Three Mile Island Nuclear Generating Station#Three Mile Island Unit 2
{{Short description|Closed power plant in Pennsylvania, US}}
{{redirect|Three Mile Island|the 1979 partial core meltdown|Three Mile Island accident|other uses}}
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{{Use American English|date=July 2025}}
{{Update|inaccurate=yes|talk=Inconsistent|date=July 2024}}
{{Use mdy dates|date=February 2013}}
{{Infobox power station
| name = Three Mile Island Nuclear Generating Station
| name_official = Unit 1: Crane Clean Energy Center
| image = Exelon Three Mile Island Nuclear Generating Station.jpg
| image_caption = Three Mile Island in 2019, prior to shutdown.
| image_alt = The Three Mile Island nuclear power plant on Three Mile Island, circa 1979
| coordinates = {{coord|40|9|14|N|76|43|29|W|region:US-PA_type:landmark|display=inline,title}}
| country = United States
| location = Londonderry Township, Dauphin County, Pennsylvania
| status = M
| construction_began = Unit 1: May 18, 1968
Unit 2: November 1, 1969
| commissioned = Unit 1: September 2, 1974
Unit 2: December 30, 1978
| decommissioned =
| cost = $1.557 billion (2007 USD){{cite web|title=EIA - State Nuclear Profiles|url=https://www.eia.gov/nuclear/state/archive/2010/pennsylvania/|website=www.eia.gov|access-date=October 3, 2017|language=en | publisher=United States Energy Information Administration | archive-url=https://web.archive.org/web/20170519163941/https://www.eia.gov/nuclear/state/archive/2010/pennsylvania/ | archive-date=May 19, 2017 | url-status=live }}
(${{format price|{{Inflation|US-GDP|1.557|2007}}}} billion in {{Inflation-year|US-GDP}} dollars{{Inflation-fn|US-GDP}})
| owner = Unit 1: Constellation Energy
Unit 2: EnergySolutions
| operator = Constellation Energy
| np_reactor_type = PWR
| np_reactor_supplier = Babcock & Wilcox
| np_fuel_type =
| np_fuel_supplier =
| ps_cogeneration =
| ps_cooling_source = Susquehanna River
| ps_cooling_towers = 4 × Natural Draft, each 113.4 metres (372 ft) tall [https://tmi.dickinson.edu/wp-content/uploads/2017/09/219.pdf]
| ps_units_operational =
| ps_units_manu_model = B&W LLP (DRYAMB)
| ps_units_uc =
| ps_units_planned =
| ps_units_cancelled =
| ps_units_decommissioned = 1 × 880 MW,
1 × 819 MW ( restart planned )
| ps_thermal_capacity = 1 × 2568 MWth
| ps_heating_capacity =
| ps_electrical_capacity = 819
| ps_electrical_cap_fac = 95.65% (2017)
73.25% (lifetime)
| ps_storage_capacity =
| ps_annual_generation = 7.3 TWh (2018)
245.12 TWh (lifetime){{cite web | url=https://pris.iaea.org/PRIS/CountryStatistics/ReactorDetails.aspx?current=637 | title=PRIS - Reactor Details }}
| website = {{url|https://www.constellationenergy.com/our-company/locations/decommissioning.html}}
| extra =
}}
Three Mile Island Nuclear Generating Station (abbreviated as TMI), is a shut-down nuclear power plant on Three Mile Island{{refn|group=lower-alpha|Contrary to popular belief, Three Mile Island is named after the length of the island itself, not because it is three miles downriver from Middletown, Pennsylvania. The name based on the island's length was also a mistake, as the island is only about two-miles long.{{Cite web |first=Jack |last=Brubaker |title=How did Three Mile Island get its name? It was another mistake! [The Scribbler] |url=https://lancasteronline.com/news/local/how-did-three-mile-island-get-its-name-it-was-another-mistake-the-scribbler/article_1e5ff44e-4ffa-11e9-ac7c-d70488f8c501.html |access-date=2021-11-07 |website=LancasterOnline |date=March 27, 2019 |language=en}}}} in Pennsylvania, US, on the Susquehanna River just south of Harrisburg. It has two separate units, Unit 1 (TMI-1) (owned by Constellation Energy) and Unit 2 (TMI-2) (owned by EnergySolutions).{{Cite web |date=2022-06-01 |title=Damaged Three Mile Island reactor gets a new corporate parent |url=https://www.pennlive.com/news/2022/06/damaged-three-mile-island-reactor-gets-a-new-corporate-parent.html |access-date=2022-06-04 |website=pennlive |language=en}}
The plant was the 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 U.S. Nuclear Regulatory Commission (NRC) report, the accident resulted in no deaths or injuries to plant workers or in nearby communities.{{cite web |url=https://www.nrc.gov/reading-rm/doc-collections/fact-sheets/3mile-isle.html |title=Fact Sheet on the Three Mile Island Accident |publisher=US Nuclear Regulatory Commission |access-date=2008-12-18}} Follow-up epidemiology studies did not find causality between the accident and any increase in cancers.{{cite journal |author=Hatch |first=Maureen C. |display-authors=etal |year=1990 |title=Cancer near the Three Mile Island Nuclear Plant: Radiation Emissions |journal=American Journal of Epidemiology |publisher=Oxford Journals |volume=132 |issue=3 |pages=397–412 |doi=10.1093/oxfordjournals.aje.a115673 |pmid=2389745 |doi-access=free}}{{cite journal |author=Levin |first=R. J. |year=2008 |title=Incidence of thyroid cancer in residents surrounding the three mile island nuclear facility |journal=Laryngoscope |volume=118 |issue=4 |pages=618–628 |doi=10.1097/MLG.0b013e3181613ad2 |pmid=18300710 |s2cid=27337295 |quote=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.