ML17328A524
| ML17328A524 | |
| Person / Time | |
|---|---|
| Site: | Cook  |
| Issue date: | 12/29/1989 |
| From: | ALEXICH M P INDIANA MICHIGAN POWER CO. (FORMERLY INDIANA & MICHIG |
| To: | MURLEY T E NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML17328A525 | List: |
| References | |
| AEP:NRC:0900H, AEP:NRC:900H, NUDOCS 9001090184 | |
| Download: ML17328A524 (21) | |
Text
ACCELERATED DISTRIBUTION DEMONSIRQION SYSFEMREGULATORY INFORMATION DISTRIBUTION SYSTEM(RIDS)IACCESSION NBR:9001090184 DOC.DATE:
89/12/29NOTARIZED:
NODOCKETFACIL:50-315 DonaldC.CookNuclearPowerPlant,Unit,1,Indiana&05000315.50-316DonaldC.CookNuclearPowerPlant,Unit2,Indiana&05000316AUTH.NAMEAUTHORAFFILIATION ALEXICH,M.P.
IndianaMichiganPowerCo.(formerly Indiana&MichiganEleRECIP.NAME RECIPIENT AFFILIATION RMURLEY,T.E.
OfficeofNuclearReactorRegulation, Director(Post870411,I
SUBJECT:
Application foramendstoLicensesDPR-58&DPR-74,modifying TechSpecs3/4.6.5.1
&3/4.6.5.3.
DDISTRIBUTION CODE:A001DCOPIESRECEIVED:LTR ENCLSIZE:TITLE:ORSubmittal:
GeneralDistribution NOTESRECIPIENT IDCODE/NAME PD3-1LAGIITTER;J.
INTERNAL:
NRR/DET/ECMB 9HNRR/DST8E2NRR/DST/SICB 7ENUDOCS-ABSTRACT OGC/HDS1RES/DSIR/EIBEXTERNALLPDRNSICCOPIESLTTRENCL11551111111110111111RECIPIENT IDCODE/NAME PD3-1PDNRR/DOEA/OTSB11 NRR/DST/SELB 8DNRR/DST/SRXB 8E/NRCPDRCOPIESLTTRENCL111'11111101111DSANOTETOALL"RIDS"RECIPIENTS:
PLEASEHELPUSTOREDUCEWASIElCONTACTTHE,DOCUMENI'ONTROL DESK,'ROOMPl-37(EXT.20079)TOELIMINATE YOURNAMEFROMDISIRIBUTION LISTSFORDOCUMENTS YOUDON'TNEEDtTOTALNUMBEROFCOPIESREQUIRED:
LTTR21ENCL19
)1(IfE('\V~*IJ>,IIy~)/'5gt~
IndianaMichiganPowerCompanyP.O.Box16631Cotumbus, OH43216ÃEHNMSlHSl MCMEGQHPQWMAEP:NRC:0900H DonaldC.CookNuclearPlantUnits1and2DocketNos.50-315and50-316LicenseNos.DPR-58andDPR-74ICECONDENSER TECHNICAL SPECIFICATIONS U.S.NuclearRegulatory Commission DocumentControlDeskWashington, DEC.20555Attn:T,E.MurleyDecember29,1989
DearDr.Murley:
Thisletteranditsattachments constitute anapplication foramendment totheTechnical Specifications (T/Ss)fortheDonaldC.CookNuclearPlantUnits1and2.Specifically, weproposetomodifyT/S3/4.6.5.1 (IceCondenser IceBed)andT/S3/4.6.5'(IceCondenser Doors).Thejustifications fortheproposedchangesandouranalysesconcerning significant hazardsconsiderations arecontained inAttachment 1tothisletter.TheproposedrevisedT/Spagesarecontained inAttachment 2.BothunitsatCookNuclearPlantoperateonan18-monthfuelcycle.ExistingT/Ssrequirecertainicecondenser surveillances tobeperformed atninemonths.Sincesomeofthesesurveillances cannotbeperformed atpower,amid-cycle outagelastingatleastthreetofivedaysisrequired.
Attachment 1tothisletterprovidesjustification forextending thesurveillance intervalforthesubjectT/Ssfromninetoeighteenmonths.Asindicated, theproposedamendment isnotexpectedtohaveanadverseimpactonthepublichealthandsafety.Implementation ofthechangewill,ontheotherhand,eliminate theneedforaplantshutdownduringeachfuelcycle,andtherebycontribute tooverallplantsafetybyreducingthenumberofshutdown/startup transients theplantwillexperience.
