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Molten salt NaCl-CaCl2 is a viable candidate for the base fuel salt of a molten salt reactor (MSR). Molten salt mixtures NaCl-CaCl2-UCl3 (16 wt%) and NaCl-CaCl2-UCl3 (14.5 wt%)-CeCl3 (1.0 wt%) were analyzed using electrochemical methods to assess the feasibility of using these methods to measure the concentration of PuCl3 in MSR fuel in real time. CeCl3 was used as a surrogate for PuCl3 in this study. Different electrochemical test methods including electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and square wave voltammetry (SWV) were used at 923 K. Visible WE deposition is observed after running electrochemical tests, and a net 1 V underpotential deposition of Na from NaCl was observed. This indicates that there are serious challenges for application of electrochemical methods to quantitative analysis of actinides in MSR fuel containing NaCl. [ABSTRACT FROM AUTHOR]

Using cyclic voltammetry and UV-vis absorption spectroscopic methods, we studied the precipitation reactions of trivalent uranium and lanthanides (Nd, Ce, and La)with the oxide ion in LiCl-KClmolten salts, which are likely side reactions during the electrorefining process for nuclear fuel treatment. The in situ electrochemical and spectroscopic monitoring demonstrated that U3+ consumed O2- with the mole ratio of 2:1, whereas the lanthanide ions reacted with O2- with the mole ratio of 1:1. Raman spectroscopy and X-ray diffraction were also employed to analyze the precipitates, confirming that U3+ was precipitated and oxidized into UO2, while the trivalent lanthanide ions formed oxychlorides (LnOCl). As a preliminary study of actinide co-precipitation, we also electrochemically monitored the precipitation reactions in a mixed melt containing uranium and lanthanides, demonstrating a higher reactivity of the former with the oxide ion in LiCl-KCl. [ABSTRACT FROM AUTHOR]