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102-598: Throughout its operation, Davis–Besse has been the site of several safety incidents that affected the plant's operation. According to the Nuclear Regulatory Commission (NRC), Davis–Besse has been the source of two of the top five most dangerous nuclear incidents in the United States since 1979. The most severe occurring in March 2002, when maintenance workers discovered corrosion had eaten

204-613: A deferred prosecution agreement with the United States Department of Justice (DOJ). The deferred prosecution agreement related to the March 2002 incident. The deferment granted by the NRC were based on letters from Davis–Besse engineers stating that previous inspections were adequate. However, those inspections were not as thorough as the company suggested, as proved by the material deficiency discovered later. In any case, because FirstEnergy cooperated with investigators on

306-407: A football -sized hole into the reactor vessel head. The NRC kept Davis–Besse shut down until March 2004, so that FirstEnergy was able to perform all the necessary maintenance for safe operations. The NRC imposed an over $ 5 million fine, its largest fine ever to a nuclear power plant, against FirstEnergy for the actions that led to the corrosion. The company paid an additional $ 28 million in fines under

408-500: A loss of coolant , loss of coolant pressure, or low coolant flow rate or be the result of a criticality excursion in which the reactor is operated at a power level that exceeds its design limits. Alternately, an external fire may endanger the core, leading to a meltdown. Large-scale nuclear meltdowns at civilian nuclear power plants include: Other core meltdowns have occurred at: A criticality accident (also sometimes referred to as an "excursion" or "power excursion") occurs when

510-634: A tritium leak accidentally discovered during an unrelated fire inspection on October 22, 2008. Preliminary indications suggest radioactive water did not infiltrate groundwater outside plant boundaries. During a scheduled refueling outage in 2010, ultrasonic examinations performed on the control rod drive mechanism nozzles penetrating the reactor vessel closure head identified that two of the nozzles inspected did not meet acceptance criteria. FirstEnergy investigators subsequently found new cracks in 24 of 69 nozzles, including one serious enough to leak boric acid. Crack indications required repair prior to returning

612-720: A 954-acre (386 ha) site in the Carroll Township. The plant only utilizes 221 acres (89 ha), with 733 acres (297 ha) devoted to the Ottawa National Wildlife Refuge . The entrance to the Magee Marsh Wildlife Area is approximately 5 miles east of the power station. The official name according to the U.S. Energy Information Administration is the Davis–Besse Nuclear Generating Station. It

714-573: A criticality accident was reported at the Afrikantov OKBM Critical Test Facility in Russia. Decay heat accidents are where the heat generated by radioactive decay causes harm. In a large nuclear reactor, a loss of coolant accident can damage the core : for example, at Three Mile Island Nuclear Generating Station a recent shutdown ( SCRAMed ) PWR reactor was left for a length of time without cooling water. As

816-593: A fatality) in the U.S. back to 1880. The Fujita scale was adopted in most areas outside of the United Kingdom . On February 1, 2007, the Fujita scale was decommissioned, and the Enhanced Fujita Scale was introduced in the United States. The new scale more accurately matches wind speeds to the severity of damage caused by the tornado. Though each damage level is associated with a wind speed,

918-399: A flash of blue light (caused by excited, ionized air particles returning to their unexcited states). Slotin reflexively separated the hemispheres in reaction to the heat flash and blue light, preventing further irradiation of several co-workers present in the room. However, Slotin absorbed a lethal dose of the radiation and died nine days later. The infamous plutonium mass used in the experiment

1020-409: A gap on the underside. It is thought that no human has been seriously harmed by the escaping radiation. On 17 January 1966, a fatal collision occurred between a B-52G and a KC-135 Stratotanker over Palomares , Spain (see 1966 Palomares B-52 crash ). The accident was designated a " Broken Arrow ", meaning an accident involving a nuclear weapon that does not present a risk of war. Equipment failure

1122-414: A key factor in public concern about nuclear facilities . Technical measures to reduce the risk of accidents or to minimize the amount of radioactivity released to the environment have been adopted; however, human error remains, and "there have been many accidents with varying impacts as well near misses and incidents". As of 2014, there have been more than 100 serious nuclear accidents and incidents from

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1224-403: A means to differentiate tornado intensity and path area, assigned wind speeds to damage that were, at best, educated guesses. Fujita and others recognized this immediately and intensive engineering analysis was conducted through the rest of the 1970s. This research, as well as subsequent research, showed that tornado wind speeds required to inflict the described damage were actually much lower than

1326-419: A meltdown or related event are typically dispersed into the atmosphere and then settle on the surface through natural occurrences and deposition. Isotopes settling on the top soil layer can remain there for many years, due to their slow decay (long half-life). The long-term detrimental effects on agriculture, farming, and livestock, can potentially affect human health and safety long after the actual event. After

1428-543: A million tons of contaminated water, and by 2022 they would be out of space to safely store the radioactive water. Multiple private agencies as well as various North American governments monitor the spread of radiation throughout the Pacific to track the potential hazards it can introduce to food systems, groundwater supplies, and ecosystems. In 2014, the United States Food and Drug Administration (FDA) released

