Portsmouth Gaseous Diffusion Plant

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Coordinates: 39°00′30″N 83°00′00″W / 39.00833°N 83.00000°W / 39.00833; -83.00000

The Portsmouth Gaseous Diffusion Plant is a facility located in Scioto Township, Pike County, Ohio, just south of Piketon, Ohio that previously produced enriched uranium, including weapons-grade uranium, for the United States Atomic Energy program and U.S. nuclear weapons program. The plant is in shutdown status and is in preparation for decontamination and decommissioning (D&D), with some facilities overseen by the United States Enrichment Corporation, a subsidiary of USEC Incorporated, a publicly traded corporation (NYSE: USU). The D&D work on the older facilities to prepare the site for future use is expected to continue through 2024 and is being conducted by Fluor-B&W Portsmouth LLC.

The Portsmouth plant, so named because of its proximity to the city of Portsmouth, Ohio, was one of three gaseous diffusion plants in the United States, alongside the K-25 plant in Oak Ridge, Tennessee and the Paducah Gaseous Diffusion Plant in Kentucky. The plant was constructed from 1952–1956, with the first enrichment cells going online in 1954. The plant was operated by the Goodyear Tire and Rubber Company from its startup to 1986, when the contract was taken over by Martin Marietta. In 1993, the USEC took overall responsibility for the Paducah and Portsmouth enrichment plants, continuing the operating contract with Martin Marietta. In 1995, the operator became Lockheed Martin with the merger of Martin Marietta and Lockheed. In May 2001, the Piketon plant ceased operations and was placed in cold standby. In 2006, the site work shifted into cold shutdown transition in preparation for future Decontamination and Decommissioning (D&D).

The former gaseous diffusion plant covers 640 acres (260 ha) of the 3,777-acre (1,528 ha) site. The largest buildings, the process buildings, have a combined length of approximately one and a half miles (2.4 km), and cover about 93 acres (38 ha) and contain 10 million square feet (0.93 km2) of space. In use, the plant consumed a peak electrical demand of 2,100 megawatts.[1]

A commercial centrifuge plant at the Portsmouth site began construction in May 2007 for the production of commercial nuclear fuel for power reactors. Once completed, the commercial plant will use approximately 11,500 centrifuge machines to generate 3.8 million separative work units (SWU) a year.[2]

History – The Portsmouth Project[edit]

In August 1952, the U.S. Atomic Energy Commission (AEC) selected Scioto Township, a rural area occupied by family-owned farms, as the site for a new gaseous diffusion plant to produce highly enriched uranium, U-235, for use in military reactors and nuclear weapons production. Located near the junction of the Scioto and Ohio rivers, the site was chosen due to the economic availability of electric energy, availability of water for plant operation, adequate potential labor, suitable transportation facilities, geographic traits, and relative flatness of the topography.[3]

The project was given expedited priority. Due to this prioritization, construction of the site had to start before all the architectural drawings for the site were completed. The Oak Ridge operations of the AEC set up an organization designated “The Portsmouth Area” to direct construction and operation of the plant, select engineers, construction contractors, schedule delivery of critical materials, and any other contingency. Uniform agreements were set up between labor and management to minimize the number of stoppages. Early planning and organization took place in improvised offices in city buildings of Portsmouth, including the National Guard Armory, the Elks City Club, and the old farmhouses on the site itself. Nine architect engineer firms shared in the design of the plant, producing 12,000 design drawings, 40,000 construction drawings, and 16,000 shop drawings. Advanced planning and scheduling were extremely important because the plant was designed to go into operation, or “on stream,” as soon as each unit or segment in a process building was completed while construction continued in other parts of the building.

Groundbreaking for the plant was November 18, 1952. Earthmovers began leveling the rolling farmland for the building foundations on the same day. One hundred thousand tons of structural steel, 14,500 tons of reinforcing steel in the concrete floors, 600 miles of process piping and 1,000 miles of copper tubing were used in the construction of the three process buildings. An additional 1,000 miles of tubing ran through the rest of the plant and into the control rooms. Five hundred thousand cubic yards of concrete were required to complete the project. To support this, a separate concrete batching plant was constructed on plant site to serve all contractors. It produced 200 cubic yards of concrete per hour. It took 70 million man hours for construction.

Two railroad lines, financing their own work, built spurs into the area to haul in building materials and heavy equipment including 22 miles of track on site. Twenty-five miles of roads were laid in the plant area as well as a seven-mile perimeter road that encircles the plant.

