Radioactive waste is generated from commercial power stations, medical and research reactors and the decommissioning of nuclear weapons. Long-term solutions to waste storage usually involve planned deposition or isolation in a geologic repository. Geologists and mineralogists play an essential role in the siting and planning of rock-hosted repositories, providing scientific insight into the long-term performance and safety of repositories. This book brings together international experts and presents an overview of the geology and mineralogy of proposed high-level geologic repositories and related issues. The exposure of this knowledge is vital for modern earth scientists concerned with waste disposal now and in the future.