Si-Hyung Kim

Performance of the mesh-type liquid cadmium cathode structure for the electrodeposition of uranium from the molten salt

Abstract A mesh-type liquid cadmium cathode (LCC) structure has been devised to improve the performance of the electro-winning process for the recovery of actinides in a molten chloride system. For the verification of its performance, electrodeposition experiments of uranium from the molten LiCl-KCl-UCl3 salt were conducted at 773 K for different current densities using the mesh-type LCC structure. Uranium was successfully collected over 5ߙwt.ߙ% in the LCC without growing uranium dendrites. The mesh-type LCC structure prevented the uncontrolled growth of uranium dendrites into the electrolyte phase above the cadmium surface and caused the LCC deposit to accumulate at the higher in the cadmium phase over uranium solubility in cadmium. After cooling the LCC crucible, its solid deposits were identified as an intermetallic compound UCd11 by EPMA and XRD analysis. The cathode potential profiles from the electrochemical experiments and the chemical structure of the LCC deposits showed that it could be applied practically to recover the actinides above their solubility in cadmium.

Computational electrochemo-fluid dynamics modeling in a uranium electrowinning cell

A computational electrochemo-fluid dynamics model has been developed to describe the electrowinning behavior in an electrolyte stream through a planar electrode cell system. Electrode reaction of the uranium electrowinning process from a molten-salt electrolyte stream was modeled to illustrate the details of the flow-assisted mass transport of ions to the cathode. This modeling approach makes it possible to represent variations of the convective diffusion limited current density by taking into account the concentration profile at the electrode surface as a function of the flow characteristics and applied current density in a commercially available computational fluid dynamics platform. It was possible to predict the conventional current–voltage relation in addition to details of electrolyte fluid dynamics and electrochemical variables, such as the flow field, species concentrations, potential, and current distributions throughout the galvanostatic electrolysis cell.

Reusability Test for Ceramic Crucibles as Liquid Cadmium Cathode Containers inPyroprocessing

The compatibility of various ceramic crucibles (AlN, BeO, and SiC) for repeated use in pyroprocessing was investigated. Each ceramic crucible loaded with liquid cadmium was immersed in molten chloride salt containing uranium and rare earth elements (Nd, Ce, and La) at 500 °C to perform an electrodeposition, followed by heating to 920°C to separate the metal deposits from Cd during distillation. Repeated process runs showed that the ceramic crucibles could be recycled and reused, more specifically, 7 times for AlN, >13 times for BeO, and 4 times for the SiC crucible. Considering the reactivity of ceramic materials with metal deposits as well as their durability at high temperature, the crucible composed of BeO was concluded to be suitable for use in electrorefining and distillation.