This two-volume special issue of Daedalus highlights the challenges associated
with the global expansion of nuclear power. The topics covered include environmental
impacts, nuclear safety, and the economics of nuclear power production, but the major emphasis is on nonproliferation and security aspects. To develop an understanding of possible problems and their potential solutions in all of these areas, it is necessary to
understand the nuclear fuel cycle. This article focuses on the back-end stages of the fuel cycle--namely, storage, reprocessing and disposal.