1530-406: A nuclear chain reaction is accidentally allowed to occur in fissile material , such as enriched uranium or plutonium . The Chernobyl accident is not universally regarded an example of a criticality accident, because it occurred in an operating reactor at a power plant. The reactor was supposed to be in a controlled critical state, but control of the chain reaction was lost. The accident destroyed

1632-690: A number of the population to the hazards of fallout. Estimating exact numbers, and the exact consequences, of people exposed has been medically very difficult, with the exception of the high exposures of Marshall Islanders and Japanese fishers in the case of the Castle Bravo incident in 1954. A number of groups of U.S. citizens — especially farmers and inhabitants of cities downwind of the Nevada Test Site and U.S. military workers at various tests — have sued for compensation and recognition of their exposure, many successfully. The passage of

1734-661: A reactor core meltdown or widespread dispersal of radioactivity, external attacks such as an aircraft crash into a reactor complex, or cyber attacks. The United States 9/11 Commission found that nuclear power plants were potential targets originally considered as part of the September 11 attacks . If terrorist groups could sufficiently damage safety systems to cause a core meltdown at a nuclear power plant, or sufficiently damage spent fuel pools, such an attack could lead to widespread radioactive contamination. The Federation of American Scientists have said that if nuclear power use

1836-486: A release of radioactivity resulting in contamination or shielding to be damaged resulting in direct irradiation. In Cochabamba a defective gamma radiography set was transported in a passenger bus as cargo. The gamma source was outside the shielding, and it irradiated some bus passengers. In the United Kingdom , it was revealed in a court case that in March 2002 a radiotherapy source was transported from Leeds to Sellafield with defective shielding. The shielding had

1938-459: A report stating that radionuclides, traced from the Fukushima facility, were present in the United States food supply, but not to levels deemed to be a threat to public health – as well as any food and agricultural products imported from Japanese sources. It is commonly believed that, with the rate of the current radionuclide leakage, the dispersal into the water would prove beneficial, as most of

2040-548: A result of the distribution of radioactive isotopes through water systems. In 2013, contaminated groundwater was found in between some of the affected turbine buildings in the Fukushima Daiichi facility, including locations at bordering seaports on the Pacific Ocean. In both locations, the facility typically releases clean water to feed into further groundwater systems. The Tokyo Electric Power Company (TEPCO),

2142-405: A result, the nuclear fuel was damaged, and the core partially melted. The removal of the decay heat is a significant reactor safety concern, especially shortly after shutdown. Failure to remove decay heat may cause the reactor core temperature to rise to dangerous levels and has caused nuclear accidents. The heat removal is usually achieved through several redundant and diverse systems, and the heat

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2244-407: A risky experiment known as "tickling the dragon's tail" which involved two hemispheres of neutron-reflective beryllium being brought together around a plutonium core to bring it to criticality. Against operating procedures, the hemispheres were separated only by a screwdriver. The screwdriver slipped and set off a chain reaction criticality accident filling the room with harmful radiation and

2346-484: A settlement with the United States Department of Justice (DOJ). Davis–Besse was expected to close in 2020 as it is no longer profitable to run when competing against natural gas plants. Plans were updated indicating possible shut down by May 31, 2020. However, Ohio House Bill 6 was signed into law in July 2019 which added a fee to residents' utility bills that funded subsidies of $ 150 million per year to Davis–Besse and

2448-502: A tornado rated F4 based on damage with a path length of 63 miles (101 km) and a path width of 800 yards (730 m) would be rated F,P,P 4,4,4. Use of the Pearson scales was not widespread, however, and it remained more common to simply list a tornado's path length and path width directly. For purposes such as tornado climatology studies, Fujita scale ratings may be grouped into classes. The Fujita scale, introduced in 1971 as

2550-472: Is "a persistent problem with the illicit trafficking in nuclear and other radioactive materials, thefts, losses and other unauthorized activities". The IAEA Illicit Nuclear Trafficking Database notes 1,266 incidents reported by 99 countries over the last 12 years, including 18 incidents involving HEU or plutonium trafficking: A nuclear meltdown is a severe nuclear reactor accident that results in reactor core damage from overheating. It has been defined as

2652-500: Is a scale for rating tornado intensity , based primarily on the damage tornadoes inflict on human-built structures and vegetation. The official Fujita scale category is determined by meteorologists and engineers after a ground or aerial damage survey , or both; and depending on the circumstances, ground-swirl patterns ( cycloidal marks), weather radar data, witness testimonies, media reports and damage imagery, as well as photogrammetry or videogrammetry if motion picture recording

2754-467: Is an example of a limited scope accident where only a few people can be harmed, while no release of radioactivity into the environment occurred. A criticality accident with limited off site release of both radiation ( gamma and neutron ) and a very small release of radioactivity occurred at Tokaimura in 1999 during the production of enriched uranium fuel. Two workers died, a third was permanently injured, and 350 citizens were exposed to radiation. In 2016,

