Safe and effective management of nuclear waste provides a broad range of challenges for materials science. Waste processing, waste form and engineered barrier properties, interactions between engineered and geological systems, radiation effects, chemistry and transport of waste species, and long-term predictions of repository performance are just some of the scientific problems facing modern society. This book, the nineteenth in a very successful series from MRS, offers an international and interdisciplinary perspective on the issues, and features developments in both fundamental and applied areas. Topics include: excess plutonium dispositioning; spent nuclear fuel; glass waste forms; ceramic and crystalline waste forms; cement waste forms; waste processing; waste container materials; speciation and sorption; bentonite barriers; flow and transport; repository site characterization; natural analogs and performance assessment.