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PGDP

Paducah Gaseous Diffusion Plant Paducah Site

Tour

In October 1950, as a result of joint recommendations from the U.S.

Department of Defense (DOD), Department of State, and the U.S. Department of Energy’s (DOE) predecessor, Atomic Energy Commission (AEC), President Harry Truman directed the AEC to expand production of atomic weapons. The National Security Resources Board was instructed to select areas within a strategically safe area of the United States. Eight government-owned sites initially were selected as candidate areas. One of the principal facets of this expansion program was the provision for a new gaseous diffusion plant. On October 18, 1950, the AEC approved the Paducah Site for construction of a uranium enrichment facility and formally requested the Department of the Army to transfer the site from the General Services Administration to the AEC. DOD and the AEC began efforts to expand fissionable material production capacity.

SITE HISTORY

“At first, things did not change. But as the construction got underway, change came with lightning speed. The communities in west McCracken County and other areas, as well, were not equipped to handle all the people, automobiles, housing, etc.”

- Mary Ella Scruggs

Construction on the Paducah Gaseous Diffusion Plant (PGDP) started in 1951 and was completed by the mid-1950s, at a cost of $800 million ($6 billion in today’s dollars), by the AEC for national defense.

Although construction of the plant was not complete until the mid- 1950s, production of enriched uranium began in 1952.

In 1953, recycled uranium from nuclear reactors was introduced into the plant’s process equipment and continued through 1964, when feed material was switched to uranium hexafluoride (UF6) made from virgin-mined uranium.

Use of recycled uranium resumed in 1969 and continued through 1976.

In 1976, the practice of recycling uranium feed material from nuclear reactors was halted and never resumed. During the recycling periods, Paducah received approximately 100,000 tons of recycled uranium.

It is a complicated process to go from uranium ore to fuel fabrication to be used by nuclear power companies. The plant played a central role between the mining, electrical power, and fabrication operations. When Paducah’s mission was to supply uranium for defense needs, it was a hub for its sister plants in Oak Ridge and Portsmouth for further enrichment. From 1963 until plant operations ceased, the mission shifted to commercial enrichment, as depicted in the above graphic.

TIMELINE OF OPERATIONS AT THE PLANT

Over 60 years of uranium enrichment operations and support activities, the plant generated hazardous, radioactive, mixed (both hazardous and radioactive), and nonchemical (sanitary) waste. Past operations also resulted in soil, groundwater, and surface water contamination.

In 1989, DOE established the environmental management program to address contamination and waste created by nuclear weapons production, research, and testing activities from the Manhattan Project and the Cold War era, consistent with applicable environmental laws. On July 1, 1993, DOE leased the plant for production of nuclear fuel for commercial reactors. Under the terms of the lease, the company assumed responsibility for environmental compliance activities directly associated with uranium enrichment.

In 2013, uranium enrichment ceased, and the plant was returned to DOE in 2014.

DOE’s mission involves the deactivation of uranium enrichment and support facilities to prepare the site for future demolition and build upon the success of previous environmental cleanup work. Facility modifications and repairs, and utility optimization activities are ongoing to prepare facilities for future decontamination and demolition. DOE and its contractors continue to employ ~1,400 workers and is among western Kentucky’s largest industrial employers. In its more than 60 years of operation, the plant pumped more than $5 billion into the regional economy.

LAND TRANSFER

As cleanup continues, the community has been engaged in the future use of the site.

The Paducah-McCracken County Industrial Development Authority and the Paducah Area Community Reuse Organization have formally requested the transfer of property at the site to promote reindustrialization and economic growth. DOE has identified a 209-acre section of the site that can be made available to community for future reindustrialization and will reduce site maintenance costs.

DOE is currently evaluating this request and has begun the process to transfer property in the near future. The parcel identified by DOE and the community is located on the southeastern corner of the DOE property and has been managed by the West Kentucky Wildlife Management Area since 1953. The site has road access, utility rights-of-way, and power lines.

Surveyors mark the coordinates for easements on the parcel of land being evaluated for transfer. These surveys support the Environmental Baseline Survey, which provides a detailed record of the property’s history, including impacts from past plant operations and environmental sampling efforts to assess potential issues that may need to be addressed before transferring the property to the community.