2856-718: Is available. The Fujita scale was replaced with the Enhanced Fujita scale (EF-Scale) in the United States in February 2007. In April 2013, Canada adopted the EF-Scale over the Fujita scale along with 31 "Specific Damage Indicators" used by Environment Canada (EC) in their ratings. The scale was introduced in 1971 by Ted Fujita of the University of Chicago , in collaboration with Allen Pearson , head of

2958-465: Is believed to have been created by the United States and Israel to attack Iran's nuclear facilities. It switched off safety devices, causing centrifuges to spin out of control. The computers of South Korea 's nuclear plant operator ( KHNP ) were hacked in December 2014. The cyber attacks involved thousands of phishing emails containing malicious codes, and information was stolen. In March 2022,

3060-671: Is failure of control software , as in the cases involving the Therac-25 medical radiotherapy equipment: the elimination of a hardware safety interlock in a new design model exposed a previously undetected bug in the control software, which could have led to patients receiving massive overdoses under a specific set of conditions. Some major nuclear accidents were attributable in part to operator or human error . At Chernobyl, operators deviated from test procedure and allowed certain reactor parameters to exceed design limits. At TMI-2, operators permitted thousands of gallons of water to escape from

3162-445: Is of concern in the area of nuclear safety and security . Nuclear power plants , civilian research reactors, certain naval fuel facilities, uranium enrichment plants, fuel fabrication plants, and potentially even uranium mines are vulnerable to attacks which could lead to widespread radioactive contamination . The attack threat is of several general types: commando-like ground-based attacks on equipment which if disabled could lead to

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3264-554: Is often dissipated to an 'ultimate heat sink' which has a large capacity and requires no active power, though this method is typically used after decay heat has reduced to a very small value. The main cause of the release of radioactivity in the Three Mile Island accident was a pilot-operated relief valve on the primary loop which stuck in the open position. This caused the overflow tank into which it drained to rupture and release large amounts of radioactive cooling water into

3366-416: Is one possible type of accident. In Białystok , Poland, in 2001 the electronics associated with a particle accelerator used for the treatment of cancer suffered a malfunction. This then led to the overexposure of at least one patient. While the initial failure was the simple failure of a semiconductor diode , it set in motion a series of events which led to a radiation injury. A related cause of accidents

3468-480: Is the 57th commercial power reactor to commence building in the United States of America (construction began on September 1, 1970) and the 50th to come on-line July 31, 1978. The plant was originally jointly owned by Cleveland Electric Illuminating (CEI) and Toledo Edison (TE) and was named for former TE Chairman John K. Davis and former CEI Chairman Ralph M. Besse. Unit One is an 879 MWe pressurized water reactor supplied by Babcock & Wilcox . The reactor

3570-665: Is the one where lost sources are most likely to be found. Experts believe that up to 50 nuclear weapons were lost during the Cold War . Comparing the historical safety record of civilian nuclear energy with other forms of electrical generation, Ball, Roberts, and Simpson, the IAEA , and the Paul Scherrer Institute found in separate studies that during the period from 1970 to 1992, there were just 39 on-the-job deaths of nuclear power plant workers worldwide, while during

3672-605: Is to expand significantly, nuclear facilities will have to be made extremely safe from attacks that could release radioactivity into the environment. New reactor designs have features of passive nuclear safety , which may help. In the United States, the NRC carries out "Force on Force" (FOF) exercises at all Nuclear Power Plant (NPP) sites at least once every three years. Nuclear reactors become preferred targets during military conflict and have been repeatedly attacked during military air strikes, occupations, invasions and campaigns over

3774-635: Is visible from the Michigan and Ontario shores and on clear days the condensing steam plume can be seen from Bowling Green, Ohio , over 40 miles away. Nuclear and radiation accidents and incidents A nuclear and radiation accident is defined by the International Atomic Energy Agency (IAEA) as "an event that has led to significant consequences to people, the environment or the facility." Examples include lethal effects to individuals , large radioactivity release to

3876-868: The K-19 (1961), K-11 (1965), K-27 (1968), K-140 (1968), K-429 (1970), K-222 (1980), and K-431 (1985) accidents. Serious radiation incidents/accidents include the Kyshtym disaster , the Windscale fire , the radiotherapy accident in Costa Rica , the radiotherapy accident in Zaragoza , the radiation accident in Morocco , the Goiania accident , the radiation accident in Mexico City ,

3978-757: The Battle of Enerhodar caused damage to the Zaporizhzhia Nuclear Power Plant and a fire at its training complex as Russian forces took control, heightening concerns of nuclear contamination. On September 6, 2022, IAEA Director General Rafael Grossi addressed the UN Security Council, calling for a nuclear safety and security protection zone around the plant and reiterating his findings that "the Seven Pillars [for nuclear safety and security] have all been compromised at

4080-682: The Pacific Ocean , over 900 of them at the Nevada Test Site , and ten on miscellaneous sites in the United States ( Alaska , Colorado , Mississippi , and New Mexico ). Until November 1962, the vast majority of the U.S. tests were atmospheric (that is, above-ground); after the acceptance of the Partial Test Ban Treaty all testing was regulated underground, in order to prevent the dispersion of nuclear fallout. The U.S. program of atmospheric nuclear testing exposed

