Thermodynamic assessment of the NaCl-ThCl₄-PuCl₃ system

T. Dumaire

J.A. Ocádiz-Flores, R.J.M. Konings, A.L. Smith

TU Delft


Molten salt fast reactors (MSFRs) are considered very promising for the production of energy in the future. Using a liquid fuel in the form of a molten salt as combustible and coolant at the same time, MSFRs could allow the access to a more compact and safer source of nuclear power. Mainly appreciated for the possibility to use thorium as fertile material, the MSFR design is a potential solution to reprocess a portion of the large stock of actinides from the spent fuel of the current generation of reactors or high-enriched military stocks [1]. To this date, fluoride and chloride salts are considered as the reference for MSR designs. In particular, the chloride salt mixture NaCl-ThCl4-PuCl3 is an appealing option with a relatively low melting temperature (598 K) at the eutectic 46.5 NaCl – 35 ThCl4 – 18.5 PuCl3 composition, a high stability and a rich neutron economy [2].

This work focuses on the thermodynamic assessment of the NaCl-ThCl4 and ThCl4-PuCl3 binary systems and the NaCl-ThCl4-PuCl3 ternary system, using the CALPHAD (Computer Coupling of Phase Diagrams and Thermochemistry) method and the quasi-chemical formalism in the quadruplet approximation [3]. This work is completed by Molecular Dynamic simulations to assess the structural properties of the liquid solution, density, thermal expansion, and excess thermodynamic properties.

  1. Mourogov, A. and P.M. Bokov, Potentialities of the fast spectrum molten salt reactor concept: REBUS-3700. Energy Conversion and Management, 2006. 47(17): p. 2761-2771.
  2. Katsuta, H., LIQUID TARGET/FUEL AND ASSOCIATED FUEL CYCLE TECHNOLOGIES. 1997, Japan Atomic Energy Research Institute: Tokai-mura, Naka-gun, Ibaraki-ken 319-11 Japan. p. 17-22.
  3. Ocádiz-Flores, J.A., et al., Thermodynamic assessment of the KF-ThF4, LiF-KF-ThF4 and NaF-KF-ThF4 systems. The Journal of Chemical Thermodynamics, 2020. 145.

Event Timeslots (1)

Wednesday – 15th September 2021
Thomas Dumaire