Once the world’s largest, K-25 Building will be completely demolished Thursday

K-25 Demolition December 2013

Demolition work on the former uranium-enriching K-25 Building in west Oak Ridge is expected to be completed Thursday. (Photo courtesy U.S. Department of Energy/Lynn Freeny)

It was once the world’s largest building under one roof, but on Thursday, federal officials expect to complete demolition work at the K-25 Building in west Oak Ridge.

K-25 was built during World War II to enrich uranium for the world’s first atomic bombs as part of the top-secret Manhattan Project. After the war, it enriched uranium for nuclear weapons and commercial nuclear power plants.

But the site shut down in the mid-1980s, and demolition work on the K-25 Building started five years ago, in December 2008, under former cleanup contractor Bechtel Jacobs.

Officials and workers expect to tear down the last remaining piece of K-25 starting at about 11 a.m. Thursday. They have invited media to attend to witness the historic event.

UCOR workers began tearing down the last six units in the east wing of the mile-long Manhattan Project-era gaseous diffusion building in September. UCOR is the U.S. Department of Energy’s cleanup contractor in Oak Ridge.

In November, DOE said the entire project, including waste removal, should be completed next year.

K-25 Building Aerial View

Now mostly demolished, the former mile-long, U-shaped K-25 Building is pictured above. The site could be included in a Manhattan Project National Historical Park. (Photo courtesy of U.S. Department of Energy)

The gaseous diffusion operations at the U-shaped building ended in 1964, and the former K-25 site, which is now known as Heritage Center, is slowly being converted into a massive industrial park.

Demolition work on the North End, which historic preservationists had lobbied to save for years, was completed in January.

At one time, plans had called for completing the demolition work on the remaining six units in the east wing by 2015, so it appears that the project is ahead of schedule.

Earlier this year, officials said the K-25 Building demolition project is the largest in DOE’s Environmental Management program. They said the project has an approved value of up to $1.4 billion, although they said the total cost—including expenses for maintenance, repairs, and security patrols dating back to the mid-1980s—could come in under budget at roughly $1.1 billion.

UCOR began working at the K-25 site, now known as East Tennessee Technology Park, in August 2011.

Construction on the 44-acre K-25 Building started in November 1943 as part of the top-secret Manhattan Project and was finished in August 1945, about the time World War II ended. The K-25 site was used to enrich uranium for commercial use after the war. K-25 also worked with sites in Portsmouth, Ohio, and Paducah, Ky., to enrich uranium for nuclear weapons.

UCOR is a partnership between URS and CH2M Oak Ridge LLC.

More information will be added as it becomes available.

Note: This story was updated at 1:03 p.m.



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  • Helen Standifer

    So sad, I worked there. But, a park? I just don’t see anyone bringing the family for a picnic. Or maybe it’s just me.

    • Trevor Rasmussen

      An industrial park…not a city park. Lots of building for industrial use.

  • Joshua Hamilton

    I could understand not saving the buildings, but I sure hope they took lots of pictures for generations to come to understand exactly how massive that site was… But then again, I’m the kind of guy who gets a huge kick out of finding flat top houses in odd places outside Oak Ridge :)

  • Don Miller

    As an ASME volunteer, I regret not being able to send visitors to see the massive structure, but time does march on. I agree with Joshua.

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