Three Mile Island Nuclear Generating Station
   HOME

TheInfoList



OR:

Three Mile Island Nuclear Generating Station (commonly abbreviated as TMI) is a closed
nuclear power plant A nuclear power plant (NPP) is a thermal power station in which the heat source is a nuclear reactor. As is typical of thermal power stations, heat is used to generate steam that drives a steam turbine connected to a electric generator, generato ...
on Three Mile Island in
Londonderry Township, Dauphin County, Pennsylvania Londonderry Township is a township in Dauphin County, Pennsylvania, United States. The population was 4,890 at the 2020 census. The township includes the Three Mile Island Nuclear Generating Station, the location of the largest accident in the hi ...
on Lake Frederic, a reservoir in the
Susquehanna River The Susquehanna River (; Lenape: Siskëwahane) is a major river located in the Mid-Atlantic region of the United States, overlapping between the lower Northeast and the Upland South. At long, it is the longest river on the East Coast of the ...
just south of
Harrisburg Harrisburg is the capital city of the Pennsylvania, Commonwealth of Pennsylvania, United States, and the county seat of Dauphin County, Pennsylvania, Dauphin County. With a population of 50,135 as of the 2021 census, Harrisburg is the List of c ...
. It has two separate units, TMI-1 (owned by Constellation Energy) and TMI-2 (owned by EnergySolutions). 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 Meltdown may refer to: Science and technology * Nuclear meltdown, a severe nuclear reactor accident * Meltdown (security vulnerability), affecting computer processors * Mutational meltdown, in population genetics Arts and entertainment Music * Me ...
. According to the
Nuclear Regulatory Commission The Nuclear Regulatory Commission (NRC) is an independent agency of the United States government tasked with protecting public health and safety related to nuclear energy. Established by the Energy Reorganization Act of 1974, the NRC began operat ...
(NRC) report, the accident resulted in no deaths or injuries to plant workers or in nearby communities. Follow-up
epidemiology Epidemiology is the study and analysis of the distribution (who, when, and where), patterns and determinants of health and disease conditions in a defined population. It is a cornerstone of public health, and shapes policy decisions and evidenc ...
studies did not find
causality Causality (also referred to as causation, or cause and effect) is influence by which one event, process, state, or object (''a'' ''cause'') contributes to the production of another event, process, state, or object (an ''effect'') where the cau ...
between the accident and any increase in cancers. One work-related death has occurred on-site during decommissioning. The
reactor core A nuclear reactor core is the portion of a nuclear reactor containing the nuclear fuel components where the nuclear reactions take place and the heat is generated. Typically, the fuel will be low-enriched uranium contained in thousands of indiv ...
of TMI-2 has since been removed from the site, but the site has not been fully decommissioned. In July 1998, Amergen Energy (now
Exelon Exelon Corporation is an American Fortune 100 energy company headquartered in Chicago, Illinois and incorporated in Pennsylvania. It generates revenues of approximately $33.5 billion and employs approximately 33,400 people. Exelon is the larges ...
Generation) agreed to purchase TMI-1 from General Public Utilities for $100 million. The plant was originally built by General Public Utilities Corporation, later renamed GPU Incorporated. The plant was operated by
Metropolitan Edison Company FirstEnergy Corp is an electric utility headquartered in Akron, Ohio. It was established when Ohio Edison acquired Centerior Energy in 1997. Its subsidiaries and affiliates are involved in the distribution, transmission, and generation of electri ...
(Met-Ed), a subsidiary of the GPU Energy division. In 2001, GPU Inc. merged with FirstEnergy Corporation. On December 18, 2020 - FirstEnergy transferred Unit 2's license over to
EnergySolutions EnergySolutions (stylized as Energy''Solutions''), headquartered in Salt Lake City, Utah, is one of the largest processors of low level waste (LLW) in America, making it also one of the world's largest nuclear waste processors. It was formed in 20 ...
' subsidiary TMI-2 Solutions after receiving approval from the NRC. Exelon was operating Unit 1 at a financial loss since 2015. 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. Unit 1 officially shut down at noon on September 20, 2019. Unit 1 decommissioning is estimated to be finished in 2079, and will cost $1.2 billion. Unit 2, which has been dormant since the accident in 1979, is estimated to close in 2037.


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 , concerned primarily with exposure to, and inhalation of, airborne
radioactive contamination Radioactive contamination, also called radiological pollution, is the deposition of, or presence of radioactive substances on surfaces or within solids, liquids, or gases (including the human body), where their presence is unintended or undesirab ...
, and an ingestion pathway zone of about , concerned primarily with ingestion of food and liquid contaminated by radioactivity. 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. 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).


