ML17037C271

Nine Mile Point Unit 1 - Letter Enclosing a Report on Environmental Qualification Test Results Applicable to the Main Steam Isolation Valve Position Switch

ML17037C271
Person / Time
Site:	Nine Mile Point
Issue date:	07/29/1975
From:	Rhode G K Niagara Mohawk Power Corp
To:	Rusche B C Office of Nuclear Reactor Regulation
References
Download: ML17037C271 (12)

Text

NRCDISTRIBUTION FORf'ART50DOCKETMATERIAL(TEMPORARYFORM)fROMagaraoawoweroSyracuse, N.Y,GeraldKRhodes'ATEQFDOC7-29-75DATEREC'D8>>4-75'TR CONTROLNO:FI)E'WXRPTOTHERTO:BernardC.RuscheORIG1SignedCCOTHERSENTNRCPDRSENTLOCALPDRCLASSUNCLASSPROPINFOXXXxINPUTNOCYSREC'DDOCKETNO:50-220DESCRIPTION:

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N.Y.132023~'1JcYa+r00Spy,u~aeV"'-g~lhO"R,ouoacIeiJuly29,1975Mr.BernardC.Rusche,DirectorOfficeofNuclearReactorRegulations U.S.NuclearRegulatory Commission Washington, D.C.20555Be:NineMilePointUnit¹1DocketNo.50-220j

DearMr.Rusche:

Areportonenvironmental qualification testresultsapplicable tothemainsteamisolation valvepositionswitchatNineMilePointUnit¹1isattached.

Thisreportisintendedtofulfillthecommitment madeinAmendment No.2tothe"Application toConvertProvisional Operating LicensetoFull-Term Operating License."

Resultsareforasimilartypeswitchsuccessfully testedbytheGeneralElectricCompany.Testconditions weremorestringent thanthosecommitted.

Insummary,testresultsindicatethatthemainsteamisolation valvepositionswitcheswillperformtheirrequiredfunctionduringnormalandincidentconditions.

Sincerely, eraldK.RdeVicePresident-Engineering Attachment 8285 IIe~~Pt~

MAINSTEAMISOLATION VALVEPOSITIONSWITCHENVIRONMENTAL TESTREPORT~SummarThisreportwaspreparedtodocumentthequalification oftheNationalAcmeCompanylimitswitch.modelnumberSL-3MDP-DT.

Limitswitchesofthisdesignareusedtomonitorthepositionofmainsteamisolation valvestemsandtogeneratescramsignals.Theobjective ofthesteamchambertestwastoqualifytheoperation ofthesubjectlimitswitchesintheabnormalambientconditions duringthefirst24hoursafteraLoss-of-Coolant Accident.

Toqualify,thelimitswitchwasrequiredtooperatefor24hoursunderthecontrolled atmosphere.

Twoswitchesweretestedforaddedconfidence.

Thereareminordifferences betweenthetestswitchandtheinstalled switchatNineMilePointUnit1.Thesedonotaltertheapplicability ofthetestresults.(SeetheDiscussion Section.)

Inaddition, thetestconditions weremoreconservative thanthosecommitted.

Atwenty-fourhourtestwasperformed; threehoursat103psigand340F,3hoursat75psigand320Fand18hoursat16psigand250F.Ascommitted atestat340Fand62psigwasrequired.

Theaboveconservative testingconditions wouldalsotendtonegateanyslightdifferences betweentheinstalled switchandthetestedswitch.Ithasbeendemonstrated bythetestingdescribed hereinthattheswitcheswilloperateforatleast24hoursinthesteamatmosphere inwhichitwastested.Sincethetestconditions conservatively simulateLoss-of-Coolant Accidentambientconditions, itisconcluded thatthelimitswitcheswilloperatenormallyundertheactualpost-Loss-of-Coolant Accidentconditions foratleast24hours.Inaddition, thejunctionboxandthehookupwirewerealsofoundtoretaintheirintegrity andfunctionproperly.

Procedure Twolimitswitches'weretestedinaccordance withthetestdescription, entitled"TestDescription, PositionSwitchforMainSteamIsolation Valve,SteamEnvironment" (attached asExhibit1).Briefly,thetestconsisted ofthefollowing.

Thelimitswitchestestassembly(including thejunctionboxandhookupwire)wasplacedinasteamchamber.Steamwasgenerated toproduceanenvironment ofabout103psigpressureand340F.Theswitcheswereoperatedduringa3hourperiod.Theenvironment wasthenchangedto75psigpressureand320F.Theswitcheswereagainoperatedduringthenext

18hours.Theactionsofthelimitswitchesweresignified byonandoffcon-ditionsofthelightbulbsandtheactionofthesolenoidvalveconnected tothelimitswitches.

