Innovation has been required as federal cleanup crews work to deactivate and demolish the final portion of the former Radioisotope Development Laboratory at Oak Ridge National Laboratory.
The structure is known as the East Cell Bank, and it is on the U.S. Department of Energy’s list of high-risk excess contaminated facilities, said a press release from DOE Office of Environmental Management. The East Cell Bank is located in the heart of ORNL, near ongoing research missions.
Workers with cleanup contractor UCOR characterized the final cell to identify potential radiological and hazardous contamination, the press release said. They conducted the work in stages under a six-story protective structure erected to ensure nearby facilities and ongoing research missions at ORNL aren’t impacted by the cleanup.
The crews began by taking surveys and readings from an opening at the front of the structure, the release said. They used long-reach tools and a specialized radiation detector. The detector overlays a radiation-intensity color map on a picture of the environment and identifies gamma-ray emitting nuclides and their locations.
Once data showed it was safe for people to enter the facility, the workers moved the equipment farther inside to perform more characterization and surveys, the press release said. They continued this process safely and methodically, gathering data and processing the results from one area before moving forward to another area to characterize and survey.
Portions of the structure had contamination levels requiring remote entry to get readings, the press release said. The team developed a plan to access those areas by removing a concrete plug in the roof and lowering equipment inside to complete the characterization. However, the plug could not be removed due to it being sealed in place more than a decade ago.
The employees used a system they designed to crack the seal. An 80-ton mobile crane lifted the 9,000-pound plug, allowing workers to access areas of the facility to capture remaining readings and complete characterization, the release said.
The tool they used to capture the readings detects sources of gamma-emitting radioisotopes and locates sources of detected gamma ray. The instrument identifies hot spots in large areas, eliminating the need for crews to take samples by hand, thereby reducing the time workers spend in a radiation environment.
With characterization complete, deactivation is under way. Workers are safely removing, packaging, and shipping waste for disposal. Once deactivation and decontamination phases are complete, crews will tear down the structure. Demolition is expected to be completed next year, the press release said.
More information will be added as it becomes available.
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