Uranium Enrichment Determination with Commercial CZT Detectors and a Non-proprietary Analysis Algorithm

Sandia National Laboratories, in partnership with the Y-12 National Security Complex and Lawrence Livermore National Laboratory, 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 a number of 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 standards were designed with enrichment levels that bracket important enrichment thresholds to assess the accuracy of new measurement systems. These measurements were made using a commericailly available 1 cubic centimeter CZT detector and custom collimator with the goal of developing an accurate system which utilizes the \"enrichment\" meter\" method. Recent improvements in CZT detector systems, both in crystal size and resolution, make these detectors practical in this application and point the way towards more portable and affordable equipment for potential 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, was evaluated for application to the CZT spectra obtained during the measurements. HYPERMET is a well-known application which uses a zero-area filter and a non-linear least-squares fitting routine to provide more accurate peak area calculations, and showed excellent results in determining enrichment levels of the Y-12 standards