Dans le concept actuel du stockage géologique des déchets radioactifs en France, les interfaces entre la roche encaissante, une argilite, et les matériaux cimentaires utilisés pour les bouchons de scellement et les corps des alvéoles de stockage pourraient subir une température de 70°C due à l’activité exothermique de déchets. Les évolutions minéralogiques, microstructurales et leurs conséquences sur les propriétés de transport à ces interfaces sont mal connues dans ces conditions de température.Deux dispositifs expérimentaux sont conçus. Le premier consiste à créer des interfaces pâte de ciment CEM I / argilite de Tournemire en cellules de diffusion. La chimie des solutions est suivie dans le temps et quatre échéances permettent d’étudier l’évolution temporelle des matériaux. Le second dispositif consiste à créer de telles interfaces in situ à 70°C dans le laboratoire souterrain de Tournemire. Ce dispositif, plus représentatif des conditions de stockage, est démantelé après un an d’interaction. Au préalable, le comportement de la pâte de ciment CEM I à l’issue d’une augmentation de température de 20 à 70°C est analysé. La modélisation en transport réactif (Hytec) est utilisée en support à la compréhension des évolutions physico-chimiques.La néoformation de tobermorite, de phillipsite (in situ uniquement), de C-A-S-H et de calcite formant un ruban à l’interface est avérée. Une cinétique de précipitation de la tobermorite a ainsi pu être évaluée. La pâte de ciment est décalcifiée et carbonatée. La porosité totale diminue dans la pâte de ciment, malgré une ouverture de la macroporosité par dissolution de portlandite. L’argilite semble être peu altérée. La température accélère la diffusion, tandis que les variations de porosité et le ruban ne changent pas significativement les propriétés de diffusion sur une année. / Radioactive wastes in future deep geological disposals will generate heat and locally increase temperature in the engineered barriers and host-rock. In the French design of disposal cells, temperature may reach 70°C in cementitious materials and at their contact with the clayey host-rock. The impact of temperature under such disposal conditions is still poorly known, especially regarding the geochemical and physical evolution at the interface between these two materials.Two experimental devices are designed. The first involves creating interfaces between OPC paste and argillite of Tournemire in diffusion cells. The evolution of solutions and materials are analysed over time. The second device involves creating OPC paste / argillite interfaces at 70°C under in situ conditions in the underground laboratory of Tournemire (France). This device, more representative of a deep disposal, is dismantled after one year. Prior to interface study, behaviour of the OPC paste after a temperature increase from 20 and 70°C was analysed and simulated. Reactive transport modelling supports the experimental results in order to better understand the physico-chemical evolutions at the interface.Neoformation of tobermorite (well-crystallised C-S-H), phillipsite (only in situ), C-A-S-H and calcite formed a layer at the interface. A kinetic of tobermorite precipitation is evaluated. Significant decalcification and carbonation were noticed in the cement paste. Total porosity decreases in the cement paste despite an opening of the macroporosity due to portlandite dissolution. Argillite seems to be weakly altered even if alkaline plume goes deeply through it. Porosity changes do not alter significantly diffusive properties at the studied time scale.

The Institute of Resource Ecology (IRE) is one of the eight institutes of the Helmholtz-Zentrum Dresden – Rossendorf (HZDR). The research activities are mainly integrated into the program “Nuclear Waste Management, Safety and Radiation Research (NUSAFE)” of the Helmholtz Association (HGF) and focused on the topics “Safety of Nuclear Waste Disposal” and “Safety Research for Nuclear Reactors”. Additionally, various activities have been started investigating chemical and environmental aspects of processing and recycling of strategic metals, namely rare earth elements. These activities are located in the HGF program “Energy Efficiency, Materials and Resources (EMR)”. Both programs, and therefore all work which is done at IRE, belong to the research sector “Energy” of the HGF. The research objectives are the protection of humans and the environment from hazards caused by pollutants resulting from technical processes that produce energy and raw materials. Treating technology and ecology as a unity is the major scientific challenge in assuring the safety of technical processes and gaining their public acceptance. We investigate the ecological risks exerted by radioactive and nonradioactive metals in the context of nuclear waste disposal, the production of energy in nuclear power plants, and in processes along the value chain of metalliferous raw materials. A common goal is to generate better understanding about the dominating processes essential for metal mobilization and immobilization on the molecular level by using advanced spectroscopic methods. This in turn enables us to assess the macroscopic phenomena, including models, codes, and data for predictive calculations, which determine the transport and distribution of contaminants in the environment.