As the site continues cleanup and optimizes utilities, key upgrades have enhanced efficiency and safety, and reduced costs. Dual electric vehicle charging stations for electric vehicles have recently been installed at the site, supporting DOE’s overall objectives to enhance sustainability.

The site is like a city with its own infrastructure, including utilities that were designed to support full operations.

Since uranium enrichment ceased, DOE has made it a priority to optimize the existing infrastructure to reduce costs and maintenance. Electricity usage at the site has decreased from 3,000 MW to approximately 10 MW, and water usage has been reduced 30 million gallons per day to about 3 million gallons per day. Additionally, outdoor street lights were replaced with energy-efficient LEDs, cutting electricity use by 50% and improving safety for the workforce.

SITE INFRASTRUCTURE

The checkered water tower on the east side of the plant, used for storing water for fire suppression systems, was a landmark of the site skyline for over 70 years. Fire suppression systems were updated with new technology and infrastructure, and the 325-foot tall water tower was demolished in 2024. The result was 463,120 pounds of steel to be recycled and reinvested into the community through the Paducah Area Community Reuse Organization.

Lubrication oil was removed from enrichment systems. Filters, located throughout the process buildings, were removed to ensure the oil could be efficiently pumped out of the system. More than 250,000 gallons were removed and shipped off-site for disposal.

REMOVAL OF HAZARDS

Polychlorinated biphenyls (PCB) oils were commonly used at industrial facilities across the country and Paducah was no exception. PCB oils were used in transformers to provide electrical insulation between internal components.

There were about 70 PCB transformers in the process buildings at the site, all of which were disconnected from power, drained of any PCB oils, and rinsed with recycled lubrication oil, which saved taxpayers nearly a half million dollars.

Draining the PCB oils is an essential step of deactivation. PCB oils present a health risk, so removing the PCB oil improves worker safety, public health, and the environment.

The C-300 Central Control Building sits east of the C-710 Analytical Lab, adjacent to the C-333 Process Building and the C-310 Purge and Product Building

C-300 CENTRAL CONTROL

Built in 1952, the 16,000 ft2 C-300 Central Control Building was used to monitor, coordinate, and control critical plant processes, power distribution, utilities, communications, plant alarms systems, and emergency communications.

More than 10,000 miles of cable– enough to almost stretch halfway around the earth–supplied the central control building with electronic information from the plant’s process systems.

The Central Control Facility was home to four main entities: the plant shift superintendent, the shift coordinator, the power supervisor, and the emergency operations center.

C-333 PROCESS BUILDING

Each cell arrangement contains multiple compressors (orange), motors (blue), and converters (silver) in ~4,000 sq feet.

Uranium enrichment at the plant occurred primarily in four large process buildings.

Uranium enrichment occurred through a process that consisted of approximately 1,760 stages. Each stage had a 1,750- 3,300 horsepower motor, compressor, and converter. Each process building utilized a dedicated switchyard that handled the enormous amount of power necessary for the gaseous diffusion process. C-337 and C-333, the two largest process buildings, are each more than 80 foot high and cover about 25 acres on each floor–larger than 20 football fields. C-335 and C-331, the two smaller process buildings, are each 68 foot high and cover nearly 12 acres per floor.

Deactivation of the C-333 Process Building is well underway and an integral piece of the deactivation is the material-sizing-area (MSA). MSA construction began in 2022 with the clearing of an area roughly the size of a football field inside the C-333 Process Building. Two identical work areas provide the space, equipment, and infrastructure for workers to segment or cut up the large converters that were integral to uranium enrichment operations. Using large cranes, converters can be maneuvered into place for workers to safely segment the equipment for disposal.

Operation of the MSA began in late 2023 with the goal of removing and segmenting the nearly 500 converters in the C-333 Process Building. Worker safety has been the top priority in all phases of the MSA, taking lessons learned and knowledge from similar operations at DOE’s Portsmouth Site, including the design of a dust collection system for use when cutting. Worker feedback from both Paducah and Portsmouth have led to several modifications addressing the challenges in working with these large pieces of equipment.

