The U.S. until fairly recently had two gaseous diffusion plants, Portsmouth and Paducah. These were built by the government and privatized as USEC in 1992. Af

The U.S. until fairly recently had two gaseous diffusion plants, Portsmouth and Paducah. These were built by the government and privatized as USEC in 1992. After the cold war, the U.S. had a program to import high enriched Uranium from bombs from Russia, and downblend it to reactor purity. This, combined with the inefficiency of gaseous diffusion, caused the shutdown of those two plants. USEC (Now Centrus) was supposed to replace Portsmouth and Paducah with a new centrifuge plant using centrifuges they designed, but progress has been slow. Meanwhile, Urenco (the Dutch company that pioneered centrifuge enrichment) set up a centrifuge plant in New Mexico in 2010 that can meet a significant portion of U.S. demand. There is also a proposed laser (SILEX) plant. I'm not sure what the current status of it, but SILEX and laser enrichment have been generally very controversial, because once the technology is developed and working at scale, it will be hard to protect the secret. When Urenco developed centrifuges, the technology leaked through AQ Khan to Pakistan, and from there it wound up powering the bomb programs of North Korea and Iran. Laser separation is even more energy efficient than centrifuges, so a laser enrichment plant would potentially be even easier to hide, and controlling proliferation would be even harder. There is a desire among many people in the government to basically try not let that genie out of the bottle.