The Institute of Resource Ecology (IRE) is one of the eight institutes of the Helmholtz-Zentrum Dresden – Rossendorf (HZDR). The research activities are mainly integrated into the program “Nuclear Waste Management, Safety and Radiation Research (NUSAFE)” of the Helmholtz Association (HGF) and focused on the topics “Safety of Nuclear Waste Disposal” and “Safety Research for Nuclear Reactors”...

Electricity generation at nuclear power plants produces a large amount of high-level radioactive waste (HLW) every year, which has long-term detrimental effects on humans and the environment. Other applications of nuclear technology (e.g., medicine, research, nuclear weapons, industry) also produce radioactive waste (e.g., low-level radioactive waste, LLW, Intermediate-level waste, ILW). The potential of deep geological repositories (DGRs) as an option for disposal of radioactive waste (HLW, ILW, LLW) has been examined in several countries, including Bulgaria, Canada, China, Finland, France, Germany, India, Japan, Russia, Spain, Sweden, Switzerland, Ukraine and the United Kingdom and are still under discussion. In Ontario, Canada, DGRs with a multi-barrier system comprised of a sedimentary rock formation (i.e., a natural barrier) and an engineered barrier system (EBS) are currently under consideration. An EBS consists of various components, such as waste containers, buffer, backfill, and tunnel sealing materials, intended to prevent the release of radionuclides. Several engineered barrier materials, including a mixture of bentonite and sand, are currently being considered for use in DGRs for nuclear waste in Ontario. Bentonite has some advantageous physical and chemical properties, such as low permeability, high plasticity, and high swelling potential, which provide it with a good sealing ability and thus make it an effective barrier. However, interaction between the compacted bentonite–sand mixture and underground water chemistry fluids (chemical factor) in the DGR could significantly alter the favourable properties of bentonite (e.g., swelling potential), thus influencing its performance when used in an EBS and eventually jeopardizing the overall safety of DGRs. In addition, other parameters, such as the clay content, initial dry density and moisture content of the compacted barrier (physical factors), as well as the presence of salts in groundwater may affect the physical and physiochemical properties of barrier materials. Moreover, during the lifetime of a DGR for used spent fuel, the bentonite–based barrier material will not only be exposed to a broad range of groundwaters with different chemical compositions, but also to high temperatures (heat generated by the nuclear wastes) (thermal factor). Thus, the interaction between the compacted bentonite–sand mixture, the surrounding groundwater and the heat from the nuclear waste material could jeopardize the favourable properties of the bentonite-based (bentonite-sand) barrier material. Properties of a bentonite-sand barrier is an important characteristic to study while designing and constructing an EBS for a DGR. Thus, to understand and assess the operations of DGRs in Ontario, comprehensive studies must be performed on engineering properties like swelling behaviour, permeability, and thermal conductivity. The goal of this research study is to experimentally investigate the physical, chemical and thermal factors that influencing the engineering properties of a barrier material made up of bentonite-sand composite used in DGRs for nuclear waste in Ontario. Compacted samples are subjected to one-dimensional free swell test to understand the swelling behaviour of the material. Hydraulic conductivity was investigated using a flexible wall permeability test. Thermal conductivity and diffusivity were tested using Decangon KD2 Pro with TR-1 and and KS-1 sensors. The specimens contain different bentonite–sand mixture ratios (20:80, 30:70, 50:50, and 70:30 dry mass), and they are tested under conditions with differing bentonite content, dry density, groundwater chemistry, and temperature. Additional tests were conducted to investigate the microstructure of the specimens. These tests include X-ray diffraction (XRD) analysis, mercury intrusion porosimetry (MIP), and thermogravimetric analyses (TG/DTG). The results reveal that the time and strain required to achieve maximum swelling of compacted bentonite–sand specimens increase with the increase of initial dry density. The simulated saline solutions of Guelph and Trenton groundwater are found to suppress the swelling of the bentonite–sand specimens. This in turn leads to the increase of hydraulic conductivity and decrease of thermal properties of the barrier material. However, the impact of the salinity is significantly reduced by increasing the dry densities and sand content of the compacted material. Moreover, the coupled effect of salinity and temperature decreases the swelling potential of the bentonite-sand mixture. Also, some transformation of Na-montmorillonite into Ca-Montmorillonite was observed. The results also indicate that some montmorillonites might have been transformed into illites, thereby further decreasing the swelling potential of the bentonite-based barrier.

