Geological Media and Factors for the Long-Term Emplacement and Isolation of Carbon Dioxide and Radioactive Waste

Abstract

A review is presented of the factors considered important in the selection of environments and sites for the geological storage of carbon dioxide (CO2) and the disposal of radioactive waste (RW)—with a focus on those of a geological nature. The distinction between the terms storage for CO2 and disposal for RW is not significant in this regard. The relevant properties of the two product types are presented, as are the desirable characteristics and types of geological environments that are considered suitable for disposal purposes. The role that the geological barrier plays in trapping the disposed substance, in the case of CO2, and in containing and slowly releasing the waste, in the case of RW, is explained. The comparative roles played by the geological barrier and the engineered barrier system of a repository for RW is also outlined—although the emphasis of the discussion is on the geological barrier itself. The status and challenges associated with the storage of CO2 are presented, together with a discussion of the geographic distribution of areas of the world potentially suitable for its storage and the criteria for site selection that could be applied. A discussion is also presented of the geological environments that are most likely to be used for the disposal of RW. A considerable part of the chapter presents a comparison between the storage or disposal of the two types of disposed substances, discussing their similarities and differences. This comparison is considered under the four subject headings: Characteristics of the Geological Media, Emplacement Characteristics, Effects of Emplacement and Potential Migration from the Disposal Site, and Site Activities.