The Three Mile Island accident was the worst accident in American commercial nuclear power generating history, even though it led to no deaths or injuries to plant workers or members of the nearby community.
On March 28, 1979, the Unit 2 nuclear power plant (a pressurized water reactor manufactured by Babcock & Wilcox) on the Three Mile Island Nuclear Generating Station in Dauphin County, Pennsylvania near Harrisburg suffered a partial core meltdown.
The accident unfolded over the course of five tense days, as a number of agencies at the local, state and federal levels tried to diagnose the problem and decide whether or not the on-going accident required a full emergency evacuation of the population. The full details of the accident were not discovered until much later. In the end the reactor was brought under control. Although approximately 25,000 people lived within five miles (8 km) of the island at the time of the accident, no identifiable injuries due to radiation occurred, and a government report concluded that "the projected number of excess fatal cancers due to the accident... is approximately one". But the accident had serious economic and public relations consequences, and the cleanup process was slow and costly. It also furthered a major decline in the public popularity of nuclear power, exemplifying for many the worst fears about nuclear technology and, until the Chernobyl disaster seven years later, it was considered the world's worst civilian nuclear accident.