To expedite removal of a key radioactive threat close to the Columbia River, the U.S. Energy Dept. hopes to dismantle a long-dormant nuclear reactor at the Hanford nuclear-waste site in Washington state with robotic technology instead of “cocooning” the structure for long-term storage, as has been done with five similar structures at the site.
The multistory, 50,000-sq-ft K-East Reactor, which houses 240,000 graphite blocks that make up the reactor core, is a special case because of soil contamination around and under the structure, says Tom Teynor, DOE project director for the reactor. The agency and its contractors are testing new technology that makes robotic removal of the graphite a plausible option, he says. If all goes well, the approach could be used at other DOE sites nationwide. DOE, the U.S. Environmental Protection Agency and the Washington State Dept. of Ecology—all party to the cleanup agreement at Hanford—are seeking public comment on the approach until Nov. 17. DOE officials, however, will make the final decision on whether or not it is used.
Of the nine reactors at Hanford dating back to the site’s World War II-era weapons production mission, five have been cocooned since 1993. The process involves partly demolishing each structure to its core and then containing it to allow radioactivity to decay safely for 75 years.
Geoffrey Tyree, a DOE Hanford spokesman, says that K-East—built in 1952 and operated until 1971—is unique because the water-filled cooling basin used to store its spent uranium fuel rods already has leaked twice, in the 1970s and again in the 1990s, which caused the soil contamination. The structure is just 400 yd from the river.
This past summer, DOE used remote robotics to remove a nuclear core from the Brookhaven National Laboratory in Upton, N.Y., proving that the technology is effective, even though the K-East reactor core is larger, he adds.
While DOE may pursue the robotic removal at K-East, it has not yet developed a timetable to execute the approach because other projects at the site might be higher on the priority list—for example, the cleanup of a plutonium finishing plant and development of a groundwater treatment plan. Teynor says the work to dismantle the core would take about 12 months, with another nine months needed to remove the surrounding structure. Teynor says DOE’s two-year budgeting cycle could delay final approval until 2013.
Englewood, Colo.-based CH2M Hill Cos. would oversee cleanup work at the K-East Reactor but would subcontract robotic removal to Special Applications Technology, Loveland, Colo.
DOE officials say expediting the reactor cleanup would save on soil disposal costs because cleanup managers could use the site’s huge landfill before it is set to close by 2050. The robotic proposal is expected to cost $75 million to $95 million, which, not including the price of soil disposal, would cost about the same as cocooning. “Would we have the capability at that time to do the work, and would we have a facility [to store the soil]?” says Teynor. “We are trying to seriously look at this now.”
Of the nine reactors, five have been placed in long-term storage and another is in the process. The site’s historic Reactor B is now open for public tours. K-West, the last of the nine, does not have a history of contamination and likely will go into long-term storage as well. “We are not trying to set a precedent but to get to cleanup of the soil,” says Teynor.