As a result of the civilian nuclear power program that began more than 45 years ago, many nuclear facilities have been sited in the United States. They include more than 100 nuclear power plants and several low-level radioactive waste disposal facilities. Extensive efforts are under way to site a high-level radioactive waste disposal facility (repository) at Yucca Mountain in the state of Nevada. These projects have resulted in the accumulation of an extraordinarily large and detailed geological database that has been useful to many outside the nuclear industry. These efforts, both successful and unsuccessful, have provided important insights into the role of geology, which often has played a critical or apparently critical role in siting and operating decisions. Some of these decisions have highlighted the interactions between scientific issues and political and social issues and the difficulty often faced in distinguishing between them. Geological uncertainties and the highly interpretive nature of the geologic sciences have made a particularly fertile ground for disputes between those in favor of and those opposed to the siting and operation of nuclear facilities.

Although this chapter discusses both nuclear power plants and nuclear waste disposal facilities, the role of geology in these two types of facilities is different. Nuclear power plants are highly complex, relatively short-lived (typically assumed to be 40 years, but see discussion by Chapman et al., Chapter 1, this volume) facilities, requiring sophisticated control technologies, whose failure could result in the immediate release of large amounts of harmful radionuclides. The role of geology is to provide sufficiently stable locations so that these facilities can operate safely.