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A '''nuclear and radiation accident''' is defined by the [[International Atomic Energy Agency]] as "an event that has led to significant consequences to people, the environment or the facility. Examples include [[radiation poisoning|lethal effects to individuals]], [[ionizing radiation|large radioactivity release]] to the [[Natural environment|environment]], or [[nuclear meltdown|reactor core melt]]."<ref name="INES-DefinitionOfAccident">{{cite book|title=International Nuclear and Radiological Events Scale Users' Manual, 2008 Edition|publisher=International Atomic Energy Agency|url=www-pub.iaea.org/MTCD/publications/PDF/INES-2009_web.pdf|author=Staff, IAEA, AEN/NEA|accessdate=2010-07-26|location=Vienna, Austria|page=184|language=Technical English}}</ref> The prime example of a "major nuclear accident" is one in which a [[reactor core]] is damaged and large amounts of radiation are released, such as in the [[Chernobyl Disaster]] in 1986.
A '''nuclear and radiation accident''' is defined by the [[International Atomic Energy Agency]] as "an event that has led to significant consequences to people, the environment or the facility. Examples include [[radiation poisoning|lethal effects to individuals]], [[ionizing radiation|large radioactivity release]] to the [[Natural environment|environment]], or [[nuclear meltdown|reactor core melt]]."<ref name="INES-DefinitionOfAccident">{{cite book|title=International Nuclear and Radiological Events Scale Users' Manual, 2008 Edition|publisher=International Atomic Energy Agency|url=www-pub.iaea.org/MTCD/publications/PDF/INES-2009_web.pdf|author=Staff, IAEA, AEN/NEA|accessdate=2010-07-26|location=Vienna, Austria|page=184|language=Technical English}}</ref> The prime example of a "major nuclear accident" is one in which a [[reactor core]] is damaged and large amounts of radiation are released, such as in the [[Chernobyl Disaster]] in 1986.


The likelihood and potential impact of nuclear accidents has been a topic of debate practically since the first [[nuclear reactor]]s were constructed. It has also been a key factor in [[Anti-nuclear movement|public concern about nuclear facilities]].<ref name=mvr>M.V. Ramana. Nuclear Power: Economic, Safety, Health, and Environmental Issues of Near-Term Technologies, ''Annual Review of Environment and Resources'', 2009, 34, p. 136.</ref> Many technical measures to reduce the risk of accidents or (should one occur) to minimize the amount of [[radioactivity]] released to the environment have been adopted.
The likelihood and potential impact of nuclear accidents has been a topic of debate practically since the first [[nuclear reactor]]s were constructed. It has also been a key factor in [[Anti-nuclear movement|public concern about nuclear facilities]].<ref name=mvr>M.V. Ramana. Nuclear Power: Economic, Safety, Health, and Environmental Issues of Near-Term Technologies, ''Annual Review of Environment and Resources'', 2009, 34, p. 136.</ref> Many technical measures to reduce the risk of accidents or (should one occur) to minimize the amount of [[radioactivity]] released to the environment have been adopted. Despite the use of such measures, "there have been many accidents with varying impacts as well near misses and incidents".<ref name=mvr>M.V. Ramana. Nuclear Power: Economic, Safety, Health, and Environmental Issues of Near-Term Technologies, ''Annual Review of Environment and Resources'', 2009, 34, p. 136.</ref>


Stuart Arm states, "apart from [[Chernobyl Disaster|Chernobyl]], no nuclear workers or members of the public have ever died as a result of exposure to [[ionizing radiation|radiation]] due to a commercial [[nuclear reactor]] incident."<ref>{{cite journal|last=Arm|first=Stuart T. |title=Nuclear Energy: A Vital Component of Our Energy Future|journal=Chemical Engineering Progress|year=2010|month=07|pages=27–34|url=http://www.aiche.org/uploadedFiles/About/Press/Articles/1007_Nuclear_Energy_Preprint.pdf|accessdate=2010-07-26|publisher=American Institute of Chemical Engineers|location=New York, NY|issn=0360-7275|oclc=1929453}}</ref>
Stuart Arm states, "apart from [[Chernobyl Disaster|Chernobyl]], no nuclear workers or members of the public have ever died as a result of exposure to [[ionizing radiation|radiation]] due to a commercial [[nuclear reactor]] incident."<ref>{{cite journal|last=Arm|first=Stuart T. |title=Nuclear Energy: A Vital Component of Our Energy Future|journal=Chemical Engineering Progress|year=2010|month=07|pages=27–34|url=http://www.aiche.org/uploadedFiles/About/Press/Articles/1007_Nuclear_Energy_Preprint.pdf|accessdate=2010-07-26|publisher=American Institute of Chemical Engineers|location=New York, NY|issn=0360-7275|oclc=1929453}}</ref>

