Irse~HRC%%drm3(SEA's/(12)osooo316900020000CONDITIONS PRIORTOOCCURRENCE Unit2inMode3(HotStandby).

DESCRIPTION OFEVENTOnJanuary8,1990,surveillance testingoftheMainSteamIsolation Valves(MSIV'-s)

(EIIS/SB-ISV) wasconducted.

TwooftheMSIV'sexhibited aclosingtimeinexcessoftheTechnical Specification 3.7.1.5limitoffiveseconds.Following eachMSIVfailure,theMSIVwasdeclaredinoperable andimmediately retested.

Inbothcasestheretestdemonstrated thevalveclosedwithintheTechnical Specification timelimitandthe,MSIVwasdeclaredoperable.

Additional testswereconducted onJanuary9,1990.Asubstantial amountofwaterwasobservedtoflashoutofthedumpvalve(EIIS/SB-VTV) ventstacksduringthefirst'est ofeachMSIV.ThreeMSIV's.exhibited aclosingtimeinexcessoftheTechnical Specification 3.7.1.5limitoffiveseconds.Following eachMSIVfailure,theMSIVwasdeclaredinoperable andretested.

In-eachcasetheretestdemonstrated thevalveclosedwithintheTechnical Specification timelimitandtheMSIV'sweredeclaredoperable.

(Seeattachedtesttable).TheJanuary9,1990testingverifiedthatenoughcondensation couldaccumulate ontheventsideofthepistonwithina24hourperiodto'enderthevalveinoperable.

Unit2washeldinMode3tofurtherdiagnosetherootcauseofthisissue.5Sec.6Sec.TIMECONTROLROOMSWITCHACTUATION TOLIGHTMSIVSTEMTRAVELOnJanuary10,'1990,aseriesofdiagnostic testswereperformed todetermine theextentthatcondensate withintheMSIVoperating cylindervolumecouldaffectMSIVstroketime.Astripchartwasusedtorecordpressurewithinthevolumeasafunctionoftime.Closuretimewasmeasuredinthecontrolroom,measuring thetimefromthedumpvalveswitchactuation untiltheMSIVvalvelightindicated thevalvewasclosed.MSIVstemtraveltimewasmeasuredlocally.Thefollowing time.lineissimilartoeachMSIVtestedandrepresents typicalcircumstances experienced byallMSIV's.01Sec:2Sec.3Sec.4Sec.FLASHINGrNRCForm366A(669)

NRCFORM355A~)549)U.S.NUCLKARREGULATORY COIAMISSION LICENSEEEVENTREPORTILER)TEXT.CONTINUATION APPROVEDOMSNO.31504104EXPIRES.4/30/92ESTIMATED bURDENPERAESPONSETOCOMPLYWTHTHISINFORMATION COLLECTION REQUEST)500HRS.FORWARDCOMMENTSREGARDING SURDENESTIMATETOTHERECORDSANDREPORTSMANAGEMENT SRANCHIP430).U.S.NUCLEARREGULATORY COMMISSION.

WASHINGTON.

OC20555,ANDTO1HEPAPERWORK REDUCTION PAO/ECT13150410i)i OFFICEOFMANAGEMENT ANDSUDQET,WASHINGTON.

DC20503.FACILITYNAMEl1)DOCXETNUMSER(21LERNUMSERIS)~AGE13)D,C.CookPlant-Unit2TEXT///verePPPCP)I/Pquia/,MPP//I/bbP//YRC

%%dnt)30SA'P/)IT)osooo316YEAR9.0SEQUENTIAL NUMKll@002.'-REVISIONNUM9II000OF10Localobservation verifiedsubstantial quantities ofwaterandsteambeingdischarged fromtheventstackfromT0untilMSIVstemtravelbegan.TwooftheMSIV'sexhibited aclosingtimeinexcessoftheTechnical Specification 3.7.1.5limitoffiveseconds.'Following eachMSIVfailure,theMSIVwasdeclaredinoperable andretested.

Ineachcasetheretestwasanacceptable valueandtheMSIVwasdeclaredoperable(seeattachedtesttable).TheActionRequirements ofTechnical Specification 3.7.1.5werefulfilled atalltimesforModes2and3.WhenanMSIVfai'lureoccurred, animmediate retestdemonstrated thatthevalvewasoperable.

OnJanuary10,1990,itwasrealizedthatthefailureswhichoccurredonJanuary8,1990,werebelievedtohaveexistedduringpoweroperation.

