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【英文标准名称】:StandardTestMethodforDeterminingThermalNeutronReactionRatesandThermalNeutronFluenceRatesbyRadioactivationTechniques
【原文标准名称】:用放射性技术测定热中子反应和注量率的标准试验方法
【标准号】:ASTME262-2008
【标准状态】:现行
【国别】:美国
【发布日期】:2008
【实施或试行日期】:
【发布单位】:美国材料与试验协会(US-ASTM)
【起草单位】:E10.05
【标准类型】:(TestMethod)
【标准水平】:()
【中文主题词】:
【英文主题词】:Cobaltmethod;Fluence;Neutronactivationreactions;Standardfoiltechnique;Thermalneutronflux
【摘要】:Thistestmethodcanbeextendedtouseanymaterialthathasthenecessarynuclearandactivationpropertiesthatsuittheexperimenter''sparticularsituation.Noattempthasbeenmadetofullydescribethemyriadproblemsofcountingtechniques,neutron-fluencedepression,andthick-foilself-shielding.Itisassumedthattheexperimenterwillrefertoexistingliteratureonthesesubjects.Thistestmethoddoesofferarefereetechnique(thestandardgoldfoilirradiationatNationalInstituteofStandardsandTechnology(NIST)toaidtheexperimenterwhenheisindoubtofhisabilitytoperformtheradiometrictechniquewithsufficientaccuracy.Thestandardcomparisontechniqueusesasetoffoilsthatareasnearlyidenticalaspossibleinshapeandmass.Thefoilsarefabricatedfromanymaterialthatactivatesbyan(n,x03B3;)reaction,preferablyhavingacrosssectionapproximatelyinverselyproportionaltoneutronspeedinthethermalenergyrange.Someofthefoilsareirradiatedinaknownneutronfield(atNIST)orotherstandardslaboratory).Thefoilsarecountedinafixedgeometryonastableradiation-detectinginstrument.Theneutroninducedreactionrateofthefoilsiscomputedfromthecountingdata,andtheratiooftheknownneutronfluenceratetothecomputedreactionrateisdetermined.Foranygivenfoil,neutronenergyspectrum,andcountingset-up,thisratioisaconstant.Otherfoilsfromtheidenticalsetcannowbeexposedtoanunknownneutronfield.Themagnitudeofthefluencerateintheunknownfieldcanbeobtainedbycomparingthereactionratesasdeterminedfromthecountingdatafromtheunknownandreferencefield,withpropercorrectionstoaccountforspectraldifferencesbetweenthetwofields(seeSection5).Oneimportantfeatureofthistechniqueisthatiteliminatestheneedforknowingthedetectorefficiency.1.1Thepurposeofthistestmethodistodefineageneralprocedurefordetermininganunknownthermal-neutronfluenceratebyneutronactivationtechniques.Itisnotpracticabletodescribecompletelyatechniqueapplicabletothelargenumberofexperimentalsituationsthatrequirethemeasurementofathermal-neutronfluencerate.Therefore,thismethodispresentedsothattheusermayadapttohisparticularsituationthefundamentalproceduresofthefollowingtechniques.1.1.1Radiometriccountingtechniqueusingpurecobalt,puregold,pureindium,cobalt-aluminum,alloy,gold-aluminumalloy,orindium-aluminumalloy.1.1.2Standardcomparisontechniqueusingpuregold,orgold-aluminumalloy,and1.1.3Secondarystandardcomparisontechniquesusingpureindium,indium-aluminumalloy,puredysprosium,ordysprosium-aluminumalloy.1.2Thetechniquespresentedarelimitedtomeasurementsatroomtemperatures.However,specialproblemswhenmakingthermal-neutronfluenceratemeasurementsinhigh-temperatureenvironmentsarediscussedin9.2.Forthosecircumstanceswheretheuseofcadmiumasathermalshieldisundesirablebecauseofpotentialspectrumperturbationsoroftemperaturesabovethemeltingpointofcadmium,themethoddescribedinTestMethodE481canbeusedinsomecases.Alternatively,gadoliniumfiltersmaybeusedinsteadofcadmium.Forhightemperatureapplicationsinwhichaluminumalloysareunsuitable,otheralloyssuchascobalt-nickelorcobalt-vanadiumhavebeenused.1.3Thistestmethodmaybeusedtodeterminetheequivalent2200m/sfluencerate.Theaccuratedeterminationoftheactualthermalneutronfluenceraterequiresknowledgeoftheneutrontemperature,anddeterminationoftheneutrontemperatureisnotwithinthescopeofthestandard.1.4Thetechniquespresentedaresuitableon......
【中国标准分类号】:F74
【国际标准分类号】:27_120_30
【页数】:9P.;A4
【正文语种】:英语