Development of Near-Real Time Material Detection and Analysis by Coupling Electrochemical & Optical Spectroscopy Methods for Molten Salt Systems

For both pyroprocessing and molten salt reactors (MSRs), it is desirable from a process control and nuclear safeguards perspective to monitor the species in the molten salts for material accountancy. Many traditional monitoring techniques, even simple salt sample retrieval, are time exhaustive or rendered useless for these systems due to the high thermal loads, high radiation zones, and corrosive nature of molten salts. Therefore, the main motivation for this work is the need for an online monitoring system for a molten salt system that is robust enough to handle the extreme environment yet deliver quantifiable salt concentrations. The intent of this dissertation is to demonstrate the combined use of cyclic voltammetry (CV) and laser-induced breakdown spectroscopy (LIBS) as an analytical technique for quantifying the concentration of species in the molten salt medium, mainly LiCl-KCl eutectic. CV is a robust electrochemical method that can be run without interruption and at varying speeds while LIBS has desirable qualities such as little to no sample preparation, low limits of detection (LOD), and rapid analysis. Three experimental programs were developed to demonstrate the parallel and eventual combined use of these methods. The first investigates the parallel use of CV and LIBS on a SmCl3 salt system. The second focuses on improvements to the experimental system and adds GdCl3 as an additional salt component. The final experimental program focuses on combining CV and LIBS through sensor fusion to monitor UCl3, GdCl3, and MgCl2 simultaneously in a LiCl-KCl salt system