RG1.012 核电厂地震仪表 1997

Revision2March1997RegulatoryGuide1.12NuclearPowerPlantInstrumentationForEarthquakes(DraftissuedasDG-1033)[DivisionIndex|RegulatoryGuideIndex|NRCHomePage]PublicationInformationA.INTRODUCTIONIn10CFRPart20,StandardsforProtectionAgainstRadiation,licenseesarerequiredtomakeeveryreasonableefforttomaintainradiationexposuresaslowasisreasonablyachievable.ParagraphIV(a)(4)ofAppendixS,EarthquakeEngineeringCriteriaforNuclearPowerPlants,to10CFRPart50,DomesticLicensingofProductionandUtilizationFacilities,requiresthatsuitableinstrumentationmustbeprovidedsothattheseismicresponseofnuclearpowerplantfeaturesimportanttosafetycanbeevaluatedpromptlyafteranearthquake.ParagraphIV(a)(3)ofAppendixSto10CFRPart50requiresshutdownofthenuclearpowerplantifvibratorygroundmotionexceedingthatoftheoperatingbasisearthquakegroundmotion(OBE)occurs.1ThisguidedescribesseismicinstrumentationthatisacceptabletotheNRCstaffforsatisfyingtherequirementsofPart20andAppendixStoPart50.Theinformationcollectionscontainedinthisregulatoryguidearecoveredbytherequirementsof10CFRPart50,whichwereapprovedbytheOfficeofManagementandBudget,approvalnumber3150-0011.TheNRCmaynotconductorsponsor,andapersonisnotrequiredtorespondto,acollectionofinformationunlessitdisplaysacurrentlyvalidOMBcontrolnumber.B.DISCUSSIONWhenanearthquakeoccurs,itisimportanttotakepromptactiontoassesstheeffectsoftheearthquakeatthenuclearpowerplant.Thisassessmentincludesbothanevaluationoftheseismicinstrumentationdataandaplantwalkdown.Solid-statedigitaltime-historyaccelerographsinstalledatappropriatelocationswillprovidetime-historydataontheseismicresponseofthefree-field,containmentstructure,andotherSeismicCategoryIstructures.Theinstrumentationshouldbelocatedsothattheresponsemaybecomparedandevaluatedwiththedesignbasisandsothatoccupationalradiationexposuresassociatedwiththeirlocation,installation,andmaintenancearemaintainedaslowasreasonablyachievable(ALARA).Instrumentationisprovidedinthefree-fieldandatfoundationlevelandatelevationinSeismicCategoryIstructures.Free-fieldinstrumentationdatawillbeusedtocomparemeasuredresponsetotheengineeringevaluationsusedtodeterminethedesigninputmotiontothestructuresandtodeterminewhethertheOBEhasbeenexceeded(seeRegulatoryGuide1.166).Theinstrumentslocatedatthefoundationlevelandatelevationinthestructuresmeasureresponsesthataretheinputtotheequipmentorpipingandwillbeusedinlong-termevaluations(seeRegulatoryGuide1.167,RestartofaNuclearPowerPlantShutDownbyaSeismicEvent).Foundation-levelinstrumentationwillprovidedataontheactualseismicinputtothecontainmentandotherSeismicCategoryIstructuresandwillbeusedtoquantifydifferencesbetweenthevibratorygroundmotionatthefree-fieldandatthefoundationlevel.Instrumentationisnotlocatedonequipment,piping,orsupportssinceexperiencehasshownthatdataobtainedattheselocationsareobscuredbythevibratorymotionassociatedwithnormalplantoperation.TheguidanceinRegulatoryGuide1.166isbasedontheassumptionthatthenuclearpowerplanthasoperableseismicinstrumentation,includingtheequipmentandsoftwareneededtoprocessthedatawithin4hoursafteranearthquake.Thisisnecessarytodeterminewhetherplantshutdownisrequired.ThisdeterminationwillbemadebycomparingtherecordeddataagainstOBEexceedancecriteriaandbyevaluatingtheresultsoftheplantwalkdowninspectionsthattakeplacewithin8hoursoftheevent.Itmaynotbenecessaryforidenticalnuclearpowerunitsonagivensitetoeachbeprovidedwithseismicinstrumentationifessentiallythesameseismicresponseateachoftheunitsisexpectedfromagivenearthquake.AnNRCstaffevaluationofseismicinstrumentationnotedthatinstrumentshavebeenoutofserviceduringplantshutdownandsometimesduringplantoperation.Theinstrumentationsystemshouldbeoperableandoperatedatalltimes.IftheseismicinstrumentationordataprocessinghardwareandsoftwarenecessarytodeterminewhethertheOBEhasbeenexceededisinoperable,theguidelinesinAppendixAtoRegulatoryGuide1.166shouldbeused.Thecharacteristics,installation,activation,remoteindication,andmaintenanceoftheseismicinstrumentationaredescribedinthisguidetohelpensure(1)thatthedataprovidedarecomparablewiththedatausedinthedesignofthenuclearpowerplant,(2)thatexceedanceoftheOBEcanbedetermined,and(3)thattheequipmentwillperformasrequired.Itisimportantthatallthesignificantgroundmotionassociatedwithanearthquakeisrecorded.Thisisaccomplishedbyspecifyinghowlongbeforeandaftertheactuationoftheseismictriggerthedatashouldberecorded.Settingsfortheinstrumentation'spre-eventmemoryshouldbecorrelatedwiththemaximumdistancetoanypotentialepicenterthatcouldaffectaspecificsite.ThePwavemaynotberecordedwithonlya3-secondmemorysetting.Also,whenaneventoccursatsomedistanceandthetriggerthresholdlimitisnotexceededuntil15or20secondsintotheevent,apartoftherecord,althoughatlowamplitude,islost.A30-secondvaluemaybemoreappropriateandiswithinthecapabilitiesofcurrentdigitaltime-historyaccelerographsatnoadditionalcost.Theappendixtothisguideprovidesdefinitionstobeusedwiththisguidance.C.REGULATORYPOSITIONThetype,locations,operability,characteristics,installation,actuation,remoteindication,andmaintenanceofseismicinstrumentation