ML17244A374

Forwards Review of Safety Actuation Circuits W/Manual Override.Reset Operation Does Not Prevent Equipment from Operating,Which Is Necessary to Mitigate a Postulated Accident

ML17244A374
Person / Time
Site:	Ginna
Issue date:	02/16/1979
From:	WHITE L D ROCHESTER GAS & ELECTRIC CORP.
To:	ZIEMANN D L Office of Nuclear Reactor Regulation
References
TASK-06-04, TASK-6-4, TASK-RR NUDOCS 7902210226
Download: ML17244A374 (8)

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NOTES.tBEGULAT(gINFORMATIONDISTBIBUTIONyYSTEM(RIDE>ACCESSIONNBR-7902210226DOC.DATEi79/02/16NOTARIZED~NODOCKET0FACILt50-244RobertEmmetGinnaNuclear.PowerPlant,UnitI,Roches05000244AUTH.NAMEAUTHORAFFILIATIONWHITE,L.D.RochesterGas8,ElectricCorp.RECIP.NAMERECIPIENTAFFILIATIONZIEMANN,.D.L.,OperatingRector+Branch2SUBJECTSForwardsreviewofsafetyactuation..circuitsw/manualoverride.Concludesresetoperationdoesnotpreventequipmentfrom.operating.whi'chisnecessarytonitigateapostulatedaccident.eDISTBIBUTI(>NCODEFAOOISCOPIESRECEIVED(LTRMENCL~SIZE<~TITLE(GENERALDISTRIBUTIONFOBAFTERISSUANCEOFOPERATINGLIC~((-~ll~~a<o45RFCIPIENTIDCODE/NAMEACTION-05BCA@6+~INTERNAL-t03.EGFILE1.215KORE,PERFBR.I7ENGRBR019PLANT.SYSBR21EFLTTRT.SYSEXTERNAL.i03LPDR23ACRSCOPIESLTTRENCL77.II22.I.I,I~1II.I,II1616RECAPIENTID'ODE/NAME02NRCPDRI'((ITA/ED()16AD5YS/PROJ18REACSFTYBR20EEB22BRINKMAN04NSICCOPIESLTTRENCL.III.III.II.II.II.II~((UfgQt6Ad~sgagric~TOTALNUMBER.OFCOPIESREQUIRED'TTR38ENCL38 IE1IIr,rr

~Pr~*February16,1979DirectorofNuclearReactorRegulationAttention:Mr.DennisL.Ziemann,ChiefOperatingReactorBranchNo.2U.S.NuclearRegulatoryCommissionWashington,D.C.20555

Subject:

ReviewofSafetyActuationCircuitswithOverridesR.E.GinnaNuclearPowerPlantDocketNo.50-244

DearMr.Ziemann:

4YourletterdatedNovember29,1978requestedrestrictionsbeplacedoncontainmentpurgingduringnormaloperationandthatareviewofallsafetyactuationsignalcircuitswhichincorporatemanualoverridefeaturesbemade.TheRochesterGasandElectricCorporation(RGB)letterdatedJanuary2,1979transmittedtheRG6EcommitmentsonpurgingduringnormaloperationandstatedthattherequiredreviewofoverridefeatureswouldbecompletedbymidFebruary1979.Thepurposeofthisletteristotransmittheresultsofthatreview.DetailsofthereviewarepresentedinAppendixA.Thereviewofallsafetyactuationsignalcircuitswhichincorporateamanualoverridefeatureindicatesthatactuatingaparticularoverride(reset)doesnotcausethebypassofothersafetyactuationsignals.TheresetswitchesdescribedinAppendixAarepushbuttonswitcheslocatedonthecontrolboardwithnophysicalrestraints.Inallcaseswherethesafetyactuationsignalisgeneratedautomaticallyandtheresetswitchisactuated,thesafetyactu-ationsignalwillbeinhibiteduntilalllogicpathsforauto-maticallygeneratingthesafetyactuationsignalhaveopened.Oncealllogicpathsopen,theparticularsafetyactuationsignalresetrelaysde-energizeandre-establishtheabilitytoauto-maticallygeneratethesafetyactuationsignal.Sincetheresetremainsactuatedonlyiftheinputsignalscausingtheautomaticsafetyactuationsignalpersistandtheseinputsignalsareannunciated,noseparateannunciationfortheresetactuationisnecessary.Theoperatorhassufficientinformationtodeducea~certainsystemisintheresetmode.p0v80zzaoww4e,'g~(g',

