|
Three Mile Island Nuclear Generating Station (TMI) is a nuclear power plant located on Three Mile Island in the Susquehanna River, south of Harrisburg, Pennsylvania in Londonderry Township. It has two separate units, TMI-1 and TMI-2. The plant is widely known for having been the site of the most significant accident in United States commercial nuclear energy, on 28 March 1979, when TMI-2 suffered a partial meltdown. According to the Nuclear Regulatory Commission, the accident resulted in no deaths or injuries to plant workers or members of nearby communities.〔(【引用サイトリンク】title=Fact Sheet on the Three Mile Island Accident )〕 Follow-up epidemiology studies have also not linked any incidents of cancer with the accident.〔http://www.ncbi.nlm.nih.gov/pubmed/18300710 RJ Levin (2008), "Incidence of thyroid cancer in residents surrounding the three mile island nuclear facility", Laryngoscope 118 (4), pp. 618-628 "Thyroid cancer incidence has not increased in Dauphin County, the county in which TMI is located. York County demonstrated a trend toward increasing thyroid cancer incidence beginning in 1995, approximately 15 years after the TMI accident. Lancaster County showed a significant increase in thyroid cancer incidence beginning in 1990. These findings, however, do not provide a causal link to the TMI accident."〕〔http://www.uvm.edu/~vlrs/Energy/NuclearPower.pdf〕 The reactor core of TMI-2 has since been removed from the site, but the site has not been decommissioned.〔(【引用サイトリンク】title=Accident at Three Mile Island )〕 Three Mile Island is so named because it is located three miles downriver from Middletown, Pennsylvania.〔(【引用サイトリンク】title=Middletown – Three mile Island )〕 The plant was originally built by General Public Utilities Corporation, later renamed GPU Incorporated.〔(【引用サイトリンク】title=GPU, Inc. – Company History )〕 The plant was operated by Metropolitan Edison Company (Met-Ed), a subsidiary of the GPU Energy division. During 2001 GPU Inc. merged with FirstEnergy Corporation.〔(【引用サイトリンク】title=FirstEnergy — Company history )〕 The Nuclear Regulatory Commission defines two emergency planning zones around nuclear power plants: a plume exposure pathway zone with a radius of , concerned primarily with exposure to, and inhalation of, airborne radioactive contamination, and an ingestion pathway zone of about , concerned primarily with ingestion of food and liquid contaminated by radioactivity.〔http://www.nrc.gov/reading-rm/doc-collections/fact-sheets/emerg-plan-prep-nuc-power-bg.html〕 The 2010 U.S. population within of Three Mile Island was 211,261, an increase of 10.9 percent in a decade, according to an analysis of U.S. Census data for msnbc.com. The 2010 U.S. population within was 2,803,322, an increase of 10.3 percent since 2000. Cities within 50 miles include Harrisburg (12 miles to city center), York (13 miles to city center), and Lancaster (24 miles to city center).〔Bill Dedman, Nuclear neighbors: Population rises near US reactors, ''msnbc.com'', April 14, 2011 http://www.msnbc.msn.com/id/42555888/ns/us_news-life/ Accessed May 1, 2011.〕 ==Three Mile Island Unit 1== The Three Mile Island Unit 1 is a pressurized water reactor designed by Babcock and Wilcox with a net generating capacity of 852 MWe. The initial construction cost was , equal to $ today. Unit 1 first came online on April 19, 1974, and began commercial operations on September 2, 1974.〔(【引用サイトリンク】title=Three Mile Island )〕 TMI-1 is licensed to operate for 40 years from its first run, and in 2009, was extended 20 years, which means it may operate until April 19, 2034.〔(【引用サイトリンク】title=Three Mile Island 1 – Pressurized Water Reactor )〕 TMI-1 has a closed-cycle cooling system for its main condenser using two natural draft cooling towers. Makeup water is drawn from the river to replace the water lost via evaporation in the towers. Once-through cooling with river water is used for the service water system which cools auxiliary components and removes decay heat when the reactor is shutdown. When TMI-2 suffered its accident in 1979, TMI-1 was offline for refueling. It was brought back online in October 1985, after public opposition, several federal court injunctions, and some technical and regulatory complications.〔Stephanie Cooke (2009). ''In Mortal Hands: A Cautionary History of the Nuclear Age'', Black Inc., p. 299.〕 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 not apprehended for 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." , it is believed that no radiation escaped the containment building and the public is 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 has 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.〔(【引用サイトリンク】title=Radiation leak at Three Mile Island )〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Three Mile Island Nuclear Generating Station」の詳細全文を読む スポンサード リンク
|