Adaptation of Transactinide Handling Methods in Support of Gas-Phase Separations of Rare Earth Elements and Nuclear Forensic Analysis

The intent of this work is to reduce the time needed for isotopic analysis of trace fission products following a large dispersal event. Trace fission products often have insufficient radiation signatures and overlapping atomic mass numbers, which requires time consuming separations of each element prior to isotopic analysis using well established methods. This work adapts transactinide characterization methods for the goal of continuously collecting and dissolving trace fission products immediately after their gas-phase separation by element, which will substantially reduce the time needed for characterization. Obstacles to widespread use were considered, resulting in a final prototype that demonstrates the feasibility of this endeavor using a minimalistic design and readily available components.

Conventional transactinide characterization designs of interest utilize gas-solid isothermal chromatography to separate chemical complexes based on their thermodynamic properties in conjunction with rapid transport methods that place the samples in proximity to appropriate characterization systems. These systems require an extensive laboratory setup to operate, so an alternative low-pressure spray system was designed using various drafting and modeling software suites. A prototype was constructed for feasibility demonstrations using readily available components. Each computational fluid dynamics (CFD) model was validated by constructing and testing an intermediate prototype, with the final prototype having no observable discrepancies compared to the CFD model.

Important to this work, the spray system incorporates a unique design that avoids cross contamination of separated elements, which would otherwise cause isobaric interferences. The spray system rinses aerosol samples into a collection chamber, where they are dissolved in dilute nitric acid and continuously withdrawn for analysis. To expedite the design process, less hazardous surrogates were used in the development process. Collection efficiencies up to 85 percent were observed in the final prototype. Sample collection efficiency and peak concentrations are strongly influenced by the spray rate and collection reservoir volume of the apparatus, respectively.