ML17037C261

Nine Mile Point Unit 1 - Letter Responding to a Request for Additional Information Concerning the Drywell Vacuum Breakers

ML17037C261
Person / Time
Site:	Nine Mile Point
Issue date:	07/20/1973
From:	Schneider R R Niagara Mohawk Power Corp
To:	Skovholt D J US Atomic Energy Commission (AEC)
References
Download: ML17037C261 (10)

Text

.AECDISBUTIONFORPART50DOCKETMA~AL'TEMPORARY FORM)CONTROLNO:PILE:'RON:NiagaraMohawkPowerCorporation

Syracuse, N.Y.13202R.R.Schneider'-20-73 7-25-73DATEOFDOCDATEREC'DMEMORPTOTHERTOvhCLASSUNCLASSXXPROPINFOORIG3si~nedINPUTCCOTHERNOSREC'D40SENTAECPDRXSENTLOCALPDRXDOCKETNO:50-220DESCRIPTION:

Ltrfurnishing requested inforedrywellvacuumbreakersattheNineMilePointNuclearStationUnit0l.......PLANTNAME..NineMilePointUnit81ENCLOSURES:

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'NIAGARAMOHAWKPOWERCORPORATION NIAGARA~MOHAWK300ERIEBOULEVARD WESTSYRACUSE, NY.l3202July20,1973~III'r"gJulg5)gg~

DearMr.Skovholt:

Re:Provisional Operating License:DocketNo.:50-220DPR-17Mr.DonaldJ.SkovholtAssistant DirectorforReactorOperations DivisionofReactorLicensing UnitedStatesAtomicEnergyCommission Washington, D.C.20545O0,<<~)8jpjogg6'OIIQggIIII II~idltlfRegarding yourletterrequesting additional information concerning thedrywellvacuumbreakersatNineMilePointNuclearStationUnit81,thefollowing issubmitted:

ITEM1Thepresentpositionindicating systemutilizestwosetsoflimitswitches, thesnaplocklimitswitchmanufactured bytheNationalAcmeCompanyandtheHoney-wellModelDTE6-2RNheavyduty,microswitches.

Thesnaplocklimitswitchisusedtodetermine andindicatetheopenpositionofanyonevalve'tothecontrolroom.TheHoneywell microswitchisusedtodetermine andindicatetheclosedpositionofanyonevalvetothecontrolroom.ThissystemwasreviewedduringtheSpring",.I973 refueling outageandtheHoneywell microswitchesinstalled atthattime.Sincethepurposeoftheselimitswitchesistoprovidethecontrolroomoperatorwithinformation regarding thepositionofthebreakervalves,physicalseparation ofthecontrolwiringorindicating lightsisnotrequired.

However,anadditional Honeywell limit,switchwillbeinstalled todetecttheclosedpositionandprovideanalarmtothecontrolroomintheeventanydrywellvacuumbreakervalvemovesoffitsseatapredetermined amount.Redundances inthealarmcircuitwillthusbeprovidedandIEEE279criteriasatisfied.

Thepretravel ontheHoneywell

'switchis.065"maximumandmeasurements haveshownthemtobe.04"ofpretravel.

Thevacuumbreakerpositionisdetectedbythoselimitslvitches andareactuatedbysmallarmsattachedtothevalveshaft.Thediscmusttravelapproximately

.2"beforeactuation ofthelimitswitchisachieved.

Thlerefore, thefullpotential accuracycannotberealizedduetotheexistingmountingoftheswitches.

At,thepresenttime,thesystemisunderastaffreviewtodetermine whatmustbedonetoachievethedesiredaccuracyof.05"-.06"ofdiscmovement.

