Enhanced electrochemical reduction of rare earth oxides in simulated oxide fuel via co-reduction of NiO in Li2O-LiCl salt

Rare earth oxides in spent oxide fuel from nuclear plants have poor reducibility in the electrochemical reduction process due to their high oxygen affinity and thermodynamic stability. Here, we demonstrate that the extent of their reduction can be enhanced via co-reduction of NiO in a Li2O-LiCl electrolyte for the electrochemical reduction of a simulated oxide fuel (simfuel). First, the electrochemical behaviors of Nd2O3, NiO, and Nd2O3-NiO were studied by cyclic voltammetry and voltage control electrolysis. Then, the electrochemical reduction of the simfuel containing UO2 and rare earth oxides (Nd2O3, La2O3, and CeO2) was conducted in molten LiCl salt with 1 wt.% Li2O via the co-reduction of NiO. The extent of reduction of the rare earth oxides was found to be significantly improved.