ROCHFST=RGwSAiVOL=CTR)CCORP.February16,1979TcMr.D.L.Ziemann,ChiefryEET,VO1Znnocasedoesactuationofaparticularresetswitchpreventtheoperatorfrommanuallyoperatingtheequipmentfromthecontrolboard.Therefore,operationofaresetdoesnotpreventequipmentfromoperatingwhichisnecessarytomitigatetheconsequencesofapostulatedaccident.Verytrulyyours,~~+L.D.White,Jr.LDW:npAttachment AppendixAReviewofSafetyActuationSignalCircuitsIncorporatingmanualOverridesThefollowingsummaxizestheresultsofareviewofsafetyactu-ationsignalcircuitswhichincorporateamanualoverridefeature.Thepurposeofthereviewistoensurethatoverridingofonesafetyactuationsignaldoesnotalsocausethebypassofanyothersafetyactuationsignals:SAFETYINJECTIONCIRCUIT:Thiscircuithasaresetswitchwhichgivestheoperatorthemeansofresettingsafetyinjectionone-minuteorlongerafterinitiation.Actuationofthereset.swatchinitselfdoesnotchangethestateofanyequipment,butpermitstheoperatortoplacetheequipmentaffectedbysafetyinjectiontothepositiondesired.Ifsafetyin]ectioniscausedbyautomaticactuation,andtheresetswitchisactuated,automaticsafetyingectionwillbeinhibiteduntilalllogicpathsforautomaticsafetyinjectionhaveopened.Oncealllogicpathsopen,thesafetyinjectionresetrelaysde-energizeandre-establishesautomaticsafetyinjectioncapabilities.Manualsafetyinjectioninitiationisavailableatalltimes.Thereisnoannunciationofthesafetyxngectioncircuitbeingintheresetmode.ThepurposeoftheresetswitchonthesafetyinjectionsystemistoallowequipmenttoberealignedfortherecirculationphaseofapostulatedLOCA.2.CONTAINMENTVENTILATIONISOLATIONCIRCUIT:Thiscircuithasaresetswitchwhichgivestheopexatorthemeansofresettingcontainmentventilationisolation.Oncetheresetswitchhasbeenactuated,most'oftneequipment.willautomaticallyreturntothestateselectedpriortotheisolationsignal.Ifcontainmentventilationisolationwascausedautomatically,eitherbysafetyinjectionorhighradiationalarmoncontainmentgasand/orparticulatemonitors,andthisconditioncontinuestoexist:afterthexesetswitchhasbeenactuated,thencontainmentventilationisolationcannotbeachievedautomaticallyorbythemanualisolationswitchesuntilth'islogicclears.Oncetheautomaticlogicclears,thecontainmentventilationisolationresetrelaysde-energizeandre-establishesautomaticormanualisolationcapabilities.

Manualoperationofthevalvesfromthecontrolboardisavailableatalltimes.Thereisnoannunciationoftheautomaticcontainmentventilationisolationsystembeingintheresetmode.IJThepurposeoftheresetswitchonthecontainmentventi-lationisolationsystemistoallowpurgingofcontainmentinordertolimitpotentialhydrogenconcentrationbuildupfollowingapostulatedLOCAwhenhighcontainmentactivityandsafetyinjectionsignalscouldbepresent.3.CONTAINMENTISOLATIONCIRCUIT:Thiscircuithasaresetswitchwhichgivestheoperatorthemeansofresettingcontainment.isolation.Oncetheresetswitchhasbeenactuated,someequipmentwillreturn,automaticallytothepositionselectedpriortotheiso-lationsignal.Ifcontainmentisolationwascausedautomaticallybyanautomaticsafetyinjectionsignal,andcontainmentiso-lationresetswitchisactuatedwithoutresettingsafetyinjection,containmentisolationcannotbeobtainedbythemanualcontainmentisolationswitchesuntilsafetyinjec-tionisreset.Actuationoftheresetpermitstheoperatortoplacethevalvesaffectedbythecontainmentisolationsignalintheposition~desired.Thiscapabilityisnecessarysothattheoperatorhasflexibilityindealingwithpostaccidentconditionswithincontainment.Thereisnoannunciat'ionoftheautomaticcontainmentisolationbeingintheresetmode.4.CONTAINMENTSPRAYCIRCUIT:Thiscircuithasaresetswitchwhichgivestheoperatorthemeansofresettingcontainmentspray.Oncetheresetswitchhasbeenactuatedthesprayadditivetankdischargevalveswillreturnautomaticallytothepositioncalledforbythecontrollerpriortothecontainmentspraysignal.Thecontainmentspraypumpsandtheirdischargevalveswouldrequireoperatoractiontochangestate.Ifcontainmentspraywascausedautomaticallybythehighcontainmentpressurelogic,andthislogiccontinuestoexistafterreset,containmentspraycannotbeinitiatedbythemanualsprayswitches.Oncethehighpressurelogichascleared,thecontainmentsprayresetrelaysde-energizeandre-establishesautomaticormanualcontain-mentspraycapabilities.

