The U.S. Energy Dept. announced on Dec. 28 a plan to treat thousands of cubic yards of radioactive waste at the Idaho National Laboratory site in Idaho Falls, beating a court-ordered deadline by four days. The practice of reprocessing spent nuclear fuel produced about 9 million gallons of high-level liquid waste at the site over a 40-year span. DOE halted reprocessing in 1992, converting liquid waste into 5,750 cu yd of a powdered material called calcine, which it must now dispose of outside the state. The agency says it intends to convert the powder into a ceramic-like solid through a
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.