Molten salt chemistry in MSRs

The molten salt reactor (MSR) was selected as one of the promising designs by the International Generation IV Forum for the next generation of nuclear reactors. Running on a liquid molten salt fuel as opposed to the oxide fuel of current Light Water Reactors, the Molten Salt Reactor technology provides a safe and truly innovative concept. Moreover, it can be coupled to a thorium fuel cycle, which produces much less long-lived radioactive waste and allows a more sustainable energy production, as thorium is three times more abundant on Earth than uranium. 

Before the Molten Salt Reactor technology can be realised, a thorough safety assessment of all components of the reactor must be carried out. In particular, understanding the chemistry of the liquid fuel and acquiring a thorough knowledge of its physical and chemical properties such as density, viscosity, heat capacity, thermal conductivity and vapour pressure is essential. At TU Delft, we investigate the structural, physico-chemical properties of the molten salt fuel, its chemical interaction with structural materials, and the potential release of radioactive fission products from the fuel using a combination of experimental studies (X-ray and neutron diffraction, X-ray Absorption Spectroscopy, Differential Scanning Calorimetry) and thermodynamic modelling assessments using the CALPHAD method. Our laboratories are well equipped to handle molten salt materials, which are radioactive, highly hygroscopic and corrosive at high temperatures.

Thermodynamic model and excess molar volume in the LiF-BeF2 system

References

J.A. Ocadiz-Flores, A.E. Gheribi, J. Vlieland, D. de Haas, K. Dardenne, J. Rothe, R.J.M. Konings, A.L. Smith, Examination of the short-range structure of molten salts: ThF4, UF4, and related alkali actinide fluoride systems, Phys. Chem. Chem. Phys. 23 (2021) 11091-11103, DOI: 10.1039/d1cp00566a 

A.L. Smith, E. Capelli, R.J.M. Konings, A.E. Gheribi, A new approach for coupled modelling of the structural and thermos-physical properties of molten salts. Case of a polymeric liquid LiF-BeF2, Journal of Molecular Liquids 299 (2020) 112165

G.I.L. van Oudenaren, J.A. Ocadiz-Flores, A.L. Smith, Coupled structural-thermodynamic modelling of the molten salt system NaCl-UCl3, Journal of Molecular Liquids 342 (2021) 117470