Solubility Phenomena In The Context Of Nuclear Waste Disposal

Safety concepts regarding nuclear waste disposal in underground repositories generally rely on a combination of engineered and geological barriers that minimize potential radionuclide release out of the containment-providing rock zone and transport through the biosphere. The presence of water, however, may alter the engineered barrier system, dissolve radionuclides, and facilitate radionuclide transport that over time may permeate the biosphere. So while barrier systems aim to prevent or hinder water from contacting the waste, the possible intrusion of aqueous solutions must be considered for several safety case scenarios impacted by the long-term evolution of a repository. Dissolution and solubility phenomena thus arise as important processes controlling the chemical behaviour of radionuclides and other key materials of relevance in the context of such repositories and their safety assessments. The solubility and aqueous speciation of radionuclides is of particular interest as they provide upper limits of water-transportable concentrations of radionuclides. Solubility phenomena of radioactive and other gases in water provide important information on gas transport and pressure build-up. Moreover, solubility assessments offer insight into time-independent constraints on the evolution of the disposal system. Particularly important in this regard is the geochemical modelling of radionuclide behaviour in the engineered barrier system as well as in natural aquatic systems along the transport path of radionuclides to the biosphere. The obtained information provides valuable inputs that appropriately constrain safety analyses of nuclear waste disposal.

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.

Understanding radionuclide behaviour in the natural environment is essential to the sustainable development of the nuclear industry and key to assessing potential environmental risks reliably. Minimising those risks is essential to enhancing public confidence in nuclear technology. Scientific knowledge in this field has developed greatly over the last decade.Radionuclide behaviour in the natural environment provides a comprehensive overview of the key processes and parameters affecting radionuclide mobility and migration. After an introductory chapter, part one explores radionuclide chemistry in the natural environment, including aquatic chemistry and the impact of natural organic matter and microorganisms. Part two discusses the migration and radioecological behavior of radionuclides. Topics include hydrogeology, sorption and colloidal reactions as well as in-situ investigations. Principles of modelling coupled geochemical, transport and radioecological properties are also discussed. Part three covers application issues: assessment of radionuclide behaviour in contaminated sites, taking Chernobyl as an example, estimation of radiological exposure to the population, performance assessment considerations related to deep geological repositories, and remediation concepts for contaminated sites. With its distinguished editors and international team of expert contributors, Radionuclide behaviour in the natural environment is an essential tool for all those interested or involved in nuclear energy, from researchers, designers and industrial operators to environmental scientists. It also provides a comprehensive guide for academics of all levels in this field. Provides a comprehensive overview of the key processes and parameters affecting radionuclide mobility and migration Explores radionuclide chemistry in the natural environment Discusses the migration and radioecological behaviour of radionuclides

Over the past decade significant progress has been achieved in the development of waste characterization and control procedures and equipment as a direct response to ever-increasing requirements for quality and reliability of information on waste characteristics. Failure in control procedures at any step can have important, adverse consequences and may result in producing waste packages which are not compliant with the waste acceptance criteria for disposal, thereby adversely impacting the repository. The information and guidance included in this publication corresponds to recent achievements and reflects the optimum approaches, thereby reducing the potential for error and enhancing the quality of the end product. -- Publisher's description.