Advantages of “Known Multiplication” Method Application for Plutonium Mass Controlin PuO2 Samples at RT-1 Plant of PA “Mayak”

摘要

“Known multiplication” method is the one of neutron method for Pu mass determinationrnin samples. It is also included in basic software for neutron analysis such as INCC, NCC,rnNDA2000, NAS etc. Nevertheless, application of method was very confined, whereas primaryrn(standard) methods were “known alpha” and “multiplicity”.rnHowever, there are cases when standard methods come into collision with insuperablerndifficulties. It is a matter mainly about control of so-called impure plutonium compound, whichrncan contain unknown amount of low-Z impurities. At that the value of neutron yield due to (a,n)rnreaction becomes unknown and “known alpha” method become invalid. At same timernimplementation of “multiplicity” method required suitable neutron counters with high efficiencyrnand shift registers for multiplicity counting, which were not delivered to Russian nuclearrnfacilities.rnUselessness of application of standard neutron methods for plutonium mass control wasrndisplay for most of samples during neutron measurements of samples with plutonium dioxide atrnRT-1 plant in Mayak facility. Detailed chemical analysis of samples shows presence ofrnconsiderable and not well defined amount of low-Z impurities, which makes impossible ofrn“known alpha” method application for proper analysis.rnIn this paper authors consider the advantages of “known multiplication” methodrnapplication for plutonium mass assay in plutonium dioxide samples at RT-1 plant. Also theyrncompare the results of analysis for all four methods “calibration curve”, “known alpha”,rn“multiplicity” and “known multiplication”, consider reasons of difficulties of analysis by thesernmethods and possibility of “known multiplication” method using for confirmatory measurementsrnof various plutonium materials at Russian nuclear facilities.