During uranium enrichment operations, the site was powered by four electrical switchyards. By the end of 2021, all four switchyards had been deenergized. DOE constructed a new electrical substation and power distribution system, operated by the Tennessee Valley Authority, which is connected into the existing utility distribution systems.

By the end of 2024, partial dismantlement of the C-535 and C-537 Switchyards resulted in more than 318,000 lbs of copper, 98,000 lbs of aluminum and 69,000 lbs of steel that was transferred to the Paducah Area Community Reuse Organization (PACRO) to support economic development.

ELECTRICAL SWITCHYARDS

More than 500,000 gallons of insulating oil from the plant’s switchyards was transferred to the Paducah Area Community Reuse Organization to provide a revenue stream in support of economic development for surrounding counties.

Demolition of the 120 foot high C-340 Metals Plant, the tallest building at the site, was completed in 2013. The building encompassed about 1.5 million ft3, the volume of a football field roughly three stories tall. From upper left, the C-340 Metals Plant is shown before and after workers began removing lower transite panels, completing removal in

December 2012. An ultra-high-reach demolition machine was brought in for the building’s last standing section. Demolition was completed in February 2013, two months ahead of the DOE baseline schedule and within budget. Twenty-eight rail cars filled with demolition debris were shipped to a waste facility in Clive, Utah.

C-340 METALS PLANT

C-410 FEED PLANT COMPLEX

Before it ceased operations in 1977, the C-410 Feed Plant manufactured UF6 for use in uranium enrichment. The 5-acre, 7-story C-410 Feed Plant reacted uranium oxides with hydrogen fluoride to make

UF4.

Other parts of the facility made fluorine and combined UF4 with fluorine to make the UF6 used in uranium enrichment. Besides the removal of equipment used to manufacture UF6, more than 2,600 panels of exterior siding were removed from the building before its demolition in 2015. More than 4,700 tons of waste were generated and removed as a result of decontamination and demolition.

BEFORE

AFTER

C-400 DEACTIVATION

The C-400 Cleaning Building, built in 1952 and located near the center of the site, was the primary facility for cleaning and decontaminating parts and equipment used in uranium enrichment.

This often meant using chemical treatments for the recovery of uranium from equipment and the recertification for, among other things, cylinders that held UF6. C-400 also housed processes for everyday work such as the plant laundry. In 2014, workers began deactivating the building and disconnecting utilities going to the building to prepare for demolition. In December 2020, workers completed the deactivation activities for C-400.

The equipment removed from C-400 was dispositioned as waste. After equipment was identified and disconnected, it was sheared or downsized to fit into railcars, which were positioned on the south side of the building. The waste was shipped off-site for disposal. In total, more than 116,000 ft2 of floor space was cleared.

GROUNDWATER SOURCE TREATMENT

Over the years, DOE has continued various environmental monitoring and sampling activities at the site, which include collecting data from monitoring wells. Data from the monitoring wells has allowed a better understanding of groundwater contamination.

Based on current monitoring data, the area of groundwater contamination is smaller than first identified at the time the Water Policy was established.

When groundwater contaminated with the degreaser trichloroethene (TCE) was discovered off-site in 1988, DOE responded by providing temporary water supplies to residents potentially affected by the discovery.

To protect the public, DOE, the U.S. Environmental Protection Agency (EPA) and the Commonwealth of Kentucky created the Water Policy in 1988, which extended municipal water lines at no cost to people whose wells could be affected by contaminated groundwater.

DOE agreed to pay the reasonable monthly cost for homes and businesses and in exchange, the landowners pledged to cease using the groundwater.

Today, about 100 homes and businesses neighboring the site are included in the water policy area.

A heavy equipment operator lowers a water line pipe into a trench. DOE extended the municipal water lines to local residents whose wells could be affected by off-site plumes.

GROUNDWATER SOURCE TREATMENT

In 2005, DOE, the U.S. Environmental Protection Agency (EPA) and the Commonwealth of Kentucky agreed to the installation of a treatment system using electrical resistance heating (ERH) that would remove significant amounts of the degreaser TCE from the ground near the C-400 Cleaning Building near the center of the site.

