Development of transuranic isotope assay system using an active neutron technique

It is required that such waste containing transuranic (TRU) isotopes as arises from spent fuel reprocessing and mixed-oxide fuel fabrication plants should be managed in separation from other radioactive wastes due to its extremely long decay time. For its efficient practice, the authors have been developing a high sensitivity non- destructive TRU assay system to classify TRU waste from others. The system, in expectation of a high sensitivity, uses an active neutron technique which is called a differential die-away technique (DDT). The principle of DDT is based on irradiating drummed waste with thermalized pulsed neutrons which induce fission/neutron emission of the fissile TRU isotopes and detecting the induced-fission prompt neutrons whose count ratio to the thermalized monitor counts is proportional to the quantity of the TRU isotopes contained