Legacy cleanup supports modernization and economic development in Oak Ridge

UCOR's work began by completing cleanup of the former Oak Ridge Gaseous Diffusion Plant, now called East Tennessee Technology Park (ETTP). That historic cleanup involved the removal of more than 500 facilities, including the iconic K-25 building, and turning a former uranium enrichment site into a thriving economic hub that has attracted 25 businesses to the area.

Cleanup at ETTP-one of the nation's largest environmental cleanup projects-required extensive demolition and significant soil excavation. Initial estimates indicated that approximately 100,000 cubic yards of soil would require excavation, but those estimates increased as work progressed. By the end of the project in 2024, workers had removed and disposed of more than 554,000 cubic yards of soil, equaling nearly 50,000 dump truck loads.

Once soil remediation at the site was completed, the DOE transferred the remaining federally owned parcels of land to the community for beneficial reuse. To date, the DOE has transferred more than 2,500 acres of land to the community to help attract and generate new economic development for the region. The private businesses that have located or announced plans to build on these parcels of transferred land are bringing in $12 billion in capital investments and generating an anticipated 2,500 new jobs, many of which will support nuclear technology development.

"Oak Ridge is the epitome of legacy nuclear cleanup done right. Tennessee is leading the nation's civil nuclear resurgence because UCOR's successful land remediation efforts have spurred new economic development. The former K-25 site is now home to nuclear companies representing almost the entire fuel cycle, with investments in the billions," said Rep. Chuck Fleischmann (R., Tenn.). He added, "As chairman of the House Energy and Water Appropriations Subcommittee, I am also keenly aware of how cleanup efforts are essential to modernizing DOE and National Nuclear Security Administration infrastructure across the country. Oak Ridge is again a prime example where we are tearing down contaminated, antiquated buildings to construct the next generation of cutting-edge facilities for national security, technological innovation, and scientific discovery at Oak Ridge National Laboratory and the Y-12 National Security Site. The nuclear cleanup mission is truly transforming local communities, spurring job creation and private investment, and ensuring our national lab system and nuclear security enterprise are prepared for the next American century."

With work at ETTP wrapping up, most of UCOR's workforce is deactivating and demolishing unneeded facilities at two other Oak Ridge Reservation sites: Oak Ridge National Laboratory and the Y-12 National Security Complex.

"We have completed the first phase of cleanup in Oak Ridge but there is still more to accomplish," said Clint Wolfley, UCOR senior vice president of end state delivery. "Some of the most hazardous facilities across the DOE complex are located here in Oak Ridge, and we have the experience and knowledge to safely handle and remove those obstacles."

For example, earlier this year and six months ahead of schedule, crews demolished the massive Alpha-2 building, a 325,000-square-foot former uranium enrichment facility. During the Manhattan Project era, the "calutron girls" were famously photographed by Ed Westcott at their calutron control panels inside Alpha-2. Although they were unaware at the time, their efforts aided in the development of the nuclear weapons that helped end World War II.

Alpha-2 marks the largest demolition project to date at Y-12. UCOR crews achieved the Alpha-2 deactivation and demolition milestones all while extending an impressive safety record. Employees on the project worked more than 800,000 hours without a recordable injury or illness.

UCOR's first large-scale demolition project at Y-12 was the former Biology Complex, comprising 11 buildings, which reached final demo in 2021. Initially built in the 1940s to recover uranium from process streams, it was later used for research that led to strides in understanding genetics and the effects of radiation. When operational, the complex once housed more individuals with doctorates than anywhere in the world.

Up next is demolition of a single-story old steam plant that was constructed in 1943. Over the decades, it supported multiple missions, including uranium enrichment activities, fuels testing and maintenance, and storage operations. Following the steam plant, demolition will start on the first of nine beta buildings that were built in 1944 to house calutron tracks for electromagnetic uranium enrichment. In the years that followed, they were used to support research and development of various other activities. Crews are expected to start tearing down the 210,000-square-foot Beta-1 building later this year.

In recent years, crews at ORNL have completed several major demolition projects, cleaning up outdated, contaminated facilities for new science missions. These projects include demo of the Low Intensity Test Reactor, the Bulk Shielding Reactor, and a Graphite Reactor support facility.