}}{{cite journal |title=Cancer rates after the Three Mile Island nuclear accident and proximity of residence to the plant |vauthors=Hatch MC, Wallenstein S, Beyea J, Nieves JW, Susser M |date=June 1991 |journal=American Journal of Public Health |volume=81 |issue=6 |pages=719–724 |doi=10.2105/AJPH.81.6.719 |pmid=2029040 |pmc=1405170 |quote=RESULTS: A modest association was found between postaccident cancer rates and proximity (OR = 1.4; 95% CI = 1.3, 1.6). After adjusting for a gradient in cancer risk prior to the accident, the odds ratio contrasting those closest to the plant with those living farther out was 1.2 (95% CI = 1.0, 1.4). A postaccident increase in cancer rates near the Three Mile Island plant was notable in 1982, persisted for another year, and then declined. Radiation emissions, as modeled mathematically, did not account for the observed increase.}}{{Cite web |url=http://www.uvm.edu/~vlrs/Energy/NuclearPower.pdf |title=Vermont Legislative Research Shop |access-date=June 19, 2013 |archive-date=March 17, 2016 |archive-url=https://web.archive.org/web/20160317020327/http://www.uvm.edu/~vlrs/Energy/NuclearPower.pdf |url-status=dead }} One work-related death has occurred on-site during decommissioning.{{Cite web |date=September 14, 2021 |title=Contract Worker Killed in Accident at Three Mile Island Nuclear Plant in Pa., Exelon Says |url=https://www.nbcphiladelphia.com/news/local/contract-worker-killed-three-mile-island-nuclear-plant-exelon/2956846/ |access-date=2021-12-08 |website=NBC10 |language=en-US |publication-place=Philadelphia, Pennsylvania}}
The reactor core of TMI-2 has since been removed from the site, but {{as of|lc=yes|2009}} the site has not been fully decommissioned.{{cite web |url=http://www.policyalmanac.org/environment/archive/three_mile_island.shtml |title=Accident at Three Mile Island |publisher=Policy Almanac |access-date=2008-12-18 |archive-url=https://web.archive.org/web/20090207074453/http://www.policyalmanac.org/environment/archive/three_mile_island.shtml |archive-date=February 7, 2009 |url-status=dead }} In July 1998, Amergen Energy (now Exelon Generation) agreed to purchase TMI-1 from General Public Utilities for $100 million.{{Cite news|url=http://local21news.com/news/local/history-of-three-mile-island|title=History of Three Mile Island|work=WHP|access-date=2017-12-07|language=en-US}}
The plant was originally built by General Public Utilities Corporation, later renamed GPU Incorporated.{{cite web |title=GPU, Inc. – Company History |url=http://www.fundinguniverse.com/company-histories/GPU-Inc-Company-History.html |access-date=2009-04-01}} The plant was operated by Metropolitan Edison Company (Met-Ed), a subsidiary of the GPU Energy division. In 2001, GPU Inc. merged with FirstEnergy Corporation.{{cite web |title=FirstEnergy – Company history |url=http://www.firstenergycorp.com/corporate/Corporate_Profile/Company_History.html |url-status=dead |archive-url=https://web.archive.org/web/20081219145602/http://www.firstenergycorp.com/corporate/Corporate_Profile/Company_History.html |archive-date=December 19, 2008 |access-date=2009-04-01}} On December 18, 2020, FirstEnergy transferred Unit 2's license to EnergySolutions' subsidiary, TMI-2 Solutions, after receiving approval from the NRC.{{Cite web |title=FAQ |url=https://www.tmi2solutions.com/FAQ |access-date=2021-11-22 |website=EnergySolutions TMI2 |language=en}}
Exelon was operating Unit 1 at a financial loss since 2015.{{Cite web|url=https://www.pennlive.com/news/2019/03/save-three-mile-island-what-a-difference-40-years-makes.html|title=Save Three Mile Island? What a difference 40 years makes|last=Thompson|first=Charles|date=2019-03-19|website=pennlive.com|language=en-US|access-date=2019-03-25}} In 2017, the company said it would consider ceasing operations at Unit 1 because of high costs unless there was action from the Pennsylvania government.{{cite news|url=http://www.utilitydive.com/news/after-failing-to-clear-pjm-auction-exelon-says-three-mile-island-nuke-will/443794/|title=After failing to clear PJM auction, Exelon says Three Mile Island nuke will close in 2019|last1=Bade|first1=Gavin|date=30 May 2017|access-date=30 May 2017|publisher=Utility Dive}}{{cite web|url=https://www.axios.com/nuclear-power-three-mile-island-climate-change-c5e7a387-3aa4-48f3-bbae-58a8e5bb0f26.html|title=Middletown – Three mile Island|date=December 3, 2018 |access-date=2019-02-03}} Unit 1 officially shut down at noon on September 20, 2019.{{Cite news|url=https://www.kpbs.org/news/2019/sep/20/three-mile-island-nuclear-power-plant-shuts-down/|title=Three Mile Island Nuclear Power Plant Shuts Down|last=Sholtis|first=Brett|language=en-US|access-date=2019-09-20}}
