Modern Problems, Old Solutions? Reigniting Laser-Induced Breakdown Spectroscopy for Advanced Nuclear Reactor Applications

Molten salt reactors (MSRs) are one of the generation IV advanced nuclear reactor design concepts. In liquid fueled MSRs, the design breaks from traditional nuclear reactors by dissolving the fuel material into a molten salt matrix that circulates the primary circuit. This design offers advantages in terms of passive safety and improved efficiency but creates challenges related to corrosion and fission product dispersion. The redox levels of the salt will vary depending on the impurities in the salt (e.g., H and O), which can then induce corrosion of the structural materials. Fission products will be generated as nuclear fission occurs; these resultant elements will transport throughout the system based on their properties. Some elements (e.g., noble gases) will evolve from the salt into the headspace where they must be properly removed through an off-gas system. Other species will remain in the salt, where their concentrations may be indicative of reactor performance.
Laser-induced breakdown spectroscopy (LIBS) is being investigated as a sensing method for elemental composition and select isotope ratios across the MSR fuel cycle. While traditional radiation-based measurements will be hindered by high background levels and a dispersed fuel salt, LIBS can provide an in-situ measurement of elemental composition regardless of if a species is radioactive. This talk will provide an overview of the recent advancements in the application of LIBS to molten salts, including aerosolized sampling, off-gas monitoring, and directly monitoring flowing molten salts.