From Wikipedia

Meltdown on Five Mile Island

On March 28, 1979, equipment failures and operator error contributed to loss of coolant and a partial core meltdown of Unit 2's pressurized water reactor at the Three Mile Island Nuclear Power Plant in Pennsylvania. The scope and complexity of this reactor accident became clear over the course of five days, as a number of agencies at the local, state and federal levels tried to solve the problem and decide whether the ongoing accident required an emergency evacuation, and to what extent.

The TMI accident forced regulatory and operational improvements on a reluctant industry, but it also increased opposition to nuclear power. The accident triggered protests around the world.