Three Mile Island Unit 1

The Three Mile Island Unit 1 is a
pressurized water reactor A pressurized water reactor (PWR) is a type of light-water reactor, light-water nuclear reactor. PWRs constitute the large majority of the world's nuclear power plants (with notable exceptions being the UK, Japan and Canada). In a PWR, the primary ...
designed by
Babcock & Wilcox Babcock & Wilcox is an American renewable, environmental and thermal energy technologies and service provider that is active and has operations in many international markets across the globe with its headquarters in Akron, Ohio, USA. Historicall ...
with a net generating capacity of 819  MWe. The initial construction cost for TMI-1 was , equal to $ billion in 2018 dollars. Unit 1 first came online on April 19, 1974, and began commercial operations on September 2, 1974. TMI-1 is licensed to operate for 40 years from its first run, and in 2009, was extended 20 years, which means it could have operated until April 19, 2034. 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 towers. Once-through cooling with river water is used for the service water system which cools auxiliary components and removed 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. 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 unable to continue operating the reactor. TMI-1 was shut down on September 20, 2019.


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. During and following the
September 11 attacks The September 11 attacks, commonly known as 9/11, were four coordinated suicide terrorist attacks carried out by al-Qaeda against the United States on Tuesday, September 11, 2001. That morning, nineteen terrorists hijacked four commercia ...
, there was a
moral panic A moral panic is a widespread feeling of fear, often an irrational one, that some evil person or thing threatens the values, interests, or well-being of a community or society. It is "the process of arousing social concern over an issue", usua ...
that
United Airlines Flight 93 United Airlines Flight 93 was a domestic scheduled passenger flight that was hijacked by four al-Qaeda attackers aboard the plane on the morning of September 11, 2001, as part of the September 11 attacks. The plane eventually crashed in Som ...
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 about 135 miles west (217 km) of Three Mile Island in Stonycreek Township, just outside
Shanksville, Pennsylvania Shanksville is a borough in Somerset County, Pennsylvania. It has a population of 197 as of the 2020 U.S. census. It is part of the Somerset, Pennsylvania Micropolitan Statistical Area and is located southeast of Pittsburgh and west of Philade ...
, with its actual target believed to be intended for
Washington, D.C. ) , image_skyline = , image_caption = Clockwise from top left: the Washington Monument and Lincoln Memorial on the National Mall, United States Capitol, Logan Circle, Jefferson Memorial, White House, Adams Morgan, ...
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 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.


Material handling accident

On September 10, 2021, a contractor from
Alabama (We dare defend our rights) , anthem = "Alabama (state song), Alabama" , image_map = Alabama in United States.svg , seat = Montgomery, Alabama, Montgomery , LargestCity = Huntsville, Alabama, Huntsville , LargestCounty = Baldwin County, Al ...
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 Dead on Scene ('' 'DOS' '') Found dead before first responders get on scene and no medical treatment was given. Dead on arrival (DOA), also dead in the field and brought in dead (BID), are terms which indicate that a patient was found to be ...
. The
Nuclear Regulatory Commission The Nuclear Regulatory Commission (NRC) is an independent agency of the United States government tasked with protecting public health and safety related to nuclear energy. Established by the Energy Reorganization Act of 1974, the NRC began operat ...
said the injury was work-related, and the contractor was outside the radiological controlled area.


Three Mile Island Unit 2

The Three Mile Island Unit 2 was also a pressurized water reactor constructed by B&W, similar to Unit 1. The only difference was that TMI-2 was slightly larger with a net generating capacity of 906 MWe, compared to TMI-1, which delivers 819 MWe. Unit 2 received its operating license on February 8, 1978, and began commercial operation on December 30, 1978. TMI Unit 2 has been permanently shut off after the Three Mile Island accident in 1979.


Accident

On March 28, 1979, a cooling system malfunction caused a partial
meltdown Meltdown may refer to: Science and technology * Nuclear meltdown, a severe nuclear reactor accident * Meltdown (security vulnerability), affecting computer processors * Mutational meltdown, in population genetics Arts and entertainment Music * Me ...
of the
reactor core A nuclear reactor core is the portion of a nuclear reactor containing the nuclear fuel components where the nuclear reactions take place and the heat is generated. Typically, the fuel will be low-enriched uranium contained in thousands of indiv ...
. This
loss-of-coolant accident A loss-of-coolant accident (LOCA) is a mode of failure for a nuclear reactor; if not managed effectively, the results of a LOCA could result in reactor core damage. Each nuclear plant's emergency core cooling system (ECCS) exists specifically t ...
resulted in the release of an estimated 43,000 curies (1.59  PBq) of
radioactive Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is consid ...
krypton Krypton (from grc, κρυπτός, translit=kryptos 'the hidden one') is a chemical element with the symbol Kr and atomic number 36. It is a colorless, odorless, tasteless noble gas that occurs in trace amounts in the atmosphere and is often ...
-85 gas (half life 10 yrs), and less than 20 curies (740 GBq) of the especially hazardous
iodine-131 Iodine-131 (131I, I-131) is an important radioisotope of iodine discovered by Glenn Seaborg and John Livingood in 1938 at the University of California, Berkeley. It has a radioactive decay half-life of about eight days. It is associated with nuc ...
(half life 8 days), into the surrounding environment. Nearly 2 million people were exposed to radiation from the accident. A review by the
World Nuclear Association World Nuclear Association is the international organization that promotes nuclear power and supports the companies that comprise the global nuclear industry. Its members come from all parts of the nuclear fuel cycle, including uranium mining, ur ...
concluded that no deaths, injuries or adverse health effects resulted from the accident, and a report by Columbia University epidemiologist Maureen Hatch confirmed this finding. Because of the health concerns, the Pennsylvania Department of Health kept a registry of more than 30,000 people that lived within 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. Further
epidemiology Epidemiology is the study and analysis of the distribution (who, when, and where), patterns and determinants of health and disease conditions in a defined population. It is a cornerstone of public health, and shapes policy decisions and evidenc ...
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. Unit 2 has not been operational since the accident occurred. ''The New York Times'' reported on August 14, 1993, 14 years after the accident, that the cleanup had been finished. According to the United States NRC, 2.3 million gallons of waste water had been removed. The incident was widely publicized internationally, and had far-reaching effects on public opinion, particularly in the United States. ''
The China Syndrome ''The China Syndrome'' is a 1979 American disaster thriller film directed by James Bridges and written by Bridges, Mike Gray, and T. S. Cook. The film stars Jane Fonda, Jack Lemmon, Michael Douglas (who also produced), Scott Brady, James ...
'', 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.


