The United States once had worries of nuclear radiation much like the people of Japan since its March 11 disaster. On March 28, 1979 a nuclear power plant near Harrisburg, Penn. suffered a partial meltdown. A voluntary evacuation was advised after an explosion in the reactor became difficult to control. After an investigation ordered by then-President Jimmy Carter, the accident was blamed on mechanical failure and inadequate employee training. In the end, studies declared that non-harmful amounts of radiation seeped into the local community, but cleanup on the tower lasted until 1993. That unit of the power plant is inactive while another still operates.