During the Cold War, the U.S. nuclear stockpile reached more than 30,000 nuclear weapons. Research and production of these weapons resulted in large volumes of nuclear waste—some of the most dangerous materials known to mankind—posing significant environmental risks and challenges. “The U.S. Department of Energy has under its purview the Environmental Management program, which is responsible for cleaning up the legacy of the Cold War,” says Dr. Inés Triay, assistant secretary, Environmental Management within the U.S. Department of Energy.