The United States currently has no place to dispose of the high-level radioactive waste resulting from the production of the nuclear weapons and the operation of nuclear electronic power plants. The only option under formal consideration at this time is to place the waste in an underground geologic repository at Yucca Mountain in Nevada. However, there is strong public debate about whether such a repository could protect humans from the radioactive waste that will be dangerous for many thousands of years. This book shows the extent to which our scientific knowledge can guide the federal government in developing a standard to protect the health of the public from wastes in such a repository at Yucca Mountain. The U.S. Environmental Protection Agency is required to use the recommendations presented in this book as it develops its standard.