Even as workers collapsed on the factory flood or suffered from serious ailments, including leukemia, the Paducah uranium processing plant in Kentucky, U.S. , hid radiation levels from its staff , a newspaper has claimed. The workers were unwittingly exposed to highly radioactive plutonium and neptunium from the 1950s to the 1970s as the plant kept them "uninofrmed about chemical and radiation hazards," the Washington Post said on Thursday after a four-month investigation.