Fission products Sr and Ba in actinide (U, Th) chloride systems: Thermodynamic modelling, experimental investigation and application calculations

In this study, new insights into the solid state chemistry and melting behaviour of the system are presented, building on results in the simulant system . Our studies have revealed the solubility of U in the high-temperature β -phase of BaCl 2 ( i.e ) and an intermediate compound, Ba 3 U 2 Cl 12 , which has led us to revisit or present for the first time the phase diagrams of this system accordingly. Furthermore, we present revised thermodynamic models for the systems , , and (AE = Sr, Ba) based on existing literature data. With the constructed multi-component database , the effect of fission products on the melting behaviour of molten chloride salts containing uranium and thorium is investigated through higher order phase equilibria calculations. • Thermochemistry of the BaCl 2 -UCl 3 system has been elucidated and exhibits very similar behaviour to that of BaCl 2 -CeCl 3 . • With targeted experiments based on simulant chemistry, molten salt systems with actinides can be evaluated in a quick and safe manner. • The intermediate compound Ba 3 U 2 Cl 12 has been proven to exist. • Fission product behaviour in (U,Th) molten chloride fuels shows the potential for precipitation of the fissile material through the formation of Ba 3 U 2 Cl 12