page_title: Three Mile Island Nuclear Generating Station
section_title: Incidents
hierarchical_section_title: Three Mile Island Nuclear Generating Station / Three Mile Island Unit 1 / Incidents
caption_attribution_description: English: Three Mile Island Nuclear Plant as viewed from Goldsboro Historic District (this side of the tracks). The historic district was listed on the NRHP on June 14, 1984	and is roughly bounded by North, 3rd, Fraser, and Railroad Streets, in Goldsboro, York County, Pennsylvania This is an image of a place or building that is listed on the National Register of Historic Places in the United States of America. Its reference number is 84003589
context_page_description: Three Mile Island Nuclear Generating Station is a closed nuclear power plant on Three Mile Island in Londonderry Township, Pennsylvania, on the Susquehanna River just south of Harrisburg. It had two separate units, TMI-1 and TMI-2. The plant was site of the most significant accident in United States commercial nuclear energy when, on March 28, 1979, TMI-2 suffered a partial meltdown. According to the Nuclear Regulatory Commission report, the accident resulted in no deaths or injuries to plant workers or in nearby communities. Follow-up epidemiology studies have linked no incidents of cancer to the accident.
  The reactor core of TMI-2 has since been removed from the site, but the site has not been decommissioned. In July 1998, Amergen Energy agreed to purchase TMI-1 from General Public Utilities for $100 million.
  Three Mile Island is so named because it is located three miles downriver from Middletown, Pennsylvania. The plant was originally built by General Public Utilities Corporation, later renamed GPU Incorporated. The plant was operated by Metropolitan Edison Company, a subsidiary of the GPU Energy division. During 2001, GPU Inc. merged with FirstEnergy Corporation.
context_section_description: In February 1993, a man drove his car past a checkpoint at the TMI nuclear plant, then broke through an entry gate. He eventually crashed the car through a secure door and entered the Unit 1 turbine building. The intruder, who had a history of mental illness, hid in the turbine building and was apprehended after four hours.
  
  On November 21, 2009, a release of radioactivity occurred inside the containment building of TMI-1 while workers were cutting pipes. Exelon Corporation stated to the public that "A monitor at the temporary opening cut into the containment building wall to allow the new steam generators to be moved inside showed a slight increase in a reading and then returned to normal. Approximately 20 employees were treated for mild radiation exposure." As of November 22, 2009, it was believed that no radiation escaped the containment building and the public was not in any danger. The inside airborne contamination was caused by a change in air pressure inside the containment building that dislodged small irradiated particles in the reactor piping system. Some of the small particles became airborne inside the building and were detected by an array of monitors in place to detect such material. The air pressure change occurred when inside building ventilation fans were started to support outage activities. The site modified the ventilation system to prevent future air pressure changes. Work continued on the project the following day. On January 24, 2010, TMI-1 was brought back online.
caption: Three Mile Island from Goldsboro, Pennsylvania in 2013
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