Unit 1 decommissioning was expected to be completed in 2079 and would have cost $1.2 billion,{{Cite web|title=Three Mile Island Decommissioning |url=https://www.constellationenergy.com/our-company/locations/decommissioning.html|access-date=2022-02-13|website=www.constellationenergy.com|language=en}}{{cite web|url=https://stateimpact.npr.org/pennsylvania/2020/04/17/pennsylvania-raises-alarms-on-transfer-of-radioactive-three-mile-island-reactor/ |title=Pennsylvania Raises Alarms on Transfer of Radioactive Three Mile Island Reactor |last=Phillips |first=Susan |date=April 17, 2020 |publisher=State Impact Pennsylvania |access-date=January 13, 2023}} but in September 2024, Constellation Energy, the owner of the Unit, announced plans to invest $1.6 billion to bring the facility back online. The plant is expected to resume operations in 2028 as the Crane Clean Energy Center (CCEC).{{Cite news |date=2024-09-20 |title=Microsoft AI Needs So Much Power It's Restarting Site of US Nuclear Meltdown |url=https://www.bloomberg.com/news/articles/2024-09-20/microsoft-s-ai-power-needs-prompt-revival-of-three-mile-island-nuclear-plant |access-date=2024-09-20 |work=Bloomberg.com |language=en}}{{cite web |title=Three Mile Island, Unit 1 / Crane Clean Energy Center (Pending) |url=https://www.nrc.gov/info-finder/reactors/tmi1/ccec.html |website=NRC Web |publisher=United States Nuclear Regulatory Commission |access-date=29 May 2025 |date=8 May 2024}} The entirety of the plant's energy output will be sold to Microsoft Corporation. Microsoft entered into a 20-year agreement to purchase as much electricity as possible from the plant, which will support the company’s growing energy needs for its expanding network of data centers.{{Cite news |last=Plumer |first=Brad |date=2024-09-20 |title=Three Mile Island Plans to Reopen as Demand for Nuclear Power Grows |url=https://www.nytimes.com/2024/09/20/climate/three-mile-island-reopening.html |work=New York Times}}
Unit 2, which has been dormant since the accident in 1979, is expected to close in 2052.{{Cite web |date=2021-03-24 |title=NRC: Three Mile Island – Unit 2 |url=https://www.nrc.gov/info-finder/decommissioning/power-reactor/three-mile-island-unit-2.html |access-date=2021-04-01 |website=www.nrc.gov}}
Emergency zones and nearby population
The NRC defines two emergency planning zones around nuclear power plants: a plume exposure pathway zone with a radius of {{convert|10|mi}}, concerned primarily with exposure to, and inhalation of, airborne radioactive contamination, and an ingestion pathway zone of about {{convert|50|mi}}, concerned primarily with ingestion of food and liquid contaminated by radioactivity.{{Cite web|url=https://www.nrc.gov/about-nrc/emerg-preparedness/about-emerg-preparedness/planning-zones.html|title=NRC: Emergency Planning Zones|website=United States Nuclear Regulatory Commission|access-date=2019-12-22}}
The 2010 U.S. population within {{convert|10|mi}} 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. The 2010 U.S. population within {{convert|50|mi}} 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).{{Cite web |date=2011-04-14 |title=Nuclear neighbors: Population rises near US reactors |url=https://www.nbcnews.com/id/wbna42555888 |access-date=2024-08-16 |website=NBC News |language=en}}
Electricity production
During its last full year of operation in 2018, Three Mile Island generated 7,355 GWh of electricity. In that same year, electricity from nuclear power produced approximately 39% of the total electricity generated in Pennsylvania (83.5 TWh nuclear of 215 TWh total), with Three Mile Island Generating Station contributing approximately 4% to the statewide total generation. In 2021 electrical generating facilities in the state of Pennsylvania generated approximately 241 TWh of total electricity.{{Cite web |title=Electricity Data Browser |url=https://www.eia.gov/electricity/data/browser/#/topic/0?agg=2,0,1&fuel=vvvvu&geo=0001&sec=g&linechart=ELEC.GEN.ALL-PA-99.A&columnchart=ELEC.GEN.ALL-PA-99.A&map=ELEC.GEN.ALL-PA-99.A&freq=A&ctype=linechart<ype=pin&rtype=s&maptype=0&rse=0&pin= |access-date=2023-01-07 |website=www.eia.gov}}
class="wikitable"
|+Generation (MWh) of Three Mile Island Generating Station{{Cite web |title=Electricity Data Browser |url=https://www.eia.gov/electricity/data/browser/#/plant/8011/?freq=M&pin= |access-date=2023-01-07 |website=www.eia.gov}} !Year !Jan !Feb !Mar !Apr !May !Jun !Jul !Aug !Sep !Oct !Nov !Dec !Annual (Total) |
2001
|598,586 |558,484 |617,640 |540,691 |309,720 |427,684 |591,460 |588,699 |562,563 |130,208 |0 |491,028 !5,416,763 |
---|
2002
|628,077 |569,814 |631,547 |606,413 |622,103 |575,870 |609,816 |609,997 |595,565 |619,838 |610,530 |633,949 !7,313,519 |
2003
|631,984 |572,521 |631,971 |605,628 |624,685 |597,862 |610,219 |609,588 |592,306 |309,494 |-8,042 |418,815 !6,197,031 |
2004
|628,992 |592,136 |630,817 |606,796 |595,895 |590,383 |593,006 |609,964 |594,931 |628,330 |606,727 |595,257 !7,273,234 |
2005
|634,556 |574,716 |633,072 |603,671 |622,371 |590,245 |606,729 |606,110 |590,523 |431,976 |227,852 |633,640 !6,755,461 |
