Special Session: Basis for the design of multiscale/multiphase materials for nuclear waste management (organised by Agnes Grandjean, CEA, Marcoule France)

The goal of this session is to exchange information and discuss the challenges and limits of novel hierarchical structure materials for the creation of safe, efficient, and stable waste forms for fission products and transuranic elements. The efforts to generate the scientific basis for such waste forms will be presented including materials synthesis, characterization, modeling, and radiation effects. The long-term behavior of nuclear waste form materials under high radiation fluxes and the reliable containment of radionuclides within their structure are key issues for safe and successful nuclear waste management. The development of waste form materials with structural flexibility at various scales (from atomic to micrometer) for targeted compositions and phases offers a unique opportunity to achieve the safe and sustainable storage of nuclear waste. This is enabled by advances in the chemical/structural understanding of innovative hierarchical structure motifs able to incorporate transuranic or fission products elements, such as salt inclusion materials, metal organic frameworks, tunnel structures, and multi-scale porous structures. The activities of necessity include investigation and development direct and indirect synthesis routes to obtain structure motifs for hosting specific elements these will be discussed as will fundamental transport process in multi-scale porous and hierarchical materials. The expected scientific exchange will allow the advancement of the understanding of waste form materials, will strengthen the research potential, and ultimately generate solutions to meet the existing challenges of advanced waste forms.