Foryourinformation, thenextscheduled mid-cycle outageforicecondenser inspection isJanuary5,1990forUnit2.900i090184 891229PDRADOCK05000ai5PDC Dr.T.E.Murley-2-AEP:NRC:0900H Webelievethattheproposedchangeswillnotresultin(1)asignificant changeinthetypesofeffluents orasignificant increaseintheamountsofanyeffluentthatmaybereleasedoffsite,or(2)asignificant increaseinindividual orcumulative occupational radiation exposure.
ThesechangeshavebeenreviewedbythePlantNuclearSafetyReviewCommittee andtheNuclearSafetyandDesignReviewCommittee.
Incompliance withtherequirements of10CFR50.91(b)(1),
copiesofthisletteranditsattachments havebeentransmitted toMr.R.C.CallenoftheMichiganPublicServiceCommission andtotheMichiganDepartment ofPublicHealth.Thisdocumenthasbeenpreparedfollowing Corporate procedures thatincorporate areasonable setofcontrolstoensureitsaccuracyandcompleteness priortosignature bytheundersigned.
Sincerely, M.P.AxichVicePresident MPA/ehAttachments cc:D.H.Williams, Jr.A.A,Blind-BridgmanR.C.CallenG.CharnoffA.B.DavisNRCResidentInspector
-BridgmanNFEMSectionChief ATTACHMENT 1TOAEP:NRC:0900H JUSTIFICATION AND10CFR50.92ANALYSESFORCHANGESTOTHEDONALDC.COOKNUCLEARPLANTUNITNOS,1AND2TECHNICAL SPECIFICATIONS
Attachment 1toAEP:NRC:0900H Page1I'ntroduction andBackroundThislicenseamendment requestproposestomodifyT/S3/4.6.5.1 (IceCondenser IceBed)andT/S3/4.6.5.3 (IceCondenser Doors).TheproposedchangesareintendedtopositionCookNuclearPlantUnits1and2sothatmid-cycle (9-month) outagesforicecondenser surveillances canbeeliminated.
Specifically, therequested changeswilleliminate theneedtoshutdowntoMode3toperformthefollowing surveillances:
(1)visualinspection oftheicecondenser turningvanesandlowersupportstructure forfrostandiceaccumulation (T/S4.6.5.l.b.3) and(2)opening/closing torquetestingoftheicecondenser inletdoors(T/S4.6.5.3.1.b).
Othersurveillances requiredbyT/S4.6.5.1.b.3, i.e.iceweighingandflowpassageinspections intheicebedabovethelowersupportstructure andtheturningvanes,areunaffected bythisrequestandwouldstillbeperformed everyninemonthswhileatpower.Eliminating theneedforamid-cycle outagecanbeaccomplished byanextension ofthesurveillance intervalforthelowersupportstructure andturningvanevisualinspections andinletdoorinspections to18months.Basedonourexperience todate,therequested extension ofthesurveillance intervalto18monthshasinsignificant impactonsafetyand,toadegree,contributes tooverallsafetybyeliminating oneshutdown/startup transient percycle.Thesafetyimpactoftherequested changesisdiscussed below.AfootnotetoT/S3/4'.5.1oftheUnit2T/Ssisalsobeingdeletedasaneditorial changebecauseitisnolongerapplicable.
II.Technical Secification Chane-IceCondenser IceBedFlow~PassaesThetechnical basisforthesurveillance requirements foricecondenser icebedflowpassagesistoprovidereasonable assurance thatthereisadequateflowareathroughtheicecondenser following aloss-of-coolant accident(LOCA)orahighenergylinebreak(HELB).TheT/Scallsforverifying atleastonceeveryninemonths,byavisualinspection ofatleasttwoflowpassagespericecondenser bay,thattheaccumulation offrostoriceonflowpassagesbetweenicebaskets,pastlatticeframes,throughtheintermediate andtopdeckfloorgrating,orpastthelowerinletplenumsupportstructures andturningvanesisrestricted toanominalthickness of3/8inches.Theproposedchangewouldreviseonlythesurveillance intervaltoperformthevisual Attachment 1toAEP:NRC:0900H Page2inspection ofthelowerinlet,plenumsupportstructures andturningvanesfromninemonthstoeighteenmonths(i.e.,atrefueling outages).
