This book features scientific research that supports the safe and effective disposal of radioactive waste in a geological repository. One highlight of the volume is the opening talk by Rustum Roy, who was instrumental in establishing the first symposium on this topic in 1978. Professor Roy summarizes his views of the past 19 years of progress in the field. A second highlight is the participation by several Russian and Ukrainian scientists who authored papers on nuclear waste disposal aspects of the Chernobyl Unit 4 reactor that exploded in April 1986. Additional topics include: glass formulations and properties; glass/water interactions; cements in radioactive waste management; ceramic and crystalline waste forms; spent nuclear fuel; waste processing and treatment; radiation effects in ceramics, glasses and nuclear waste materials; waste package materials; radionuclide solubility and speciation; radionuclide sorption; radionuclide transport; repository backfill; performance assessment; natural analogues and excess plutonium dispositioning.