Uponremovalfromthetestchamber,thetestassemblywasdisassembled andinspected.

Discussion Limitswitchesofthemodeltestedareusedtomonitorthemainsteamisolation valvepositionandtogeneratescramsignals.Thelimitswitchesperformtheirsafetyfunctionwithin5to10minutesaftertheLoss-of-Coolant Accident.

Atestperiodof24hourswasselectedformarginofconfidence.

Therearedifferences betweenthetestswitchandtheinstalled switchatNineMilePointUnit1,TheNineMilePointswitchhasanepoxysealedconduitopeningfortheelectrical leadswhereastheswitchtesteddidnot.Thisdifference isexpectedtoimprovetheperformance oftheNineMilePointswitch.TheNineMilePointswitchhasanoilimpregnated brassshaftbushinginsteadofthesolidbrassbushingonthetested.switch.Basedontheabove,theswitchesareessentially thesameandtheresultsreceivedforthetestswitchareapplicable totheoperation oftheinstalled switchesatNine.MilePoint.ResultsAnevaluation ofthedatareceivedindicates thatthelimitswitchqualifies fortheabnormalambientconditions ofthefirst24hoursafteraLoss-of-Coolant Accident.

Thetestitselfproceeded inaroutinemanner,andtheswitchesfunctioned normallyforthe24hourtestperiod.Visualinspection ofthetestassemblyrevealedpeelingofthepaintonthesurfacesofthejunctionbox,slightcharringofthelubricant, andbendingofthelongersidesofthejunctionbox(inwardforabout1/8ofaninch).Thecontactsoftheswitcheswerefoundintact,withnosignsofpittingorburning.'he

.hookup-wireswerefoundingoodcondition.

Therewasnodiscoloration oftheinsulation.

Thejunctionboxwasfoundtohavemaintained itsintegrity.

Therewasnotraceofmoistureorcondensate inthejunctionbox.Thepeelingofpaints,andbendingofthejunctionboxdidnotinterfere withtheswitchoperation.

Thetestpressureof103psigismuchhigherthanthepeakpressureexpected, soinrealitythejunctionboxwouldbendevenlessthan1/8ofaninch.Thecharredlubricant didnotinterfere withswitchoperation duringthetest.Therefore, theswitcheswillprovidetheirdesignfunctionduringnormalandincidentconditions.

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EXHIBIT1TESTDESCRIPTION POSITIONSl(ITCHFORMAINSTEAMISOLATION VALVESTEAMENVIRONMENT I.EuimentToBeTestedA.PositionSwitchManufacturer:

Model:RatedCapacity:

NationalAcmeMfg.Co.SL-3MDP-DT 125volts,20ampsB.WiringSize:Type:16GaStrandedGeneralElectricVulkene-insulated hookupwireA.Autoclave capableof350FTemperature and150psigpressure.

B.Calrodtypeheatercontrolled byanautotransformer andasafetyrelaytolimitmaximumtemperature.

C.Temperature isrecordedbasedonoutputfromathermocouple locatedinthesteamregionoftheautoclave.

Apressureindicator isavailable.

III.TestProcedure A.Thetwoswitchestobetestedaremountedwithaprcssure-operated devicetoactuatetheswitches.

Cablesfromtheswitchesarecontained withintheautoclave andconnected towireswhichpenetrate theauto-clave.i%enthepressure-operated deviceisenergized, theswitchisactuatedandasignalobservedoutsidetheautoclave.

B.Theswitchesaremountedinsidetheautoclave andwateraddedtoimmersetheheaters.Thetemperature israisedtoboilingandtheairpurgedfromtheautoclave, Thetemperature israisedfurthertothedesiredlevelandrecorded.

Thepressureisobservedandcheckedagainstsaturated steampressureforthecorresponding temperature,

C.Conditions withintheautoclave areheldatorabovethefollowing conditions foratleasttheperiodindicated:

340F320F2SOF3hours3hours18hours'.Thetestswitchesareactuatedfromopentoclosedtoopenatthebeginning, theend,andatleastoneothertimeduringthetestperiodforeachtemperature level.Thetestsignalisatleast120volts,4Svolt-amperes inrushand25volt-amperes steadystate.E.Criteriaforsuccessful completion A.Thesignaldescribed inIII.D.aboveshallbeobservedeachtimetheswitchisactuated.

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