Chemical Interactions between Thorium(IV) and O2- in the FLiBe and FLiNaK Molten Salt Systems

The chemical interactions between thorium(IV) and O2- in the LiF-BeF2 (2 : 1 mol%) (FLiBe) LiF-NaF-KF (46.5 11.5 42 (FLiNaK) molten salt systems were studied at 873 K. precipitation-dissolution behavior of Th(IV) oxide/oxyfluoride species, as well speciation law these species their relationship with oxide concentration fluoride melts, clarified. results showed that FLiBe melt would only produce ThO2. saturated solubility ThO2 was 0.057 mol/kg, its corresponding apparent product ( K s p ? ) id="M2"> 8.8 ± 0.1 × 10 ? 4 mol3/kg3 id="M3"> 8.6 0.7 by dissolution titration methods, respectively. However, FLiNaK melt, more complex than FLiBe, oxyfluoride (i.e., Th2OF104- ThOF2) produced. initially formed ratio id="M4"> r ? 0.5 id="M5"> = open="[" close="]"> O 2 added / Th IV initial ), converted to ThOF2 precipitate when id="M6"> > . Therefore, soluble is important intermediate Th(IV), O2-, precipitation. difference melts attributed free F- content two systems. present work provided reference fundamental data for understanding nature thorium fuel precipitation how control it media, which significant importance safe operation reactor (MSR).