Neutron tomographic fissile assay in spent fuel using the lead slowing down time spectrometer

A tomographical fissile assay technique for light water reactor spent fuels was developed based on the lead slowing down time spectrometer (LSDTS). The Monte Carlo method was used for system performance and for simulation of the sensitivity of detection of fissile materials using neutron emission tomography. A typical spent PWR fuel element was simulated and the spatial and mass sensitivity of the fissile components were investigated. From these studies, the LSDTS system is shown to be a very sensitive device for analyzing the spatial distribution of total fissile materials of a spent fuel assembly in a properly selected assay neutron energy range. This method is also applicable to nuclear waste assay.