【英文标准名称】:StandardMethodforDeterminingThermalNeutronReactionandFluenceRatesbyRadioactivationTechniques
【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】:ASTME262-2003
【标准状态】:现行
【国别】:
【发布日期】:2003
【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】:测量技术;热学;积分通量;核能;放射性;辐射;粒子通量;中子
【英文主题词】:cobalt;dysprosium-aluminum;alloy;spectrum;environments;temperature
【摘要】:Thismethodcanbeextendedtouseanymaterialthathasthenecessarynuclearandactivationpropertiesthatsuittheexperimenter’particularsituation.Noattempthasbeenmadetofullydescribethemyriadproblemsofabsolutecountingtechniques,neutron-fluencedepression,andthick-foilself-shielding.Itisassumedthattheexperimenterwillrefertoexistingliteratureonthesesubjects.Thismethoddoesofferarefereemethod(thestandardgoldfoilirradiationatNationalInstituteofStandardsandTechnology(NIST)toaidtheexperimenterwhenheisindoubtofhisabilitytomeasureanabsolutethermalfluencerate.Thestandardfoiltechniqueusesasetoffoilsthatareasnearlyidenticalaspossibleinshapeandmass.Thefoilsarefabricatedfromanymaterialthatactivatesbyan(n,x03B3;)reaction,preferablyhavingacrosssectionapproximatelyinverselyproportionaltoneutronspeedinthethermalenergyrange.Someofthefoilsareirradiatedinaknownneutronfield(atNIST)orotherstandardslaboratory).Thefoilsarecountedinafixedgeometryonastableradiation-detectinginstrument.Theneutroninducedreactionrateofthefoilsiscomputedfromthecountingdata,andtheratiooftheknownneutronfluenceratetothecomputedreactionrateisdetermined.Foranygivenfoil,neutronenergyspectrum,andcountingset-up,thisratioisaconstant.Otherfoilsfromtheidenticalsetcannowbeexposedtoanunknownneutronfield.Themagnitudeofthefluencerateintheunknownfieldcanbeobtainedbycomparingthereactionratesasdeterminedfromthecountingdatafromtheunknownandreferencefield,withpropercorrectionstoaccountforspectraldifferencesbetweenthetwofields(seeSection4).Oneimportantfeatureofthistechniqueisthatiteliminatestheneedforabsolutecounting.1.1Thepurposeofthismethodistodefineageneralprocedurefordetermininganunknownthermalneutron-fluenceratebyneutronactivationtechniques.Itisnotpracticabletodescribecompletelyatechniqueapplicabletothelargenumberofexperimentalsituationsthatrequirethemeasurementofathermal-neutronfluencerate.Therefore,thismethodispresentedsothattheusermayadapttohisparticularsituationthefundamentalproceduresofthefollowingtechniques.1.1.1Absolutecountingtechniqueusingpurecobalt,puregold,orcobalt-aluminumorgold-aluminumalloy.1.1.2Standardfoiltechniqueusingpuregold,orgold-aluminumalloy,and1.1.3Secondarystandardfoiltechniquesusingpureindium,indium-aluminumalloy,anddysprosium-aluminumalloy.1.2Thetechniquespresentedarelimitedtomeasurementsatroomtemperatures.However,specialproblemswhenmakingthermal-neutronfluenceratemeasurementsinhigh-temperatureenvironmentsarediscussedin.Forthosecircumstanceswheretheuseofcadmiumasathermalshieldisundesirablebecauseofpotentialspectrumperturbationsoroftemperaturesabovethemeltingpointofcadmium,themethoddescribedinTestMethodE481canbeusedinsomecases.Alternatively,gadoliniumfiltersmaybeusedinsteadofcadmium.Forhightemperatureapplicationsinwhichaluminumalloysareunsuitable,otheralloyssuchascobalt-nickelorcobalt-vanadiumhavebeenused.1.3indicatestheusefulneutron-fluencerangesforeachdetectormaterial.1.4Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappropriatesafetyandhealthpracticesanddeterminetheapplicabilityofregulatorylimitationspriortouse.
【中国标准分类号】:F04
【国际标准分类号】:17_240;27_120_30
【页数】:9P.;A4
【正文语种】: