Authorities at Pennsylvania's Three Mile Island nuclear plant were investigating what caused a weekend radiation leak that resulted in 150 workers being sent home, officials said Sunday.
An airborne radiological contamination alarm sounded about 4 p.m. Saturday in the Unit 1 containment building, according to a statement from Exelon Nuclear, which operates the Three Mile Island plant near Middletown, Pennsylvania. The unit had been shut down since October 26 for refueling, maintenance and steam generator replacement, the company said....