Development of technology to assay plutonium in waste containers using the passive neutron coincidence method. Creation of correlated equations for matrix effects and plutonium calibration for waste containers

The Plutonium Fuel Center at Tokai Works has developed a hybrid-type waste container assay system (WCAS)no.1. The system utilizes the passive neutron coincidence method and high-resolution γ spectrometer accurately to assay the quantity of plutonium in waste containers. The center has also performed characterization examinations of this equipment. The examinations revealed that the matrix effects correction equation and the plutonium calibration equation, these were the main assay uncertainty factors of this equipment, were within ±2.7% (2σ) error and ±2.8% (2σ) error, respectively. Consequently, this system was able to assay the quantity of plutonium within an accuracy of 5-10%. (author)