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.