Following construction and testing in 2008- 2009, Phase I of the heating system project was completed in October 2010, treating more than 4 million gallons of groundwater and recovering about 580 gallons of TCE from 20 to 60 feet deep in the ground southwest and east of the C-400 Cleaning Building. Phase IIa of the ERH project began operating in August 2013 to remove TCE from 20 to 60 feet deep in the ground southeast of the cleaning building. With 52 borings, each containing three electrodes, the system had removed ~1,120 gallons of TCE when operations were completed in 2014. As part of Phase IIb, a treatability study was completed in June 2015 that determined full-scale steam injection is technically implementable in lower depths (below 60 feet) for the future. Fieldwork for an investigation of the entire C-400 Complex, including beneath the building, began in November 2019 and was completed in December 2021. The results of this investigation will assist in evaluating options for future cleanup.

This graphic shows how electrodes are focused in the area of the greatest concentration of TCE in the ground below C-400. Phase I incorporated the smaller groupings of electrodes on the left and right. Phase IIa, the large grouping in the center, was completed in 2014.

Drill operators complete an angled boring in the C-400 Cleaning Building east truck alley.

The angled borings enabled the project team to collect samples from the soil beneath the facility that had previously been inaccessible.

Optimized extraction wells, installed at the northwest and northeast plumes have improved removal of contamination. The graphics above show the reduction of contaminated plumes resulting from DOE's cleanup efforts.

In the early 1990s, DOE began two projects to control migration of the contaminated groundwater plume that had moved off-site. The first project was the C-612 Northwest Pump-and-Treat facility. This facility went on line in 1995 as a two-year pilot plant, where the system extracts contaminated groundwater, removes TCE and technetium-99, and then returns the treated water to the environment.

DOE optimized the extraction well network by taking the original wells offline and added two new extraction wells in 2010 to improve the removal of TCE in the Northwest Pump-and- Treat area. The northeast Pump-and-Treat facility began operation in 1997. Since they began operating, the two facilities together have treated around 5.3 billion gallons of groundwater.

PUMP-AND-TREAT

Beginning in 2016, additional work started on upgrading and optimizing both the northwest and northeast pump-and-treat systems. At the northwest pump-and-treat facility, outdated equipment was upgraded and modernized to increase the reliability of the system and improve its efficiency.

In the northeast pump-and-treat facility, two new optimized wells were drilled to increase the capture of groundwater contamination and a whole new treatment system was installed. Both projects have enhanced the control of the migration of the plumes off-site. The northwest and northeast pump-and-treat systems continue to operate, and approximately 4 million gallons of groundwater are extracted and treated weekly by these systems.

New extraction wells installed in 2017

Drill rig operators and geologists remove samples from cores drilled to determine the optimal location for the two new extraction wells installed for the northeast plume pump-and-treat system.

EAST END SMELTER

The East End Smelter was built in the early 1950s as a warehouse. In the mid-1970s, the facility was expanded and outfitted with a room-sized electric induction furnace that smelted nonferrous metals, primarily nickel.

The smelter, which closed in 1986, was contaminated with beryllium introduced into the Paducah Site during the Work for Others program during the Cold War. An extensive beryllium protection/abatement program had to be developed and implemented for workers during the cleanup of the smelter.

Accelerated federal funding advanced demolition by 22 years and $12 million in cost savings were shifted to other cleanup projects. To prepare the facility for demolition, welders and other workers removed more than 60,000 ft3 of waste.

SCRAP METAL REMOVAL PROJECT

The majority of scrap materials in the scrap yards came from equipment removed from the process buildings during the uranium enrichment upgrade program in the 1970s and 1980s.

The site once contained the largest collection of scrap metal in the DOE complex. Eight outdoor storage yards covering 27 acres were filled with more than 30,500 tons of scrap metal (enough to make more than 10,000 heavy-duty pickup trucks) from the plant upgrade program during the 1970s and 1980s. The scrap metal project began in 2000, and removal was completed in 2007.

The project was notable, not just for its size and complexity, but for the innovations developed by the project team.

