The disposal of radioactive wastes underground

Nuclear power is strategically and quantitatively an important contributor to global electricity generation capacity and produces a small amount of potentially highly hazardous wastes that require careful management. The accepted solution for disposing of higher activity and longer-lived radioactive wastes from the nuclear power industry and other sources is engineered emplacement in deep geological disposal facilities (GDFs), situated many hundreds of metres underground. The first purpose-built GDFs for the most active of these wastes (used nuclear fuel and high-level wastes) will be operational in about ten years time in a few countries, with most other countries (including the UK) developing such facilities during coming decades. This article reviews the conceptual basis for geological disposal, examines how long-term safety is provided, considers the geological challenges to developing GDFs and the uncertainties that have to be managed, and looks in more detail at some of the most advanced design concepts. Because the issue of forecasting GDF evolution and behaviour over very long time periods lies at the core of geological disposal, particular emphasis is placed on matching containment requirements with diminishing hazard potential over many thousands of years. The article concludes with a commentary on current developments in the UK geological disposal programme.