Pyroprocessing is an electrochemical fuel-recycling technique that employs a high-temperature molten salt as an electrolyte

to process used nuclear fuel. Oxide reduction (OR), which is the initial electrochemical step in pyroprocessing, involves the

conversion of oxide fuels into metals in molten LiCl-containing Li 2 O. Careful equipment design is required to minimize

impurities in the salt, such as corrosion products, for maintaining the long-term effi ciency of the OR equipment. In a previous

study, we developed OR equipment to reduce 0.6 kg of simulated oxide fuel in 5 kg of Li 2 O–LiCl salt and validated its

performance over ten consecutive OR runs. This paper presents the chemical analyses of the salt samples taken during each

OR run and the precipitate found at the bottom of the crucible after the fi nal run. An inductively coupled plasma-optical emission

spectrometer was employed to quantitatively analyze the elemental concentrations in the salt, focusing on the simulated

oxide fuel, Pt (OR anode material), and stainless steel (SS, used for the crucible containing salt and cathode basket). The

analysis results indicated a linear increase in the concentrations of salt-soluble Sr and Ba over the ten OR runs. In contrast, U

and Fe concentrations originating from the SS remained below 400 and 300 ppm, respectively, without a discernible upward

trend, whereas other elements were either undetectable or slightly above the detection limit. The precipitate recovered from

the crucible contained high concentrations of Pt and Fe, indicating the progressive corrosion of both the Pt anode and SS

crucible during the process.