The Portsmouth plant enriched uranium from 1954 until 2001 through a process called gaseous diffusion.
The Portsmouth Gaseous Diffusion Plant at Piketon, Ohio, was built from 1952 to 1956. The plant was one of three large gaseous diffusion plants in the United States initially constructed to produce enriched uranium to support the nation’s nuclear weapons program and U.S. Navy, and later enriched uranium used by commercial nuclear reactors. It occupies about 1,200 acres of the 3,777-acre Portsmouth Site. Weapons-grade uranium enrichment was later suspended, and after the Cold War the production facilities were leased to the private sector. In 2001, gaseous diffusion enrichment operations were discontinued at the site. DOE's Office of Environmental Management commenced its environmental cleanup program at the site in 1989 and the effort continues today in cooperation with the U.S. and Ohio Environmental Protection Agencies. Decontamination and decommissioning (D&D) of the plant commenced in 2011 and is ongoing.