Year
2015
Abstract
The amount of plutonium (Pu) contents should be measured accurately for nuclear material accountancy in the nuclear facility. Self-induced X-Ray Fluorescence (XRF) and gamma-ray spectroscopy are useful techniques to determine the plutonium-uranium ration and the Pu isotope ratio of the spent fuel. X-ray or gamma-ray measurements of spent nuclear fuel using high resolution spectrometers, such as a high-purity germanium (HPGe) detector, show large background continuum in the low energy region due to Compton scattering of higher energy gamma-rays. In the present study, the Compton suppression system was proposed to reduce the Compton continuum background. The HPGe main detector and BGO (Bi4Ge3O12) guard detector were used to configure the Compton suppression system. To evaluate a performance of a system for measurement of spent nuclear fuels, the Compton suppression system was installed in the hot-cell of the Post-Irradiation Examination Facility (PIEF) at KAERI. A feasibility study has been performed by deploying a Compton suppression system and spent nuclear fuel pellets, with three or four different burn-ups. Peak-to-Compton ratio, which is a figure of merit to evaluate the gamma-ray detection, was enhanced by a factor of two or more when the Compton suppression system was used. In this presentation, the detailed design considerations will be reported including results on the optimization of the Compton suppression system geometry that improves the analysis of the special nuclear material of the spent fuel.