The original estimate for construction was four years at a cost of $1.2 billion. Construction was carried out by Peter Kiewit and Sons of Nebraska at a cost of $750 million. The site was completed several months ahead of schedule at 34 percent below the original cost estimate at a $400 million savings.


Operations began in 1954 while construction was ongoing with the plant coming fully online in early 1956, several months ahead of schedule.

The primary mode of enrichment was the gaseous diffusion of uranium hexaflouride to separate the lighter fissile isotope, U-235, from the heavier non-fissile isotope, U-238. The plant initially produced material for the U.S. nuclear weapons program. In the mid-1960s, the plant converted to fuel production for commercial nuclear power plants. Portsmouth took material from Paducah that was enriched to 2.75% U-235 and further enriched it to approximately 4% and 5%.[4][5]

The Portsmouth plant had a capacity of 8.3 million separative work units per year (SWU/year) in 1984 in 4,080 stages. Three buildings, X-326, X-330 and X-333, housed gaseous diffusion equipment.[6] Three cooling tower complexes, X-626, X-630, and X-633, were used to remove process heat. Six hundred eighty-nine million gallons of water went through the 11 cooling towers daily, of which 20 million gallons evaporated into the air. Water came from well fields installed at the Scioto River supplying 40 million gallons per day when operating at full capacity.

To support operations, the AEC entered into the largest contract for a single customer in the history of the electrical utility industry for power at that time. Power usage was equal to the all-time high voltage requirements in the United States, more than 2,000 megawatts - 18 billion kilowatt hours yearly. To handle the power requirements, two large switchyards were constructed on site. Two large steam electric generating stations were built to supply power at Clifty Creek in Madison, Indiana and Kyger Creek in Gallipolis, Ohio. At the time, they were the largest power plants built by private industry as well as the most efficient, producing 1 kilowatt hour of electricity for 0.7 pounds of coal. The power plants used 7.5 million tons of coal annually to support operations.

In May 2001, USEC ceased uranium enrichment operations at the Piketon plant and consolidated operations in Paducah. The following year, transfer and shipping operations were also consolidated in Paducah.[2][3] Although USEC had nine years time and had received the funding, USEC ceased the Portsmouth enrichment cascade in a dirty power down, without purging the diffusion cells.[7] Geoffrey Sea wrote in September 2013 that USEC's demise will be either by creditors (by October 2014 loan repayment deadline), "regulators who find their spines", or by "repeal of the USEC Privatization Act by Congress."[8]


DUF6 Conversion facilities are located at the Paducah Gaseous Diffusion Plant near Paducah, KY and the Portsmouth Gaseous Diffusion Plant near Piketon, OH. Each facility consists of four buildings- a conversion building, an administration building, a warehouse and a KOH Regeneration building, as well as rail heads, five large acid storage tanks and lay-down areas for DUF6 steel cylinders. In 2002, DOE awarded Uranium Disposition Services, LLC (UDS) a contract to design, build and operate the DUF6 conversion plants to convert the DUF6 to uranium oxide and hydrofluoric acid. In December 2010, DOE awarded B&W Conversion Services, LLC (BWCS) a contract to operate the DUF6 Conversion Plants through March 2016. Babcock & Wilcox Conversion Services (BWCS) completed the transition of the contract for initial operations of the DUF6 Project in March 2011. Both plants are expected to be fully operational in fall 2011.[9][10]

Centrifuge separation[edit]

USEC ceased enrichment operations at the Portsmouth Gaseous Diffusion Plant in May 2001 after it consolidated operations at the Paducah Gaseous Diffusion Plant in Kentucky. USEC began working with the U.S. Department of Energy (DOE) in 2000 to resume gas centrifuge enrichment operation activities, which DOE originally began developing in the early 1960s. During the 1980s, DOE had begun construction of a centrifuge enrichment plant at the Portsmouth site before abandoning the project in June 1985 after spending $3 billion. USEC sited its Lead Cascade Test Program at Piketon in late 2002. The Nuclear Regulatory Commission (NRC) licensed this demonstration facility in 2004. Lead Cascade operations using prototype machines commenced in August 2007.

