Non Destructive Assay Box Counter

摘要

Many long established US DOE facilities are in possession of poorly documented wastes in a variety of formsrnspanning a broad range of waste containers, waste matrices and isotopic mixtures. Existing assay technologies suchrnas the SuperHENC can address many of the expected waste configurations. However, there are also expected wasternitems that fall outside the normal operating range of these exceptional but “standard” systems. Given the inherentrndifficulties and high costs associated with repackaging even a small number of these containers, an assay solutionrncombining multiple techniques has been studied with the objective of maximizing the likelihood of successfullyrnassaying waste for eventual shipment to WIPP or low level waste disposal.rnThe Integrated Crate Interrogation System (ICIS) is comprised of a Box Segmented Gamma Scanner (BSGS) and arnpassive/active neutron counting system called the Super IWAS. These are two physically independent assayrnsystems mounted within separate ISO Containers but connected via Ethernet to allow automated integration of thernassay results from the two systems. In operation, the waste containers will first be assayed within the BSGS systemrnto obtain both quantitative gamma-ray assay results and relative isotopic data using well-known algorithms such asrnthe MGA or FRAM. In addition to scanning in front of an array of HRGSs the item is also stepped past a 60Corntransmission station on the same line. The operator will then move the container to the neutron assay system. ThernSuper-IWAS concept considered, based on the successful IWAS installations at the AMWTP, provides both highefficiencyrnpassive neutron coincidence analysis and active neutron interrogation using the Differential Die-Awayrntechnique (DDA). The prospect of combining all three complementary assay modes to provide a reliable assayrnresult is discussed for realistic waste forms along with the extensive modeling results. Our objective was to devisernan NDA solution to this pressing problem that stretched the current state of the practice but which could bernimplemented with low technical risk using a reasonably sized resource allocation in a predictable and timely fashion.rnAt the conclusion of the study, a design without the DDA capability was selected for construction.