Year
2015
Abstract
A general purpose, high-resolution, Box Segmented Gamma Scanner (BSGS) Non-Destructive Assay (NDA) system designed for large-scale waste assay of SNM bearing materials embedded within variable waste streams has been in operation at the Savannah River Site (SRS) for several years. The BSGS was instrumental in characterizing thousands of nuclear waste generated containers consisting of 208-liter drums, 208-liter drum Pipe Over-pack Containers (POCs), Standard Waste Boxes (SWBs), and standard large box (SLB–2) containers. The waste characterization provided by the BSGS was in support of the Waste Isolation Pilot Plant (WIPP) TRU waste characterization, certification, and shipment program. Recently, the BSGS was utilized to assay, in the near-field, a more problematical waste stream consisting of Highly Enriched Uranium (HEU) POCs, containing traces of quasi-weapons grade type Pu for potential TRU waste classification and shipment to WIPP. The HEU POC drums are extremely difficult to characterize due to interferences and Compton effects from elevated quantities of Np-237, with small amounts of Pu-239 and high amounts of U-235 as well as self-absorption effects for the lower energy, lower penetrating, gamma rays. In this paper we present the challenges engaged, and new technical approaches developed, in characterizing the HEU POCS assayed with the BSGS utilizing standard NDA tools leading to TRU classification.