Innovative approach for efficient extraction of Nd from electrorefining waste salt into nuclear waste forms

Abstract

Electrorefining of the high-burnup spent nuclear fuels is critical to the closed fuel cycle in fast reactors for the sustainable development of nuclear energy. However, a remaining challenge in the electrorefining process is the separation of radioactive rare earth fission products to reduce the geological waste volume. In this work, the extraction of a major radionuclide Nd from the molten waste salt into durable waste forms was investigated through a two-step approach consisting of electrolytic reduction and oxidative extraction. Liquid Bi was found to be effective in the electrolytic extraction of Nd, leading to an extraction efficiency of up to 98.6% and a current efficiency of 93.5%. The Nd target in the resulting Nd–Bi cathode alloy was then selectively extracted using specific oxidizers in a glass melting step. High loadings of Nd2O3 in the converted zinc-in-titania glass ceramic and aluminoborosilicate glass waste forms were achieved, demonstrating the prospect of the proposed method in terms of minimizing radioactive waste generation and recycling of the electrorefining waste salt.