URS/CH2M Oak Ridge LLC (UCOR) has removed one of the highest risk components remaining in the East Tennessee Technology Park’s (ETTP) K-25 building, with the successful crane removal of five components known as NaF traps.
The NaF traps contain a material that was used to absorb uranium from the process system and were in the part of the building known as the Tc-99 area, which is undergoing deactivation in preparation for demolition.
The K-25 building was composed of three major sections — the east and west wings and the north end — which were aligned in a U-shape that was more than a mile around. The entire west wing and the vast majority of the east wing are already gone, and the north end — which makes the base of the U — is now undergoing demolition.
The portion of the east wing still remaining is the Tc-99 area, which is five segments and an additional buffer at the south end of the building.
The deactivation is more difficult due to the presence of technetium-99 (Tc-99), a slow-decaying radioactive metal.
When K-25 was operational, the NaF traps were part of the final uranium removal process. Sodium fluoride pellets were used to trap the uranium, and these particular traps still contain uranium materials from when the facility was shut down decades ago. The NaF traps are each about the size of a household hot water heater and range in weight from 150 pounds to 800 pounds each, according to Todd Phillips, project manager for the NaF trap removal.
“We performed extensive structural analyses before doing the work and used a critical lift plan to ensure it was done safely,” Phillips said.
Extensive safeguards were in place during the removal because the vessels represent a significant danger in the case of a drop or a fire.
To remove the vessels, workers cut a hole in the roof of the building, and a crane lifted them out. The entire removal activity was completed in two days. The NaF traps are now safely stored in the K-25 area until they can be sampled and a disposition path determined.
“It’s a big accomplishment to remove these vessels,” said Leo Sain, UCOR president and project manager. “They represented one of the highest risks remaining in the K-25 building. Safely removing them gets us one step closer to project completion.”
Demolition of the north end is expected to be complete in the next few months, with the Tc-99 area following.
In addition to deactivating and demolishing the K-25 Building, UCOR is responsible for other specific scopes of work at ETTP, the Y-12 National Security Complex, and the Oak Ridge National Laboratory.