【英文标准名称】:StandardTestMethodforNondestructiveAssayofPlutoniumbyPassiveNeutronMultiplicityCounting
【原文标准名称】:用无源中子重复计数法对钚进行无损测定的试验方法
【标准号】:ASTMC1500-2008
【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】:C26.10
【标准类型】:(TestMethod)
【标准水平】:()
【中文主题词】:
【英文主题词】:Multiplicitycounting;Nondestructiveevaluation(NDE)--nuclearapplications;Passiveneutroncounting;Plutonium
【摘要】:ThistestmethodisusefulfordeterminingtheplutoniumcontentofitemssuchasimpurePuoxide,mixedPu/Uoxide,oxidizedPumetal,Puscrapandwaste,Puprocessresidues,andweaponscomponents.Measurementsmadewiththistestmethodmaybesuitableforsafeguardsorwastecharacterizationrequirementssuchas:Nuclearmaterialsaccountability,Inventoryverification(7),Confirmationofnuclearmaterialscontent(8),Resolutionofshipper/receiverdifferences(9),Excessweaponsmaterialsinspections(10,11),Safeguardsterminationonwaste(12,13),Determinationoffissileequivalentcontent(14).Asignificantfeatureofneutronmultiplicitycountingisitsabilitytocapturemoreinformationthanneutroncoincidencecountingbecauseoftheavailabilityofathirdmeasuredparameter,leadingtoreducedmeasurementbiasformostmaterialcategoriesforwhichsuitableprecisioncanbeattained.Thisfeaturealsomakesitpossibletoassaysomein-plantmaterialsthatarenotamenabletoconventionalcoincidencecounting,includingmoistorimpureplutoniumoxide,oxidizedmetal,andsomecategoriesofscrap,waste,andresidues(10).Calibrationformanymaterialtypesdoesnotrequirerepresentativestandards.Thus,thetechniquecanbeusedforinventoryverificationwithoutcalibrationstandards(7),althoughmeasurementbiasmaybelowerifrepresentativestandardswereavailable.Therepeatabilityofthemeasurementresultsduetocountingstatisticsisrelatedtothequantityofnuclearmaterial,interferingneutrons,andthecounttimeofthemeasurement(15).ForcertainmaterialssuchassmallPu,itemsoflessthan1g,somePu-bearingwaste,orveryimpurePuprocessresidueswherethe(x03B1;,n)reactionrateoverwhelmsthetriplessignal,multiplicityinformationmaynotbeusefulbecauseofthepoorcountingstatisticsofthetriplecoincidenceswithinpracticalcountingtimes(12).ForpurePumetal,pureoxide,orotherwell-characterizedmaterials,theadditionalmultiplicityinformationisnotneeded,andconventionalcoincidencecountingwillprovidebetterrepeatabilitybecausethelowcountingstatisticsofthetriplecoincidencesarenotused.Conventionalcoincidenceinformationcanbeobtainedeitherbychangingtocoincidenceanalyzermode,oranalyzingthemultiplicitydataincoincidencemode.ThemathematicalanalysisofneutronmultiplicitydataisbasedonseveralassumptionsthataredetailedinAnnexA1.Themathematicalmodelconsideredisapointinspace,withassumptionsthatneutrondetectionefficiency,die-awaytime,andmultiplicationareconstantacrosstheentireitem(16,17).Asthemeasurementdeviatesfromtheseassumptions,thebiaseswillincrease.Biasinpassiveneutronmultiplicitymeasurementsisrelatedtodeviationsfromthex201C;pointmodelx201D;suchasvariationsindetectionefficiency,matrixcomposition,ordistributionofnuclearmaterialintheitem''sinterior.Heterogeneityinthedistributionofnuclearmaterial,neutronmoderators,andneutronabsorbersmayintroducebiasesthataffecttheaccuracyoftheresults.Measurementsmadeonitemswithhomogeneouscontentswillbemoreaccuratethanthosemadeonitemswithinhomogeneouscontents.1.1Thistestmethoddescribesthenondestructiveassayofplutoniuminformssuchasmetal,oxide,scrap,residue,orwasteusingpassiveneutronmultiplicitycounting.Thistestmethodp......
【中国标准分类号】:F46
【国际标准分类号】:13_030_30
【页数】:14P.;A4
【正文语种】:英语