This study examines the KBS-3 method for nuclear waste management developed by the Swedish Nuclear Fuel Waste Management Company (SKB). This report strives to uncover potential challenges and opportunities for the future development of KBS-3. The study is relevant because the Swedish government is investing in nuclear power where waste must be safely stored to protect the environment from radiation. From a technical perspective, the results indicate a difficult balance between developing the method in line with new research and realising the project. A possible method for the future is reprocessing, but even here the need for KBS-3 would remain as a smaller amount of waste still needs to be stored. Furthermore, from a social perspective, there does not seem to be a clear consensus between researchers and the industry, particularly regarding corrosion risks. Although these discussions can improve the method, there is a risk that they may negatively impact public trust in KBS-3. Similarly, regarding the commercialisation of stakeholder management: it is important that social acceptance is earned through genuine engagement rather than something being sold. From a cost perspective, small improvements are crucial for KBS-3. Saving money within the value chain without compromising safety is vital, but SKB must communicate such changes openly to ensure continued social acceptance. Balancing conflicting goals: technology, social acceptance, and costs seem to reflect a broader societal challenge where different interests often oppose each other. While some may be satisfied with KBS-3 for final disposal even in the future, others may want to continue striving for a solution that does not burden future generations at all. Regardless, KBS-3 can continue to develop as a solution for nuclear waste management in Sweden until a more sustainable method emerges.

<p>At the centre of this study lies one of the critical questions faced by (late-)modern society, namely that of taking care of the long-lived radioactive waste from nuclear power production. The problems of nuclear waste management are pictured as embracing a complex web of essential issues for society today, in terms of both its capacities and its shortcomings – so called core issues. The principal aim of the thesis is to examine the nuclear waste discourse in Malå, Västerbotten, from a critical discourse analytical perspective, through applying the approach developed by Michel Foucault in The Order of Discourse.</p><p>During the 1990s, the municipality of Malå played a prominent role as a candidate site for the geological disposal of Sweden’s spent nuclear fuel. A five-year process culminated in a local referendum on whether detailed site investigations should be permitted within the community. Following the result no further investigations have been undertaken. The discourse analysis is carried out through a study of opinion formation in the municipality during the period October 1992 to October 1997. Two main types of empirical material have been collected: interviews with opinion leaders (politicians, activists, journalists, information professionals, etc.) and contemporaneous mass media content (the local newspaper and regional television news).</p><p>In the empirical analysis, a review is made of the workings of the external and internal control mechanisms within the discourse; that is to say, how they serve to set limits on the content and form of the sense-making process concerning nuclear waste management. Important themes in the opinion forming process in Malå include information and expertise, opposition and legitimacy, the centre/periphery relationship and the themes of mistrust, partitioning and rejection. Among other themes identified as being marginalised or absent, one example is the Samish citizens’ views on the nuclear question. Four actors play a prominent role as authors of the discourse, namely the nuclear industry, the experts, Greenpeace and the mass media. The voices of resistance groups are also significant. Representatives from authorities and civil servants were most likely to take the commentary role in the discourse, along with journalists.</p><p>In the concluding analysis of the nuclear waste discourse in Malå, two main types of desire for truth, which form the discourse’s main order, are identified. The stronger concerns the will to know, which places the expert with a scientific background as the principal truth-teller. The other is ‘ordinary’ people’s desire, which influences the content and form of the opinion formation. It is also concluded that the mass media institutions play a significant role in this context, not least as mediators. Reflections on contemporary ‘core issues’ to which the analysis bears witness, such as the crisis of democracy, are also included. In addition, the implications of applying the Foucaultian research programme to a study of the nuclear question have been considered. </p>