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. TMI's Unit 2 reactor has been shut down since the partial meltdown in 1979.


Post-accident

Exelon Corporation Exelon Corporation is an American Fortune 100 energy company headquartered in Chicago, Illinois and incorporated in Pennsylvania. It generates revenues of approximately $33.5 billion and employs approximately 33,400 people. Exelon is the largest ...
was created in October 2000 by the merger of PECO Energy Company and Unicom, of
Philadelphia Philadelphia, often called Philly, is the largest city in the Commonwealth of Pennsylvania, the sixth-largest city in the U.S., the second-largest city in both the Northeast megalopolis and Mid-Atlantic regions after New York City. Sinc ...
and Chicago respectively. Unicom owned
Commonwealth Edison Commonwealth Edison, commonly known by syllabic abbreviation as ComEd, is the largest electric utility in Illinois, and the in Chicago and much of Northern Illinois. Its service territory stretches roughly from Iroquois County on the south to ...
. The PECO share in AmerGen was acquired by Exelon during late 2000. Exelon acquired British Energy's share in AmerGen in 2003, and transferred Unit 1 under the direct ownership and operation of its Exelon Nuclear business unit. 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. 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.


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, unless the Pennsylvania legislature rescued the nuclear industry, which was struggling to compete as newfound natural gas resources drove down electricity prices. 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. Shut down of Unit 1 can go in two possible directions, the first being the immediate dismantlement after the radioactive fuel has been moved away from the plant. The dismantlement can proceed after the spent fuel is removed from the pool, put into storage casks, and the casks are transferred to the ISFSI pad for storage until the DOE takes them away to a DOE repository. Dismantling the plant this way will take anywhere from 8 to 10 years. The second option Exelon could take is the long-term storage, which involves mothballing the plant and letting the radiation decay for up to 60 years on its own to a harmless level before completely dismantling the buildings. The advantage to the long-term storage is the lack of radiation when the dismantlement would begin but the disadvantage would be the possible lack of qualified workers at the time of dismantlement. Exelon would also have to pay for limited maintenance and security of the plant over the potential 60 years. The entirety of the spent fuel will be moved to the Londonderry Township facility, which is another process that could take decades to complete. 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. 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 EnergySolutions (stylized as Energy''Solutions''), headquartered in Salt Lake City, Utah, is one of the largest processors of low level waste (LLW) in America, making it also one of the world's largest nuclear waste processors. It was formed in 20 ...
.


Decommissioning

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 Idaho National Laboratory (INL) is one of the national laboratories of the United States Department of Energy and is managed by the Battelle Energy Alliance. While the laboratory does other research, historically it has been involved with nu ...
near
Idaho Falls, Idaho Idaho Falls (Shoshoni language, Shoshoni: Dembimbosaage) is a city in and the county seat of Bonneville County, Idaho, Bonneville County, Idaho, United States. It is the state's largest city outside the Boise metropolitan area. As of the 2020 Un ...
. 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 cost of decommissioning a closed nuclear reactor and related structures at Three Mile Island is estimated at $918 million.


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.


See also

*
Chernobyl disaster The Chernobyl disaster was a nuclear accident that occurred on 26 April 1986 at the No. 4 reactor in the Chernobyl Nuclear Power Plant, near the city of Pripyat in the north of the Ukrainian SSR in the Soviet Union. It is one of only two nuc ...
*
Fukushima Daiichi nuclear disaster The was a nuclear accident in 2011 at the Fukushima Daiichi Nuclear Power Plant in Ōkuma, Fukushima, Japan. The proximate cause of the disaster was the 2011 Tōhoku earthquake and tsunami, which occurred on the afternoon of 11 March 2011 and ...


Notes


References


External links


Three Mile Island
page on the operator's website
Three Mile Island – Three Mile Island Alert
{{Authority control Energy infrastructure completed in 1974 Energy infrastructure completed in 1978 Nuclear power plants in Pennsylvania Three Mile Island accident Buildings and structures in Dauphin County, Pennsylvania Towers in Pennsylvania Nuclear power stations using pressurized water reactors Susquehanna River FirstEnergy 1974 establishments in Pennsylvania Former nuclear power stations in the United States