For example:

• A commercial disposal company that operates a landfill in Utah took possession of the metal in Paducah, which eliminated complex paperwork and sped removal. This was a first within the DOE complex.

• The project used 6,000 ft3 railcars designed and built to support the work.

Drum Mountain was one of the site’s most visible environmental hazards. Many of the drums originated from the now demolished C-340 Metals Plant, where they were used to store UF4, better known as green salt, used in other manufacturing processes.

During the 1950s and 1960s, the C-340 Metals Plant at the Paducah Site recovered uranium from depleted UF6. Drums emptied during the conversion process were crushed and piled into what became a 35 foot tall mound of metal called “Drum Mountain.” In 1999, DOE began removing this mass of metal, eliminating the hazard and changing the skyline of the site. The removal of the 2,600-ton Drum Mountain was completed in 2000.

The scrap yards covered 27 acres and contained more than 30,500 tons of contaminated scrap metal. The scrap metal came from equipment taken out of the process buildings during the plant’s upgrade program in the 1970s and 1980s. The removal of the largest inventory of scrap metal in the DOE complex was completed in January 2007.

DRUM MOUNTAIN

To dispose of the 35 foot high mountain of discarded drums, heavy machinery compacted the drums on-site. The drums could then better fill the shipping containers for disposition.

Surface soils are being addressed in two phases: (1) accessible soils not associated with current plant operations, and (2) soils beneath facilities to be torn down after the plant closes. Radionuclides and polychlorinated biphenyls (PCBs) are the primary contaminants of concern for pre-closure actions.

ENVIRONMENTAL CLEANUP PROJECTS

The Paducah Site has more than 100 acres of historic waste burial grounds. The burial grounds contain construction debris, flammable waste, and contaminated scrap metal. Releases from these burial grounds may have affected, or have the potential to affect, groundwater underneath the areas.

Remediation of these burial grounds has been broken into five subprojects, with decisions pending on the various cleanup remedies. Excavation may be required at some of the burial grounds due to the potential for highly toxic, mobile waste.

Burial grounds projects use direct push technology (DPT) to collect samples. DPT uses steel rods pushed or driven into the ground to collect soil so it can be logged and sampled more easily.

WASTE BURIAL GROUNDS

Geologists examine and log samples removed by direct push technology during a project to identify and map areas of contamination for cleanup.

Between 1973 and 1979, the C-747-C Oil Landfarm was used for land farming of waste oils contaminated with TCE. These waste oils are believed to have been derived from a variety of plant processes. The landfarm consisted of two 1,125 ft2 plots plowed to a depth of one to two feet.

During the time that this was common practice, waste oils were spread on the surface every three to four months, then the area would be limed and fertilized.

The 2.2-acre C-747-C Oil Landfarm was used from 1973 to 1979 to biodegrade waste oils. Confined generally to the southwest portion of the site, the past practices at the Oil Landfarm contributed to a plume of TCE-contaminated groundwater.

Fieldwork began in 2014 to clean up TCE from the Oil Landfarm using a crane equipped with an eight foot auger bored 258 columns of soil, which mixed with steam and iron to treat TCE in a process called deep soil mixing.

Deep soil mixing was completed in October 2015 and groundwater continues to be monitored.

SOUTHWEST PLUME

In addition to the Oil Landfarm, another contributor to the Southwest Plume was discovered in subsurface soil contamination northeast of the C-720 Maintenance & Storage Building. This contamination is believed to have resulted from routine equipment cleaning and rinsing with solvents.

In 2022, the site introduced bioremediation, an effective treatment method used to remove TCE from this area. Bioremediation uses high pressure water to create openings in the subsurface for placing treatment material. These zones were created with 443,000 lbs of a specialized type of iron metal, commonly used in environmental remediation, as well as 220,000 lbs of sand.

The zones were injected with 130,000 gallons of emulsified vegetable oil and 57 gallons of a commercially-available TCE-reducing bacteria. Bioremediation, combined with natural degradation, will naturally decrease the contamination.

