Deliverable D8b: Development of the physical/statistical downscaling methodology and application to climate model CLIMBER for BIOCLIM Workpackage 3. Work Package 3, Simulation of the future evolution of the biosphere system using the hierarchical strategy. Modelling Sequential Biosphere Systems under Climate Change for Radioactive Waste Disposal (BIOCLIM)

The overall aim of BIOCLIM is to assess the possible long term impacts due to climate change on the safety of radioactive waste repositories in deep formations. This aim is addressed through the following specific objectives: • Development of practical and innovative strategies for representing sequential climatic changes to the geosphere-biosphere system for existing sites over central Europe, addressing the timescale of one million years, which is relevant to the geological disposal of radioactive waste. • Exploration and evaluation of the potential effects of climate change on the nature of the biosphere systems used to assess the environmental impact. • Dissemination of information on the new methodologies and the results obtained from the project among the international waste management community for use in performance assessments of potential or planned radioactive waste repositories. This deliverable has the following specific motivations and objectives: Its main aim is to provide time series of climatic variables at the high resolution as needed by performance assessment (PA) of radioactive waste repositories, on the basis of coarse output from the CLIMBER-GREMLINS climate model

A study on the thermal conductivity of compacted bentonites

Thermal conductivity of compacted bentonite is one of the most important properties in the design of high-level radioactive waste repositories where this material is proposed for use as a buffer. In the work described here, a thermal probe based on the hot wire method was used to measure the thermal conductivity of compacted bentonite specimens. The experimental results were analyzed to observe the effects of various factors (i.e. dry density, water content, hysteresis, degree of saturation and volumetric fraction of soil constituents) on the thermal conductivity. A linear correlation was proposed to predict the thermal conductivity of compacted bentonite based on experimentally observed relationship between the volumetric fraction of air and the thermal conductivity. The relevance of this correlation was finally analyzed together with others existing methods using experimental data on several compacted bentonites

Complex equilibria in strongly alkaline aqueous solutions containing Ca(II), Nd(III) and gluconate

Polyhydroxy carboxylates, such as gluconate (Gluc– ) play an essential role in a variety of industrial processing. Gluc– is used in large quantities because of its complexing ability: for example NaGluc is a common additive in the construction industry and employed to improve certain properties of cement. In low- and intermediate-level (LL/IL) radioactive waste repositories, containers are filled with cement to prevent leakage, but upon water intrusion, the alkaline pore water might promote the complexation of metal ions by Gluc– , therefore these complexing processes have been excessively studied in the past decades. Gluc– has been proven to be an efficient complexing agent for alkaline-earth (Ca(II), Mg(II)) and transition (Cu(II), Co(II), Ni(II), Mn(II), Zn(II)) metal ions, therefore it cannot be disregarded that it might be capable of enhancing the solubility of tri- and tetravalent actinides and lanthanides in alkaline media. Anoxic conditions characteristic of radioactive waste repositories ensure that actinides are present in reduced oxidation states (Cm(III), Am(III), Pu(III), Pu(IV)). Possible complexing agents are also present in these repositories such as organic ligands generated by the decomposition of contaminant cellulosic materials (isosaccharinate, Isa– ) or present as cement additives (Gluc– ). It is of high priority to study the capability of these ligands to enhance the solubility of actinide ions in case of water intrusion, since the calculation of the degree of mobilization these metal ions can reach is integral for estimating the associated risk of disposal. Due to the pronounced chemical analogies, stable (III) oxidation state lanthanide ions share with trivalent actinides, tri- and tetravalent actinides can be modeled by less elaborate lanthanide ions. To obtain a simplified and relevant model of possible complexation processes in radioactive waste repositories, neodymium (Nd(III)) and Gluc– have been employed previously as model ions in measurements carried out in aqueous solutions, but data acquired in alkaline equilibria are scarce

