HYDROLYSIS AND RADIATION STABILITY OF THE ALINA SOLVENT FOR ACTINIDE(III)/LANTHANIDE(III) SEPARATION DURING THE PARTITIONING OF MINOR ACTINIDES

Abstract

In the present study, the hydrolytic and radiolytic degradation of chlorine-substituted aromatic dithiophosphinic acids, which are used in the ALINA process for actinide(III)/lanthanide(III) separation was investigated. With the aid of GC-MS, the most important degradation products in the organic phase after hydrolysis with HNO₃ and γ-irradiation were identified. A quantitative determination of the course of the degradation in long-term hydrolysis experiments with 0.5–3.0 mol/L HNO₃, HCl, H₂SO₄ was performed using GC/FID. Irradiation experiments were carried out up to an absorbed total dose of 2.0 MGy, also in the presence of 0.5 mol/L HNO₃. The extraction behaviour for An(III)/Ln(III) separation was studied after hydrolysis and radiolysis. The results show that the degradation products formed by oxidation have no significant influence on extraction.

ACKNOWLEDGMENTS

We would like to thank the Helmholtz Association for financial support for the work under the HGF project “Actinide separation -- a contribution to safe final disposal”. Part of this study was financed from funds of the European Union under the PARTNEW project, Contract FIKW-CT-2000-00087. We are very grateful to Prof. Charles Madic for the coordination of this project and for scientific support.