The "Radiation research on biological systems" department studies the biological processes in a repository and its environment, as well as in nature in general, with respect to the behavior of radionuclides and chemical analogues. With the goal of gaining a comprehensive understanding, we conduct research at various bioscales. Molecules, cellular systems, and whole organisms are studied individually and in community to understand processes that influence the behavior of metal ions and the corresponding biological responses. To this end, we use the institute's expertise in spectroscopy and computational chemistry and complement it with microscopic and molecular biology techniques. Our highly interdisciplinary and collaborative research focuses on human safety and risk assessment and is also relevant to related research areas such as bioremediation of contaminated sites and resource ­manage­ment.

The "Actinide Thermodynamics" department is active in the field of aqueous speciation, precipitation/dissolution as well as water-solid interfaces. We use primarily NMR, IR, potentiometry, TRLFS and calorimetry to obtain complex formation constants, solubility products, and surface complexation constants, but also enthalpies and entropies. This is accompanied by the derivation of mineral characteristics and ion-ion interaction coefficients. Spectroscopic characterizations of involved species allow to formulate realistic reactions. All obtained parameters (and their uncertainties) undergo quality assurance measures and are fed into thermodynamic databases such as THEREDA or RES³T. Subsequent geochemical speciation calculations support long-term safety assessments; results from uncertainty and sensitivity analyses as well as geostatistics are also applied.

The "Surface Processes" department aims at fundamental and independent knowledge of the (geo)chemistry and environmental fate of long-lived radionuclides (RN). One prominent application is the safe disposal of radioactive waste. We provide the radiochemical knowledge, namely thermodynamic and mechanistic data of important mobilizing and immobilizing reactions of RNs in solution, at interfaces, and in solids. We use a variety of established and advanced microscopic and spectroscopic techniques to accurately describe complex formation reactions and complex structures that go­vern RN interactions in the geosphere. In addition, we investigate the creation and chemical speciation of activation products in materials from nuclear power plants in the context of their safe decommissioning.

The "Molecular Structures" department conducts synchrotron-based research, offering a robust toolkit for scientists investigating materials containing actinides and lanthanides. Our research provides detailed insights into the structural and electronic properties of such materials across various scientific disciplines, including physics, chemistry, environmental science, and geoscience. Experiments take place at the Rossendorf Beamline of The European Synchrotron (ESRF), in Grenoble (France) which is specifically dedicated to the actinide science and research on radioactive waste disposal. The beamline consists of four experimental stations -XAFS, XES, XRD-1, XRD-2 - with se­veral X-ray spectroscopy and X-ray diffraction methods in an alpha-lab environment. Data analysis is performed with the help of electronic structure calculations. We study fundamental electron interactions, bonding properties, probing the local structures and oxidation states of complex systems.

The "Biophysics" department investigates the physics that underlies fundamental processes of life. Although ubiquitously involved cellular function, the role of water is little understood in biomolecular assemblies at the nanoscale. We are interested in the functional implications of biomolecule hydration in condensates, membrane proteins and DNA supramolecular structures. These systems co­ver key process in the cytosol and the plasma membrane of a cell as well as nano-technological applications of rationally designed DNA nanostructures. Our studies concern systems of different complexity, ranging from liquid-liquid phase-se­parated proteins states o­ver lipid protein interactions to tightly packed DNA. Particularly, ionic and heavy metal-induced effects are elucidated for ecological and radiological purposes. In the even more complex system of a living microorganism, we study the metabolic response to radionuclides, using state of the art microcalorimetry to derive novel measures of toxicity. The Biophysics Department is part of the Clus­ter of Excellence “Physics of Life”.

In the "Reactive Transport" department we study the heterogeneity of material surface reactivity, including sorption and dissolution reactions and material degradation. We use experimental and numerical methods to quantify and predict surface reaction rates using rate maps. Transport in complex porous materials is another important aspect of our work. We develop conservative and reactive radionuclide tracers using our cyclotron laboratory and apply positron emission ­tomo­graphy (PET). We use and develop numerical methods for transport analysis at the pore scale and above. Our research is motivated and driven by applications in nuclear safety research and we provide critical links to earth, environmental and materials sciences.

The "Reactor Safety" department deals with the safety assessment of internationally operated Generation III and III+ light water reactors as well as innovative reactor concepts currently under development (e.g. SFR - sodium cooled fast reactor, SMR - small modular reactors). The work concentrates on the development of new methods of accident analysis, which are able to bring the computational accuracy and the spatial/temporal resolution to a qualitatively new level. The aim is to provide a validated tool for accident analysis of conventional and innovative reactors using multi-physics approaches that couple high-resolution neutron kinetics with state-of-the-art computational fluid dynamics (CFD) methods, advanced one-dimensional thermohydraulic plant models and calculations of fuel rod behavior. Furthermore, the rich expertise in the development and application of reactor dosimetry calculation programs is being used to apply these tools to determine the activity level of power plant componen­ts during the dismantling of nuclear power plants.

In the "Chemistry of the f-elements" department, we study the chemistry of the actinides and their lanthanide homologues in solid state as well as in solution with the goal to understand chemical bonding in actinide compounds on the electronic level. Our main focus is on the coordination chemistry of f-elements with inorganic and organic ligands, with various donor atoms. These studies use single-crystal X-ray diffraction to study structures in the solid state, and spectroscopic techniques, such as NMR, XANES, and TRLFS, to characterize structures in solution. EPR and SQUID are used to elucidate ­magnetic properties. All studies are complemented by state-of-the-art quantum-chemical calculations.

The safety of nuclear reactors critically depends on the mechanical behavior of structural materials under harsh environmental conditions (neutron irradiation, high temperatures). The department of "Structural Material­s" focusses on the multi-scale characterization of irradiated reactor materials including reactor pressure vessel steels as well as innovative materials for future reactor concepts including nuclear fusion. The methodic spectrum co­vers the full functional chain from nm-scale irradiation-induced defects to macroscopic mechanical properties and aims at the identification, bet­ter understanding and mitigation of irradiation effects. The research relies on a unique infrastructure including the hot cell labs for the investigation of neutron-irradiated materials as well as the HZDR Ion Beam Cen­ter for ion irradiation experiments.

The Solid State Chemistry of Radionuclides department focuses on research related to the structure and properties of solid phases containing radioactive elements. We are especially interested in crystalline inorganic solid phases such as zircon (ZrSiO₄), zirconia (ZrO₂), and pyrochlore (Ln₂Zr₂O₇), as well as lanthanide (Ln-)orthophosphates of the monazite type (LnPO₄). These solid phases are of relevance in the corrosion of the Zircaloy cladding surrounding spent nuclear fuels rods, or they are envisioned as ceramic hosts for the immobilization and safe disposal of specific actinide-bearing waste streams generated in the late stages of the nuclear fuel cycle. We produce polycrystalline powders or single crystals doped with actinide elements using hydrothermal, flux growth, and solid-state synthesis routes. Combining X-ray diffraction and various microscopic and spectroscopic techniques, we explore the microstructure, redox chemistry, and local structural order/disorder phenomena in the doped solid phases. With this, we aim to develop a detailed understanding of actinide immobilization in crystalline matrices on an atomic basis and to make reliable statements with regard to the performance of the host materials under repository conditions.