Year
1997
Abstract
Gamma-ray and neutron imaging technology is emerging as a useful tool for nuclear materials safeguards. Principal applications include improvements in accuracy for nondestructive assay of heterogeneous material (e.g., residues) and wide-area imaging of nuclear material in facilities (e.g., holdup). Portable gamma cameras with gamma-ray spectroscopy area available commercially and are being applied to holdup measurements. The technology has the potential to significantly reduce effort and exposure in holdup campaigns; and, with imagining, some of the limiting assumptions required for conventional holdup analysis can be relaxed, resulting in a more general analysis. Methods to analyze spectroscopic-imaging data to assay plutonium and uranium in processing equipment are being developed. Results of holdup measurements using a commercial, portable gamma-camera are presented. We are also developing fast neutron imaging techniques for NDA, search and holdup. Fast neutron imaging provides a direct measurement of the source of neutrons and is relatively insensitive to surroundings when compared to thermal or epithermal neutron materials in interim storage, for which gamma-ray measurements may be inadequate due to self-shielding. Results of numerical simulations to predict the performance of fast-neutron telescopes for safeguards applications are presented.