Uranium Isotopic Analysis with Commercial CZT Detectors and a Generic Algorithm

Sandia National Laboratories, in partnership with the Y-12 National Security Complex, has worked to develop a generalized method for isotopic analysis of enriched uranium using commercial cadmium-zinc-telluride (CZT) detectors and a non-proprietary analysis algorithm. Measurements of several different enrichment levels of uranium were made at the Y-12 Nuclear Detection and Sensor Testing Center Site 2, using the site’s uranium enrichment standards. These measurements were made using commercially available CZT detectors with the goal of identifying an appropriate algorithm for measuring enrichment levels. Recent improvements in CZT detector systems, both in crystal size and resolution, may make these detectors practical in this application and point the way towards more portable and affordable equipment for arms control monitoring applications. The HYPERMET peak detection algorithm, which was first developed for high-purity germanium detectors at the U.S. Naval Research Laboratory (Phillips and Marlow, 1976), was evaluated for application to the CZT spectra obtained during the measurements. HYPERMET is a well-known algorithm which uses a zero-area filter and a non- linear least-squares fitting routine to find doublets and triplets which may otherwise be hidden in the data, and was used to find overlapping peaks in the uranium spectrum. Significant areas of interest in the spectrum were analyzed for peaks that could be used to find enrichment levels. Results from this analysis are presented, as well as future potential for applying this algorithm to arms control monitoring applications or other applications such as international safeguards. This work was sponsored by the National Nuclear Security Administration Office of Nuclear Verification.