Applicability of passive neutron non-destructive assay technique for Pu quantification in MOX fuels containing minor actinides

Advanced fast reactor fuel contains minor actinides (MAs) and fission products (FPs) such as lanthanides in addition to uranium and plutonium, and it is supposed to include neutrons and gamma-ray originating from sources other than nuclear materials even in its fresh status. Due to these radioactive rays, it is considered difficult to use existing non-destructive assay technique for quantification of Pu in MOX fuels for that in advanced fast reactor fuels. The Differential Die-away Self Interrogation (DDSI) assay technique is a passive neutron non-destructive assay technique that does not require an external neutron source and is a simple technique that does not require large-scale equipment or radiation sources. The DDSI method evaluates the neutron leakage multiplication factor and determines the mass of spontaneous fission nuclides by utilizing and discriminating the difference in neutron die-away time between spontaneous fission neutrons and induced fission neutrons. The purpose of this study is to evaluate the applicability of passive neutron non-destructive assay technique for Pu quantification in MOX fuels containing minor actinides.