Sub-MeV Neutron Assay Systems for Nuclear Materials

Some of the basic principles, applications, and limitations of non- destructive assay system based on sub-MeV isotopic sources are dis- cussed. The performance of one system is shown. This system which is based on low sub-MeV neutrons from an antimony beryllium source is sensitive only to presence of fissile material and is very suitable to the assay of fuel elements with a highly probable future application to spent fuel elements. A second system which is briefly discussed is based on unmoderated/moderated high energy neutron source and is sensitive, but to a different extent, to both fissile and fertile materials.