In March 2010, USEC began operating a new test cascade of commercial-ready AC100 centrifuge machines. USEC has been demonstrating AC100 cascade operations since then. USEC's prototype and AC100 centrifuge machines have accumulated hundreds of thousands of hour of runtime since August 2007. Performance of the Lead Cascade has been confirmed under a variety of operating conditions with product assays consistent with industry standards for the production of commercial nuclear fuel for power reactors. The NRC licensed USEC to construct and operate the commercial American Centrifuge Plant at the Portsmouth site in April 2007, and construction began in May 2007. Construction was demobilized in August 2009 due to the delay in receiving a loan guarantee from the U.S. Department of Energy. USEC currently awaits approval of this $2 billion loan guarantee before it can remobilize the construction, which will create nearly 8,000 jobs in the United States. Once completed, the commercial plant will use approximately 11,500 centrifuge machines to generate 3.8 million separative work units (SWU) a year.[2]

Decontamination and ongoing cleanup[edit]

During its nearly 60 years of operations, the cleaning, maintenance, and change out of process equipment at the site generated spent solvents and other contaminants that were disposed of in onsite landfills and surface storage buildings. To date, contamination has been found in various locations on site including the process buildings, the former cooling towers, landfills, waste water ponds, and other buildings. There are also groundwater plumes from the landfills. The Ohio EPA is monitoring cleanup operations, pursuant to a 1989 consent decree.[11]

On June 27, 2005, the Department of Energy awarded a contract to LATA/Parallax Portsmouth, LLC (LPP). This was the first small business contract by DOE at the Portsmouth site. As part of the environmental remediation of the site, LPP removed 31 facilities; an 18-acre switchyard complex which included 160 towers, 18 large transformers, 10 synchronous condensers, 2 switch houses, 1 2-story control room and numerous other structures. LPP's contract was extended as part of the American Recovery and Reinvestment Act of 2009 (ARRA) stimulus project with their contract ending on March 29, 2011. In 2008, a large project was completed to remove 7,640 tons of scrap material by shearing and disposing of 382 old process equipment converter shells. Between 2003 and 2010, more than 59,500 cubic meters of legacy waste was removed from the site. In September 2010, the DOE awarded the $1.2 billion follow up contract to Fluor-B&W Portsmouth LLC. Fluor-B&W transitioned the remaining LPP scope and workforce on March 29, 2010 and is currently working with USEC to transition remaining personnel and responsibilities for the site.

Nuclear power[edit]

The site was evaluated for a potential nuclear power plant by a consortium including Areva, Duke Energy, USEC and UniStar Nuclear Energy, with no proposal as of 2011.[12]

The future of the site[edit]

The DOE, in partnership with the counties of Pike, Jackson, Ross, and Scioto and the D&D contractor, Fluor-B&W Portsmouth, are working on preparing the site for future use.

See also[edit]


  1. ^ "Key Facts: Portsmouth Gaseous Diffusion Plant". Gaseous Diffusion Plants. USEC, Inc. Archived from the original on 21 May 2011. Retrieved 14 November 2010. 
  2. ^ a b "The American Centrifuge". USEC, Inc. Archived from the original on 15 November 2010. Retrieved 14 November 2010. 
  3. ^ "Gaseous Diffusion Plants". USEC, Inc. Retrieved 14 November 2010. [permanent dead link]
  4. ^ "History: Portsmouth Gaseous Diffusion Plant". Gaseous Diffusion Plants. USEC, Inc. Archived from the original on 2 January 2011. Retrieved 14 November 2010. 
  5. ^ "Overview: Portsmouth Gaseous Diffusion Plant". Gaseous Diffusion Plants. USEC Inc. Archived from the original on 24 November 2010. Retrieved 14 November 2010. 
  6. ^ Cochran, Thomas B.; Arkin, William M.; Norris, Robert S.; Hoening, Milton M. (1987). Nuclear Weapons Databook, Vol. III: U.S. Nuclear Warhead Facility Profiles. Natural Resources Defense Council. pp. 127–128. ISBN 0-88730-146-0. 
  7. ^ Sea, Geoffrey (June 4, 2013). "Stiffed USEC Sues Feds in Nuclear Slugfest (Part 4)". ecowatch. Retrieved 22 September 2013. 
  8. ^ Sea, Geoffrey (September 19, 2013). "USEC's Tsunami: Uranium Company Washes Out". ecowatch. Retrieved 22 September 2013. 
  9. ^ "AREVA Starts Operations at the Portsmouth Facility". NuclearStreet. September 10, 2010. 
  10. ^ "DOE Gives AREVA Joint Venture Permission to Begin Operational Testing of New Ohio Facility". AREVA. Retrieved 14 November 2010. 
  11. ^ "Ohio EPA, U.S. Department of Energy Rech Cleanup Agreement" (PDF). Ohio EPA. Archived from the original (PDF) on 27 December 2010. Retrieved 14 November 2010. 
  12. ^ Piatt, G.Sam. "Public comment sought on nuclear power plant". Portsmouth Daily Times. Archived from the original on 15 July 2011. Retrieved 14 November 2010. 


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