Toss a dart at a map of the United States and, more often than not, it will land where shale can be found underground. A drab, relatively featureless sedimentary rock that historically attracted little interest, shale (as used here, the term includes clay and a range of clay-rich rocks) is entering Americans’ consciousness as a new source of gas and oil. But shale may also offer something entirely different—the ability to safely and permanently house high-level nuclear waste.
More than 70,000 metric tons of commercial spent nuclear fuel currently sit aboveground at 75 power-generation facilities across the United States. Surface storage of this growing inventory of long-lived waste is both a financial and security burden, and as the 2011 tsunami at Fukushima graphically showed, threats can be hard to anticipate. Recognizing this, plans in the United States and other nuclear nations, however vague, call for the eventual isolation of high-level waste underground. The devil is in the details of where and how to accomplish this.
Because spent nuclear fuel remains dangerous for hundreds of thousands of years, it is helpful (and arguably necessary) for the rock housing an underground repository to provide long-term containment as a backup to the waste packaging and repository engineering itself. Globally, considerable research is being devoted to determining what types of rock can do this. Sweden and Finland are almost entirely underlain by granite and well along with plans for granite-hosted repositories. Germany, once focused on underground salt formations, is considering its options. France, Switzerland, and Belgium are planning or considering repositories in shale.
Continue reading at Bulletin of the Atomic Scientists - Shale: an overlooked option for US nuclear waste disposal