4182-552: The Perry Nuclear Generating Station to keep both plants operational. The bill was alleged to be part of the Ohio nuclear bribery scandal revealed by the United States Department of Justice (DOJ) in July 2020. The power station is located on the southwest shore of Lake Erie about 10 miles (16 km) north of Oak Harbor, Ohio and is on the north side of Highway 2 just east of Highway 19 on

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4284-657: The Samut Prakan radiation accident , and the Mayapuri radiological accident in India. The IAEA maintains a website reporting recent nuclear accidents. In 2020, the WHO stated that "Lessons learned from past radiological and nuclear accidents have demonstrated that the mental health and psychosocial consequences can outweigh the direct physical health impacts of radiation exposure." " The world's first nuclear reactor meltdown

4386-672: The Shimantan Dam , the three other most expensive accidents involved the Exxon Valdez oil spill (Alaska), the Prestige oil spill (Spain), and the Three Mile Island nuclear accident (Pennsylvania). Nuclear safety covers the actions taken to prevent nuclear and radiation accidents or to limit their consequences and damage to the environment. This covers nuclear power plants as well as all other nuclear facilities,

4488-401: The containment building . For the most part, nuclear facilities receive their power from offsite electrical systems. They also have a grid of emergency backup generators to provide power in the event of an outage. An event that could prevent both offsite power, as well as emergency power is known as a "station blackout". In 2011, an earthquake and tsunami caused a loss of electric power at

4590-620: The EF scale wind speeds, but these are biased to United States construction practices. The EF scale also improved damage parameter descriptions. The original scale as derived by Fujita was a theoretical 13-level scale (F0–F12) designed to smoothly connect the Beaufort scale and the Mach number scale. F1 corresponds to the twelfth level of the Beaufort scale, and F12 corresponds to Mach number 1.0. F0

4692-540: The F-scale indicated, particularly for the upper categories. Also, although the scale gave general descriptions of damage a tornado could cause, it gave little leeway for strength of construction and other factors that might cause a building to sustain more damage at lower wind speeds. Fujita tried to address these problems somewhat in 1992 with the Modified Fujita Scale, but by then he was semi-retired and

4794-402: The Fujita scale is effectively a damage scale, and the wind speeds associated with the damage listed are not rigorously verified. The Enhanced Fujita Scale was formulated due to research that suggested that the wind speeds required to inflict damage by intense tornadoes on the Fujita scale are greatly overestimated. A process of expert elicitation with top engineers and meteorologists resulted in

4896-756: The Fukushima Daiichi accident in 2011, surrounding agricultural areas were contaminated with more than 100,000 MBq km in cesium concentrations. As a result, eastern Fukushima food production was severely limited. Due to Japan's topography and the local weather patterns, cesium deposits as well as other isotopes reside in top layer of soils all over eastern and northeastern Japan. Luckily, mountain ranges have shielded western Japan. The Chernobyl disaster in 1986 exposed to radiation about 125,000 mi (320,000 km ) of land across Ukraine, Belarus, and Russia. The amount of focused radiation caused severe damage to plant reproduction: most plants could not reproduce for at least three years. Many of these occurrences on land can be

4998-470: The Fukushima Daiichi nuclear power plant in Japan (via severing the connection to the external grid and destroying the backup diesel generators). The decay heat could not be removed, and the reactor cores of units 1, 2 and 3 overheated, the nuclear fuel melted, and the containments were breached. Radioactive materials were released from the plant to the atmosphere and to the ocean. Transport accidents can cause

5100-863: The National Severe Storms Forecast Center/NSSFC (currently the Storm Prediction Center /SPC). The scale was updated in 1973, taking into account path length and width. In the United States, starting in the late 1970s, tornadoes were rated soon after occurrence. The Fujita scale was applied retroactively to tornadoes reported between 1950 and the adoption of the scale in the National Oceanic and Atmospheric Administration (NOAA) National Tornado Database. Fujita rated tornadoes from 1916 to 1992 and Tom Grazulis of The Tornado Project retroactively rated all known significant tornadoes (F2–F5 or causing

5202-719: The National Weather Service was not in a position to update to an entirely new scale, so it went largely unenacted. In the United States, on February 1, 2007, the Fujita scale was decommissioned in favor of what scientists believe is a more accurate Enhanced Fujita Scale. The meteorologists and engineers who designed the EF Scale believe it improves on the F-scale on many counts. It accounts for different degrees of damage that occur with different types of structures, both manmade and natural. The expanded and refined damage indicators and degrees of damage standardize what

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5304-639: The Radiation Exposure Compensation Act of 1990 allowed for a systematic filing of compensation claims in relation to testing as well as those employed at nuclear weapons facilities. As of June 2009 over $ 1.4 billion total has been given in compensation, with over $ 660 million going to " downwinders ". For intentional or attempted theft of radioactive material, see Crimes involving radioactive substances § Intentional theft or attempted theft of radioactive material . The International Atomic Energy Agency says there

