Deep borehole disposal

Beginning in 2016, the U.S. Department of Energy funded an experimental borehole extending over 3 miles (5 km) deep, in Rugby, North Dakota.

[4] Due to public opposition to the first experimental borehole, in late 2016, the Department of Energy announced a second project which would have involved four sites: two in New Mexico, one in Texas, and one in South Dakota.

The early stages of the project required gaining public support before the Department of Energy would have selected a final site for an experimental borehole.

High level waste, like spent nuclear fuel, would be sealed in strong steel containers and lowered down the borehole, filling the bottom one or two kilometers of the hole.

[1] The rest of the borehole is then sealed with appropriate materials, including clay, cement, crushed rock backfill, and asphalt, to ensure a low-permeability barrier between the waste and the land surface.

In some concepts, waste may be surrounded by cementitious grout or a highly compacted bentonite buffer matrix to provide improved containment and to reduce the effect of rock movement on the canisters' integrity.

A high-temperature scenario involves very young hot waste in the containers which releases enough heat to create a melt zone around the borehole.

[citation needed] Current estimates suggest that spent fuel generated from a single large nuclear power plant operating for multiple decades could be disposed of in fewer than ten boreholes.