2006
|634,770 |574,064 |629,263 |604,524 |620,189 |592,955 |607,024 |610,066 |598,981 |626,894 |533,567 |594,731 !7,227,028 |
2007
|633,504 |571,450 |628,411 |604,807 |616,716 |591,972 |610,453 |608,744 |591,535 |387,453 |173,525 |626,724 !6,645,294 |
2008
|634,479 |593,989 |631,886 |606,166 |622,685 |593,699 |611,785 |615,991 |591,191 |620,414 |610,566 |632,247 !7,365,098 |
2009
|632,599 |571,398 |627,785 |601,665 |613,866 |593,159 |610,822 |607,848 |593,508 |438,962 |-2,703 |0 !5,888,909 |
2010
|132,230 |564,608 |571,255 |599,167 |558,978 |586,421 |604,409 |594,950 |568,086 |621,174 |607,344 |625,128 !6,633,750 |
2011
|625,004 |564,025 |622,273 |595,735 |593,238 |589,577 |599,464 |603,021 |563,240 |453,968 |82,899 |626,385 !6,518,829 |
2012
|629,556 |589,831 |624,849 |608,509 |613,382 |596,485 |610,350 |417,839 |478,175 |624,454 |614,324 |630,503 !7,038,257 |
2013
|629,685 |570,617 |629,618 |606,648 |621,454 |595,263 |610,260 |614,906 |599,698 |536,504 |61,179 |583,236 !6,659,068 |
2014
|629,732 |534,623 |629,723 |608,793 |614,408 |614,413 |613,793 |616,228 |598,666 |625,480 |610,804 |630,982 !7,327,645 |
2015
|631,581 |569,154 |629,454 |607,974 |490,525 |594,154 |577,760 |613,283 |593,923 |576,594 |84,416 |629,223 !6,598,041 |
2016
|630,503 |587,527 |627,463 |607,175 |620,556 |588,999 |599,964 |609,354 |593,371 |622,807 |607,486 |387,447 !7,082,652 |
2017
|629,440 |569,389 |629,237 |604,756 |622,133 |594,829 |610,064 |615,158 |336,473 |404,367 |612,290 |632,124 !6,860,260 |
2018
|633,552 |571,419 |630,787 |607,853 |614,580 |594,845 |611,421 |609,506 |594,668 |623,620 |611,295 |632,278 !7,335,824 |
2019
|632,206 |570,764 |629,016 |604,853 |617,709 |594,819 |608,513 |605,781 |350,535 |0 |-- |-- !5,214,196 |
Three Mile Island Unit 1
The Three Mile Island Unit 1 is a pressurized water reactor designed by Babcock & Wilcox with a net generating capacity of 819 MWe. The initial construction cost for TMI-1 was {{nowrap|US$400 million}}, equal to ${{Formatprice|{{Inflation|US|0.400|1974|r=2}}}} billion in 2018 dollars.{{Cite web|url=http://www.tmia.com/corp.historyTMI|title=A Corporate History of Three Mile Island {{!}} Three Mile Island Alert|website=www.tmia.com|access-date=November 11, 2016}} Unit 1 first came online on April 19, 1974, and began commercial operations on September 2, 1974.{{cite web |title=Three Mile Island |url=http://www.exeloncorp.com/powerplants/threemileisland/Pages/profile.aspx |access-date=2013-02-21 |publisher=Amerigen – Exelon Corporation}} TMI-1 was licensed to operate for 40 years from its first run, and in 2009, its license was extended by 20 years, which means it could have operated until April 19, 2034.{{cite web |url=https://www.nrc.gov/info-finder/reactor/tmi1.html |title=Three Mile Island 1 – Pressurized Water Reactor |publisher=Nuclear Regulatory Commission |access-date=2008-12-15}}{{cite news|url=https://www.reuters.com/article/companyNewsAndPR/idUSN223175220091022|title=NRC renews Exelon Pa. Three Mile Isl reactor license|date=October 22, 2009|publisher=Thomson Reuters|access-date=2009-10-23 | first=Scott | last=DiSavino}}
TMI-1 had a closed-cycle cooling system for its main condenser using two natural draft cooling towers. Makeup water was drawn from the river to replace the water lost via evaporation in the cooling towers. Once-through the cooling towers, river water was used in the service water system, cooling auxiliary components and removing decay heat when the reactor was shut down. On February 17, 1979, TMI-1 went offline for refueling. It was brought back online on October 9, 1985, after public opposition, several federal court injunctions, and some technical and regulatory complications – more than six years after it initially went offline.Stephanie Cooke (2009). In Mortal Hands: A Cautionary History of the Nuclear Age, Black Inc., p. 299.File:Tmi1.jpg
Unit 1 was scheduled to be shut down by September 2019 after Exelon announced they did not receive any commitments for subsidies from the state, rendering Exelon financially unable to continue operating the reactor.{{cite news|first1=Jacey|last1=Fortin|access-date=2019-05-13|title=Three Mile Island Nuclear Power Plant Is Shutting Down|url=https://www.nytimes.com/2019/05/08/us/three-mile-island-shut-down.html|newspaper=The New York Times|date=May 8, 2019|issn=0362-4331|via=NYTimes.com}}{{Cite web|url=https://arstechnica.com/tech-policy/2019/05/the-last-reactor-at-three-mile-island-is-shutting-down/|title=The last reactor at Three Mile Island is shutting down|last=Geuss|first=Megan|date=2019-05-09|website=Ars Technica|language=en-us|access-date=2019-05-17}} TMI-1 was shut down on September 20, 2019,{{Cite news|url=https://www.kpbs.org/news/2019/sep/20/three-mile-island-nuclear-power-plant-shuts-down.hmtl|title=Three Mile Island Nuclear Power Plant Shuts Down|last=Sholtis|first=Brett|language=en-US|access-date=2019-09-20}}{{Dead link|date=November 2023 |bot=InternetArchiveBot |fix-attempted=yes }} but may be brought back. The CEO of Constellation Energy, the owner of Unit 1, says the reactor is in "excellent shape," and estimated that it would go online within three years of committing to a restart. {{As of|2024}} Constellation is conducting tests for a potential decision to reopen.{{Cite news |last=Halper |first=Evan |date=July 10, 2024 |title=A nuclear accident made Three Mile Island infamous. AI's needs may revive it. |url=https://www.washingtonpost.com/business/2024/07/10/three-mile-island-nuclear-artificial-intelligence/ |access-date=July 12, 2024 |newspaper=The Washington Post}}