5406-598: The United States. According to Scientific American , the average coal power plant emits 100 times more radiation per year than a comparatively sized nuclear power plant in the form of toxic coal waste known as fly ash . In terms of energy accidents , hydroelectric plants were responsible for the most fatalities, but nuclear power plant accidents rank first in terms of their economic cost, accounting for 41 percent of all property damage. Oil and hydroelectric follow at around 25 percent each, followed by natural gas at 9 percent and coal at 2 percent. Excluding Chernobyl and

5508-424: The accident among those exposed to significant radiation levels. Radioactive fallout from the accident was concentrated in areas of Belarus, Ukraine and Russia. Other studies have estimated as many as over a million eventual cancer deaths from Chernobyl. Estimates of eventual deaths from cancer are highly contested. Industry, UN and DOE agencies claim low numbers of legally provable cancer deaths will be traceable to

5610-437: The accidental melting of the core of a nuclear reactor, and refers to the core's either complete or partial collapse. A core melt accident occurs when the heat generated by a nuclear reactor exceeds the heat removed by the cooling systems to the point where at least one nuclear fuel element exceeds its melting point . This differs from a fuel element failure , which is not caused by high temperatures. A meltdown may be caused by

5712-547: The actual wind speeds needed to cause that damage are unknown." Since then, the Enhanced Fujita Scale has been created using better wind estimates by engineers and meteorologists. The six categories are listed here, in order of increasing intensity. In 1973, Allen Pearson added additional path length and path width parameters to the Fujita scale. Under this version, each tornado would be assigned one Fujita scale rating and two Pearson scale ratings. For example,

5814-403: The auxiliary (emergency) feedwater pumps. These pumps both tripped on overspeed conditions because of operator error. This incident was originally classified an " NRC Unusual Event " (the lowest classification the NRC uses) but it was later determined that it should have been classified a "site area emergency". On June 24, 1998, the station was struck by an F2 tornado. The plant's switchyard

5916-419: The city centers). U.S. Census data for Canadian population within the area is not available, though Leamington, Ontario (population: 30,000) is 39 miles (63 km) away, and Windsor, Ontario (population: 241,000) is 49 miles (79 km) from Davis–Besse. The cooling tower for Davis–Besse stands at 493 feet above the surrounding area, making it a major landmark around the western end of Lake Erie. The tower

6018-667: The coast of Eureka, California in November 2014. Despite the relatively dramatic increases in radiation, the contamination levels still satisfy the World Health Organization's (WHO's) standard for clean drinking water. In 2019, the Japanese government announced that it was considering the possibility of dumping contaminated water from the Fukushima reactor into the Pacific Ocean. Japanese Environmental Minister Yoshiaki Harada reported that TEPCO had collected over

6120-540: The company indicated it would close the nuclear plant. In 2019, Ohio lawmakers debated a $ 9/MWh subsidy to keep Davis–Besse open. House Bill 6 was signed into law on July 23, 2019, and FirstEnergy announced it would refuel Davis–Besse and rescind its deactivation notice on July 24, 2019. It was later learned that the bill itself was a part of a public corruption scheme revealed by the Justice Department in July 2020. The Nuclear Regulatory Commission's estimate of

6222-447: The damage described at each category. The error manifests itself to an increasing degree as the category increases, especially in the range of F3 through F5. NOAA notes that "precise wind speed numbers are actually guesses and have never been scientifically verified. Different wind speeds may cause similar-looking damage from place to place—even from building to building. Without a thorough engineering analysis of tornado damage in any event,

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6324-846: The designers of reactors at Fukushima in Japan did not anticipate that a tsunami generated by an earthquake would disable the backup systems that were supposed to stabilize the reactor after the earthquake. According to UBS AG, the Fukushima I nuclear accidents have cast doubt on whether even an advanced economy like Japan can master nuclear safety. Catastrophic scenarios involving terrorist attacks are also conceivable. In his book Normal Accidents , Charles Perrow says that unexpected failures are built into society's complex and tightly coupled nuclear reactor systems. Nuclear power plants cannot be operated without some major accidents. Such accidents are unavoidable and cannot be designed around. An interdisciplinary team from MIT have estimated that given

6426-442: The disaster. The UN, DOE and industry agencies all use the limits of the epidemiological resolvable deaths as the cutoff below which they cannot be legally proven to come from the disaster. Independent studies statistically calculate fatal cancers from dose and population, even though the number of additional cancers will be below the epidemiological threshold of measurement of around 1%. These are two very different concepts and lead to

6528-491: The entity that manages and operates the facility, further investigated the contamination in areas that would be deemed safe to conduct operations. They found that a significant amount of the contamination originated from underground cable trenches that connected to circulation pumps within the facility. Both the International Atomic Energy Agency (IAEA) and TEPCO confirmed that this contamination

6630-476: The environment, or a reactor core melt . The prime example of a "major nuclear accident" is one in which a reactor core is damaged and significant amounts of radioactive isotopes are released, such as in the Chernobyl disaster in 1986 and Fukushima nuclear disaster in 2011. The impact of nuclear accidents has been a topic of debate since the first nuclear reactors were constructed in 1954 and has been

