Portable NDA Equipment for Enrichment Measurements in the HEU Transparency Program

The Highly Enriched Uranium (HEU) Transparency Program has used portable non-destructive assay (NDA) equipment to measure the 235U enrichment of material subject to the transparency agreement since 1997. The equipment is based on the “enrichment meter” method and uses low-resolution sodium iodide (NaI(Tl)) detectors. Although systems using high-purity germanium (HPGe) detectors can produce more accurate results we have found that the results with NaI(Tl) detectors are quite adequate for the requirements of the transparency agreement. This paper will describe the details of the equipment’s operation, calibration, testing, and deployment in Russia. We will also provide a comparison of the units originally deployed in 1997 with the upgraded systems that were deployed in 2003.