Theacceptance criteriafortheseinspections wouldremainunchanged.
Theexistingsurveillance intervals oninspection offlowpassagesbetweenicebaskets,pastlatticeframes,throughtheintermediate deckandthroughthetopdeckgratingeveryninemonthswouldberetained.
However,notethattheorderthatthesecomponents appearinT/S4.6.5.1.b,3 hasbeenchangedtobeconsistent witha"top-down" inspection oftheicecondenser.
Giventhatonlytheorderofthecomponents ischanged,thischangeisconsidered editorial.
Thelowersupportstructure isdesignedtosupportandholddowntheicebasketsintherequiredarray.Xtisalsodesignedsuchthatthereisanadequateareafortheair/steam mixturetoflowintotheicebedintheeventofaLOCAorHELB~Thelowersupportstructure hasturningvanesthataredesignedtoturntheflowupthroughtheicebedintheeventofanaccident, Forsuchanevent,thevaneswouldservetoreducethedragforcesonthelowersupportstructural members,reducetheimpingement forcesonthecontainment wallacrossfromthelowerinletdoorsanddistribute theflowmoreuniformly overtheicebed.Todetermine ifoperational historysupported extending thesurveillance interval.to18monthsfortheseT/Ss,areviewwasconducted oftheCookNuclearPlantLicenseeEventReports(LERs)andplantcondition reportssince1981(thisdatewasselectedarbitrarily).
Anyevidenceofexcessive frostoricebuildupinthelowersupportstructure wouldbereportedinthesedocuments.
Basedonthesedocuments, noconditions couldbeidentified wheretheT/Ssurveillance criteriaonaccumulation offrostoriceinthelowerinletplenumsupportstructure flowpathoronturningvaneswerenotmet.Theconclusions fromthisreviewandfromdiscussions withCookNuclearPlantpersonnel involvedwithicecondenser surveillance werethatoperating experience supportstheextension ofthesurveillance intervalto18monthsforthelowersupportstructure andturningvanes.Thephysicaldesignoftheicecondenser wasalsoconsidered intheevaluation.
Theicebeditselfistheportionoftheicecondenser withtheleastamountofflowarea.Experience alsoindicates thatitisthelocationwheremostofthe Attachment 1toAEP:NRC:0900H Page3frostandiceaccumulation occursduetosublimation.
Thus,anyevidenceofabnormaldegradation oftheicecondenser willbefoundduringthenine-month surveillance oftheicebed.Per10CFR50,92,aproposedamendment willnotinvolveasignificant hazardsconsideration iftheproposedamendment doesnot:(1)involveasignificant increaseintheprobability orconsequences ofanaccidentpreviously evaluated.
(2)createthepossibility ofanewordifferent kindofaccidentfromanyaccidentpreviously analyzedorevaluated, or(3)involveasignificant reduction inamarginofsafety.Criterion 1Theicecondenser isapassivesystemthatperformsamitigative functiontoreducecontainment pressurization following aLOCAorHELB.Therefore, theproposedchangeinthesurveillance frequency forinspection offrostandiceaccumulation onthelowerinletplenumsupportstructure andturningvaneswouldnotincreasetheprobability ofanaccidentpreviously evaluated.
Themainimpactofflowpassageblockages isontheshort-term containment subcompartment pressures following aLOCA.Blockages resultinreducedflowareasintheicecondenser andhencehigherupstreampressureduringtheblowdownphaseoftheaccident.
Asstatedearlierinthisattachment, duringsurveillance inspections oftheicecondenser turningvanesandlowerinletplenumsupportstructure flowpaths,noevidencehasbeenfoundthatfrost/ice accumulation hasexceededtheT/Srequirement.
Inaddition, theconsequences offlowpassageblockageintheicecondenser havealreadybeenevaluated.
Forexample,ourletterAEP:NRC:1067 datedOctober14,1988,andsupplemented byourletterAEP:NRC:1067C datedMarch14,1989,transmitted theresultsofsubcompartment analysestosupportoperation ofUnit1forthereducedtemperature andpressureprogram.Intheseanalysesa15'tflowblockageintheicecondenser wasassumed.Theseanalyseswereapprovedinasafetyevaluation reportattachedtoyourletterdatedJune9,1989(TACNo,71062),Similarevaluations havebeenperformed by Attachment 1toAEP;NRC:0900H Page4Westinghouse fora20%flowblockageforUnit2operating conditions.
