Staff Reports
WC Monitor
7/10/2015
The Department of Energy estimates it will cost about $292 million to complete the demolition of K-27 – the last of five gaseous diffusion plants still standing at the Oak Ridge site that once was the world’s largest uranium-enrichment complex. Ben Williams, a spokesman for DOE’s Office of Environmental Management in Oak Ridge, said about two-third of the total cost is spent to prepare the big building – still loaded with its original processing equipment – for the demolition. Once the actual demolition starts, it’s expected to take about 10 months to do the job, and URS-CH2M Oak Ridge, DOE’s cleanup manager, said the schedule calls for completion of the project by the end of 2016.
With the demolition of the nearby K-31 building now complete, the contractor’s D&D workforce – totaling about 500 people with various skills and positions and holding security clearances – will focus on the K-27 project at the government site that’s being converted to a commercial industrial park. Security clearances are required because the World War II-era gaseous diffusion technology is still classified. The current focus is on removing the highest hazards at the 383,000-square-foot building, and foaming equipment to help prevent the spread of contamination once demolition activities begin. “One of the principal things we do is called hazard abatement,” Ken Rueter, the president of UCOR, said in a recent interview. Those preliminary activities include the removal of asbestos and other materials of health concern.
A key task is establishing the nuclear facility as “criticality incredible.” That designation means there’s no longer the possibility of a nuclear criticality – an uncontrolled nuclear chain reaction, and with the presence of highly enriched uranium that’s a concern and high priority. While foaming of equipment is a significant part of the preparations for demolition, UCOR is removing the equipment that poses the greatest concerns. “That actually has gone very well,” Rueter said. “We have identified about 114 high-risk converters, and we’ve taken 100 out of the building (so far).”
The uranium-laden equipment is extracted and sent to an on-site segmentation shop, where it’s mined for enriched uranium. “That gets properly packaged and gets sent out West,” he said, making reference to the Nevada National Security Site. Much of the equipment meets the criteria for disposal at DOE’s Oak Ridge CERCLA landfill, known as the Environmental Management Waste Management Facility. Rueter said he could not discuss much enriched uranium has been removed from K-25 or specify the enrichment levels of the uranium.
UCOR is reportedly relying on lessons learned from earlier work – particularly the demolition of the mile-long, U-shaped K-25 plant – to help prevent the spread of contaminants such as technetium-99. During the last phase of K-25 demolition, some Tc-99 was carried away from the work site by rainstorms and ultimately infiltrated sewer lines and contaminated the city’s wastewater treatment plant. “One of the lessons learned from K-25 was to mitigate as much of the technetium risk as possible, take all of the technetium-laden equipment out of the building (prior to demolition),” the UCOR official said.
David Adler, a manager in DOE’s Environmental Management Office, said waste management is an important part of what’s been learned to date. “A more intensive monitoring program, minimizing the period of time that waste is available for rainfall and leaching,” Adler said. “Just a collection of more aggressive measures.” Adler noted that technetium is water soluble, which makes it a particular threat in the environment. “It can be dissolved by rainwater and carried off the site,” he said. Fortunately, he said, none of the technetium releases at K-25 exceeded regulatory criteria, although he acknowledged the significance of the radioactive material entering the city of Oak Ridge’s nearby wastewater treatment plant. “It’s a situation we expect to avoid in the next round of D&D,” Adler said. “We will be able to certainly keep it all on site, to the point where it presents no health hazard to workers on site and off site,” he said.
