Book excerpt: This volume opens with a keynote lecture by Rodney Ewing, member of the Board of Radioactive Waste Management of the National Research Council. Ewing summarizes 25 years of materials research in nuclear waste, emphasizing the progress that has been made and the challenges that still confront investigators and technologists in materials science and repository performance evaluation. The session is followed by one on container materials and engineered barriers, and includes a discussion on the corrosion performance expected for waste packages in the proposed high-level nuclear waste repository at Yucca Mountain, Nevada. Invited papers on performance assessment and repository studies for different national programs are also highlighted, with representation from the United States, Sweden, Japan, Belgium, Switzerland, Italy, and the United Kingdom. A large number of papers focus on the structure, properties, and degradation of various waste forms such as glasses, ceramics (mostly for plutonium immobilization), cements, and spent nuclear fuel. For the second consecutive time, the number of papers on ceramics far exceeds those on glass, which had been the dominant material discussed at this symposium over the prior 23 years. New studies on zirconates confirm the recently discovered high radiation damage-resistance of this material. Additional topics include: performance assessment in high-level waste disposal; performance assessment in low-level waste disposal; ceramic structure and corrosion; radiation effects in ceramics; glass structure and corrosion; spent fuel; spent fuel cladding and alternative waste forms; cements in radioactive waste immobilization; contaminant transport; natural analogs; and waste processing.