6732-452: The existing nuclear infrastructure in use is old due to these reasons. To combat accidents associated with aging nuclear power plants, it may be advantageous to build new nuclear power reactors and retire the old nuclear plants. In the United States alone, more than 50 start-up companies are working to create innovative designs for nuclear power plants while ensuring the plants are more affordable and cost-effective. Isotopes released during

6834-749: The expected growth of nuclear power from 2005 to 2055, at least four serious nuclear accidents would be expected in that period. There have been five serious accidents ( core damage ) in the world since 1970 (one at Three Mile Island in 1979; one at Chernobyl in 1986; and three at Fukushima-Daiichi in 2011), corresponding to the beginning of the operation of generation II reactors . This leads to on average one serious accident happening every eight years worldwide. When nuclear reactors begin to age, they require more exhaustive monitoring and preventive maintenance and tests to operate safely and prevent accidents. However, these measures can be costly, and some reactor owners have not followed these recommendations. Most of

6936-461: The federal investigation. Two former employees and one former contractor were indicted for statements made in multiple documents and one videotape, over several years, for hiding evidence that the reactor pressure vessel was being corroded by boric acid . The maximum penalty for the three was 25 years in prison. The indictment mentions that other employees also provided false information to inspectors, but does not name them. In 2007, one of these men

7038-490: The government's most dangerous military material". Nuclear weapons materials on the black market are a global concern, and there is concern about the possible detonation of a small, crude nuclear weapon or dirty bomb by a militant group in a major city, causing significant loss of life and property. The number and sophistication of cyber attacks is on the rise. Stuxnet is a computer worm discovered in June 2010 that

7140-517: The high-pressure (~2155 psi, 14.6  MPa ) reactor coolant. A breach most likely would have resulted in a massive loss-of-coolant accident , in which reactor coolant would have jetted into the reactor's containment building and resulted in emergency safety procedures to protect from core damage or meltdown. Because of the location of the reactor head damage, such a jet of reactor coolant might have damaged adjacent control rod drive mechanisms, hampering or preventing reactor shut-down. As part of

7242-515: The huge variations in estimates. Both are reasonable projections with different meanings. Approximately 350,000 people were forcibly resettled away from these areas soon after the accident. 6,000 people were involved in cleaning Chernobyl and 10,800 square miles (28,000 km ) were contaminated. Social scientist and energy policy expert, Benjamin K. Sovacool has reported that worldwide there have been 99 accidents at nuclear power plants from 1952 to 2009 (defined as incidents that either resulted in

7344-568: The isotopes would be diluted by the water as well as become less radioactive over time, due to radioactive decay. Cesium (Cs-137) is the primary isotope released from the Fukushima Daiichi facility. Cs-137 has a long half-life, meaning it could potentially have long-term harmful effects, but as of now, its levels from 200 km outside of Fukushima show close to pre-accident levels, with little spread to North American coasts. Fujita scale The Fujita scale ( F-Scale ; / f u ˈ dʒ iː t ə / ), or Fujita–Pearson scale ( FPP scale ),

7446-513: The local power grid at May 12 after repairs were completed. The facility's original nuclear operating license was set to expire on April 22, 2017. In August 2006, FirstEnergy Nuclear Operating Company (FENOC) submitted a letter of intent to renew. The submission date for the application was August 10, 2010. On December 8, 2015, the NRC granted a 20-year license extension to expire on April 22, 2037. On March 31, 2018, FirstEnergy Nuclear Operating Company filed for Bankruptcy protection. Around that time,

7548-526: The loss of human life or more than US$ 50,000 of property damage, the amount the US federal government uses to define major energy accidents that must be reported), totaling US$ 20.5 billion in property damages. There have been comparatively few fatalities associated with nuclear power plant accidents. An academic review of many reactor accident and the phenomena of these events was published by Mark Foreman. The vulnerability of nuclear plants to deliberate attack

7650-710: The maintenance procedure's intention of about 4 inches. An assessment conducted by the Commissariat à l'Énergie Atomique (CEA) in France concluded that no amount of technical innovation can eliminate the risk of human-induced errors associated with the operation of nuclear power plants. Two types of mistakes were deemed most serious: errors committed during field operations, such as maintenance and testing, that can cause an accident; and human errors made during small accidents that cascade to complete failure. In 1946 Canadian Manhattan Project physicist Louis Slotin performed

7752-499: The matter, they were able to avoid more serious penalties. The company paid $ 28 million under a settlement with the Justice Department. $ 23.7 million of that were fines, with an additional $ 4.3 million to be contributed to various groups, including the National Park Service , the U.S. Fish and Wildlife Service , Habitat for Humanity , and the University of Toledo as well as to pay some costs related to

7854-502: The mothballed Midland Nuclear Power Plant in Midland, Michigan . The NRC determined that this incident was the fifth-most dangerous nuclear incident in the United States since 1979, and imposed its largest fine ever—more than $ 5 million—against FirstEnergy for the actions that led to the corrosion. In January 2006, First Energy, the owner of Davis–Besse, acknowledged a series of safety violations by former workers, and entered into