Notification totheNRCwasmadeonJanuary10,1990,reporting thatwewereoutsidetheplants'esign basesonJanuary-8,1990.Atthetimethisnotification wasmade,theMISV'swereoperableperTechnical Specification ActionRequirements forModes2and3operation.

TheMSIV'swereoperablesincethetestingresultedinexpelling thecondensate, fromtheventsideofthevalve'soperating piston.TheMSIV'swouldremainoperableaslongasthevalveswerecycledfrequently enoughtdpreventexcessive amountsofcondensate fromcollecting ontopoftheoperating piston.~TheMSIVtestingconfirmed thattheslower,mainsteamstopvalvestroketimesweresymptomsofanunacceptab1e quantityofcondensate accumulating intheuppervalvevolume;Whenadumpvalveisopenedthecondensate flashestosteam'thiscausesincreased ventingtimeduetodelayingthedevelopment ofsufficient Delta-PacrosstheMSIVpiston,toclosetheMSIV's.A"logical hypothesis wasformulated thatcondensate was'notdrainingdownintothelowervolumethroughthedraintube(seeattacheddrawings) fastenoughtopreventaccumulation intheuppervolume.Actingunderthepremisethatthisflowpathwasinsomewayrestricted, possiblyduetomineraldepositsplatingoutontheinsidediameterofthedraintube,itwasdecidedtoattempttoblow-outthisdraintube.Aprocesswasdevisedtoremove(blow-out) anypossiblerestrictions locatedwithineachMSIVdraintubes.Thiswasaccomplished bymaintaining theMSIVinitsclosedpositionandforapproximately onehourwiththedumpvalvesopen.In'doingso,mainsteamwascapableofforcingitswaypasttheparallelclosuredisc,throughthedraintubeintotheuppervolume,andexhausted outtheventstack.,Itwashopedthatthisexhausted steamwouldbeofsufficient velocitytocarryawayanyrestrictive material.

NACForm395A1509)

NRCFORMSSSAISeS)tU.S.NUCLEAAREGULATORY COMMISSION PLICENSEEEVENTREPORTILER)TEXTCONTINUATION APPAOVEDOMSNO.S)504104E)IPIRES:S/20/02ESTIMATED BURDENPERRESPONSETOCOMPLYWTHTHISINFORMATION COLLECTION REOUESTI50.0HRS.FORWARDCOMMENTSREGARDING BURDENESTIMATETOTHERECORDSANDREPOATSMANAGEMENT BRANCHIPe30).U.S.NUCLEARREGULATORY COMMISSION, WASHINGTON, DC20555,ANDTOTHEPAPERWORK REDUCTION PRO/ECT121504)OS).

OFFICEOFMANAGEMENT ANDBUDGET,WASHINGTON, OC2050KIrACILITY NAME)1)DOCKETNUMBER)2)LERNUMBERIS)PAGEIS)D.C.CookPlant-Unit2TEXTlllmore<<eoe/ereevrw/,ow//r/orO///RC%%dnIISSSAB/)12)osooo'316YEAR4g90sEovsNTIAL oENVMSSR002IISVISION NVMSN0004.OF10Additional testingwasperformed todetermine ifthemaintenance actionwassuccessful andensure.MSIVoperability.

Thisseriesoftestshadstaggered

'estintervals toensureMSIVoperability w'asmaintained.

OnJanuary11,1990,at0916hours,2-MRV-220 exceededtheallowedclosingtime.AnUnusualEventwasdeclaredasallfour(4)MSIV'sweredeclaredinoperable causingaTechnical Specification 3.0.3shutdown.

Thiswasclassified asa'One-Hour

,Reportable EventandNRCnotification wasmadeat0930hours.AcooldowntoMode5(ColdShutdown) wascommenced.

CAUSEOFEVENTInvestigation revealedthatthefailureof'heMSIV'swascausedbyexcessive condensate accumulation ontheventsideoftheMSIV'operating piston.Theexcessive condensate accumulation wasaresultofthefollowing contributing factors:Insulation LessthanCurrentDesin-Insulation onMSIV,theventpipingandassociated valveswaslessthancurrentdesignspecifications.

Theinsufficient insulation resultedinincreased condensation ratesintheMSIV.2.DumValveSeatLeakaeThequantityofcondensate thatcancollectisrelatedtothemassofsaturated steampermitted toentertheupperequalizing steamvolume.Whensteamisallowedtoescapethisvolume,itwillbereplacedbyadditional saturated steamwhichincreases theDelta-Pandpreventsdrainage.