Insummary,theproposedT/Schangewillnotincreasetheconsequences ofapreviously analyzedaccidentbecauseflowblockagehasbeenaccounted forintheaccidentanalysesandoperating experience indicates thatthisparticular areaoftheicecondenser is.notverysusceptible tofrost/ice accumulation.
Criterion 2Thesurveillance intervalincreaseto18monthswillnotresultinachangeinplantconfiguration oroperation.
Further,asindicated above,theicecondenser isapassivesystemthatonlyperformsamitigative functionfollowing certainaccidents.
Therefore, thischangewillnotcreatethepossibility ofanewordifferent kindofaccidentfromanyaccidentpreviously analyzedorevaluated.
Criterion 3Theicecondenser performsthemitigative functionoflimitingcontainment pressurebuildupfollowing aLOCAorHELB.Toensurethattheicecondenser willfulfillitsfunction, buildupoffrostandiceintheflowpassageareamustbelimited.However,thereareallowances forfrost/ice buildupassumedinthesafetyanalysisasindicated above.Therequested changeincreases thesurveillance intervalforanareawithintheicecondenser that,basedonoperating experience, isnotverysusceptible tofrost/ice buildup.Further,surveillance inspections oftheflowpassagesintheicebedwill'ontinue tobeperformed everyninemonthsfortheareaoftheicecondenser thatismostsusceptible tofrost/ice buildup.Therefore, itisapparentthattheproposedT/Schangewillnotinvolveasignificant reduction inthemarginofsafety.Lastly,wenotethattheCommission hasprovidedguidanceconcerning thedetermination ofsignificant hazardsbyproviding certainexamples(48FR14870)ofamendments considered notlikelytoinvolvesignificant hazardsconsideration, Thesixthoftheseexamplesreferstochangesthatmayresultinsomeincreasetotheprobability ofoccurrence'r consequences ofapreviously analyzedaccident, buttheresultsofwhicharewithinlimitsestablished asacceptable.
Webelievethischangefallswithinthescopeofthisexample.Thisrequesttoincreasethesurveillance intervalmayresultinsomeincreaseintheprobability offrostandiceaccumulation ontheicecondenser lowersupport Attachment 1toAEP:NRC:0900H Page5structure andturningvanes.However,basedonplantoperational experience, thedegreeofflowblockagewi11bewithinthelimitsofthesafety.analysisandtherefore theconsequences arenotincreased.
Vebelievethischangedoesnotinvolveasignificant hazardsconsideration asdefinedin10CFR50.92.III'echnical Secification Chane-IceCondenser InletDoorsTheT/Sbasis(3/4.6.5,3) foricecondenser doorsstatesthattheoperability oftheicecondenser doorsandtherequirement thattheybemaintained closedensures1)thatthereactorcoolantsystemfluidreleasedduringaLOCAwillbedivertedthroughtheicecondenser baysforheatremovaland2)thatexcessive sublimation oftheicebedwillnotoccurbecauseofwarmairintrusion.
Excessive sublimation iscontrolled duringnormaloperation throughcontinuously monitoring anddetermining theinletdoorsclosedusingtheinletdoorpositionmonitoring system(T/S4,6,5.3.1.a).
Toverifythatthedoorswillopenduringanaccident, T/S4.6.5.3.l.b requiresthatonehalfoftheicecondenser inletdoorsbedemonstrated operableduringshutdownatleastonceeveryninemonths.TheproposedT/Schangeswouldrequirethatthesurveillance testingonalllowerinletdoorsbeperformed atleastonceevery18months,Theproposedchangeforinletdoorsurveillances isidentical tothatpreviously approvedfortheMcGuireandCatawbaNuclearStations.
(Forthesafetyevaluation-report onthischange,seeHood,NRC,toTucker,DukePower,"Issuance ofAmendment No.83toFacilityOperating LicenseNPF-9andAmendment 64toFacilityOperating LicenseNPF-17-McGuireNuclearStation,Units1and2,"datedMay11,1988.)Theprimarypurposeofthelowerinletdoorsurveillance istodetermine thatthedoorsarecapableofopeningproperlywhenrequiredduringaLOCAorotherhighenergylinebreak.Thisensuresthatthesteamreleasedinthelowercontainment compartment canentertheicecondenser compartment andbecondensed bytheiceinside.Thelowerinletdoorsareequippedwithspringsthatproduceasmallforcetoresistdooropeningduringnormaloperation.
