The China Syndrome (1979)

A news reporter (Jane Fonda) and her cameraman (Michael Douglas) are unintentional witnesses to a SCRAM incident, an emergency core shutdown procedure at a nuclear power plant in California. The crew prevents a catastrophe, but the plant supervisor (Jack Lemmon) begins to suspect the plant is in violation of safety standards, and tries desperately to bring it to the attention of the public, fearing that another SCRAM incident will produce an atomic disaster.