Managing Conflict In Facility Siting: an international comparison

The siting or development of risky facilities, such as nuclear power plants or waste repositories, remains an intractable policy problem for all democratic nations. In this valuable new book, the authors present a comparative study of various siting controversies in North America, Asia, Europe and Australia. They argue that devising effective policies for dealing with siting conflicts will require social learning and changes in both institutional design and policy process. This volume studies the issue of siting in the context of a transactions cost framework. It analyses the extent to which the institutional and policy environment can assist in managing siting conflicts, as well as considering the effect of other important factors such as equity, incentive structures, social pressures, alliances, the nature of decision processes and information strategies. By adopting a broad comparative perspective and using international case studies, the authors are able to identify the similarities and differences in siting problems between nations, and the approaches and policies adopted. As well as extending the theoretical and comparative knowledge of siting conflicts, they also help to develop more robust and effective policies for managing and resolving future disputes. This book addresses a growing policy problem confronting all democratic nations. By exploring the lessons to be learned from international siting experiences, it will prove invaluable reading for academics, policymakers, government agencies, NGOs, and other societal interests involved in environmental and siting issues

Experimental Simulation of the Radionuclide Behaviour in the Process of Creating Additional Safety Barriers in Solid Radioactive Waste Repositories Containing Irradiated Graphite

Results of the experimental modeling of radionuclide behavior when creating additional safety barriers in solid radioactive waste repositories are presented. The experiments were run on the repository mockup containing solid radioactive waste fragments including irradiated graphite. The repository mockup layout is given; the processes with radionuclides that occur during the barrier creation with a clayey solution and during the following barrier operation are investigated. The results obtained confirm high anti-migration and anti-filtration properties of clay used for the barrier creation even under the long-term excessive water saturation of rocks confining the repository

Colloid/nanoparticle formation and mobility in the context of deep geological nuclear waste disposal (Project KOLLORADO-2) ; final report (KIT Scientific Reports ; 7645)

To assess the relevance of colloidal influences on radionuclide transport for the long-term safety of a radioactive waste repository, the KOLLORADO-2 project integrates the results of geochemical and hydrogeological studies. The results may serve as a basis for an appraisal of the implications of colloid presence in the vicinity of radioactive waste repositories in different deep geological host-rock formations

A comparison between probabilistic and Dempster-Shafer Theory approaches to Model Uncertainty Analysis in the Performance Assessment of Radioactive Waste Repositories

Model uncertainty is a primary source of uncertainty in the assessment of the performance of repositories for the disposal of nuclear wastes, due to the complexity of the system and the large spatial and temporal scales involved. This work considers multiple assumptions on the system behavior and corresponding alternative plausible modeling hypotheses. To characterize the uncertainty in the correctness of the different hypotheses, the opinions of different experts are treated probabilistically or, in alternative, by the belief and plausibility functions of the Dempster-Shafer theory. A comparison is made with reference to a flow model for the evaluation of the hydraulic head distributions present at a radioactive waste repository site. Three experts are assumed available for the evaluation of the uncertainties associated with the hydrogeological properties of the repository and the groundwater flow mechanisms

Unravelling the corrosion processes at steel/bentonite nterfaces in in situ tests

Microscopic and spectroscopic analyses were conducted on steel/bentonite interface samples removed from four in situ experiments that were carried out in three underground research laboratories at different temperatures and under different hydraulic and geochemical conditions. The results provide valuable information about the corrosion processes occurring in high-level radioactive waste repositories. Systematic patterns can be deduced from the results, irrespective of carbon steel grade, type of bentonite and its degree of compaction, geochemical environment or experimental setup. Thus, a clear dependence of the corrosion rates on temperature and exposure period, as well as on the availability of H2O and O2 provided by the surrounding bentonite buffer, is observed. Furthermore, Fe(II) ions released by corrosion interact with the structural Fe in the clay. Recent developments highlight the usefulness of reactive transport modelling in understanding the coupled corrosion and Fe–clay interaction processes