Behavior of Molybdenum Chloro-Species in Alkali Chloride-Based Melts: Implications for Spent Nuclear Fuel Treatments

Chloro-species of molybdenum in oxidation states (III), (IV) and (V) were studied in a range of alkali chloride melts employing high temperature electronic absorption spectroscopy. The reaction rates of disproportionation of MoCl63- complex ions in various melts between 550 and 750 oC were determined. Mo(IV) species MoCl62- were generated and thermodynamic properties of Mo(IV) chloride in NaCl-CsCl eutectic melt estimated. Absorption spectra of molybdenum(V) MoCl6- were measured in a chloride melt for the first time. Speciation and behavior of molybdenum is required for designing processes for molten salt reprocessing of spent nuclear fuel (SNF).