Research for the Safe Management of Nuclear Waste at Forschungszentrum Julich: Materials Chemistry and Solid Solution Aspects

The safe management of high-level nuclear wastes, including their final disposal in a deep geological repository, requires a sound scientific understanding of the processes affecting the various materials present in the multibarrier system of the disposal facility, including the radioactive waste forms. Thus materials science aspects play an important role in the multidisciplinary and complex field of long-term safety assessments. As many of these issues are related to mixed solid compounds, the aspect of structural radionuclide uptake by a host structure and subsequent solid solution formation is one of the key topics of the research related to nuclear waste management at Forschungszentrum Julich. The adopted practice for deriving an in-depth understanding of materials behavior by combining state-of-the-art experimental and computational approaches is presented in the context of three examples: 1) corrosion of spent nuclear fuels, 2) radionuclide retention by secondary phases, and 3) innovative ceramic waste forms. New nano- and microanalytical tools, as well as advanced spectroscopic techniques and computational methods, further developed and tailored at Forschungszentrum Julich, allowed for refined views on these materials.