= Incidents =
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.{{cite news|url=https://www.latimes.com/archives/la-xpm-1993-02-08-mn-1195-story.html|title=Man Crashes Car Through Gates at Three Mile Island|newspaper=Los Angeles Times|date=February 8, 1993|access-date=October 15, 2019}}
During and following the September 11, 2001 attacks, there was a concern that United Airlines Flight 93 was headed towards Three Mile Island. On that day, the NRC placed all of the nation's nuclear power plants into the highest level of security. United Flight 93 crashed into a field (present-day Flight 93 National Memorial) about 135 miles (217 km) west of Three Mile Island in Stonycreek Township, just outside Shanksville, Pennsylvania, with its actual target believed to have been Washington, D.C.{{Cite web|date=2021-08-24|title=Remembering 9/11: Fear at Three Mile Island|url=https://www.abc27.com/news/remembering-september-11/remembering-9-11-what-if-three-mile-island-became-a-target-for-a-terrorist-attack/|access-date=2022-01-29|website=ABC27|language=en-US}}{{Cite web|title=US attacks: The Three Mile Island connection {{!}} Wise International|url=https://www.wiseinternational.org/nuclear-monitor/554/us-attacks-three-mile-island-connection|access-date=2022-01-29|website=www.wiseinternational.org}}
File:3 mile Island from Goldsboro PA.JPG in 2013]]
File:Three Mile Island Nuclear Generating Station.jpg in 2014]]
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."{{cite news |date=November 22, 2009 |title=Three Mile Island radiation leak investigated |url=http://www.cnn.com/2009/US/11/22/pennsylvania.three.mile.island/index.html |access-date=May 25, 2010 |work=CNN}} {{As of|2009|11|22|df=US}}, it was believed that no radiation escaped the containment building and the public was not in any danger.{{citation needed|date=September 2020}} 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 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.{{cite web |title=Radiation leak at Three Mile Island |url=https://6abc.com/archive/7131935/ |access-date=November 22, 2009 |publisher=ABC News – WPVI Philadelphia}}
= Material handling accident =
On September 10, 2021, a contractor from Alabama was fatally injured while unloading equipment from a truck. Fire and emergency medical personnel from Londonderry Township were dispatched and declared the contractor dead on arrival. The Nuclear Regulatory Commission said the injury was work-related, and the contractor was outside the radiological controlled area.{{Cite web|date=2021-09-13|title=Worker killed in 'material handling accident' at Three Mile Island|url=https://local21news.com/news/local/worker-killed-in-material-handling-accident-at-three-mile-island|access-date=2021-12-08|website=WHP}}{{Cite web|last=Gish|first=Jere|date=2021-09-13|title=Worker dies in 'material handling accident' at Three Mile Island|url=https://www.wgal.com/article/three-mile-island-contract-worker-dies-in-material-handling-accident/37577320|access-date=2021-12-08|website=WGAL|language=en}}
Three Mile Island Unit 2
File:Three Mile Island nuclear power plant.jpgThe Three Mile Island Unit 2 was also a pressurized water reactor constructed by B&W, similar to Unit 1. TMI-2 was slightly larger with a net generating capacity of 906 MWe, compared to TMI-1, which delivered 819 MWe. Unit 2 received its operating license on February 8, 1978, and began commercial operation on December 30, 1978. TMI Unit 2 was permanently shut down after the Three Mile Island accident in 1979.{{cite web |title=Three Mile Island – Unit 2 |url=https://www.nrc.gov/info-finder/decommissioning/power-reactor/three-mile-island-unit-2.html |access-date=2008-12-15 |publisher=Nuclear Regulatory Commission}}
=Accident=
File:Harrisburg Int Airport with Pennsylvania ANG aircraft 1979.jpg in background behind Harrisburg International Airport, a few weeks after the accident]]
{{Main|Three Mile Island accident}}
On March 28, 1979, a cooling system malfunction caused a partial meltdown of the reactor core. This loss-of-coolant accident resulted in the release of an estimated 43,000 curies (1.59 PBq) of radioactive krypton-85 gas (with an approximate half-life of 11 years), and less than 20 curies (740 GBq) of the especially hazardous iodine-131 (with a half-life of around 8 days), into the surrounding environment.
