Separation of americium from highly active raffinates by an innovative variant of the AmSel process based on the ionic liquid Aliquat-336 nitrate

Abstract

A new variant of the AmSel (Americium Selective Separation) system for the separation of Am(III) from a PUREX raffinate was tested in which the aliphatic diluent was replaced by the ionic liquid Aliquat-336 nitrate. For this ionic liquid variant, the kinetics, and the influence of both the HNO₃ concentration and the ligand concentration on the stripping were evaluated. In addition, both the original AmSel system, and the ionic liquid variant were demonstrated on a simulated highly active raffinate. The introduction of Aliquat-336 nitrate results in an improved separation between Am(III) and the fission products, in particularly for the light lanthanides and strontium. The Am/Cm separation factors of the ionic liquid variant were found to remain similar to the original AmSel process. Despite the improved separation, slower stripping kinetics were observed and extraction of the SO₃-Ph-BTBP complexant to the Aliquat 336 nitrate phase occurred at low HNO₃ concentrations during the stripping step. However, adequate mitigation actions to counteract these issues were found and applied.