7956-537: The period 1980–2007. Various acts of civil disobedience since 1980 by the peace group Plowshares have shown how nuclear weapons facilities can be penetrated, and the group's actions represent extraordinary breaches of security at nuclear weapons plants in the United States. The National Nuclear Security Administration has acknowledged the seriousness of the 2012 Plowshares action. Non-proliferation policy experts have questioned "the use of private contractors to provide security at facilities that manufacture and store

8058-440: The radiation source of an expired teletherapy unit was sold unregistered, and stored in an unguarded car park from which it was stolen. Other cases occurred at Yanango , Peru where a radiography source was lost, and Gilan , Iran where a radiography source harmed a welder . The International Atomic Energy Agency has provided guides for scrap metal collectors on what a sealed source might look like. The scrap metal industry

8160-581: The rating of F6, but both were later downgraded to F5. Based on aerial photographs of the damage it caused, Fujita assigned the strongest tornado of the 1974 Super Outbreak , which affected Xenia, Ohio, a preliminary rating of F6 intensity ± 1 scale. The 1977 Birmingham–Smithfield F5 tornado's damage was surveyed by Ted Fujita and he "toyed with the idea of rating the Smithfield tornado an F6". In 2001, tornado expert Thomas P. Grazulis stated in his book F5–F6 Tornadoes ; "In my opinion, if there ever

8262-409: The reactor and left a large geographic area uninhabitable. In a smaller scale accident at Sarov a technician working with highly enriched uranium was irradiated while preparing an experiment involving a sphere of fissile material. The Sarov accident is interesting because the system remained critical for many days before it could be stopped, though safely located in a shielded experimental hall. This

8364-426: The reactor coolant had leaked from cracked control rod drive mechanisms directly above the reactor and eaten through more than six inches (150 mm) of the carbon steel reactor pressure vessel head over an area roughly the size of a football (see photo). This significant reactor head wastage on the exterior of the reactor vessel head left only 3 ⁄ 8 inch (9.5 mm) of stainless steel cladding holding back

8466-435: The reactor plant before observing that the coolant pumps were behaving abnormally. The coolant pumps were thus turned off to protect the pumps, which in turn led to the destruction of the reactor itself as cooling was completely lost within the core. A detailed investigation into SL-1 determined that one operator (perhaps inadvertently) manually pulled the 84-pound (38 kg) central control rod out about 26 inches rather than

8568-488: The reactor, running at only 9% power, shut down because of a disruption in the feedwater system. This incident later became a precursor to the Three Mile Island accident , in which a pilot-operated relief valve also became stuck open, leaking thousands of gallons of coolant water into the basement of the reactor building. On June 9, 1985, the main feedwater pumps , used to supply water to the reactor steam generators, shut down. A control room operator then attempted to start

8670-711: The risk each year of an earthquake intense enough to cause core damage to the reactor at Davis–Besse was 1 in 149,254, according to an NRC study published in August 2010. The Nuclear Regulatory Commission defines two emergency planning zones around nuclear power plants: a plume exposure pathway zone with a radius of 10 miles (16 km), concerned primarily with exposure to, and inhalation of, airborne radioactive contamination, and an ingestion pathway zone of about 50 miles (80 km), concerned primarily with ingestion of food and liquid contaminated by radioactivity. The 2010 U.S. population within 10 miles (16 km) of Davis–Besse

8772-577: The same time period, there were 6,400 on-the-job deaths of coal power plant workers, 1,200 on-the-job deaths of natural gas power plant workers and members of the general public caused by natural gas power plants , and 4,000 deaths of members of the general public caused by hydroelectric power plants with failure of Banqiao Dam in 1975 resulting in 170,000-230,000 fatalities alone. As other common sources of energy, coal power plants are estimated to kill 24,000 Americans per year due to lung disease as well as causing 40,000 heart attacks per year in

8874-412: The site." Serious radiation and other accidents and incidents include: Between 16 July 1945 and 23 September 1992, the United States maintained a program of vigorous nuclear weapons testing , with the exception of a moratorium between November 1958 and September 1961. By official count, a total of 1,054 nuclear tests and two nuclear attacks were conducted, with over 100 of them taking place at sites in

8976-533: The system reviews following the accident, significant safety issues were identified with other critical plant components, including the following: The resulting corrective operational and system reviews and engineering changes took two years. Repairs and upgrades cost $ 600 million, and the Davis–Besse reactor was restarted in March ;2004. To replace the reactor vessel head, FirstEnergy purchased one from

9078-399: The transportation of nuclear materials, and the use and storage of nuclear materials for medical, power, industry, and military uses. The nuclear power industry has improved the safety and performance of reactors, and has proposed new safer (but generally untested) reactor designs but there is no guarantee that the reactors will be designed, built and operated correctly. Mistakes do occur and