Revision as of 08:15, 13 December 2010

This article is about nuclear and radiation accidents in general. For a list of military nuclear accidents, see List of military nuclear accidents. For a list of civilian nuclear accidents, see List of civilian nuclear accidents. For a discussion of the controversy over nuclear power, see Nuclear debate (disambiguation).
See also: Lists of nuclear disasters and radioactive incidents
Pathways from airborne radioactive contamination to man

A nuclear and radiation accident is defined by the International Atomic Energy Agency 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 the environment, or reactor core melt."[1] The prime example of a "major nuclear accident" is one in which a reactor core is damaged and large amounts of radiation are released, such as in the Chernobyl Disaster in 1986.

The likelihood and potential impact of nuclear accidents has been a topic of debate practically since the first nuclear reactors were constructed. It has also been a key factor in public concern about nuclear facilities.[2] Many technical measures to reduce the risk of accidents or (should one occur) to minimize the amount of radioactivity released to the environment have been adopted. Despite the use of such measures, "there have been many accidents with varying impacts as well near misses and incidents".[2]

Stuart Arm states, "apart from Chernobyl, no nuclear workers or members of the public have ever died as a result of exposure to radiation due to a commercial nuclear reactor incident."[3]

Benjamin K. Sovacool has reported that worldwide there have been 99 accidents at nuclear power plants.[4] Fifty-seven accidents have occurred since the Chernobyl disaster, and almost two-thirds (56 out of 99) of all nuclear-related accidents have occurred in the USA. Relatively few accidents involved fatalities.[4]

Serious radiation accidents include the radiotherapy accident in Costa Rica,[5] radiotherapy accident in Zaragoza,[6] radiation accident in Morocco,[7] Goiania accident,[8] radiation accident in Mexico City, radiotherapy unit accident in Thailand,[9] and the Mayapuri radiological accident.[9]

The International Atomic Energy Agency maintains a website reporting recent accidents: [14].

History

The abandoned city of Prypiat, Ukraine, following the Chernobyl disaster. The Chernobyl nuclear power plant is in the background.

The worst nuclear accident to date was the Chernobyl disaster which occurred in 1986 in Ukraine. That accident killed 56 people directly, and caused an estimated 4,000 additional cases of fatal cancer, as well as damaging approximately $7 billion of property.[10] Radioactive fallout from the accident was concentrated in areas of Belarus, Ukraine and Russia. Approximately 350,000 people were forcibly resettled away from these areas soon after the incident.[10]

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 - 1992, there were just 39 on-the-job deaths of nuclear power plant workers worldwide, while during 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.[11][12][13] In particular, coal power plants are estimated to kill 24,000 Americans per year, due to lung disease[14] as well as causing 40,000 heart attacks per year[15] in the United States. According to Scientific American, the average coal power plant emits more than 100 times as much radiation per year than a comparatively sized nuclear power plant in the form of toxic coal waste known as fly ash.[16]

List of accidents

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 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.[4] Fifty-seven accidents have occurred since the Chernobyl disaster, and almost two-thirds (56 out of 99) of all nuclear-related accidents have occurred in the USA. There have been comparatively few fatalities associated with nuclear power plant accidents.[4]