Actuationoftheresetpermitstheoperatortoplacethevalvesandpumpsaffectedbythecontainmentspraysignalinthestatedesired.Thiscapabilityisnecessarysothattheoperatorhasflexibilityindealingwithpostaccidentconditionswithincontainment.Thereisnoannunciationoftheautomaticcontainmentspraysystembeingintheresetmode.5.FEEDNATERISOLATIONRESET:Thiscircuithasaresetswitchwhichgivestheoperatorthemeansofresettingtheisolationsignaltothefeed-waterbypassvalvesonly.Themainfeedwatervalveswillremaincloseduntiltheisolationlogicclears,andthentheyautomaticallyassumethepositionrequestedbytheircontrolcircuit.Iffeedwaterisolationiscausedbyhighsteamgeneratorlevellogic,andthisconditionstillexistsaftertheresetswitchisactuated,-asafetyinjectionsign'alwouldnotcauseanisolationtothatparticularfeedwaterbypassvalve.Itshouldbenotedthatasafetyinjectionsignalalsocausesthemainfeedwaterpumpstobetripped,therefore,closingthefeedwaterbypassvalvesonasafetyinjectionsignalisredundant.Thereisnoannunciationoftheautomaticfeedwateriso-lationsystembeingintheresetmode.6NUCLEARINSTRUMENTATIONSYSTEMDEFEAT~BYPASSgANDBLOCKSWITCHES:~Thissystemhasseveralswitcheswhichareusedforthefollowingpurposes:(a)DefeatSwitches-Defeatsapermissivewhichrein-statesatriplogic.(b)BypassSwitches-Bypassesatriporrunbackfunctionforcalibrationormaintenancepurposes.Protectionisstillprovidedbyredundantchannelorchannels.(c)BlockSwitches-Blockstripsgeneratedbysource,.intermediate,andpowerrangechannels.Theseswitchesareactuatedaspermissivesetpointsarereachedtopermittakingreactorcriticalandupinpower.Theseblocksautomaticallyresetaspowerisdecreasedbelowitsparticularsetpoint.Alltheaboveswitchesifactuated,areindicatedbyoneormoreofthefollowing:statuslight,alarmonthecomputer,oractuateanannunciator.

7.INSTRUMENTANDCONTROLDEFEATSWITCHES:Thefollowingswitchesandtheircircuitswerereviewedtoinsurethattheyareonlyperformingtheirintendedfunction,andnoothersafetyfunctionsarebeingbypassed.The-purposefortheseswitchesistobeabletoswitchcontrolfromonesensorlooptoanotherfortesting,calibrationandmaintenancepurposes.Inallcases,reactortripandsafetyinjectionsignalsaregeneratedpriortodefeatswitches,andarenotaffectedbyswitchposition.(a)P/429APressurizerPressureSelectorSwitcn-Usedtoselecttwoofthefourpressurizerpressurechannelsforcontrollingpressurizerheaters,sprays,andpowerreliefvalvePCV-430.(b)L/428APressurizerLevelSelectorSwitch-Vsedtosele'cttwoofthethreepressurizerlevelchannelsforcontrollingchargingpumpspeed,letdowniso-lation,andpressurizerheaters.(c)T/405EandT/405FDeltaTDefeatSwitches-Vsedtodefeatachannelfromtheovertemperatureandoverpowerturbinerunbackcircuit,andtoremoveachannelDeltaTsignalfromtheinputofthesummerforgeneratingtheaverageDeltaTsignalortheRodInsertionLimitCircuit.(d)T/401AandT/401BTavgDefeatSwitches-UsedtodefeataTavgchannelfromtheinputtotheaverageTavgsummerwhichisusedforfulllengthrodcontrol,condensersteamdump,andpressurizerlevelsetpoint.