Measurement of oxide ion (O2-) concentration is a basic technology required in molten salt fields, from energy storage systems to electrolytic reduction of rare earth elements or spent nuclear fuels. In a molten salt reactor, O2- ions react with actinide elements to form their oxides or oxy-chlorides to induce actinide precipitation, and promote metal corrosion to cause a failure of structural material. For these reasons, removal of O2- ions and monitoring of the O2- concentration in molten salt reactors are essential. In this study, methods using chemical and electrochemical methods were investigated for measuring the concentration of O2- ions in a molten salts. The acid-base neutralization reaction was used as a chemical analysis method. And electrochemical methods using the O2- diffusion limit current and YSZ (yttria stabilized zirconia) indicator electrode were used for measuring the O2- concentration. Finally, a modified method using porous membrane electrode was applied to monitor the O2- concentration. The O2- concentration was measured up to about 2wt% of Li2O by the method using the O2- diffusion current, up to about 4wt% by the YSZ indicator electrode, and about 6wt% by the porous membrane electrode in LiCl molten salts.

• Jei-Won Yeon(Korea Atomic Energy Research Institute (KAERI))