LANL Inventory Difference Evaluation Process

A facility responsible for processing Special Nuclear Material (SNM) makes several Non Destructive Assay Measurements (NDA) on an item before, during and after the SNM is processed. There is an inherent uncertainty associated with each measurement method. This results in an inventory difference (ID) that could be a gain or loss in the overall inventory of the facility. The ID evaluation is performed to assure SNM is not diverted. This is one of many barriers that deters diversion of SNM material and provides a level of confidence that the SNM in the facility is in control. This paper will discuss the inventory difference evaluation process at LANL. Los Alamos’ ID Program includes daily analysis and review of inventory adjustments on each batch processed, weekly review of inventory differences, monthly analysis and review of inventory adjustments by Process Status (sub material balance area) and by Material Balance Areas. This paper, by providing an introduction to a site-specific application of ID evaluations, assists safeguards professionals in understanding the significance of an ID Program in detecting a diversion/theft of special nuclear material.