Thedoorsarenormallyheldshut,againstasealmountedontheframe,bythestaticdifferential pressureduetothehigherdensityairintheicecondenser compartment.
Wi.thzerodifferential pressureacrossthedoors(nocoldairhead),theneutralpositionofthespringissetsothatthedoorsareslightlyopen
Attachment 1toAEP:NRC:0900H Page6(3/8"+1/8").Thespringtorqueisthensetsothatthedoorswillopenrapidlyinresponsetoalowercontainment pressureincreaseduringalinebreak.Thespringtorqueaidsinpreventing maldistribution offlowthroughthe24pairsoflowerinletdoorsduringasmalllinebreakaccidentwhenthedoorswouldonlyopenpartially.
Thesurveillance inquestionrequiresthatvariousmeasurements bemadeofdoorspringtorque,inordertoensurethattherequiredsafetyfunctions canbemet.Thesemeasurements includeinitialopeningtorque,openingtorque,closingtorqueanddoorfrictional torque.Theinitialopeningtorqueisthetorquerequiredtoopenthedoorwhenthedoorisclosedandisagainstthedoorseal.Theopeningtorqueandclosingtorquearemeasuredwhenthedoorisopen40degrees.Thedoorfrictional torqueiscalculated basedontheopeningandclosingtorques.TheproposedT/Schangeswouldnotchangetheacceptance criteriafortheabovetorquemeasurements butwouldrevisethesurveillance intervalontheicecondenser inletdoorsfromninemonthsto18months(i.e.,atrefueling outages).
Further,whilethecurrentT/Srequirestestingof50tofthedoorseveryninemonths,theproposedT/Swouldrequiretestingallofthedoorsevery18months.Inthisway,theintervalforcompletetestingofanyonedoorwillremainunchanged fromthecurrentsurveillance
- interval, Todetermine ifoperational historysupported extension ofthesurveillance intervalto18months,areviewofplantLERsandcondition reportssince1981wasconducted.
Theyear1981wasselectedarbitrarily.
Since1981,theCookNuclearPlantUnits1and2icecondenser inletdoorshavefailedT/Ssurveillance criteriaonsevenoccasions.
ThereasonsforthefailureofinletdoorstomeetT/Srequirements andthecorrective/preventive actionstakenarehighlighted below.InaJune1983surveillance itwasfoundthatoneUnit2inletdoorexceededtheacceptance criteriafortheinitialopeningtorque.Aninspection ofthedoorfoundthattheproblemwastheresultoftheframesealsinitially stickingtothedoorbecauseofglycolontheseal.Thesealwascleanedandthedoortestedsatisfactorily, Nofurtheractionwasperformed becausetheincidentwasconsidered isolated.
Inasurveillance performed inAugust1983,itwasfoundthatfiveUnit2inletdoorsexceededtheacceptance criteriafor
Attachment 1toAEP:NRC:0900H Page7initialopeningtorque,Theinvestigation revealedthatthreeofthedoorsrequiredad]ustments tothedoorframeandonedoorwasclosedonalooseRTDcable,Thecablewasremovedandsecured.Theremaining doorwasinspected andthesealswerecleaned.Topreventrecurrence, theappropriate procedures weremodifiedtoensurethatalldoorsarefreeofobstructions andthatthesealsandsealingsurfacesarefreeofdebristhatcouldcausebindingfollowing completion oficebasketweighing.
InJune1984,twoUnit2inletdoorsfailedtheacceptance criteriaintheT/Ss.Onedoorexceededtheopeningtorquebyasmallamount(198inch-lbwhiletheT/Scriteriais195inch-lb).
Theinvestigation foundthatthedoorbumper(shockabsorber) coverhadanaccumulation oficebehinditandwasrestricting thedoormovement.
Theicewasremovedandthedoorretestedsatisfactorily.
Theappropriate procedure wasrevisedtoincludeaninspection foriceaccumulation inthedoorbumper.Theotherdoorfailedtheacceptance criteriaforclosingtorquebyasmallamount(76.4inch-lbversustheT/Scriteriaof78inch-lb).
Thedoorwasretestedandfoundtobeacceptable.