Nuclear power plant accidents
with multiple fatalities and/or more than US$100 million in property damage, 1952-2010[4][10][17]
Date Location Description Fatalities Cost
(in millions
2006 $) 		INES
level[18]
September 29, 1957 Mayak/Kyshtym, Russia In the Kyshtym Disaster, a cooling system failure causes an explosion of dried waste, knocking off the lid of the storage vessel and releasing a large amount of radiation 200 6
October 8, 1957 Windscale, UK Windscale fire ignites plutonium piles, contaminating surrounding dairy farms 33 US$78 5
January 3, 1961 Idaho Falls, Idaho, US Explosion at National Reactor Testing Station 3 US$22
February 22, 1977 Jaslovské Bohunice, Czechoslovakia Severe corrosion of reactor and release of radioactivity into the plant area, necessitating total decommission 0 US$1,700 4
March 28, 1979 Middletown, Pennsylvania, US Loss of coolant and partial core meltdown, see Three Mile Island accident and Three Mile Island accident health effects 0 US$2,400 5
September 15, 1984 Athens, Alabama, US Safety violations, operator error, and design problems force six year outage at Browns Ferry Unit 2 0 US$110
March 9, 1985 Athens, Alabama, US Instrumentation systems malfunction during startup, which led to suspension of operations at all three Browns Ferry Units 0 US$1,830
April 11, 1986 Plymouth, Massachusetts, US Recurring equipment problems force emergency shutdown of Boston Edison’s Pilgrim Nuclear Power Plant 0 US$1,001
April 26, 1986 Pripyat, Ukraine Steam explosion and meltdown (see Chernobyl disaster) necessitating the evacuation of 300,000 people from Kiev and dispersing radioactive material across Europe (see Chernobyl disaster effects) 53 US$6,700 7
May 4, 1986 Hamm-Uentrop, Germany Experimental reactor releases excessive radiation to four square kilometers surrounding the facility 0 US$267
March 31, 1987 Delta, Pennsylvania, US Peach Bottom units 2 and 3 shutdown due to cooling malfunctions and unexplained equipment problems 0 US$400
December 19, 1987 Lycoming, New York, US Malfunctions force Niagara Mohawk Power Corporation to shut down Nine Mile Point Unit 1 0 US$150
March 17, 1989 Lusby, Maryland, US Inspections at Calvert Cliff Units 1 and 2 reveal cracks at pressurized heater sleeves, forcing extended shutdowns 0 US$120
November 24, 1989 Greifswald, East Germany Electrical error causes fire in the main trough that destroys control lines and five main coolant pumps 0 UD$443
February 20, 1996 Waterford, Connecticut, US Leaking valve forces shutdown Millstone Nuclear Power Plant Units 1 and 2, multiple equipment failures found 0 US$254
September 2, 1996 Crystal River, Florida, US Balance-of-plant equipment malfunction forces shutdown and extensive repairs at Crystal River Unit 3 0 US$384
September 30, 1999 Ibaraki Prefecture, Japan Workers at the Tokaimura uranium processing facility try to save time by mixing uranium in buckets, killing two and injuring 120 2 US$54 4
February 16, 2002 Oak Harbor, Ohio, US Severe corrosion of control rod forces 24-month outage of Davis-Besse reactor 0 US$143 3
August 9, 2004 Fukui Prefecture, Japan Steam explosion at Mihama Nuclear Power Plant kills 5 workers and injures dozens more 5 US$9 1

Radiation accidents

Serious radiation accidents include:

Accident types

Loss of coolant accident

Main article: Loss of coolant
See also: Nuclear meltdown and Design Basis Accident

Criticality accidents

A criticality accident (also sometimes referred to as an "excursion" or "power excursion") occurs when a nuclear chain reaction is accidentally allowed to occur in fissile material, such as enriched uranium or plutonium. The Chernobyl accident is an example of a criticality accident. This accident destroyed a reactor at the plant 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.[21] This 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.[22] Two workers died, a third was permanently injured, and 350 citizens were exposed to radiation.

Decay heat

Decay heat accidents are where the heat generated by the radioactive decay causes harm. In a large nuclear reactor, a loss of coolant accident can damage the core: for example, at Three Mile Island a recently shutdown (SCRAMed) PWR reactor was left for a length of time without cooling water. As 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 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. However, the main cause of 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 the containment building.

Transport

Transport accidents can cause 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 a gap on the underside. It is thought that no human has been seriously harmed by the escaping radiation.[23]

Equipment failure

Equipment failure is one possible type of accident, recently at Białystok in Poland the electronics associated with a particle accelerator used for the treatment of cancer suffered a malfunction.[24] 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 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 lead to patients receiving massive overdoses under a specific set of conditions.

Human error

A sketch used by doctors to determine the amount of radiation to which each person had been exposed during the Slotin excursion.

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.[25]

In 1946 Canadian Manhattan Project physicist Louis Slotin performed a risky experiment known as "tickling the dragon's tail" [26] 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 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 afterwards.

