Molten Salt Reactors (MSRs) are one category of advanced nuclear reactor designs receiving increased attention, which is evidenced by significant investments from both government and private industry into MSR technology development. The attractiveness of MSR technology predominately stems from inherent safety features including low pressure operation, passive decay heat cooling, and large negative temperature coefficient of reactivity. A key component of any nuclear reactor is the off-gas system. MSR designs present a unique set of off-gas related challenges due to the fuel being in liquid form. A generalized MSR concept involves the flowing of an inert cover-gas, such as argon or helium, over the molten salt fuel. Volatile species and aerosols can be caught within the cover-gas under both normal and off-normal operating conditions. It is therefore required that off-gas treatment technologies be developed to ensure that radioactive species are not released under any condition. A key aspect of developing and deploying these off-gas treatment technologies is instrumentation for monitoring the concentrations of species in the off-gas before and after treatment. Laser Induced Breakdown Spectroscopy (LIBS) is one of several promising analytical techniques for MSR off-gas monitoring. LIBS has been used to detect hydrogen through curium. Typical limits of detection of in the low tens of parts-per-million and can be lowered further with optimal system design and advanced LIBS set-ups (double-pulse LIBS, hyphenated techniques, etc.). In addition to elemental concentrations, extremely high-resolution spectrometers may be used to obtain isotopic information. This contribution will give an overview of MSR off-gas monitoring requirements, potential approaches to using LIBS for off-gas monitoring, as well as recent progress on the design and testing of a LIBS off-gas monitoring system for MSRs.

Molten salt reactor off-gas monitoring using laser induced breakdown spectroscopy

2019 Fall National Meeting

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