Square wave voltammetry for real time analysis of minor metal ion concentrations in molten salt reactor fuel

Molten salt mixtures containing LiCl-KCl-UCl3-CeCl3 were used as surrogates for molten salt reactor fuel in a study of electrochemical concentration analysis. Current responses to low concentration CeCl3 (0.5 wt% Ce) in molten eutectic LiCl-KCl with high concentration UCl3 (5 and 10 wt% U) were measured using cyclic voltammetry (CV) and square wave voltammetry (SWV). CV peaks associated with CeCl3 were impossible to quantify because of dominant reducing current contribution from UCl3. SWV results featured peaks from UCl4, UCl3, and CeCl3 with minimal baseline interference. A potential hold at −1.5 V for 100 s was effective at cleaning the working electrode in between each SWV scan, which enabled generating reproducible (with ±1.10% average error) peak current results for CeCl3 over a period of 2 h. The peak current density for CeCl3 increased by 8.3% from doubling the U concentration from 5 to 10 wt%, thus indicating that this method is promising for measuring minor metal ion concentrations in molten salt reactor fuel with high U concentrations.