Oxoacidic characterization of zirconium(IV)-based molten fluoride mixtures relevant to future nuclear systems

ANYL 19

Sylvie Delpech, sylvie-delpech@enscp.fr and Gérard S Picard, gerard-picard@enscp.fr. LECA (CNRS), ENSCP, 11 rue Pierre et Marie Curie, Paris, 75005, France
The molten salt reactor was one of the concepts retained in the international forum Generation IV (2001) for the future nuclear energy systems. In this concept, the ThF4-UF4 fuel is dissolved in a molten fluoride mixture whose composition is not yet totally defined. In order to prevent any ThO2 or UO2 precipitation, ZrF4 is strongly envisaged as a component (from 5 to 20 mol%) of these future mixtures. Oxoacidic properties of Zr(IV) - which govern the ability to form either zirconium oxyfluoride or oxide - were thermodynamically determined with an oxide amperometric titration technique using a calibrated gold working electrode. The required equilibrium data necessary to precise the oxoacidic range of zirconium(IV)-based molten fluoride salts were so determined