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Paducah Gaseous Diffusion Plant (PGDP)

The Paducah Gaseous Diffusion Plant is located in western Kentucky, 10 miles west of the City of Paducah. The plant, inside a 3,422-acre tract of property, is owned by the Department of Energy. The site contains uranium enrichment process equipment and support facilities. The mission of the Plant is to "enrich" uranium for use in domestic and foreign commercial power reactors. Enrichment involves increasing the percentage of uranium-235 in the material used for creating reactor fuel (UF6). Uranium-235 is highly fissionable, unlike the more common isotope uranium-238. The PGDP enriches the UF6 from roughly 0.7 percent uranium-235 to about 2.75 percent uranium-235. In the 1960s, the Paducah plant's mission changed from enriching uranium for nuclear weapons to a more commercial focus. Today, the USEC facilities in Paducah, Kentucky, and Portsmouth, Ohio, work in tandem to enrich uranium for fuel in commercial nuclear power plants. The Paducah plant enriches uranium up to 2.75 percent and then ships it to the Portsmouth Gaseous Diffusion Plant for further enrichment to five percent. Past operations at the plant have resulted in the contamination of a number of areas, both at the site and beyond its boundaries, with radioactive and hazardous materials.

The plant, which employs approximately 1,700 people, has a fenced area of about 750 acres, 74 of which contain process buildings under roof that include nearly 1,800 enrichment stages. The plant has a design capacity of 11.3 million SWU per year. SWU stands for separative work unit, the industry standard for measuring uranium enrichment services. Customers pay for the number of SWU required to enrich their uranium feed to their specifications.

In August 1950, the U.S. government determined that it would need to double the capacity of domestic fissionable materials production that existed at the Oak Ridge K-25 Plant. The Atomic Energy Commission (AEC) selected a Plant option consisting of 400 stages modeled after the K-31 facility at Oak Ridge (which would become C-331 at the Paducah Plant) and 480 stages twice the size of the Oak Ridge K-31 stages (which would become C-333 at the Paducah Plant). Based on a decision to disperse the major portions of the new production capacity, eight areas were identified as candidate locations for the Plant, all in the southeastern U.S. From the application of additional criteria, three sites were identified: the Kentucky Ordnance Works (KOW) at Paducah, the Louisiana Ordnance Plant at Shreveport, and the Longhorn Ordnance Works at Marshall, Texas. From these, the AEC approved, on October 18, 1950, the KOW site as the location for the new gaseous diffusion plant.

PGDP construction spanned 1951 through 1956 and was conducted in two phases. Construction of the first phase began January 2, 1951, and included erection of the following process and production facilities: C-331 and C-333, the gaseous diffusion process buildings; C-410/420, UF6 Feed Plant; C-310, Purge and Product Withdrawal Building; C-315, Surge and Waste Building; and C-300, Central Control Building. Authorization to proceed with the second phase of Plant construction was received on July 15, 1952. Two additional enrichment facilities, C-335 and C-337, were added, and construction was completed in 1956.

On January 6, 1951, the Tennessee Valley Authority began construction of the four-unit Shawnee Steam Plant near the Paducah Plant on the Ohio River to provide a portion of the needed electricity. On February 15, 1951, Electric Energy, Incorporated began construction of the Joppa Steam Plant, in Joppa, Illinois, to also provide electricity to PGDP.

Although major construction activities would continue through 1956, Union Carbide began hiring approximately 1,700 permanent Plant workers in 1951. The first process buildings, C-331, C-333, C-310, and C-315, were completed and started operation in September 1952, and the first product was withdrawn in November. PGDP enriches feed material in the form of UF6 gas with approximately 0.7 percent uranium-235 to UF6 with one to three percent uranium-235. The enriched product from PGDP was sent to other DOE sites at Portsmouth or Oak Ridge for further enrichment. Most UF6 feed material came from the depleted tails produced during normal diffusion operations at PGDP and from Oak Ridge and Portsmouth. From 1952 through 1977, UF6 feed material was also produced from uranium trioxide or UO3 (called "yellowcake") at PGDP in Buildings C-410 and C-420; this feed material was supplied by sources such as El Dorado Mining and Refining, Mallinkrodt Chemical Works, and General Chemicals (now Allied Chemical) and comprised less than 10 percent of the UF6 fed to the cascade. From 1953 through 1964 and intermittently from 1968 through 1977, the feed plant also produced UF6 from UO3 from spent reactor fuel processed at the Hanford and Savannah River sites. After 1977, all feed came in the form of UF6 from outside sources such as Oak Ridge, Portsmouth, and Allied Chemical.

Carbide and Chemicals Company (which became Union Carbide Corporation Nuclear Division) was named as the original site contractor based on the company's experience with gaseous diffusion operations at Oak Ridge. Carbide operated PGDP for the AEC, and its successor agencies the Energy Research and Development Administration (ERDA) and DOE, until 1984, when they were replaced through a competitive procurement by Martin Marietta Energy Systems, Inc.

In July 1993, the United States Enrichment Corporation, through Congressional legislation, became responsible for uranium enrichment operations at PGDP. Although the plant is now leased and operated by US Enrichment Corporation, environmental restoration and related waste management activities associated with past practices will be conducted by the Department of Energy. However, under the provisions of the lease, future plant shut down and cleanup activities will be the responsibility of US Enrichment Corporation.

PADUCAH PLANT TIMELINE

Paducah Gaseous Diffusion Plant
	Toll Transfer and Receiving Facility Trucks deliver cylinders full of natural assay uranium hexafluoride (UF-6) to the plant's Toll Transfer and Receiving Facility. Incoming cylinders are inspected, weighed and sampled.
	Feed Facilities The plant feeds UF-6 into its enrichment process at one of two feed facilities. Here, large containment autoclaves are used to heat the cylinders, converting the solid UF-6 to a liquid and then to a gas.
	Central Control Center The Central Control facility is the heart of the plant. From this location, the Shift Superintendent and his staff monitor plant functions around the clock. Careful coordination is required to balance the plant's production needs and electricity purchases. Also based here is the plant's Emergency Operations Center, a specially trained group of managers that can be summoned at any time to respond to a plant emergency.
	Process Buildings There are four enrichment process buildings at the plant, each supported by its own switchyard and cooling towers. The buildings house the motors, compressors and process piping used to enrich uranium. The steaming cooling towers are part of the plant's recirculating cooling water system. Evaporation claims about 12 million gallons of that water every day. Water pumped from the nearby Ohio River replaces what is lost as steam.
	Converters Production equipment inside the process buildings is made up of converters like this one. Each converter contains separating barriers and gas cooler. An axial compressor, powered by an electric motor, pumps gas through each converter.
	Product Withdrawal Facility Enriched UF-6 is removed from the process at the Product Withdrawal Facility. It is cooled to convert the gas back to a liquid, then drained into the cylinders. The liquid is allowed to cool and return to a solid form before it is transported.
	Cylinder Shipping Cylinders of enriched uranium hexafluoride (UF-6) are loaded into protective overpacks for shipment to the Portsmouth, Ohio, plant for further enrichment before being shipped to USEC customers around the world.
	Switchyards There are four switchyards at the plant to control and route the incoming electricity.
	Cooling Towers Each process building has its own set of cooling towers. The cooling towers remove the heat generated during the enrichment process. Up to 12 million gallons of water are lost each day through steam-off from the cooling towers.
	Administration Building This administration building houses the general manager's office, the engineering organization, accounting functions, computer and telecommunications support. A medical center and cafeteria are also located here.
	Fire Station A fully equipped fire-fighting team is a key element in the plant's emergency response program.