- For other uses of "K25", see K25 (disambiguation).
K-25 is a former uranium enrichment facility of the Manhattan Project which used the gaseous diffusion method. The plant is located in Oak Ridge, Tennessee, on the southwestern end of the Oak Ridge Reservation.
Work on the facility began in June 1943 and was completed in early 1945 employing 12,000 workers and costing $512 million (equivalent to $6.5 billion in today dollars). The U-shaped K-25 building measured half a mile by 1,000 feet (300 m) – over 2,000,000 square feet (190,000 m2). Construction began before completion of the design for the process. Due to construction needs at K-25 and elsewhere on the reservation, the town of Oak Ridge, originally designed for 13,000 people, grew to 50,000 by summer 1944. The people needed for the construction of K-25 lived nearby, in a community that came to be known as Happy Valley. Built by the Army in 1943, Happy Valley was a temporary community that housed 15,000 people in trailer homes.
In the post-war years, additional uranium enrichment facilities were built adjacent to K-25 forming a complex officially known as the Oak Ridge Gaseous Diffusion Plant and commonly called the "K-25 site". Uranium enrichment operations at the K-25 site ceased in 1987. This entire site is now called the East Tennessee Technology Park.
The gaseous diffusion method enriches uranium by separating uranium-235 from uranium-238. Based on the principle that molecules of a lighter isotope would pass through a porous barrier more readily than molecules of a heavier one, gaseous diffusion of uranium hexafluoride produced a gas increasingly rich in uranium-235 as the heavier uranium-238 was separated out in a system of cascades. As it produced minute amounts of final product compared to the total amount of uranium in the plant, gaseous diffusion required a massive facility to house the thousands of cascades and consumed enormous amounts of electric power. Uranium hexafluoride is highly corrosive, and the recently developed plastic teflon was used to coat the valves and seals that came in contact with the gas.
Gaseous diffusion was one of three isotope separation processes that provided uranium-235 for the Hiroshima weapon (Little Boy) - the other two being electromagnetic separation and liquid thermal diffusion. All of the plants were located on the Oak Ridge reservation. The Y-12 electromagnetic separation plant was located about 8 miles (13 km) northeast of the K-25 plant. The S-50 liquid thermal diffusion plant, using convection to separate the isotopes in thousands of tall columns, was built next to the K-25 power plant, which provided the necessary steam. Much less efficient than K-25, the S-50 plant was torn down after the war.
Gaseous diffusion was the only uranium enrichment process used during the Cold War. K-25 was the prototype for later Oak Ridge gaseous diffusion facilities and those at Paducah, Kentucky and Portsmouth, Ohio. Today, uranium isotope separation is preferably done by the much more energy-efficient ultra centrifuge process.
Closure and demolition 
The United States Department of Energy contracted with Bechtel Jacobs  to dismantle and demolish the K-25 facility. The work under the current contract was scheduled to be completed by the end of 2011, though the current timeline is for demolition to be complete in 2014. Bechtel Jacobs will not complete the D&D of the K-25 building under its contract. It will be completed by URS | CH2M Hill Oak Ridge (UCOR).
See also 
Notes and references 
- "Response to letter from Mr. Gus Robinson to General Nichols, providing information relating to Site designations and Site codes for Manhattan District facilities., 10/17/1949", digitized and online as ARC Identifier 281585 at National Archives Archival Research Catalog.
- R.P. Prince and A. Milton Stanley (2000). "What Does K-25 Stand For? Deciphering the Origins of the Manhattan Project Code Names in Oak Ridge". The Journal of East Tennessee History (72): 83.
- Staff. Consumer Price Index (estimate) 1800–2012. Federal Reserve Bank of Minneapolis. Retrieved March 31, 2013.
- "Manhattan Project Signature Facilities". atomicarchive.com. Retrieved 2 March 2008.
- "K-25 tour attracts international visitors". oakridger.com. Retrieved 2 March 2008.[dead link]
- Melton Valley Hydrologic Isolation and Soils/Stabilization Remediation Projects
- "DOE and Bechtel Jacobs sign $1.48B cleanup contract". Retrieved 2009-02-14.
- "Oak Ridge Environmental Cleanup". Retrieved 2009-02-14.
- "DOE issues Draft RFP on ETTP contract; value up to $2.6B". Frank Munger's Atomic City Underground. Knoxville News Sentinel. 10 May 2010. Retrieved 2010-08-02.
- Melton Valley Remediation
|Wikimedia Commons has media related to: K-25|
- The Manhattan Project: Making the Atomic Bomb
- Site X A map of Manhattan Project Era Oak Ridge, Tennessee.
- Atomic Heritage Foundation Preservation Efforts at K-25
- Google Maps K-25 on Google Maps
- Historic photos of K25 by Ed Westcott