The chemistry and corrosion mechanisms associated with reduced sulfur compounds such as calcium sulfide, present in ground granulated blast-furnace slag (GGBFS), have been studied in high-density concrete, mortar and simulated pore-water environments. The high-density concrete and mortar samples were produced to replicate the high-density GGBFS concrete, in the dry storage containers (DSCs), used for radiation shielding from used nuclear fuel. Electrochemical measurements on embedded steel electrodes in high-density GGBFS concrete and mortar samples, showed that sulfide is capable of consuming oxygen to create a stable, reducing environment, though not in all cases, and the high-frequency electrolyte resistance increases with hydration time. Ion chromatography on simulated pore-water environments determined that thiosulfate is quite kinetically stable as a sulfide oxidation product and magnetite is capable of oxidizing sulfide. Microscopy has also been used to provide visual evidence of GGBFS hydration and elemental quantification of the hydrating microstructure in different environments.

The chemistry and corrosion mechanisms associated with reduced sulfur compounds such as calcium sulfide, present in ground granulated blast-furnace slag (GGBFS), have been studied in high-density concrete, mortar and simulated pore-water environments. The high-density concrete and mortar samples were produced to replicate the high-density GGBFS concrete, in the dry storage containers (DSCs), used for radiation shielding from used nuclear fuel. Electrochemical measurements on embedded steel electrodes in high-density GGBFS concrete and mortar samples, showed that sulfide is capable of consuming oxygen to create a stable, reducing environment, though not in all cases, and the high-frequency electrolyte resistance increases with hydration time. Ion chromatography on simulated pore-water environments determined that thiosulfate is quite kinetically stable as a sulfide oxidation product and magnetite is capable of oxidizing sulfide. Microscopy has also been used to provide visual evidence of GGBFS hydration and elemental quantification of the hydrating microstructure in different environments.

At the centre of this study lies one of the critical questions faced by (late-)modern society, namely that of taking care of the long-lived radioactive waste from nuclear power production. The problems of nuclear waste management are pictured as embracing a complex web of essential issues for society today, in terms of both its capacities and its shortcomings – so called core issues. The principal aim of the thesis is to examine the nuclear waste discourse in Malå, Västerbotten, from a critical discourse analytical perspective, through applying the approach developed by Michel Foucault in The Order of Discourse. During the 1990s, the municipality of Malå played a prominent role as a candidate site for the geological disposal of Sweden’s spent nuclear fuel. A five-year process culminated in a local referendum on whether detailed site investigations should be permitted within the community. Following the result no further investigations have been undertaken. The discourse analysis is carried out through a study of opinion formation in the municipality during the period October 1992 to October 1997. Two main types of empirical material have been collected: interviews with opinion leaders (politicians, activists, journalists, information professionals, etc.) and contemporaneous mass media content (the local newspaper and regional television news). In the empirical analysis, a review is made of the workings of the external and internal control mechanisms within the discourse; that is to say, how they serve to set limits on the content and form of the sense-making process concerning nuclear waste management. Important themes in the opinion forming process in Malå include information and expertise, opposition and legitimacy, the centre/periphery relationship and the themes of mistrust, partitioning and rejection. Among other themes identified as being marginalised or absent, one example is the Samish citizens’ views on the nuclear question. Four actors play a prominent role as authors of the discourse, namely the nuclear industry, the experts, Greenpeace and the mass media. The voices of resistance groups are also significant. Representatives from authorities and civil servants were most likely to take the commentary role in the discourse, along with journalists. In the concluding analysis of the nuclear waste discourse in Malå, two main types of desire for truth, which form the discourse’s main order, are identified. The stronger concerns the will to know, which places the expert with a scientific background as the principal truth-teller. The other is ‘ordinary’ people’s desire, which influences the content and form of the opinion formation. It is also concluded that the mass media institutions play a significant role in this context, not least as mediators. Reflections on contemporary ‘core issues’ to which the analysis bears witness, such as the crisis of democracy, are also included. In addition, the implications of applying the Foucaultian research programme to a study of the nuclear question have been considered.