Paducah Gaseous Diffusion Plant, Kentucky

A former uranium enrichment facility, the Paducah Gaseous Diffusion Plant (PGDP) operated from 1952 until 2013, initially producing enriched uranium for military applications, before switching to the production of low-enriched uranium (U-235) for civilian nuclear power plants. While the 3,423-acre plant was owned throughout by the Department of Energy, it was leased from 1995 until 2013 by a public-private entity known as the United States Enrichment Company (USEC), although day-to-day operations were overseen by then Martin Marietta. In 1994, PGDP was officially declared a Superfund cleanup site due to extensive groundwater, surface water, and soil contamination, measured both on-site and off-site, although remediation efforts have been ongoing since the late 1980s, and are projected to continue through 2040; if not beyond. In 2014, USEC returned the facility to the Department of Energy's Environmental Management program. Two other uranium enrichment plants in the United States, at Portsmouth, Ohio and Oak Ridge, Tennessee, ceased operations more than a decade ago. A new facility, Urenco USA, which uses the more modern centrifugal enrichment process, opened for business in Eunice, New Mexico in 2010. As of 2017, it is  the only uranium enrichment facility currently in operation in the United States.