(259h) The Heat and Mass Transport Questions in Molten Fluoride Salts that are Relevant to Advanced Nuclear Reactors

Scarlat, R. - Presenter, University of Wisconsin Madison
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. There are more than a dozen start-up companies pursuing molten salt technology, both U.S. and internationally. Some are driven by sustainability characteristics of molten salt reactors, which can recycle spent fuel from conventional nuclear reactors. 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 at atmospheric pressure without boiling up to very high temperature (1000 oC and above). The atmospheric pressure operation significantly reduces costs and material testing timelines for advanced nuclear reactors. The high temperature operation enables coupling to high-efficiency modern gas turbines (open air Brayton cycles with combined cycle efficiencies of >60%), compared to steam turbines that are used by conventional, water-cooled nuclear power plants that operate below 350 oC (with efficiencies of ~35%). 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 co-firing.

Some of the technical challenges important in the commercialization of advanced nuclear reactors that use molten salts are tritium management and more generally containment of radionuclides, control of actinide inventory in the liquid phase, and management of transients that involve liquid-solid phase changes. This talk will provide an overview of ongoing research at the University of Wisconsin on heat and mass transport phenomena in molten fluoride salts.