Nofurtheractionsweretaken.InAugust1984,oneUnit1inletdoorfailedthehingefrictional torquetest(although passingtheinitialopeningtorque,openingtorqueandclosingtorquetests).Duringinspection ofthedoor,aniceaccumulation wasfoundbetweenthedoorbumperandthebumpercover,Theicewasremovedandthedoorretestedsatisfactorily, Theiceaccumulation occurredasaresultoffreshicebeingblownintosomebasketsintheparticular baywherethefailureoccurred, Duetotheshortness oftheoutage,inletdoortestingwasscheduled tobecompleted priortothefinalinspection foriceaccumulation inthelowerpartoftheicecondenser.
Theicewouldhavebeenremovedpriortopoweroperation duringtheicecondenser finalinspection asrequiredbytheprocedure changesimplemented asaresultoftheJune1984eventdiscussed above.InaDecember1984surveillance, oneUnit2inletdoorexceededtheacceptance criteriaforinitialopeningtorque.Thedoorwasinspected andadryresiduewasfoundonthedoortopseal.Thesealwascleanedandthehingeslubricated.
Thedoorwouldhaveopenedatadifferential pressureofonlyabout1.3poundspersquarefoot(psf)ratherthan1psf,whichisthebasisfortheacceptance criteria.
Attachment 1toAEP:NRC:0900H Page8InJanuary1985,14of48Unit1inletdoorsfailedtomeettheacceptance criteriaforinitialopeningtorque(although alldoorsdidopen).Inonlythreecasesdidbothdoorsinaparticular bayfailtomeettheacceptance criteria.
Adifferential pressureofonlyabout1.1psfwouldhaveopenedatleastonedoorineachofthesethreebays,Therefore, atadifferential pressureof1.1psf,allbayswouldhavehadatleastonedooropen.Doorswhichfailedwereretestedtodetermine iftheproblemwaswiththedoorsealsorthedoorhinges.Theretestindicated thattheproblemwaswiththeseals'opreviousfailuresofthistypehadbeenfound.Althoughthedoorsealswereinspected andfoundtobeveryclean,testpersonnel believethatlightfrosthadcausedthedoorstostickduetovaportransferbetweentheseals.Topreventthismoistureinfiltration betweentheseals,asiliconelubricant isnowappliedtothesealsandthenwipeddownpriortoreturntopower.Inasurveillance performed inDecember1985,sevendoorsfailedtheinitialopeningtorqueacceptance criteriaduetoiceaccumulation.
Aftertheicewasremoved,allofthedoorspassedtheretestandshowednosignsofmechanical failure.Anothersurveillance wasperformed inJune1986,withalldoorssuccessfully passing.ThefailuresfoundduringtheDecember1985surveillance arebelievedtohaveoccurredasaresultofoutageworkperformed duringtheUnit11985refueling outage,Someofthisworkinvolveddeliberate defrosting oftheicecondenser, andwasdoneaftertheSeptember 1985inletdoorsurveillances wereperformed.
Itisbelievedthatwaterandicefromthedefrostoperation accumulated onthedoors,causingtheopeningtorquestoexceedT/Slimits.Topreventrecurrence, theicecondenser defrostprocedure nowrequiresthatthedooropeningtorquesbetestedfollowing adefrostoperation.
Otheradditional preventive measureshavealsobeenimplemented asfollows.Operations personnel arerequiredbyprocedure tomakeacontainment closeoutinspection tourpriortostartupafteranextendedoutage,Thisinspection includeslookingforfrostbuildupondoors.Astephasalsobeenaddedtotheoperation departments plantheatupprocedure thatrequiresanevaluation andsignoffbytheperformance department oftheneedtoperformalowerinletdoorsurveillance testbasedonconditions intheicecondensez sincetheprevioussurveillance test.Forexample,unusually highicebedtemperature duringanoutageisacondition thatwouldrequirearetestofthedoors.
Attachment 1toAEP:NRC:0900H Page9Thepurposeofdetailing theT/Ssurveillance historyoftheinletdoorsistodemonstrate thateitherfailureshavebeensingle,isolatedoccurrences oreffective corrective actionshavebeenimplemented throughdoorsealmaintenance oradditional doorinspections mandatedbyprocedures.
Asaresultoftheseefforts,noinletdoorsatCookNuclearPlanthavefailedanyoftheT/Sacceptance criteriarelatedtoinitialopeningtorque,openingtorque,closingtorqueorhingefrictiontorquesinceDecember1985inUnit1andDecember1984inUnit2.Further,thefailuresidentified priortoDecember1985werelargelyconfinedtothedoorsealsandiceaccumulation andnottothehingesorspringsonthedoors,thusconfirming thedesignadequacyofthedoorsthemselves.
