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High Level Radioactive Waste
About
Due to the chemical and structural complexity of spent fuel assemblies and their high radiation levels, studies using spent fuel samples cannot document all the mechanisms and processes that contribute to the long-term oxidative matrix corrosion of spent fuel assemblies in the final disposal environment. Therefore, we also investigate simplified UO2-based model systems using a multi-step bottom-up approach. These single-effect studies help quantify the contributions of various processes to the overall long-term matrix corrosion of spent fuel assemblies. In addition to the various experimental approaches, atomistic simulations of the chemical states of fission and activation products in spent fuel aim to provide further insights into the behavior of these materials. These innovative approaches, pursued at IFN-2, refine our understanding of the behavior of spent fuel in the disposal environment. The results contribute to the scientific basis for the safety case for deep geological disposal by reducing uncertainties regarding the matrix dissolution of spent fuel elements and the release of radionuclides from spent fuel elements.
Research Topics
The research activities on high-level radioactive waste (HLW) at IFN-2 are focused on materials science aspects of the behaviour of waste forms under repository relevant conditions with a focus on the interactions of spent nuclear fuel (SNF) with groundwater. This comprises research into the fast or "instant" release of some volatile radionuclides (e.g. fission gases, and parts of the Cs and I inventories) from SNF immediately after contact with water (so-called instant release fraction IRF) as well as into long-term SNF matrix corrosion processes.
Besides leaching experiments in hot cell facilities (in collaboration with SCK CEN in Belgium) this includes microstructural and microanalytical investigations of SNF segments prior and after corrosion studies. Additionally single effect studies are performed on model systems (link zu Gabriels team) Complementary to the various experimental approaches, thermodynamic simulations on the chemical states of fission and activation products in SNF aim at providing further insight into the behaviour of these materials.
These activities aim at an enhanced mechanistic understanding of processes that govern the radionuclide release from SNF in the repository environment (i.e. the radionuclide source term) on a molecular level to reduce uncertainties and conservatisms in performance assessments (PA), and to improve the confidence in system understanding beyond a simple phenomenological description.
Current projects
Last Modified: 08.07.2026