SWMU 211-A

Built in 1952, the C-720 Maintenance and Stores Building contains both high bay and low bay areas with large storage areas, maintenance shops, and loading docks in 336,498 ft2 of floor space. The crafts housed in this building had the capability to fabricate, repair, maintain, and calibrate almost every piece of equipment essential to the operation of the plant. The high bay portion of the facility contains metal fabrication and machining equipment, climate-controlled shop areas for precision work, electronic repair facilities, paint-spraying facilities, and electrical motor areas capable of fabricating all the equipment needed to support operations.

There are 72 milling machines, both horizontal and vertical, ranging in size from a 9-inch by 36-inch table to a 20 foot table with a 72-inch vertical head travel. Various equipment was available for all types of grinding, shaping, forming, and welding.

C-720 MAINTENANCE AND STORES

AFTER

BEFORE

When the plant was in operation, the site required about 85,000 ft² of storage space to house inventory ranging from light bulbs to pumps, compressors and spare/replacement parts for larger equipment. The site recently downsized its Stores inventory and today uses only about 10,000 ft² of storage space.

In 2023, the site began operation of a state-of-the-art scanning facility called the Large Item Neutron Assay System (LINAS). LINAS houses scanning equipment used to support the deactivation of several facilities, including the site’s four large process buildings. The LINAS facility allows workers to collect accurate measurements of deposits left over from uranium enrichment operations within process gas equipment.

Large equipment from buildings across the site can be transported into this facility and scanned using helium-3 detector tubes. These tubes scan measure of the contents of the equipment to determine the best disposal path. During startup of LINAS, the scanning technology test data demonstrated it is the most accurate measuring system in the world for the large equipment at the site.

The LINAS chamber is designed with a three foot thick ceiling, two foot thick walls, and 18-inch thick doors to ensure the accuracy of the data captured from the scan.

More than 500 cubic yards of concrete was used to pour the thick walls, cap, and slab needed to ensure accurate measurements inside the LINAS chamber.

LARGE ITEM NEUTRON ASSAY SYSTEM

The mission of the depleted uranium hexafluoride (DUF6) plant is to convert about 46,000 cylinders of DUF6 located on-site into a more stable chemical form for reuse or disposal and to reduce the risk to workers and the surrounding community.

The conversion method is a continuous process where DUF6 is vaporized and converted to uranium oxide in a fluidized bed conversion unit. The process equipment is arranged in parallel lines, each line consisting of two autoclaves, two conversion units, a hydrofluoric acid recovery system, and process offgas scrubbers. In the conversion process, DUF6 reacts with steam and hydrogen to produce uranium oxide and hydrofluoric acid.

DUF6 CONVERSION PLANT

DUF6 is a by-product of the uranium enrichment process. DUF6 was placed in large steel cylinders and stored in outdoor yards. The Paducah Site has multiple cylinder yards on-site that are home to about 46,000 cylinders. The DUF6 mission to convert all of the cylinders will take ~30 years.

ACRONYMS

AEC – Atomic Energy Commission ARRA – American Recovery & Reinvestment Act CAB – Citizens Advisory Board D&D – Decontamination and Decommissioning DOE – U.S. Department of Energy DUF6 – Depleted Uranium Hexafluoride ERH – Electrical Resistance Heating FRNP – Four Rivers Nuclear Partnership, LLC FY – Fiscal Year HF - Hydrogen fluoride KOW – Kentucky Ordnance Works LA – Limited Area MCS – Mid-America Conversion Services, LLC NASA – National Aeronautics and Space Administration NRC – Nuclear Regulatory Commission NSDD – North-South Diversion Ditch PACRO – Paducah Area Community Reuse Organization PGDP – Paducah Gaseous Diffusion Plant PPPO – Portsmouth/Paducah Project Office PSS – Plant Shift Superintendent SST – Swift & Staley Team TCE – Trichloroethene TVA – Tennessee Valley Authority UF6 – Uranium Hexafluoride WKWMA – West Kentucky Wildlife Management Area

Updated: February 2025

Buz Smith Department of Energy 5501 Hobbs Rd C-103

Kevil, KY 42053

(270) 441-6821 http://energy.gov/pppo

For information about the Paducah site, our latest videos and the Paducah Site Virtual Museum visit https://www.energy.

gov/pppo/paducah-community-outreach