In-Situ Spectroelectrochemistry of Lanthanides in Molten Chloride Salts

Abstract

Molten Salt Reactors (MSRs) are a potential game-changing technology for next-generation nuclear power. Although the MSR concept was demonstrated at Oak Ridge National Laboratory (ORNL) in the 1960’s, it had not gathered attention from commercial vendors until recently. A fundamental knowledge of salt chemistry, including the speciation and solubility of corrosion and fission products is central to the safe and reliable operation of MSRs. The structural properties of fused salt solutions, especially the coordination geometry around the metal ions in the melt, are intricately dependent on the melt composition and temperature. In this work, a combination of in-situ electrochemistry and optical absorption spectroscopy techniques are utilized to understand the speciation and structure of lanthanides in molten chloride salts as a function of temperature, concentration and melt composition. The spectroelectrochemistry of metal species in molten salt media can be used as a potential process monitoring technique enabling the quantitative measurement of lanthanide and actinide metals within molten salt reactors or nuclear fuel pyro-processing applications.This work was supported as part of the Molten Salts in Extreme Environments Energy Frontier Research Center, funded by the U.S. Department of Energy (US-DOE), Office of Science, Basic Energy Sciences, at BNL, INL and ORNL under contracts DE-SC0012704, DE-AC07-05ID14517 and DE-FC02-04ER15533, respectively.