The Low Intensity Test Reactor was built in 1949 as a criticality testing facility that used highly enriched fuel with water as a coolant. It remained operational until 1968. UCOR completed demolition in 2023. To reach this milestone, workers used a high-reach crane to remove a trolley and bridge crane from the building before removing concrete slabs and shield blocks to access the main 37,600-pound reactor structure. Workers placed the 30-foot-long reactor in a specialized carbon metal container for disposal shipment. In total, the project demo produced more than 1.1 million pounds of waste.

The Bulk Shielding Reactor complex was constructed in the 1950s to support radiation shielding studies as part of the federal Aircraft Nuclear Propulsion Program. It included a 27-foot-deep reactor pool filled with water used to shield the radioactive components contained in the pool. In 1963, the facility's mission transitioned into a general-purpose research reactor, and operations were permanently shut down in 1991. UCOR successfully demolished the facility in 2022.

In 2025, UCOR completed demolition of a former Graphite Reactor support facility that was built in 1943 containing a fan house to provide ventilation. The structure was located on a small, heavily congested footprint. By removing this building, UCOR provided the necessary space to support future teardowns of neighboring facilities that are surrounded by ongoing ORNL operations.

Before demolition can begin, a great deal of preparation work must be done. These tasks involve meticulous removal of radiological and chemical hazards from inside the facilities and rerouting of active utility lines that support ongoing science and national security efforts. Completing these steps places the facility in a stable condition to minimize risks and protect workers, the public, and the environment.

UCOR is currently deactivating nine facilities across the Y-12 and ORNL sites.

ORNL workers are deactivating several facilities, including the former Radioisotope Development Laboratory (Building 3026), one of the most contaminated structures on-site. Crews constructed a six-story protective cover over the hot cells to ensure nearby research facilities are not impacted during demolition. Building this protective cover required installing a foundation of nearly 100 16,000-pound blocks and erecting 20 steel trusses for the frame. Due to the layout and high risk of this facility, deactivation and demolition efforts were completed in various stages. When constructed in the early 1940s, the laboratory contained six hot cells where radioisotopes from ­ORNL's Graphite Reactor and succeeding reactors were processed for shipment. Over the years, the outer structure and five hot cells were demolished with one final hot cell split into subcells A and B. UCOR successfully demolished subcell B in 2025 and is currently deactivating subcell A.

To increase the workforce's safety, a remote-controlled robot was deployed at 3026 to reduce the size of contaminated items in subcell A, load them into containers, and prepare the debris for final packaging and disposal. Operators will also use the equipment to remove a contaminated stainless steel liner in the cell prior to demolition. There are future opportunities to use this equipment to aid in the deactivation of other highly contaminated facilities at ORNL, including the former Fission Production Development Laboratory (Building 3517).

Most recently, crews finished years of deactivation and began a demolition project to bring down 10 former radioisotope processing facilities known as Isotope Row. Built between the late 1940s and early 1960s, these facilities previously supported ORNL's isotopes program. For decades, employees produced, processed, and researched isotopes used in medical, industrial, scientific, and national defense applications. As the DOE's largest multiprogram national lab expanded, Isotope Row remained in place following the discontinuation of operations there in the early 1990s. The shutdown of Isotope Row left behind contaminated ventilation systems, hot cells, process equipment, and legacy radioactive materials requiring specialized cleanup approaches. UCOR addressed those complex tasks and deactivated the facilities under strict radiological and industrial safety controls.

Deactivation efforts are active at two Y-12 legacy facilities. These buildings were used to house large-scale calutron electromagnetic separation machines that enriched uranium-235 during the Manhattan Project. One of these buildings was later repurposed for lithium isotope separation, a process that required a large amount of mercury.

Since 2020, UCOR has safely removed 264 gallons, or approximately 13 tons, of elemental mercury. To reduce mercury vapors inside the buildings, crews are using innovative techniques such as reinstalling legacy fans inside the facilities and real-time radiography efforts.

In the last four years, UCOR has cleared more than 30 acres of land at ORNL and Y-12 for modernization and development. To put that into perspective, it would take 14,816 cars or nearly 23 football fields to fill 30 acres.

UCOR's removal of the Y-12 Biology Complex in 2021 significantly changed the site's skyline and made room for a planned lithium processing facility. Once cleanup of Isotope Row is finished, that space will be available for future science missions in the heart of ORNL's Central Campus.

UCOR's environmental cleanup positions the American nuclear innovation district to be centered in Oak Ridge and enables ORNL's ongoing science directive and national security efforts at Y-12.

Ella Stewart is a communications specialist and staff writer at UCOR.