Thisreviewshouldbecompleted withinamonthandactualimplimentations willtakeplace,afterappropriate reviews,within30-60days.Thedrywellvacuumbreakersarecompletely accessible duringthe II Mr.DonaldJ.SkovholtUnitedStatesAtomicEnergyCommission Page27/20/73poweroperating condition andthusonlinemodifications canbemade.Untiltheaccuracyof.05"-.06"discopeningcanbemetandthealarmredundancy completed thefollowing willbedone:a.Eachreactortransient involving thesuppression chamberwillbefollowedwithanoperability testofthedrywellvacuumbreakervalves.b.Adialindication willbeinstalled oneachvalveaccuratetoindicate.06"move-mentofthedisc.Thissystemwillprovideadailysurveillance ofvalveclosurewithintheacceptable limitsasinITEM3below.Theseindicators willbeinstalled priortoAugust1,1973.'ITEM2Duringthevalveoperability test,whenairisreleasedfromtheairtestcylinderthevalverapidlyclosesleavingoperating personnel noactiontotaketomanuallyclosethevalve.However,toprecludeagainstmanualclosure.ofthevalvefollowing testingamanagement personwillbemonitoring thetestingatthetestsite(i.e.thevalvelocation) to:assure thatnomanualintervention takesplace.SeeItem1responseregarding valveoperability testandotheradditional surveillance tobedoneuntilITEM1iscompliedwithinfull.ITEM3Thelimitoneachindividual valvewillbesetsuchthatwithallvalvesattheirlimitthemaximumvalueofcumulative leakagewillnotexceedthemaximumallowable.

Thevaluewillbeapproximately

.06"ofdisc'ravel off.itsseatandwillbealarmedin.the,controlroom.Thetorusinstruments thatwouldbeusedforsurveillance testingandleakratetestingofthedrywellvacuumbreakervalvesreadoutintheauxilarycontrolroom.Theirrangeandaccuracyareasfollows:Pressure:0-50psia+.05psi.Temperature

0-200'F+1'FPSID0-1.0psid+.001psiTheinstrumentation usedbytheoperatorduringanLOCAareinthecontrolroomandincludenotonlyanindicated pressureinstrument butarecorderaswell.Theirrangeandaccuracyisasfollows:Pressure:low0-4psig+.1psihigh0-75psig+1.5psiTemperature

50-300'F+5'FThecomputer.

alsorecordsthedrywellandpressuresuppression chamberpressureandtemperature asfollows:

e~~PP Mr.DonaldJ.SkovholtUnitedStatesAtomicEnergyCommission Page37/20/73Pressure:0-40psig+.1psi-alarm at2.5psigTemperature

50-300'F+1'Falarmat100'FTorus,120'FDrywellITEM4Td'chnical Specification Considerations ProposedTechnical Specifications willbesubmitted separately, afterthenecessary reviewsarecomplete.

Consideration is,beinggiventoaddingthefollowing conditions andsurveillance requirements.

LimitingConditions forOperation 3.3.6DrywellPressureSuppression ChamberVacuumBreakersa.lienprimarycontainment isrequired, alldrywell-suppression chambervacuumbreakersshallbeoperableandpositioned intheclosedpositionasindicated bythepositionindication system,exceptduringtestingandexceptasspecified in3.3.6bandc,below.b.Anydrywell-suppression chambervacuumbreakermay.=benon-fully closedasindicated bythepositionindication systemprovidedthatadrywelltotoruspressuredifferential canbemaintained greaterthan1/2theinitialdifferential pressurefor1hourwithnoN2makeup.c.Uptoonedrywell-suppression chambervacuumbreakermaybesecuredintheclosedposition.

d.IfSpecifications 3.3.6a,borccannotbemet,thesituation shallbecorrected within24hoursor.thexeactor.shallbeplacedinacoldshut=downcondition within24hours.Surveillance Requirements 4.3.6Drywell-Pressuxe Suppression ChamberVacuumBreakersa.Eachdrywell-suppression chambervacuumbreakershallbeexercised throughanopening-closing cyclemonthly.b.1&enitisdetermined thatanyvacuumbreakervalveisnotfullyclosedasindicated bythepositionindication systematatimewhensuchclosureisrequired, theapparently malfunctioning vacuumbreakervalvesshallbeexercised andpressuretestedasspecified in3.3.6bimmediately and"every15daysthereafter untiltheapparently malfunctioning valveshavebeenreturnedtonormalservice.c.Onceeachoperating cycle,eachvacuumbreakervalveshallbevisuallyinspected toensurepropermaintenance andoperation.

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her.,Donald J.SkovholtUnited'tates AtomicEnergyCommission Page47/20/73d.Aleaktestofthedrywelltosuppression chamberstructure shallbeconducted duringeachrefueling outage.Nebelievethisreporttoberesponsive toallitemsenumerated inyourletter.Verytrulyyours,1e1eVicePresident

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