In-situ analysis of corrosion products in molten salt: concurrent X-ray absorption and electrochemistry reveal both ionic and metallic species

11 October 2022, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


Understanding and controlling the physical and chemical processes at molten salt‐alloy interfaces is vital for molten‐salt nuclear reactors. Corrosion processes in molten salts are highly dependent on the redox potential of the solution that changes with the addition of fission and corrosion products. Therefore, reactor designers develop online electrochemical methods of salt monitoring. But electrochemical spectroscopy relies on the deconvolution of broad peaks, a process that may be imprecise in the presence of multiple species in the solution. Here, we describe our developments towards monitoring the concentration and the chemical state of corrosion products in the melt by a combination of electrochemistry and X-ray absorption spectroscopy. We placed NiCr foil in molten FLiNaK and found the presence of both Ni2+ ions and metallic Ni in the melt, which we attribute to the disintegration of the corroding foil due to Cr dealloying. Although extremely challenging, spectroelectrochemical measurements add a promising rich new data stream for online salt monitoring.


Molten salts
molten salt reactors
x-ray absorption spectroscopy
open-circuit potential
electrochemical spectroscopy
Fluoride salt


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