High temperature inorganic molten salt mixtures are proposed as solvents and coolants for advanced nuclear reactors. Molten fluoride and molten chloride salts have been proposed as fuel solvent and coolant for molten salt nuclear reactors, which dissolve and circulate uranium or thorium fuel and their fission products through the core of a nuclear reactor. Molten fluoride salts have been proposed as coolants for graphitic solid fuel nuclear reactors. Lastly molten fluoride salts have also been proposed as tritium breeding blankets, coolants, and radiation shielding blankets in fusion reactors. There are more than a dozen start-up companies pursuing molten salt technology, both U.S. and internationally. Some are driven by sustainbility characteristics of molten salt reactors, which can recycle spent fuel from conventional nuclear reactors, and can reduce substantially the amount of high level radioative waste produced by nuclear power production. Other companies are driven by the economic advantages that arise from the inherent safety features of molten salts as coolants for nuclear reactors. For example, molten salt mixtures have low vapor pressure and can operate up to temperatures above 1000 oC without boiling, at atmospheric pressure. The atmospheric pressure operation enables the construction of nuclear reactor cores without the use of high pressure vessels, thus significantly reducing costs and material testing timelines for the pressure vessels. The high temperature operation (compared to 300 oC for conventional reactors) enables coupling to high-efficiency modern gas turbines (open air Brayton cycles with combined cycle efficiencies of &gt;60%), compared to steam turbines (with efficiencies of ~35%) that are used by conventional, water-cooled nuclear power plants. The high temperature operation also enables a broader market for process heat applications, and the use of gas turbines enables the production of rapidly-deployable peaking power by the use of gas-cofiring. Thus, molten salt technology that has the possibility of being a sustainable source of energy that does not produce atmospheric pollution and that is competitive with energy from fossil fuels. The talk will provide an overview of molten salt nuclear technology, and will highlight the chemistry challenges faced by molten salt reactor developers.

Use of high temperature molten salts in advanced nuclear energy systems

255th National Meeting (2018)

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