Denitration of HLLW for Actinide Partitioning

Actinide partitioning from high level liquid waste has been subject to experimental investigations at the JRC-Ispra and CEA-Fontenay-aux-Roses. In this context, two main flow-sheets based on solvent extraction were drawn up which both involved a denitration step by means of formic acid. In the first process named HDEHPl, denitration was intended to lower the HLLW acidity down to pH 2 while keeping actinides and mainly plutonium in a soluble and extractible form which was proved to be quite effective through secondary reactions between noble metals and formic acid. As for the second process -the TBP2 process — denitration was performed during and after the concentration of high level waste in order to reach a final acidity of about 1 M HNO₃. On the whole, the results of denitration experiments carried out on real waste at the technical scale agreed quite well with those previously achieved on simulates in demonstrating that plutonium can be quantitatively removed from denitration precipitate under certain operating conditions.