Themechanical designoftheinletdoorsisextremely simpleinordertoreducethechancesofanymalfunction.
Thedoorhingesaredesignedtopreventgallingorselfwelding,Thelong-term performance andcorrosion ofthedoorhingesandrelatedhardware, whenexposedtotheicecondenser atmosphere, hasbeenconsidered intheicecondenser design.Thelowtemperature (10F-20F)andlowabsolutehumidityoftheicecondenser atmosphere resultsinnegligible corrosion ofuncoatedcarbonsteel.Toensurethatcorrosion isminimized whilethecomponents areinoperation inthecontainment, components wereeithergalvanized orpainted.Galvanizing wasinaccordance withASTM,A123andpaintinginaccordance withAmericanNationalStandards Institute ANSIN101.2-72, "Protective Coatings(Paints)forLightWaterNuclearReactorContainment Facilities."
Materials, suchasstainless steels,withlowcorrosion rateswereusedwithoutprotective coatings.
Anyicecondenser equipment whoseperformance mightbeaffectedbycorrosion employscorrosion resistant materialforcriticalcomponents.
Thus,corrosion hasbeenconsidered inthedetaileddesignoftheicecondenser components, andithasbeendetermined thattheperformance characteristics oftheicecondenser materials ofconstruction arenotimpairedbylong-term exposuretotheicecondenser environment.
Thishasbeenconfirmed withregardtotheinletdoorsbytheoperating experience ofCookNuclearPlant.Justification fortheproposedincreaseintheT/Ssurveillance intervalisbased,inpart,onthereliabledesignoftheinletdoors,theprogrammatic improvements madeatCookNuclearPlantwithregardtodoorsealmaintenance andinletdoorinspections andtherecenthistoryofhighly Attachment 1toAEP:NRC:0900H Page10reliableperformance ofthedoorswithregardtoT/Ssurveillance tests.Per10CFR50.92,aproposedamendment willinvolvenosignificant hazardsconsideration iftheproposedamendment doesnot:(1)involveasignificant increaseintheprobability orconsequences ofanaccidentpreviously evaluated, (2)createthepossibility ofanewordifferent kindofaccidentfromanyaccidentpreviously analyzedorevaluated, or(3)involveasignificant reduction inamarginofsafety,Criterion 1TheproposedT/Samendment wouldnotinvolveanyincreaseintheprobability ofpreviously evaluated accidents.
Theicecondenser isapassivemitigative systemdesignedtolimitthecontainment pressureafteraLOCA'orHELB;noaccidents evaluated intheFSARareinitiated byicecondenser components.
Theproposedamendment wouldalsonotinvolveanyincrease'intheconsequences ofapreviously analyzedaccident.
Theicecondenser doorsservetwodistinctfunctions; 1)tostayclosedduringnormaloperation and2)toopenduringaLOCAorHELB.The.doorpositioniscontinuously monitored duringnormaloperation toensurethattheicecondenser inletdoorsareclosedtoprotecttheicebedfromheatsources.Thedoorsarehunginaneutralpositionandareslightlya]arwhenthedifferential pressureacrossthedooriszero.Thedoorsareheldagainstthegasketsealsbythesmallcoldairheadofonepoundpersquarefootintheicecondenser duringnormaloperation.
TheT/Sacceptance criteriaoninitialopeningtorqueisbasedonthisdifferential
- pressure, Foralargebreakloss-of-coolant accident(LBLOCA),
thepeakdifferential pressurebetweentheloweranduppercompartments ofthecontainment isatleast7,5psiwhichisontheorderof1000poundspersquarefoot.Therefore, thereislittlelikelihood thatanyinletdoorwillremainclosedduringaLBLOCAorlargeHELB.
