A New Approach to Waste Monitoring in Material Access Areas

Safeguards regulations in the United States require utilization of waste monitoring equipment in material access areas which is capable of detecting the inclusion of an excessively large quantity of special nuclear material (SNM). Because experimental results emphatically demonstrate that waste monitoring techniques currently employed in many material access areas do not provide adequate detection capability for some highly credible concealment scenarios for 200-liter waste drums or larger waste objects, it is necessary to examine whether practical revisions in waste container configuration and waste measurement techniques could greatly improve detection capabilities. The most practical solution to the problem (in the author's opinion) would be a mild change in the configuration of waste drums coupled with mild upgrades in waste non-destructive assay (NDA) equipment. Specifically, the drum should be annular rather than cylindrical, with a thickness of about 15 cm between its inner and outer walls. The upgraded assay instrument would utilize a detector in the central cylindrical \"hole\" of the drum and would feature transmission measurements to detect excessive shielding. With these modifications, the amount of SNM (in excess of a normal waste quantity) that could be concealed in a waste drum would be rather small, and assay accuracy would be improved.