Molten Salt Technologies for Advanced Nuclear Fuel Cycles and Molten Salt Reactors

This dissertation provides five topics—an assessment of different monitoring and analytical techniques often cited in the literature for molten salt systems and designs for nuclear engineering applications. First, we explored commonly used materials for quasi-reference electrodes in molten chloride salts. Second, the limitations of the electrochemical analysis known as cyclic voltammetry due to the concentration of uranium(III) present were being investigated. Third, we provided an experimental assessment on the development of a spectroelectrochemical cell for interrogating various spectroelectrochemical techniques, namely chronoabsorptometry and chronofluorometry, and their limitations due to the presence of uranium(III) ions. Fourth, a study on the corrosion resistance of a glassy metal coating used to inhibit corrosion of an alloy substrate was studied. Finally, we investigated the effect of compositions of uranium and cerium, the applied reduction potential, and ion migration-limiting reduction potentials in chloride and fluoride salts on the morphology of uranium electrodeposits. The results show that tungsten performs best compared to other quasi-reference electrodes and useful analysis with cyclic voltammetry is limited by the concentration of the analyte. There were several material issues that should be further explored to improve a future spectroelectrochemical cell design. In addition, the experimental outcomes indicate that glassy metal coatings have poor corrosion resistance. For uranium morphology, by increasing both impurity in the salt and applied overpotential, it will cause the formation of repeating dendritic morphologies in uranium electrodeposits; these dendrites can be mitigated by applying a ion migration-limited reduction potential determined from electrochemical impedance spectroscopy