Nearly 2 million people were exposed to radiation from the accident.{{Cite web |title=Three Mile Island – Facts & Summary |url=http://www.history.com/topics/three-mile-island |access-date=December 7, 2017 |website=HISTORY.com}} A review by the World Nuclear Association concluded that no deaths, injuries or adverse health effects resulted from the accident,{{cite web |url=http://www.world-nuclear.org/info/inf36.html |title=Three Mile Island: 1979 |publisher=World Nuclear Association |access-date=December 18, 2008 |archive-date=February 17, 2013 |archive-url=https://web.archive.org/web/20130217012228/http://www.world-nuclear.org/info/inf36.html |url-status=dead }} and a report by Columbia University epidemiologist Maureen Hatch confirmed this finding.{{cite news | title=No Evidence Reactor Leak Caused Cancer | url=https://www.washingtonpost.com/wp-srv/national/longterm/tmi/stories/study090190.htm | newspaper=The Washington Post | date=March 30, 1999 | access-date=May 25, 2010}} Because of the health concerns, the Pennsylvania Department of Health kept a registry of more than 30,000 people that lived within {{convert|5|miles}} of TMI at the time of the accident. The registry was kept for nearly 20 years until 1997, when no evidence was found of unusual health effects.{{Cite web |title=Three Mile Island {{!}} TMI 2 {{!}}Three Mile Island Accident |url=http://www.world-nuclear.org/information-library/safety-and-security/safety-of-plants/three-mile-island-accident.aspx |access-date=December 7, 2017 |website=www.world-nuclear.org |publisher=World Nuclear Association}} Further epidemiology studies have not shown any increase in cancer as a result of the accident. However, almost $25 million was paid in insurance settlements to people who then agreed not to discuss their injuries in ongoing litigation.{{cite web|url=https://www.scribd.com/doc/158526327/Settlement-of-Medical-Claims|title=Settlement of Medical Claims|website=Scribd|access-date=April 23, 2019}}
Unit 2 has not been operational since the accident occurred.{{Cite web |title=Three Mile Island – Unit 2 |url=https://www.nrc.gov/info-finder/decommissioning/power-reactor/three-mile-island-unit-2.html |url-status=dead |archive-url=https://web.archive.org/web/20061004083835/http://www.nrc.gov/info-finder/decommissioning/power-reactor/three-mile-island-unit-2.html |archive-date=2006-10-04 |website=www.nrc.gov |publisher=U.S. Nuclear Regulatory Commission}}
The New York Times reported on August 14, 1993, 14 years after the accident, that the cleanup had finished. According to the United States NRC, 2.3 million gallons of waste water had been removed.{{Cite web|url=https://abcnews.go.com/US/history-mile-island-nuclear-plant-1979-reactor-accident/story?id=47731028|title=A history of the Three Mile Island nuclear plant|date=May 31, 2017|website=ABC News|access-date=December 7, 2017}}
The incident was widely publicized internationally, and had far-reaching effects on public opinion, particularly in the United States. The China Syndrome, a movie about a nuclear disaster, which was released 12 days before the incident and received a glowing reception from the movie-going public, became a blockbuster hit.{{cite web |url=https://www.imdb.com/title/tt0078966/faq#.2.1.3 |title=FAQ for the China Syndrome |publisher=IMDb |access-date=December 29, 2008}}
=Unit 2 Generator=
On January 22, 2010, officials at the NRC announced the electrical generator from the damaged Unit 2 reactor at TMI will be used at Shearon Harris Nuclear Plant in New Hill, North Carolina. The generator was transported in two parts, weighing a combined 670 tons. It was refurbished and installed during a refueling outage at Shearon Harris NPP in November 2010.{{cite web |url=http://www.wral.com/news/state/story/6864151/ |title=Three Mile Island generator moving to Shearon Harris |publisher=WRAL-TV |access-date=2010-01-22|date=January 22, 2010 }}
Post-accident
Exelon Corporation was created in October 2000 by the merger of PECO Energy Company and Unicom, of Philadelphia, Pennsylvania and Chicago, Illinois respectively.{{cite web |title=Exelon – Merger Filing |url=http://www.exeloncorp.com/ourcompanies/peco/pecobiz/energy_rates/filing_information/merger_filing.htm |url-status=dead |archive-url=https://web.archive.org/web/20090210070924/http://www.exeloncorp.com/ourcompanies/peco/pecobiz/energy_rates/filing_information/merger_filing.htm |archive-date=February 10, 2009 |access-date=2009-04-01}} Unicom owned Commonwealth Edison. The PECO share in AmerGen was acquired by Exelon during late 2000. Exelon acquired British Energy's share in AmerGen in 2003,{{cite web |title=A Corporate History of Three Mile Island – Three Mile Island Alert |url=http://www.tmia.com/corp.historyTMI |access-date=2009-04-01}} and transferred Unit 1 under the direct ownership and operation of its Exelon Nuclear business unit.