page_title: Three Mile Island accident
section_title: Voluntary evacuation
hierarchical_section_title: Three Mile Island accident / Mitigation policies / Voluntary evacuation
caption_attribution_description: English: A sign in Middletown, Pennsylvania dedicated in 1999 describing the Three Mile Island accident, the evacuation of the residents in the area, and the impacts to the nuclear power industry.
context_page_description: The Three Mile Island accident was a partial meltdown of reactor number 2 of Three Mile Island Nuclear Generating Station in Dauphin County, Pennsylvania, near Harrisburg, and subsequent radiation leak that occurred on March 28, 1979. It is the most significant accident in U.S. commercial nuclear power plant history. On the seven-point International Nuclear Event Scale, the incident was rated a five as an "accident with wider consequences."
  The accident began with failures in the non-nuclear secondary system, followed by a stuck-open pilot-operated relief valve in the primary system. This allowed large amounts of nuclear reactor coolant to escape. The mechanical failures were compounded by the initial failure of plant operators to recognize the situation as a loss-of-coolant accident due to inadequate training and human factors, such as human-computer interaction design oversights relating to ambiguous control room indicators in the power plant's user interface.
context_section_description: Twenty-eight hours after the accident began, William Scranton III, the lieutenant governor, appeared at a news briefing to say that Metropolitan Edison, the plant's owner, had assured the state that "everything is under control". Later that day, Scranton changed his statement, saying that the situation was "more complex than the company first led us to believe". There were conflicting statements about radioactivity releases. Schools were closed and residents were urged to stay indoors. Farmers were told to keep their animals under cover and on stored feed.
  Governor Dick Thornburgh, on the advice of NRC chairman Joseph Hendrie, advised the evacuation "of pregnant women and pre-school age children...within a five-mile radius of the Three Mile Island facility". The evacuation zone was extended to a 20-mile radius on Friday, March 30. Within days, 140,000 people had left the area. More than half of the 663,500 population within the 20-mile radius remained in that area. According to a survey conducted in April 1979, 98% of the evacuees had returned to their homes within three weeks.
  Post-TMI surveys have shown that less than 50% of the American public were satisfied with the way the accident was handled by Pennsylvania State officials and the NRC, and people surveyed were even less pleased with the utility (General Public Utilities) and the plant designer.
caption: A sign dedicated in 1999 in Middletown, Pennsylvania near the plant describing the accident and the evaluation of the area.
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