Retrospective Source Imaging, Assay and Isotopics

The technological requirements to carry out restrospective assay of nuclear materials is first reviewed. The ability to also reconstruct source images is also described along with the potential to obtain isotopic information from the same. Specifically, it will be described how this can be done after the source is removed when no trace materials are left behind. The specific case of determining uranium enrichment retrospectively is then considered and outlined. The particular application being evaluated is the ability to determine the enrichment of UF6 well after the material has been removed from an area although in general the technique can retrospectively image and estimate isotopics of any gamma radiation source distribution. This paper demonstrates that there is a solid theoretical basis to believe that retrospective enrichment verification of UF6 can be accomplished.