Attachment 1toAEP:NRC:0900H PagellForasmallbreakloss-of-coolant accident(SBLOCA),
theinletdoorsareequippedwithspringswhichaidinpreventing maldistribution offlowthroughthedoorswhenthedoorswouldonlypartially openinordertoassureequalflowthroughalldoorpairs.Inaddition, duringthedesignoftheinletdoors,ananalysiswasperformed todetermine howmanycouldremainshutandstillpermitthesatisfactory operation oftheicecondenser system.Thisanalysisisdiscussed inSection6.9.3.1ofAppendixMoftheupdatedFSAR.Thelimitingcaseformaximummaldistribution fortheworse-case breaklocationandbreaksizefoundthat21inletdoorscouldremainclosedwithoutexceeding theicebedcapacityofthesectionoftheicebedreceiving themaximumsteam/air flow.Giventhereliability ofthedoors,theimprovements indoorsealmaintenance andimplementation ofstricterinspection procedures, itisnotexpectedthatextending thesurveillance intervalfortheinletdoorsto18monthswillhaveanyappreciable effectonthelikelihood ofadoorfailingtomeettheT/Srequirement.
Theconsequences ofanaccidentpreviously evaluated arenotincreased becausethepossibility ofalargenumberofinletdoorsremaining shuthasalreadybeenconsidered foraSBLOCAandfoundtohaveacceptable consequences asdiscussed above.Criterion 2Thesurveillance intervalincreaseto18monthswillnotresultinachangeinplantconfiguration oroperation, Therefore, thischangewillnotcreatethepossibility ofanewordifferent kindofaccidentfromanyaccidentpreviously analyzedorevaluated.
Further,asindicated above,theicecondenser isapassivesystemthatonlyperformsamitigative functionfollowing certainaccidents.
Criterion 3Theicecondenser performsthemitigative functionoflimitingcontainment pressurebuildupfollowing aLOCA(HELBisboundedbytheLOCAanalysisintermsofpressurization),
Toensurethattheicecondenser willfulfillitsfunction, theicecondenser inletdoorsmustbothinitially openfollowing certainaccidents andperformaflowproportioning, ifrequired.
TheT/Ssurveillance acceptance criteriaarebasedontheserequirements.
ForalargebreakLOCA,theresultant differential pressureacrossthedoorsissolarge ll Attachment 1toAEP:NRC:0900H Page12ascomparedtotheacceptance criteriathatthereislittlelikelihood thatthedoorswillfailtoopen.Becausealldoorswillopenfully,theflowproportioning functionisnotrequired.
ForasmallbreakLOCA,asindicated earlierinthisattachment, thepossibility ofalargenumberofinletdoorsremaining shuthasalreadybeenconsidered andfoundtobeacceptable.
Giventhattheintervalforcompletetestingofanyonedoorwillremainunchanged asaresultofthisproposedT/Schange,andthatthereliability oftheinletdoorshasbeenimprovedthroughsealmaintenance andstricterinspection procedures, thereislittlelikelihood thatthenumberofdoorsfailingtheT/Sacceptance criteriawillincrease, Therefore, theproposedT/Schangedoesnotinvolveasignificant reduction inthemarginofsafety.Lastly,wenotethattheCommission hasprovidedguidanceconcerning thedetermination ofsignificant hazardsbyproviding certainexamples(48FR14870)ofamendments considered notlikelytoinvolvesignificant hazardsconsideration.
Thesixthoftheseexamplesreferstochangeswhichmayresultinsomeincreasetotheprobability ofoccurrence orconsequences ofapreviously analyzedaccident, buttheresultsofwhicharewithinlimitsestablished asacceptable.
Basedontheabovediscussion, itisnotexpectedthattheprobability ofdoorsfailingtoopenfollowing anaccidentwouldincreaseasaresultofthisT/Schange,andthusnosignificant increaseintheconsequences ofanaccidentwilloccur.Vebelievethischangefallswithinthescopeofthisexample.Therefore webelievethatthischangedoesnotinvolveasignificant hazardsconsideration asdefinedin10CFR50.92.IV.Editorial ChaneInadditiontothechangesdescribed previously, oneeditorial changeissuggested.
ThischangedeletesthefootnoteonPage3/46-36ofUnit2T/S3/4.6.5.Thisfootnotenowreads"onaonetimebasisduringMarch/April 1987outage,theweightsofthreeRow8basketsmaybesubstituted forthreead5acentRow9baskets."
Thefootnotecanbedeletedbecauseitisnolongerapplicable.
Becausethischangeispurelyeditorial, itdoesnotreduceamarginofsafety,doesnotincreasetheprobability orconsequences ofapreviously analyzedaccident, anddoesnotintroduce thepossibility ofanewaccident.
Therefore, webelievethesechangesdonotinvolveasignificant hazardsconsideration asdefinedby10CFR50.92.