[en] This annual report is structured as follows: 1. Introduction to the Institute for Nuclear Waste Disposal (INE); 2. Education and training; 3. National and international cooperation, conferences and workshops; 4. Fundamental studies: Process understanding on a molecular scale; 5. Applied studies: Radionuclide behaviour in the multi-barrier system; 6. Coordination chemistry; 7. Deconstruction and decommissioning of conventional and nuclear buildings; 8. Development of radionuclide speciation methods; 9. (Radio-)chemical analysis; 10. Radiation protection research; 11. Geoenergy; and 12. Publications.

[en] The contributions collected in this report provide a representative overview of the scientific outcome of INE research activities in 2014. The structure of the report follows widely the organization of the institute according to research topics: basic research towards understanding geochemical reactions of radionuclides on a molecular scale and applied studies on radionuclide retention in multi-barrier system under real repository conditions.

[en] Contributions collected in this report provide a representative overview of the scientific outcome of INE research activities in 2012. The structure of the report follows widely the organization of the institute according to research topics: Basic research towards understanding geochemical reactions of radionuclides on a molecular scale and applied studies on radionuclide retention in multi-barrier system under real repository conditions.

[en] The contributions collected in this report provide a representative overview of the scientific outcome of INE research activities in 2013. The structure of the report follows widely the organization of the institute according to research topics: basic research towards understanding geochemical reactions of radionuclides on a molecular scale and applied studies on radionuclide retention in multi-barrier system under real repository conditions.

[en] The contributions collected in this report provide a representative overview of the scientific outcome of INE research activities in 2015. The structure of the report follows widely the organization of the institute according to research topics: basic research towards understanding geochemical reactions of radionuclides on a molecular scale and applied studies on radionuclide retention in multi-barrier system under real repository conditions.

[en] The contributions collected in this report provide a representative overview of the scientific outcome of INE research activities in 2016. The structure of the report follows widely the organization of the institute according to research topics: basic research towards understanding geochemical reactions of radionuclides on a molecular scale and applied studies on radionuclide retention in multi-barrier system under real repository conditions.

[en] The Proceedings of the Second Annual Workshop of the Collaborative Project CEBAMA addresses key scientific questions related to the use of cement-based materials in nuclear waste disposal applications. Progress beyond the state-of-the-art is achieved by providing basic knowledge, new experimental data, improved modeling and arguments for the Nuclear Waste Disposal Safety Case. CEBAMA is funded by the European Commission under the Horizon 2020 frame of EURATOM.

[en] The interaction of cosmic radiation with terrestrial matter leads to the in-situ production of cosmogenic nuclides in the exposed surface material. Accelerator mass spectrometry (AMS) enables us to quantitatively measure trace concentrations of in-situ produced radionuclides like ¹⁰Be and ²⁶Al. ²¹Ne can be determined by conventional noble gas mass spectrometry. This ultimately allows the determination of surface exposure ages, erosion rates and other processes of landscape evolution. The availability of a pure and well defined mineral sample is an important prerequisite for surface exposure dating. As the samples taken in the field usually do consist of many different mineral components, a quartz separation technique has to be employed. We present a chemical mineral separation that allows the isolation of a pure quartz fraction, which is quantitatively decontaminated from the atmospheric ¹⁰Be contamination lying on the sample. (orig.)

[en] Geochemical modeling of actinide solubilities in performance assessment calculations on the safety of nuclear waste disposal requires a reliable and accurate database. Under carbonate free conditions and alkaline pH, the solubility of Thorium(IV) is controlled by amorphous Th(OH)₄(am) hydroxide or ThO₂.-xH₂O(am) hydrous oxide. The solubility product of this solid (log K _sp = - 47.8 ± 0.3) is well known from our previous work. For natural systems, carbonate complexation has also to be taken into account. Because of the strong tendency of tetravalent actinides towards hydrolysis, ternary hydroxo-carbonate complexes are formed. In the present study, the solubility of X-ray amorphous Th(IV) hydroxide was determined in the system NaHCO₃-Na₂CO₃-NaOH-NaCl at I 0.5 M and 22 C. (orig.)

[en] The solubility of X-ray amorphous Th(IV) hydroxide or hydrous oxide was determined in carbonate solution at I = 0.5 M (NaHCO₃-Na₂CO₃-NaOH-NaCl) and 22 C. Two series of open system experiments were performed under CO₂ partial pressures of 1.0 and 0.1 bar at - log[H⁺] = 4.5-7.5. In three series of closed system experiments at constant total carbonate concentrations of C_tot = [HCO₃^-] + [CO₃^2-] = 0.1, 0.04 and 0.015 M, the H⁺ concentration was varied in the range - log[H⁺] = 8.5-13.5. Some additional solubility data were determined in 0.25-2 M Na₂CO₃ containing 0.1 M NaOH. There was no indication for the formation of a thorium carbonate solid. The simultaneous evaluation of the different sets of experimental data at I = 0.5 M shows that Th(OH)(CO₃)₄^5- and Th(OH)₂(CO₃)₂^2- are the most important ternary complexes. Further contributions to the Th(IV) solubility are coming from Th(OH)₂(CO₃)(aq), Th(OH)₃(CO₃)^- and Th(OH)₄(CO₃)^2-. Their formation constants, extrapolated to I = 0 with the SIT and combined with the solubility product of log K _sp = -47.8 ± 0.3, are calculated to be log β ₁₁₄ = 35.8 ± 0.3, log β ₁₂₂ = 37.0 ± 0.4, log β ₁₂₁ = 30.7 ± 0.4, log β ₁₃₁ = 38.5 ± 0.6 and log β ₁₄₁ = 40.6 ± 0.5. Pure carbonate complexes and other ternary complexes have no significant contributions to the solubility in the present studies at I = 0.5 M. Upper limits are derived for their formation constants. Using the SIT for ionic strength corrections, the evaluated set of equilibrium constants is also consistent with the solubility in Na₂CO₃-NaOH mixtures of higher ionic strength. (orig.)