Evaluating the Effectiveness of the MC&A System to Verify that Nuclear Materials are Present

Traditional materials accounting is focused exclusively on the material balance area (MBA), and involves periodically closing a material balance based on accountability measurements conducted during a physical inventory. In contrast, the physical inventory for near-real-time accounting system is established around process areas and looks more like an item inventory. That is, the intent is not to measure material for accounting purposes, since materials have already been measured in the normal course of daily operations. A given unit process may operate numerous times over the course of a material balance period. The product of a given unit process may move on to processing within another unit process in the same MBA or may be transferred out of the MBA. With this approach, few materials are ever unmeasured thus the physical inventory for a near-real-time process area looks more like an item inventory. That is, the intent is not to perform accountability measurements, since materials have already been measured in the normal course of daily operations. The intent of the physical inventory is to locate the materials on the books and verify information about the materials contained in the books. Closing a materials balance for such an area is a matter of summing all the individual mass balances for the batches processed by all unit processes in the MBA. Additionally, performance parameters are established to measure the program’s effectiveness. Program effectiveness for verifying the presence of nuclear material is required to be equal to or greater than a prescribed performance level, process measurements must be within established precision and accuracy values, physical inventory results meets or exceeds performance requirements, and inventory differences are less than a target/goal quantity. This approach exceeds DOE established accounting and physical inventory program requirements. Hence, LANL is committed to this approach and to seeking opportunities for further improvement through integrated technologies. This paper provides a detailed description of this evaluation process.