Innovative Synthesis Methods of Mixed Actinides Compounds: Control of the Composition Homogeneity at a Molecular or Nanometric Scale

摘要

Actinides contained in the used nuclear fuel need to be managed in the future fuel cycles for the sustainability of this source of energy. The major ones such as uranium or plutonium are very valuable for energy production within a new fuel. The minor ones such as neptunium, americium or curium are responsible for the long-term radiotoxicity of the ultimate waste if not separated and transmuted within new fuels or dedicated targets. Whatever the choice of management in the present or future, innovative synthesis methods are studied in many research institutions to elaborate new actinides based materials. Innovative concepts for future fuels or transmutation targets focus on mixed actinides or mixed actinide-inert element materials. For their synthesis, wet methods fulfill very useful requirements such as flexibility, compatibility with a hydrometallurgical fuel processing, less dissemination of radioactive dusts during processing, and above all a better accessibility to very homogeneous compounds and interesting nanostructures. When dealing with plutonium or minor actinides, this last characteristic is of great importance in order to avoid the so-called "hot spots" and to limit macroscopic defects in the fuel material. In this communication, experimental results are given to illustrate recent achievements to control the composition or the structure of mixed actinides compounds at a molecular or at a nanometric scale using co-precipitating techniques or sol-gel methods.