This study aims to estimate the concentration of multiple species in LiCl-KCl molten salt via the combined implementation of two methods. The first method for time efficient composition analysis utilizes laser-induced breakdown spectroscopy (LIBS). LIBS involves focusing a pulsed high energy laser onto a sample, creating a plasma plume from the sample’s ablated surface. As this plasma cools down, an elemental spectrum is generated from the elements returning to their ground state. This spectrum can be collected via fiber optics and analyzed to determine the composition of the sample. The second method of salt composition analysis utilizes a variation in the working electrode depth in the electrochemical cell. By changing the immersion depth of the electrode, the characteristic cathodic peak current density of the salt species is measured. The cathodic peak current density is directly related to the salt concentration through the Berzins-Delahay Equation. For this study a matrix of UCl3-MgCl2-GdCl3-LiCl-KCl salt concentrations will be tested with UCl3 ranging from 0.5 – 10.0 wt%, MgCl2 ranging from 1.0 – 5.0 wt%, and GdCl3 ranging from 1.0 – 5.0 wt%. MgCl2 was chosen as a surrogate for Pu in the electrorefiner due to their similar standard potential and GdCl3 was chosen to be representative of the active rare earth salt species which accumulate in the salt. The goal of this study is to show that a combined electrochemical and laser system is capable of monitoring UCl3 concentration in the presence of other species. All samples will undergo electrochemical and LIBS testing; then, a portion of these samples will be tested via ICP-MS to verify each elemental concentration.

Application of electrochemical and laser spectroscopic methods for composition measurements of UCl3-MgCl2-GdCl3 in LiCl-KCl molten salt

2019 Fall National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.