3.MSIVActuatorDesinThecombinedeffectsofoneandtwoaboveresultedinincreased condensation rates,developing greaterDelta-Pacrosstheoperating pistonthanassumedbydesignduringnormaloperation (MSIV'sinsteady-state openposition).

Therateatwhichcondensate canflowdownfromtheuppervolumethroughthedraintubeislimitedbythediameterofthedraintubeportholes.Condensate willaccumulate withintheupperequalizing volumeifitcannotbedrainedfasterthanitforms.Ifthesteamnippleisinsufficiently sized,aDelta-Pwillexistacrossthepistonrestricting condensate drainage.

NRCFomrSSSAISeS)

NRCFORM355AISJ)91US.NUCLEARREGULATORY COMMISSION LICENSEEEVENTREPORT(LER)TEXTCONTINUATION APPROVEOOM8NO,3150010>>EXPIRES:>>/30/92ESTIMATED 8UROENPERRESPONSETOCOMPLYWTHTHISINFORMATION COLLECTION REOUESTI50.0HRS.FORWARDCOMMENTSREGARDING 8URDENESTIMATETOTHERECORDSANDREPORTSMANAGEMENT SRANCHIP430).U.S.NUCLEARsREGULATORY COMMISSION, WASHINGTON, DC20555,ANDTO1HEPAPERWORK REDUCTION PROJECT13150010l).

OFFICEOFMANAGEMENT AND8UDGET,WASHINGTON, DC20503.FACILITYNAME111D.C.CookPlant-Unit2TEXT////>>P/>><<eC>>/1I>>qvnd,uJePI/P5/>>/HJICfcnn38559/)12)DOCKETNUMSER12)os0oo316YEAR90LERNUMSER15),>>jjSEOVENTIAL yg:AEVOONHVM5<<<~+HVM002-00~AGE13)050F10ANALYSES, OFEVENTInadditiontoTechnical Specification 3.7.1.5,slowMSIVclosuretimesaffectTechnical Specification items3.3.2.1,Table3.3-5,5.h(HighSteamLineFlow-LowLowTavg),6.h(SteamLinePressureLow),and7.c(Containment Pressure-High High).Theseitemsusethevalveclosuretimeaspartoftheiroveralltimeresponserequirement.

Examination ofsurveillance datafortheseitemsshowthatitem7.c,steamlineisolation onhigh-high containment pressureinsevenseconds,wouldnotbemet.ThiswasreportedtotheNRConJanuary10,1990,undertheprovisions of10CFR50.72.b.l.ii.B asacondition thatwasoutsideoftheplant'sdesignbasis.Theinvestigation ofthisproblemhasidentified thattheslowerclosuretimeswerecausedbywateraccumulation onthetopofthesteampiston.Withwaterpresent,thepistonmovementisslowedasthewaterflashestosteamduringtheventingprocess.Thewater.accumulation occursovertimeandisalsoaffectedbytheleakagepasttheMSIVdumpvalves.Oncethewaterisremovedfromthetopofthepiston,aswouldoccurduringavalvetest,.aretestconducted immediately thereafter wouldindicatenormalva3veactuation times.Aswaterwouldaccumulate duringoperation, thereisevidencethatthecondition mayhaveexistedpriortothesurveillance.

Thus,itisprobabl'e thatTechnical Specification 4.7.1.5.1 wasnotmet.Westinghouse hasevaluated theconsequences ofincreasing allapplicable Technical Specification responsetimesbythreeseconds,andtheyhaveconcluded thattheFSARacceptance criteriaaremetusingthelongerresponsetimes.Themassandenergyreleasesforanoutsideofcontainment steamlinebreakwerecomparedwiththecurrentFSARvalues,andthe'nvironmental qualification oftheequipment intheaffectedlocations hasnotbeencompromised.

Thus,therehasbeennosignificant degradation ofplantsafetyasaresultoftheincreased MSIVclosuretimes.SinceUnit1hasthesametypeofvalve,anevaluation wasalsoperformed concerning the'impacton.Unit1.Theevaluation concluded thattheMSIV'son,Unit1areconsidered tobeoperableandfullysupportive oftheChapter14accidentanalyses.

Atthelastsurveillances, allTechnical Specifications applicable tosteamlineisolation weremet,andthehistorical dataindicatenopatternofclosuretimedeterioration.