{{cite web |title=Exelon – Three Mile Island Unit – 1 |url=http://www.exeloncorp.com/ourcompanies/powergen/nuclear/three_mile_island_unit_-_1.htm |access-date=2009-04-01}}{{cite web |title=Three Mile Island: About TMI – About Us |url=http://www.threemileislandinfo.com/about/index.aspx |url-status=dead |archive-url=https://web.archive.org/web/20090402150131/http://www.threemileislandinfo.com/about/index.aspx |archive-date=April 2, 2009 |access-date=2009-04-01}} According to Exelon Corporation, "many people are surprised when they learn that Three Mile Island is still making electricity, enough to power 800,000 households" from its undamaged and fully functional reactor unit 1.Allen Abel, Life after a meltdown: Locals near Three Mile Island may be wary, but they aren't moving, The National Post, Saturday, March 19, 2011, p. A5. Exelon viewed the plant's economics of $44/MWh as challenging due to the low price of natural gas at $25/MWh. As of 2016, the average price of electricity in the area was $39/MWh.{{cite web|url= https://www.bloomberg.com/news/articles/2016-12-22/states-are-the-nuclear-industry-s-best-hope |title=States Are the Nuclear Industry's Best Hope |first=Paul |last=Barrett |date=2016-12-22 |work=Bloomberg.com |access-date= 2017-01-12 |quote=unless the government intervenes to keep the plant running, the notorious facility's "long-term future past 2019" is in doubt.}}
Closure
On June 20, 2017, Exelon Generation, the owners of Three Mile Island's Unit 1, sent to the Nuclear Regulatory Commission a formal notice of its intention to shut down the plant on September 30, 2019,{{Cite news|url=http://www.pennlive.com/news/2017/06/three_mile_island_closing_nrc.html|title=Three Mile Island operator takes another step toward closing nuclear plant|work=PennLive.com|date=2017-06-23|access-date=2017-12-07|language=en-US}} unless the Pennsylvania legislature rescued the nuclear industry, which was struggling to compete as newfound natural gas resources drove down electricity prices.{{Cite news|url=http://www.philly.com/philly/business/energy/nuke17-headline-here-20170914.html|title=Three Mile Island fights once again for its nuclear survival|work=Philly.com|access-date=2017-12-07}} Exelon Generation's Senior Vice President Bryan Hanson noted that once Three Mile Island was closed, it could never be reopened for use again. Hanson explicitly stated the reason for the shutdown is because of the unprofitability of Unit 1. Unit 1 has lost the company over $300 million over the last half-decade despite it being one of Exelon's best-performing power plants.
About 70 state legislators signed the industry-inspired Nuclear Caucus but made no financial commitments.
In April 2019, Exelon stated it would cost $1.2 billion over nearly 60 years to completely decommission Unit 1.{{cite news |last=Maykuth |first=Andrew |date=5 April 2019 |title=Three Mile Island nuclear reactor dismantling could take six decades, more than $1 billion |url=https://www.philly.com/business/energy/three-mile-island-nuclear-reactor-decommissioning-plan-exelon-years-20190405.html |access-date=6 April 2019 |website=The Inquirer |location=Philadelphia, Pennsylvania}} Unit 1 closed on September 20, 2019.
In 2022, Unit 1 was transferred to Constellation Energy following separation from Exelon. Unit 2 was also transferred to TriArtisan ES Partners, LLC – following their acquisition of EnergySolutions.
Decommissioning
{{section update|date=September 2024}}
In 2023, TMI-2 Solutions begun active cleanup of the reactor site. A temporary building is planned to contain radioactive materials before being shipped to a disposal area. Remotely operated equipment is planned to take a large part in decommissioning due to radioactivity concerns. Originally TMI-2 Solutions planned to finish decommissioning in 2037, but is now projected to finish by 2052.{{Cite web |date=2023-05-11 |title=Three Mile Island enters new phase of cleanup |url=https://stateimpact.npr.org/pennsylvania/2023/05/11/tmi-enters-new-phase-of-cleanup/ |access-date=2025-04-09 |website=StateImpact Pennsylvania |language=en}}
Following the TMI-2 accident in 1979, approximately 99% of the fuel and damaged core debris was removed from the reactor vessel and associated systems and shipped to the Idaho National Laboratory near Idaho Falls, Idaho. Since 1993, when the initial cleanup of the plant was completed, TMI-2 has been in a condition known as Post Defueling Monitored Storage (PDMS) and is under constant monitoring to ensure the plant's safety and stability. The remaining 1% of residual fuel that still remains at the site is planned to be removed by 2029.{{Cite web |date=2024-01-19 |title=Crews in training to remove last of fuel from Three Mile Island Unit 2 |url=https://stateimpact.npr.org/pennsylvania/2024/01/19/crews-in-training-to-remove-last-of-fuel-from-three-mile-island-unit-2/ |access-date=2024-10-16 |website=StateImpact Pennsylvania |language=en}}
The cost of decommissioning a closed nuclear reactor and related structures at Three Mile Island is estimated at $918 million.{{Cite web |last= |first= |date=2013-08-29 |title=Three Mile Island decommission cost put at $918M |url=https://lancasteronline.com/news/three-mile-island-decommission-cost-put-at-918m/article_6dbd62ec-3d19-5b07-87c4-8d7de3883731.html |access-date=2022-06-04 |website=LancasterOnline |language=en}}
