Solubility of Lanthanide Fluorides in Nitric Acid Solution in the Dissolution Process of FLUOREX Reprocessing System

A new reprocessing technology, FLUOREX, is proposed for the thermal reactor cycle. In the dissolution process of FLUOREX, it needs to estimate the concentration of fluoride ion in the solution to avoid formation of insoluble plutonium precipitate. We measured the solubility products of lanthanide fluorides, LaF 3 , CeF 3 , and NdF 3 in nitric acid solution and evaluate the concentration of fluoride ion in the dissolution process. Solubilities were measured by both of dissolution method and precipitation method. The solubility products are about 10 1 to 10 2 times larger than those in water. This largeness may be caused by higher ionic strength of nitric acid solution. The newly obtained solubility products for the lanthanides are useful to calculate the maximum concentration of plutonium ions in the FLUOREX dissolution process, although the further study for the solubility products for plutonium tetrafluoride is needed in the nitric acid solution.