Further,therecentWestinghouse analysisshowsthatsufficient marginexistswithMSIVclosuretimesuchthatplantsafetyisnotcompromised ifthe'system responsetimeisincreased bythreeseconds.Thus,therecenteventsassociated withtheUnit2MSIV'sdonotcauseundueconcernwithrespecttothecontinued safeoperation ofNRCFons355A(5891 NRCFORM344A~14e9)U.S.NUCLEARREGULATORY COMMISSION LICENSEEEVENTREPORTILER)TEXT.CONTINUATION APPROVEOOMSNOl31500)0O ExpIREs:el30)92ESTIMATED BURDENPERRESPONSETOCOMPLYWTHTHISINFORMATION COLLECTION REOUEST:50.0HRS.FORWARDCOMMENTSREGARDING BURDENESTIMATETOTHERECORDSANDREPORTSMANAGEMENT SRANCH(P430).U.S.NUCLEARREGULATORY COMMISSION, WASHINGTON.

DC20555,ANDTOTHEPAPERWORK REDUCTION PROJECT131504)104),

OFFICEOFMANAGEMENT ANDSUOGET.WASHINGTON.

DC20503.FACILITYNAME11)DOCKETNUMSER12)YEARLERNUMSER(4)rX<OSEQUENTIAL

?P~WIIEYISION NVMFEAi.rXNVMI'AGE13)D.C.CookPlant-Unit2TEXTNmorea>>ooJrreqond,Irreorroeo'oner HRCformSOD'e))12)osooo31690-002-0006oF10Unit1.Thisconclusion isals'obasedonthebeliefthatthepresentperformance oftheUnit1MSIV'sdonotresultintheprobability orconsequences ofanaccidentbeingincreased, anynewtypeofaccidentbeingcreated,andanyTechnical Specification marginofsafetybeingreduced.CORRECTIVE ACTIONSUponreachingMode5,allfourMSIV'sweredisassembled andavisualexamination performed.

Theseexaminations revealedthatthedraintubeshadnotexperienced anyphysicaldegradation thatcouldhaverestricted thecondensate flowpath.Alldimensions wereverified.

ElectricITEdeFrance(FDF)wascontacted concerning theirapproachatresolving similarcircumstances.

EDFprovidedtheirinvestigation findingsandvalvedesignmodifications.

Weimplemented theEDFrecommendations.

Afterallavailable sourcesofinformation weretechnically evaluated, itwasdetermined thatallUnit2MSIV'swouldbemodifiedviaMinorModification 2-Mf-079.

Underthismodification thediameterofdraintubeportholeswouldbeincreased from1'/8"(0.125")to5mm(0.197")andthediameteroftheequalizing steamnipplewouldbeincreased from1/8"(0.125")'o 10mm(0.394").

Twoperformance relatedfunctions wouldbeimprovedinthismanner.l.Increasing thesizeofthedraintubeportholesprovid'es alargerareatoimprovecondensate flowthroughtheactuatorpiston.2.Increasing thesizeoftheequalizing steamnipplewillprovidealessrestrictive pathforsteamtopassupthroughthepistontomaintainequilibrium andpreventsteamfrompassingthroughthedraintubeandinhibitdrainage.

Itwasalsodiscovered atthistimethattheinsulation ontheMSIV,ventpipingandassociated valveswaslessthanthecurrentdesignspecification requirements..

Thiscontributed toalargervarianceintemperature (Delta-T) resulting inmoreheattransferandincreasing thecondensation rate.Aftercompleting allmodifications andreassembling the,MSIV's, SpecialProcedure 2-THP.SP.MM-079 wasusedtoverifyoperability.

Thisprocedure includedaseriesoftestcyclesforallMSIV'satdifferent intervals withtheappropriate instrumentation requiredtomeasureandrecordallapplicable performance variables, specifically therateofpressuredropintheventline.NRCForm344AI5$9)P NRCFORMSSSA(5JISIU.S.NUCLEARREGULATORY COMMISSION LICENSEEEVENTREPORT(LER)TEXTCONTINUATION APPROVEDOMSNO.S1500104EXPIRES:A/SO/52ESTIMATED SUROENPERRESPONSETOCOMPLYWTHTHISINFORMATION COLLECTION REQUEST:500HRS.FORWARDCOMMENTSREGARDING SURDENESTIMATETOTHERECORDSANDREPORTSMANAGEMENT SRANCHIP5201.U.S.NUCLEARREGULATORY COMMISSION, WASHINGTON.

