sentences:  The 1979 Three Mile Island accident was a pivotal event that led to questions about U.S. nuclear safety.Earlier events had a similar effect, including a 1975 fire at Browns Ferry, the 1976 testimonials of three concerned GE nuclear engineers, the GE Three.In 1981, workers inadvertently reversed pipe restraints at the Diablo Canyon Power Plant reactors, compromising seismic protection systems, which further undermined confidence in nuclear safety.