Multi-Species Hydrodynamic Electrochemical Modeling with Liquid Metal and Rotating Cylinder Electrodes in Molten Salt

The accurate prediction of a hydrodynamic electrochemical system with radioactive materials can reduce the economic costs and radiological risk of repeated experiments. Such a prediction requires the computationally rich coupling of hydrodynamic phenomena and electrochemical reactions at a multi-dimensional domain, especially for multiple species in heterogeneous phases. This study develops a finite element method model to simulate the transport phenomena and electrochemical reactions of U, Pu, and Nd simultaneously in a molten salt metallurgical electrorefining system. The results are validated against lab-scale experimental data conducted in high temperature LiCl-KCl molten salt. The experiment conducted in the Argonne National Laboratory has a unique electrochemical cell with a combination of liquid metal and rotating solid cylinder electrodes. The model successfully simulates the time-dependent multi-species behaviors of the system such as dissolution rates from the liquid metal anode and deposit composition on the rotating cylinder electrode. In particular, it successfully predicts the transition time of depositing element at the cathode from U to Pu, which is very important information for product quality and process monitoring. In addition, it can catch the change of thermodynamic behaviors of Pu by forming intermetallic compounds with liquid Cd metal