Yuanzineng kexue jishu (Mar 2023)
Analysis of Electric Field on Metallic Spent Fuel Pyroprocessing Molten Salt Electrorefining Cell
Abstract
To assist the development of scientific research prototype and engineering prototype of melten salt electrorefining equipment, electric field analysis was carried out. By using Comsol Multiphysics software, a mathematical model of electric field and electrochemical field in 10 kg/batch uranium metal spent fuel pyroprocessing molten salt electrorefining cell was built based on Maxwell principle and electrochemical theory, under the condition of constant input current density. The effects of the electrorefining cell structure, electrode distance and cathode shape on the cell electric field and electrochemical performance were studied. The simulation results show that for the PEER square cell, the energy consumption is low, current efficiency is high and economic performance is excellent. For the highthroughput frustum cone cell, the current density is high, the electrochemical current density distribution of cathode is concentrated on the anode side, the uranium deposition morphology is uniform, and the electrochemical performance is excellent. For the flat-plate cathode square cell, the current density and current efficiency are high, electrochemical dissolution and deposition rate of uranium is fast, the economic performance and electrochemical performance are excellent. For the rod cathode square cell, the energy consumption is low, the electrochemical current density distribution of cathode is concentrated on the anode side, and the uranium deposition morphology is uniform. Within the range of this study, with the increase of electrode distance, the electric field intensity of the electrolytic cell increases, the mass transfer rate of uranium ions in molten salt increases, the electrochemical anode current density increases, the electrochemical current density of high-throughput frustum cone cell increases, and the electrochemical performance of the cell is almost unchanged. But with the increase of electrode distance, the cell voltage increases, the absolute value of electrode overpotential increases, the total cathode current density decreases, the total anode current density increases, the uniformity of thermal field temperature distribution decreases, the electrochemical cathode current density of PEER square cell decreases, the current efficiency decreases, and the economic performance and thermal stability of the electrolytic cell weaken. The simulation calculated values are in good agreement with the experimental data abroad, which indicates that the model can wholly embody the uranium metal molten salt electrorefining test practice. Taking the above factors into consideration, the high-throughput frustum cone cell with parallel-plate cathode and short spaced electrodes may be the cell with the best technical and economic indicators of electric field and electrochemical field. And it should be selected according to the requirements and process conditions in actual test and application.
