In Situ X-Ray Absorption Spectroscopy and Electrochemistry Measurements of Corrosion in Molten Fluoride Salt

Molten-salt reactors (MSR) are proposed advanced nuclear reactors that utilize molten salts for cooling and solvents for fissile material. Molten salts with dissolved nuclear fuel and fission and corrosion products present challenges due to their corrosive nature, and as such, interactions between the salts and the materials they interface with need to be understood. We are developing new in-situ analytical techniques for molten-salt characterization and monitoring, especially near the interfaces between alloys and molten salts. Here, we present our examination of the corrosion of NiCr foils in molten LiF-NaF-KF eutectic (FLiNaK) using a combination of x-ray absorption spectroscopy (XAS) and electrochemistry. We distinguished the oxidation state and coordination numbers of dissolved Ni and Cr, as well as the spatial and temporal distribution of the ions in the solution. We also describe reactions at the electrodes.