FILE - In this March 30, 1979 file photo, Pennsylvania Gov. Dick Thornburgh, left, announces the closing of schools in the area around the Three Mile Island PWR in Harrisburg, Pa., after an accident at the nuclear power plant led to the release of radioactive gas from the reactor into the atmosphere. Thornburgh died Thursday, Dec. 31, 2020 at a retirement community facility outside Pittsburgh, his son David said. The cause it not yet known. (AP Photo, File)