Pavel Soucek

Electrorefining of U-Pu-Zr-alloy fuel onto solid Aluminium cathodes in molten LiCl-KCl

An electrorefining process in molten chloride salts using solid aluminium cathodes is being developed at ITU to recover actinides (An) from the spent nuclear fuel. The maximum possible loading of aluminium electrodes with actinides was investigated during the electrorefining of U-Pu-Zr alloy in a LiCl-KCl eutectic at 450 °C. Two different electrolytic techniques were applied during the experiment and almost 6000 C has been passed, corresponding to 3.7 g of deposited actinides. A very high capacity of aluminium to retain actinides has been proven as the average Al: An mass ratio was 1:1.58 for galvanostatic and 1:2.25 for potentiostatic mode. The obtained deposits were characterized by XRD and SEM-EDX analysis and alloys composed of (U,Pu)Al3 were detected. The influence of zirconium co-oxidation during the process was also investigated and the presence of dissolved Zr ions in the melt yielded a significant deterioration of the quality of the deposit.

Development of Pyrochemical Separation Processes for Recovery of Actinides from Spent Nuclear Fuel in Molten LiCl-KCl

Abstract Effective fuel utilization and waste minimization are required to provide a sustainable and safe energy generation for the future of nuclear reactors. To obtain an efficient fuel cycle it is essential to develop an efficient and selective recovery of the key elements from spent nuclear waste. This necessitates that Am and Cm can be separated selectively from lanthanide fission products. This chapter describes two pyrochemical (dry) processes. Both processes are based on the dissolution of metallic spent fuel in a fused LiCl-KCl eutectic mixture. In the first process, U is collected selectively on a solid iron cathode; U, Pu, and minor actinides are then recovered simultaneously using a liquid Cd cathode. The technique is also used to recover actinides from oxide fuel—the oxide ions are oxidized to CO2 and CO at a carbon anode. The second process is based on electrorefining in a molten LiCl-KCl bath using a reactive solid aluminum cathode. The fuel is dissolved electrochemically into the carrier melt, forming a mixture of actinides and fission product ions. All actinides are selectively recovered together from the melt by electrodeposition on solid aluminum cathodes in the form of solid actinide–aluminum alloys. Data concerning the basic electrochemistry of actinides in a LiCl-KCl eutectic are given. Advantages and drawbacks of the pyrochemical processes are discussed.