The author's stated purpose in writing this book is to summarize the large number of government-sponsored research reports on the geochemical aspects of high-level nuclear waste isolation. Although this book has a 1984 publication date, the majority of the cited documents were published before 1982. Unfortunately, passage of the Nuclear Waste Policy Act (NWPA) of 1982 and its signing into law by President Reagan (January 1983) [U.S. Congress, 1983] has significantly altered the U.S. Department of Energy (DOE) Civilian Radioactive Waste Management (CRWM) Program. Therefore this book does not accurately reflect the present U.S. program in geologic disposal of high-level nuclear waste. For example, chapter 2, “Radioactive Waste Management,” is almost 3 years out of date in a field that is changing rapidly (see U.S. DOE [1984a] for the current status of the CRWM Program). Additionally, the source material, which forms the input for this book, is chiefly grey literature, i.e., the referenced documents may or may not have undergone peer review and therefore do not represent the technical judgment of the scientific community. Also, this book only presents a selective sampling of information because the literature cited does not include a representative selection of the widespread available literature on this topic.