About 70,000 tons of used nuclear fuel sits mostly at power plants across the country. Much is kept underwater in spent fuel pools, but utility companies have been moving the fuel into concrete and steel casks like these in Richland, Wash. Energy Northwest CEO Vic Parrish (center) tours the facility with Reps. Doc Hastings (left) and Jay Inslee.
Credit Isaac Breekken / AP
Pete Vavricka conducts an underground train from the entrance of Yucca Mountain in Nevada in 2006. President Obama canceled the planned nuclear waste repository there in 2009.
Timothy Ray Brown, widely known in research circles as the Berlin patient, was cured of his HIV infection by bone marrow transplants. Now scientists are trying to make sense of the traces of HIV they've found in some cells of his body.