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
Arch dams, classically curved monoliths situated in narrow valleys, are not as common as other types of dams, such as embankment dams and gravity dams. ENR takes a look at some of the biggest arch dams in the world, both completed and under construction.