Designation:C1807−15StandardGuideforNondestructiveAssayofSpecialNuclearMaterial(SNM)HoldupUsingPassiveNeutronMeasurementMethods1ThisstandardisissuedunderthefixeddesignationC1807;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thisguidedescribespassiveneutronmeasurementmethodsusedtonondestructivelyestimatetheamountofneutron-emittingspecialnuclearmaterialcompoundsremain-ingasholdupinnuclearfacilities.Holdupoccursinallfacilitiesinwhichnuclearmaterialisprocessed.Materialmayexist,forexample,inprocessequipment,inexhaustventilationsystems,andinbuildingwallsandfloors.1.1.1Themostfrequentusesofpassiveneutronholduptechniquesareforthemeasurementofuraniumorplutoniumdepositsinprocessingfacilities.1.2Thisguideincludesinformationusefulformanagement,planning,selectionofequipment,considerationofinterferences,measurementprogramdefinition,andtheutili-zationofresources.1.3Countingmodesincludebothsingles(totals)orgrosscountingandneutroncoincidencetechniques.1.3.1Neutronholdupmeasurementsofuraniumaretypi-callyperformedonneutronsemittedduring(α,n)reactionsandspontaneousfissionusingsingles(totals)orgrosscounting.Whilethemethoddoesnotprecludemeasurementusingcoincidenceormultiplicitycountingforuranium,measurementefficiencyisgenerallynotsufficienttopermitassaysinreasonablecountingtimes.1.3.2Formeasurementofplutoniumingloveboxes,in-stalledmeasurementequipmentmayprovidesufficienteffi-ciencyforperformingcountingusingneutroncoincidencetechniquesinreasonablecountingtimes.1.4Themeasurementofnuclearmaterialholdupinprocessequipmentrequiresascientificknowledgeofradiationsourcesanddetectors,radiationtransport,modelingmethods,calibration,facilityoperations,anduncertaintyanalysis.Itissubjecttotheconstraintsofthefacility,management,budget,andschedule,plushealthandsafetyrequirements,asw...