DC20555.ANDTOTHEPAPERWORK REDUCTION PROJECT(S(5041(M).

OFFICEOFMANAGEMENT ANDSUDGET,WASHINGTON, OC20502,FACILITYNAME(1)DOCKETNUMSER(21YEARLERNUMSER(5)YP>',SSQVSNTIA'L NVMSllII5YISIONNVMSA~AGELSID.C.CookPlant-Unit2TEXTIIImcmapeceJIIPSw'wI,PPPaAWonVHRCRPmI~SI(12(oso0031690002I-00070F10Theacceptance criteriausedwithin'2-THP.SP.MM-079 wastwofold.First,eachfullclosurestroketimemustbewithin5secondsinaccordance withTechnical Specification 3.7.1.5.Second,therateofpressure, dropintheventlinemustnotchangeasthetestintervalisextendedto24hours.Thissecondcriteriawasusedtoverifynoadditional condensate hadaccumulated withintheuppersteamvolumethatcouldlengthenstroketimeanddelaystemtraveluponflashingtosteamduringtheventingprocess.Allstroketestsperformed inaccordance with2-THP.SP.MM-079, exceptthefirsttestonMRV-210,provided.acceptable resultsandverifiedthegenericcondensate issue.hadbeenresolved; Theiniti'altestperformed onMRV-210failed.Thecorresponding rateofpressuredropintheventlinesignature verifiedsignificant quantities ofcondensate stillpresent.Investigation

.revealedthatTrainBDumpValveMRV-212wasnotse'stingproperlypermitting asignificant amountof-steamtobeexhausted outtheventstack.Underthesecircumstances, additional steamwasbroughtintotheuppervolumewithcondensate collecting ataratefasterthancouldbedrained.MRV-212wasrepairedandsubsequent closuretestscompleted onMRV-210verifiedthatthis.isolated incidenthadbeenresolved.

AllMSIV'swerereturnedtoanoperablestatusandUnit2returnedtopoweroperation.

Asstatedintheanalysis, wedonotexpecttoencounter similardifficulties withtheUnit1MSIV's.However,wearecurrently addinginsulation totheUnit1MSIV's,ventlinesandvalvestoenhancetheMSIVoperating conditions.

IFAILEDCOMPONENT IDENTIFICATION Component ID:MainSteamIsolation Valves2-MRV-210, 2-MRV-220, 2-MRV-240 Manufacturer:

Hopkinsons

-FerrantiModel:2379WPREVIOUSSIMILAREVENTS050-316/83-57 NRCFormSSSA(SSSI NRCFORM344A<Se9)LICENSEEEVENTREPORT{LERITEXTCONTINUATION t~APPROVEO 0MBNO.31500104EXPIRES)4/30/93 ESTIMATED SURDENPERRESPONSETOCOMPLYWTHTHISINFORMATION COLLECTION RFOUESTI500HRS.FORWARDCOMMENTSREGARDING SURDENESTIMATETOTHERFCORDSANDREPORTSMANAGEMENT BRANCHIPS30),U.S,NUCLEARREGULATORY COMMISSION, WASHINGTON, DC30555,ANDTOTHEPAPERWORK REDUCTION PROJECT131504))041-OFFICE OFMANAGEMFNT ANDSUDGET,WASHINGTON.

DC30503.fACILITYNAMEIl)DOCKETNUMSER)3)YEARLERNUMSER)4)SCOVCNTIAL NVMCRIICVISION NVMCA~AGE13)D.C.CookPlant-Unit2TEXTlllmorpgfdcglgnqvssd,we~HRCJtgwiiSRSC'4)(17)oeo0o316900020008oF10MAINSTEAMISOLATION VALVETESTTABLEJanuar8,1990TestinVALVEINITIALCLOSINGTIME(SEC)RETEST(SEC)2-MRV-210

=2-IIRV-240 5.945.183.011.95'Januar~9,1990Testin2-MRV-210 2-MRV-220 2-MRV-240 5.075.605.05"2.832.282.21Januar10,1990Testin2-MRV-210 2-MRV-220 5.785.733.082.55'anuar11,1990Testing2-MJRV-220 5.26NoRetestPerformed NOTE:Duringthetestprogram2-HRV-230 closingtimeswerehigh,hut'didnotexceedtheTechnical Specification LimitoffiveSeconds.NRCFoIIm344A144)9)

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WASHINGTON.

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