High-level waste partitioning constitutes one of the key step of any advanced management strategy for radioactive waste aiming at transmutation of long-lived radionuclides into short-lived ones. The main objective of this research activity is the demonstration of the suitability of new types of diamides as well as triazine-based compounds for the removal of actinides from high level liquid waste and the subsequent purification of minor actinides from rare earths respectively. This research activity is closely coordinated with that under study at the KfK-Karlsruhe on the same subject.
A wide range of routes for the synthesis of diamides and alkyltriazines (TPTZ) has been investigated. Significant quantities of the diamides may be prepared by a modification of established reactions using malonyldichloride. A new route for the synthesis of alkylTPTZ compounds has been developed.
The extraction properties of diamide molecules have also been the subjects of numerous studies such as: suppression of third phase formation when extracting nitric acid or nitrate salts by diamides in solution in aliphatic diluents by the selection of proper alkyl groups of the diamide; study of the experimental conditions to achieve the americium (III)/iron (III) separation by kinetic means; study of the actinide (III)/lanthanide (III) separation from aqueous thiocyanate/nitrate solutions using diamide extractants, alone or in synergistic combination with quaternary ammonium salts.
This study will comprise the implementation of the following steps:
- Synthesis of new organic extractants (diamides, triazine-based extractants, alpha-hydroxo or 2-oxo carboxylic acids)
- Extraction tests
- Extractants stability assessment
- Partitioning flow-sheets
- Counter-current experiments
- Scaling-up of the preparation procedure for diamides/triazine-based extractants
- Solvent regeneration
- Cooperation within the Community