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

Abstract

Pyroprocessing / Uranium / Actinide / Liquid cadmium cathode / Molten salt Summary. 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-UCl 3 salt were conducted at 773 K for different current densities using the mesh-type LCC structure. Uranium was successfully collected over 5 wt. % 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 UCd 11 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.

Recovery of uranium using electrorefining with an anode-liquid cathode module (ALCM) in molten LiCl–KCl–UCl3–NdCl3 and cadmium distillation

“…These rapid changes in the cathode potential were induced by the vertical movement of the mesh-type Cd stirrer, which was necessary to prevent the growth of U dendrites over the LCC crucible. The explanation of this phenomenon was reported in previous studies [1,8,10,11]. In Runs 3 and 4, the cathode potential was slightly lower than in previous runs, and this was due to the lower concentration of metal chlorides as a result of consecutive LCC electrorefining runs, which resulted in the increase in the overpotential.…”

Current Status of Pyroprocessing Development at KAERI

“…The electrowinning process developed at KAERI consists of three steps ( Figure 12): (i) LCC electrowinning for simultaneous recovery of U and TRU using an LCC, (ii) residual actinide recovery (RAR) process for recovery of the residual low-concentration U/TRU in the salt after the LCC electrowinning process, and (iii) Cd distillation of the cathode product (i.e., Cd ingot including the U/TRU deposits) produced from the LCC electrowinning and the RAR processes. The essential technologies that include the development of effective LCC structure [7], RAR methods [8], analytical technologies [9], and computational model of electrowinning cell [10] have been developed to enhance the operation efficiency of electrowinning process. In order to demonstrate the developed technologies, the engineering-scale electrowinning system of PRIDE was established.…”

“…Therefore, the inhibition of the growth of uranium dendrites in the LCC has been considered a critical technique for the electrowinning process. KAERI has developed a meshtype LCC assembly (i.e., mesh agitator with LCC) to prevent U deposits from growing into dendrites, resulting in the increase of U recovery [7]. The mesh agitator pushes the U deposits generated on the LCC surface into the liquid Cd.…”

Electrochemical Deposition of U and RE Elements Using the Stirred Liquid Cadmium Cathode in LiCl-KCl Molten Salts

“…In the USA, a pounder-type LCC was designed which pushed any U deposits down into the LCC [6]. At the Korea Atomic Energy Research Institute (KAERI), a mesh-type LCC structure was devised which allowed significant U deposition of over 5 wt % in the LCC without inducing U dendrite formation [7]. In this study, a series of U and U/RE electrodeposition tests were performed, utilizing a stirred LCC.…”