Corrosion-resistant microplasma anode arrays for high-temperature molten salt electrolysis and in situ analysis

Abstract

Developing a suitable corrosion-resistant anode material and monitoring the molten salt composition changes are two core challenges in the electrolytic reduction process of spent nuclear fuels. In this work, a gaseous microplasma anode was employed to induce the electrochemical reduction of UO₂ pellets, achieving a high reduction degree. Compared to traditional commonly used anode materials (platinum, carbon, molybdenum, and tungsten), microplasma electrodes presented a high corrosion resistance and remained stable during long-term operation (>150 hours) in LiCl–Li₂O molten salt. The salt composition changes could be in situ monitored by collecting the atomic emission spectra in the microplasma. Moreover, a microplasma array was designed to amplify the electrolysis current and monitor the components in different regions of the molten salt, addressing the demands of industrial-scale applications. It was calculated that the cost of the anode for reducing 1 kg UO₂ could be reduced for more than 90% by using microplasma instead of Pt electrodes, indicating that microplasma is a promising corrosion-resistant anode for high-temperature molten salt electrolysis and in situ analysis.