(Inside Science) — Nearly 30 years ago, the state of Washington and two federal agencies agreed to clean up the Hanford Nuclear Reservation, a 586-square-mile chunk of sagebrush desert where the U.S. produced plutonium for nuclear weapons starting 75 years ago. In the process, half a trillion gallons of chemically toxic and radioactive waste was dumped on the ground or injected into groundwater. Some of it has reached the Columbia River. Another 56 million gallons of concentrated, radioactiv