Spectroelectrochemistry of the Electrolytic Reduction of Trivalent Lanthanides in LiCl-KCl Eutectic Molten Salt

Abstract

Understanding the speciation of dissolved lanthanides and actinides in molten salts and the chemical behavior of those species is vital to the development of homogenously fueled molten salt reactors and pyrochemical reprocessing of used nuclear fuel. The coupling of spectroscopy and electrochemical analysis can provide complimentary information about the chemistry and speciation of elements dissolved in molten salt mixtures, which is crucial for managing, amongst other concerns, corrosion issues in the process. We have developed a custom furnace with optical pathways for spectroscopic measurements and provisions for the insertion of electrodes into samples inside the furnace. Absorbance spectra were recorded during the electrolytic reduction of trivalent lanthanides in LiCl-KCl molten salt. The absorbance spectra yield insight into the progression of the electrolytic reduction of the species of interest while the electrolytic reduction provides a means of studying the electronic structure and transitions of soluble reduced species of the lanthanides and potentially monitoring changes to concentrations of the oxidized and reduced species.Acknowledgements:This research is being performed using funding received from the DOE Office of Nuclear Energy's Nuclear Energy University Programs under award DE-NE0008889 and the US Nuclear Regulatory Commission (USNRC) under contract NRC-HQ-13-G-38-0027. Dr. Kenny Osborne and Ms. Nancy Hebron-Isreal serve as the program managers for the DOE and NRC awards, respectively.This material is based upon work supported by the National Science Foundation Graduate Research Fellowship Program under Grant No. DGE-1447692. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation, the U.S. Department of Energy, or the United States Government.