9180-691: The use of nuclear power. Fifty-seven accidents or severe incidents have occurred since the Chernobyl disaster, and about 60% of all nuclear-related accidents/severe incidents have occurred in the USA. Serious nuclear power plant accidents include the Fukushima nuclear disaster (2011), the Chernobyl disaster (1986), the Three Mile Island accident (1979), and the SL-1 accident (1961). Nuclear power accidents can involve loss of life and large monetary costs for remediation work. Nuclear submarine accidents include

9282-460: The vessel head to service. Control rod drive nozzles were repaired using techniques proven at other nuclear facilities. The plant resumed operation in 2010. The existing reactor vessel head was scheduled for replacement in 2011. An October 2011 shutdown of the plant for maintenance revealed a 30 foot long hairline crack in the concrete shield building around the containment vessel. On June 6, 2012, an approximately 0.1  gpm pinhole spray leakage

9384-405: Was 18,635, an increase of 14.2 percent in a decade, according to an analysis of U.S. Census data for msnbc.com . The 2010 U.S. population within 50 miles (80 km) was 1,791,856, an increase of 1.4 percent since 2000. Cities within 50 miles (80 km) include Sandusky, Ohio , 22 miles (35 km); Toledo, Ohio 26 miles (42 km); and Detroit, Michigan , 50 miles (80 km) (distance to

9486-438: Was a result of the 2011 earthquake. Due to damage like this, the Fukushima plant released nuclear material into the Pacific Ocean and has continued to do so. After 5 years of leaking, the contaminates reached all corners of the Pacific Ocean, from North America and Australia to Patagonia. Along the same coastline, Woods Hole Oceanographic Institution (WHOI) found trace amounts of Fukushima contaminates 100 miles (150 km) off

9588-475: Was an F6 tornado caught on video, it was the Pampa, Texas tornado of 1995 ". In 2023, it was announced by the Storm Prediction Center and National Weather Service Norman, Oklahoma that the 1970 Lubbock tornado was originally rated F6, which was later downgraded to its official rating of F5. Furthermore, the original wind speed numbers have since been found to be higher than the actual speeds required to incur

9690-553: Was available on damage caused by wind, so the original scale presented little more than educated guesses at wind speed ranges for specific tiers of damage. Fujita intended that only F0–F5 be used in practice, as this covered all possible levels of damage to frame homes as well as the expected estimated bounds of wind speeds. He did, however, add a description for F6, which he called an "inconceivable tornado", to allow for wind speeds exceeding F5 and possible advancements in damage analysis that might show it. In total, two tornadoes received

9792-402: Was convicted and another acquitted of hiding information from and lying to the NRC. Another jury trial in 2008 convicted the remaining engineer of similar crimes. In January 2003, the plant's private network became infected with the slammer worm , which resulted in a five-hour loss of safety monitoring at the plant. The NRC and Ohio Environmental Protection Agency (Ohio EPA) were notified of

9894-406: Was damaged and access to external power was disabled. The plant's reactor automatically shut down at 8:42 pm and an alert (the next to lowest of four levels of severity) was declared at 9:18 pm. The plant's emergency diesel generators powered critical facility safety systems until external power could be restored. In March 2002, plant staff discovered that the borated water that serves as

9996-432: Was identified from a weld in a seal of the reactor coolant pump during a routine reactor coolant system walkdown inspection. The plant entered limited operations, and root cause analysis was undertaken. On May 9, 2015, a steam leak in the turbine building caused FirstEnergy operators to declare an 'Unusual Event' and shut the reactor down until repairs could be made. The plant was brought back online and synchronized with

10098-410: Was placed at a position specifying no damage (approximately the eighth level of the Beaufort scale), in analogy to how Beaufort's zeroth level specifies little to no wind. From these wind speed numbers, qualitative descriptions of damage were made for each category of the Fujita scale, and then these descriptions were used to classify tornadoes. At the time Fujita derived the scale, little information

10200-539: Was referred to as the demon core . Lost source accidents, also referred to as orphan sources , are incidents in which a radioactive source is lost, stolen or abandoned. The source then might cause harm to humans. The best known example of this type of event is the 1987 Goiânia accident in Brazil, when a radiotherapy source was forgotten and abandoned in a hospital, to be later stolen and opened by scavengers. A similar case occurred in 2000 in Samut Prakan, Thailand when

10302-419: Was shut down from 2002 until early 2004 for safety repairs and upgrades. In 2012 the reactor supplied 7101.700 GWh of electricity. In 1973, two more reactors were also ordered from Babcock & Wilcox. However, construction on Units Two and Three never commenced, and these two units were officially canceled in 1981. On September 24, 1977, the relief valve for the reactor pressurizer failed to close when

10404-651: Was the NRX reactor at Chalk River Laboratories , Ontario , Canada in 1952. The worst nuclear accident to date is the Chernobyl disaster which occurred in 1986 in the Ukrainian SSR , now Ukraine. The accident killed approximately 30 people directly and damaged approximately $ 7 billion of property. A study published in 2005 by the World Health Organization estimates that there may eventually be up to 4,000 additional cancer deaths related to

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