Formation of Uranium Fluoride Complex by Addition of Fluoride Ion to Molten NaCl-CsCl Melts

The chemical properties and coordination circumstances of uranium complexes in NaCl-CsCl eutectic melts containing fluoride ion were investigated by both electrochemical and absorption spectrum measurements. Energy shifts in absorption peaks, which were caused by the formation of U4+ fluoride complex were observed when NaF was present in the melt. The formation of the fluoride complex of U3+ was not observed. When a cyclic voltammogram was measured after the addition of F-, the reduction potential of U4+ shifted negatively since the fluoride complex of U4+ was more stable than that of U3+ complex in the melt.