Electroanalytical Measurements of UCl₃ and CeCl₃ in Molten NaCl-CaCl₂

Abstract

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.

Relationship between the Thermodynamic Quantities and Coordination Structure of Oxide Ions in CaCl2-Based Chloride Melts

“…High-temperature chloride melts containing CaCl 2 have been attracting attention as reaction media in diverse engineering processes, such as thermal storage medium, , fuels and coolants for nuclear power, and electrolytes for metal electrowinning from metallic oxides . More specifically, the NaCl–CaCl 2 melt has been reported to be useful as a heat storage medium because of its low cost and high heat storage density. , Moreover, the formation process of metal carbides from CO 2 in the NaCl–KCl–CaCl 2 melt and the Si electrodeposition process from SiO 2 in a LiCl–KCl–CaCl 2 melt have been reported.…”