Nuclear material accountancy and safeguards verification is challenging for mixed nuclear materials. Determining the nuclear material content is significantly challenging for those materials containing fission products and minor actinides (e.g. spent fuel), which emit gamma rays and neutrons that hide the passive signatures from the U and Pu of interest. Presently, within reprocessing plants where this material is found, the Hybrid K-Edge Densitometry technique is used to determine the U and Pu elemental content of small samples taken from solution tanks. A small number of these samples are then evaluated using the Isotope Dilution Mass Spectrometry (IDMS) destructive analysis (DA) technique to determine the U and Pu isotopic composition and bias defects for safeguards. However, as a DA technique, this requires a long, hot-cell preparation process that produces waste and extends the reporting time with many large dry spikes needed for calibration. Since IDMS is also used for evaluating materials that contain small fractions of important nuclides (e.g. U-235 in MOX), supplemental techniques are necessary to improve the efficiency of composition evaluation for material accountancy and bias defect verification. Within this scope, the Japan Atomic Energy Agency and European Commission Joint Research Centre have been developing Delayed Gamma-ray Spectroscopy (DGS), an active-neutron non-destructive assay technique that can be used to evaluate the fissile content in small samples. As part of a series, this presentation describes the scope of the challenges we are addressing, our experimental campaign schedule, and our final goal of developing a DGS instrument to interrogate the small samples found in reprocessing and MOX fuel fabrication plants.
Year
2020
Abstract