DEVELOPMENT OF RAPID MICROSEPARATIONS OF URANIUM AND PLUTONIUM FOR NUCLEAR FORENSICS APPLICATIONS

摘要

The rapid separation and purification of uranium and plutonium from a field sample is important in identifying the presence of these signatures in nuclear forensics applications. A small separation unit would allow for simple and fast determinations of liquid samples and could be field-deployable when coupled with the appropriate sample digestor and detection systems. This separation system offers significant improvements to traditional separation methods which employ a sequence of tedious, time-consuming steps and generate large waste volumes. We have been developing a portable, separations system for U and Pu separations from iron-rich samples based upon an extraction chromatographic resin packed into a microcolumn. The microfluidic design minimizes elution volumes and concentrates the elements of interest in a purified stream. Flowsheet development and testing was demonstrated on the microcolumn system with an acidified, iron, uranium, and plutonium nitrate stream. The recovery of Pu was optimized by examining various reducing agents at different concentrations for rapid, quantitative recovery from the flow-through design. Quantitative recovery of U and Pu was achieved in the appropriate stripping stages and provided purified and concentrated U and Pu streams (95% of U and 98% of Pu was recovered with high purity; <1% of Pu or U in the respective streams). High selectivity was demonstrated from isotopic analyses of the purified streams. The microfluidic system suggests automation in a small, footprint unit while exploiting the extraction chromatographic resins as the primary means of concentrating the radionuclides from the raw acidic feed and separating the elements into purified streams.