DOE was tasked with planning, siting, building and operating permanent geologic repositories for the waste.

By 1984 the agency had investigated nine sites in the South and West and issued 1,300-page environmental assessments for each.

DOE then recommended three sites for which more intensive site characterizations should be carried out.

Those were Yucca Mountain in Nevada (volcanic tuff), Deaf Smith County, Texas (bedded salt), and Hanford, Wash. (basalt).

In 1987 Congress directed DOE to focus its efforts exclusively on Yucca Mountain. Using deeply drilled boreholes, extensive geochemical, geological and hydrologic testing was done and a five-mile-long exploratory tunnel was excavated.

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Congress approved the choice of Yucca Mountain as the depository in 2002. But political resistance has ground development to a standstill.

First resistance came from Nevada. Later the Obama, Trump and Biden administrations blocked the effort, and Congress has since ended funding for Yucca Mountain’s development and licensing.

Separately, DOE did manage to construct the Waste Isolation Pilot Plant, a repository 2,150 ft underground in a salt formation near Carlsbad, New Mexico, which holds low-level waste (clothing, tools and other items contaminated by plutonium and other radioactive elements).