Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

For the long-term safety assessment of nuclear waste repositories, neptunium and uranium are two of the most environmentally relevant components of nuclear waste to be considered. Hence, great attention is attracted to their geochemistry and migration behavior. Among the various geochemical processes, the migration of radioactive contaminants in the environment is strongly affected by molecular reactions in aqueous solution and at the solid-water interface, e.g. complexation with organic/inorganic ligands, sorption onto mineral phases, surface precipitation, and colloid formation. A detailed description of these interactions on a molecular level is required for a reliable modeling of the contaminants dissemination in the environment.
In the past decade, vibrational spectroscopy has been developed to a powerful tool for the study of dissolved complexes of heavy metal ions with a variety of inorganic and organic ligands and surface complexes on solid phases. In particular, a combined approach of in situ vibrational, time-resolved laser fluorescence and X-ray absorption spectroscopy potentially provides comprehensive molecular information. A survey of very recent spectroscopic results obtained from geochemical reactions of radionuclides, namely Np(V) and U(VI), is given.