In Situ Raman Spectroscopy for Nuclear Material Monitoring in Molten Salt Systems

Abstract

Molten salt systems are under consideration for both energy generation and used fuel processing as part of the nuclear fuel cycle. Generation IV nuclear reactor designs use molten salts as both coolants and fuel media. Advanced reprocessing technologies, such as the pyrochemical reprocessing of used nuclear fuel, rely on molten chloride melts as the electrolyte during electrochemical processing of used nuclear fuel. Before any of these technologies can reach the industrial scale, techniques for the monitoring of nuclear material in a nondestructive and in situ manner must be further developed for molten salt systems. Real-time monitoring of nuclear material allows for process optimization, along with addressing nuclear security concerns associated with the diversion of actinide materials. In this study, we explore the use of Raman spectroscopy, employed using a fiber-coupled system, as a method for the in situ­ analysis of molten salt. We present the development of an automated, in situ­ Raman system for analysis of electroactive species in molten LiCl-KCl. The Raman modes of lanthanide chlorides, serving as actinide surrogates, were investigated in LiCl-KCl eutectic at 500°C and compared with the available literature. This work was performed under the auspices of the US Department of Energy (DOE) under contracts DE-NE0008262, DE-NE0008236 and DE-NE0008572, and the US Nuclear Regulatory Commission (NRC) under contract NRC-HQ-13-G-38-0027. Dr. Kenny Osborne serves as the program manager for the DOE awards and Ms. Nancy Hebron-Isreal serves as the grants program officer for the NRC award.