Electrochemical and Laser-Induced Breakdown Spectroscopy Signal Fusion for Detection of UCl₃-GdCl₃-MgCl₂ in LiCl-KCl Molten Salt

This study sets out to demonstrate the capability of using electrochemistry and laser-induced breakdown spectroscopy (LIBS) for concentration prediction of multiple species in a molten salt system at 773 K. Samples contained UCl₃ ranging from 0 to 10 wt%, GdCl₃ ranging from 0 to 5 wt%, and MgCl₂ ranging from 0 to 1.5 wt%, with LiCl-KCl eutectic salt as the remainder. Multivariate models were produced using semi-differential cyclic voltammograms (SDCVs) and normalized spectra acquired from LIBS. The SDCV model best predicted UCl₃ levels, while the LIBS model best predicted GdCl₃ and MgCl₂ concentrations. A third model was developed by fusing the SDCV and LIBS signals. This model predicted UCl₃ well and predicted GdCl₃ and MgCl₂ better than previous models. This model was then evaluated by using blind samples. The model predictions correlated well with inductively coupled plasma mass spectroscopy measurements, passing a t-test at a 95% confidence level.