Reopening and Microsoft partnership
On September 20, 2024, citing a resurgence in the need for nuclear generated carbon free electricity, Constellation Energy announced plans to reopen Three Mile Island Unit 1 in 2028. It will be renamed the Christopher M. Crane Clean Energy Center, in honor of former Exelon Corporation CEO Chris Crane. Crane, who started his career in nuclear energy as a Reactor Operator with ComEd, retired from Exelon in December 2022 and died on April 13, 2024.{{cite web |url=https://www.constellationenergy.com/newsroom/2024/Constellation-to-Launch-Crane-Clean-Energy-Center-Restoring-Jobs-and-Carbon-Free-Power-to-The-Grid.html |title=Constellation to Launch Crane Clean Energy Center, Restoring Jobs and Carbon-Free Power to the Grid |publisher=Constellation Energy |date=September 20, 2024}}{{cite news |last=Hiller |first=Jennifer |title=Three Mile Island's Nuclear Plant to Reopen, Help Power Microsoft's AI Centers |url=https://www.wsj.com/business/energy-oil/three-mile-islands-nuclear-plant-to-reopen-help-power-microsofts-ai-centers-aebfb3c8?mod=Searchresults_pos1&page=1 |newspaper=Wall Street Journal |date=September 20, 2024}}
As part of this plan, Microsoft entered into a 20-year agreement to purchase power from the facility once it resumes operation, aiming to support the energy demands of its expanding AI data centers. Constellation Energy will invest $1.6 billion into the plant’s upgrades, pending regulatory approval.{{Cite news |title=Three Mile Island nuclear site to reopen in Microsoft deal |url=https://www.bbc.com/news/articles/cx25v2d7zexo |access-date=September 21, 2024 |work=BBC News |date=September 20, 2024 |first=Natalie |last=Sherman}}
When TMI-1 was shut down in 2019, safety diesel fuel tanks were drilled into and filled with concrete to eliminate chances of leaks into the environment. Transformers had their oil drained and then were scrapped as Exelon saw little chance for reopening. Thus, replacement transformers for the reopening of TMI-1 cost $100 million in 2025. The steam generators were drained and exposed to air during decommissioning, but were found to be in good condition during inspections in 2025. During inspections, Constellation found no parts that would require so much time to have to push back the scheduled opening past 2028.{{Cite web |title=Resurrecting Three Mile Island |url=https://www.ans.org/news/article-6714/resurrecting-three-mile-island/ |access-date=2025-04-09 |website=www.ans.org |language=en}} Since the nuclear facility was deemed to be in excellent condition, there is a chance it could reopen a year early in 2027.{{Cite web |last=Lehman |first=Tom |date=2025-06-25 |title=Nuclear plant at TMI could reopen earlier than expected |url=https://www.wgal.com/article/pennsylvania-nuclear-plant-three-mile-island-could-open-2027/65192313 |access-date=2025-06-25 |website=WGAL |language=en}}
Seismic risk
The Nuclear Regulatory Commission's estimate of the risk each year of an earthquake intense enough to cause core damage to the reactor at Three Mile Island was 1 in 25,000, according to an NRC study published in August 2010.{{cite web | author=Bill Dedman | date=March 17, 2011 | title=What are the odds? US nuke plants ranked by quake risk | url=https://www.nbcnews.com/id/wbna42103936 | website=NBC News | access-date=April 19, 2011| author-link=Bill Dedman }}{{cite web |title=Hotmail, Outlook en Skype inloggen – Laatste nieuws – MSN Nederland |url=http://msnbcmedia.msn.com/i/msnbc/Sections/NEWS/quake%20nrc%20risk%20estimates.pdf |url-status=dead |archive-url=https://web.archive.org/web/20170525170632/http://msnbcmedia.msn.com/i/msnbc/Sections/NEWS/quake%20nrc%20risk%20estimates.pdf |archive-date=May 25, 2017 |access-date=May 5, 2017 |language=dutch |df=mdy-all}}
See also
{{Portal|Pennsylvania|Energy|Nuclear technology}}
- {{annotated link|Chernobyl disaster}}
- {{annotated link|Fukushima nuclear accident}}
- List of nuclear accidents
- Nuclear power in the United States
- Nuclear power in Pennsylvania
Notes
{{reflist|group=lower-alpha}}
References
{{reflist}}
External links
{{Commons category|Three Mile Island Nuclear Generating Station}}
- [http://www.exeloncorp.com/powerplants/threemileisland/Pages/profile.aspx Three Mile Island] page on the operator's website
- [http://www.tmia.com/tmi Three Mile Island – Three Mile Island Alert]
{{U.S. Nuclear Plants}}
{{U.S. anti-nuclear}}
{{Authority control}}
Category:Energy infrastructure completed in 1974
Category:Energy infrastructure completed in 1978
Category:Nuclear power plants in Pennsylvania
Category:Three Mile Island accident
Category:Buildings and structures in Dauphin County, Pennsylvania
Category:Towers in Pennsylvania
Category:Nuclear power stations using pressurized water reactors
Category:Islands of the Susquehanna River in Pennsylvania