Lost source

Lost source accidents,[27][28] also referred to as an orphan source are incidents in which a radioactive source is lost, stolen or abandoned. The source then might cause harm to humans. For example, in 1996 sources were left behind by the Soviet army in Lilo, Georgia.[29] Another case occurred at Yanango where a radiography source was lost, also at Samut Prakarn a cobalt-60 teletherapy source was lost [30] and at Gilan in Iran a radiography source harmed a welder.[31] The best known example of this type of event is the Goiânia accident which occurred in Brazil.

The International Atomic Energy Agency has provided guides for scrap metal collectors on what a sealed source might look like.[32][33] The scrap metal industry is the one where lost sources are most likely to be found.[34]

Others

Some accidents defy classification. These accidents happen when the unexpected occurs with a radioactive source. For instance if a bird were to grab a radioactive source containing radium from a window sill and then fly away with it, return to its nest and then die shortly afterwards from direct irradiation then a minor radiation accident would have occurred. As the hypothetical act of placing the source on a window sill by a human permitted the bird access to the source, it is unclear how such an event should be classified, as a lost source event or a something else. Radium lost and found[35][36] describes a tale of a pig walking about with a radium source inside; this was a radium source lost from a hospital. There are also accidents which are "normal" industrial accidents that involve radioactive material. For instance a runaway reaction at Tomsk involving red oil caused radioactive material to be spread around the site.

For a list of many of the most important accidents see the International Atomic Energy Agency site.[37]

Analyses of nuclear power plant accidents

The Nuclear Regulatory Commission (NRC) now requires each nuclear power plant in the U.S. to have a probabilistic risk assessment (PRA) performed upon it. The two types of such plants in the US (as of 2007) are boiling water reactors and pressurized water reactors, and a study based on two early such PRAs was done (NUREG-1150) and released to the public. However, those early PRAs made unrealistically conservative assumptions, and the NRC is now generating a new study: SOARCA.

Template:Globalize/USA

Nuclear Regulatory Commission

Nuclear Regulatory Commission Headquarters and Regional staff members typically participate in four full-scale and emergency response exercises each year, selected from among the list of full-scale Federal Emergency Management Agency (FEMA)-graded exercises required of nuclear facilities. Regional staff members and selected Headquarters staff also participate in post-plume, ingestion phase response exercises. On-scene participants include the NRC licensee, and State, county, and local emergency response agencies.[38] This allows for Federal interagency participation that will provide increased preparedness during the potential for an event at an operating nuclear reactor.

The US Nuclear Regulatory Commission, (NRC) collects reports of incidents occurring at regulated facilities. The agency currently[39] uses a 4 level taxonomy to classify reported incidents:[40]

  • Notification of Unusual Event (not listed as accidents below)
Unusual events are in process or have occurred which indicate a potential degradation of the level of safety of the plant. No releases of radioactive material requiring offsite response or monitoring are expected unless further degradation of safety systems occurs.

Not all reportable events constitute accidents. Incidents which threaten the normal operation or security of a facility may be reportable but not result in any release of radioactivity.

The United States Department of Energy uses a similar classification system for events occurring at fuel cycle plants and facilities owned by the US government which are therefore regulated by the DOE instead of the NRC.

NRC Alerts

Events are in process or have occurred which involve an actual or potential substantial degradation of the level of safety of the plant. Any releases expected to be limited to small fractions of the EPA Protective Action Guideline exposure levels.

NRC Site Area Emergencies

Events are in process or have occurred which involve actual or likely major failures of plant functions needed for protection of the public. Any releases not expected to exceed EPA Protective Action Guideline exposure levels except near site boundary.

NRC General Emergencies

Events are in process or have occurred which involve actual or imminent substantial core degradation or melting with potential for loss of containment integrity. Releases can be reasonably expected to exceed EPA Protective Action Guideline exposure levels offsite for more than the immediate site area.

See also

References

  1. ^ Staff, IAEA, AEN/NEA. [www-pub.iaea.org/MTCD/publications/PDF/INES-2009_web.pdf International Nuclear and Radiological Events Scale Users' Manual, 2008 Edition] (PDF) (in Technical English). Vienna, Austria: International Atomic Energy Agency. p. 184. Retrieved 2010-07-26. {{cite book}}: Check |url= value (help)CS1 maint: multiple names: authors list (link) CS1 maint: unrecognized language (link)
  2. ^ a b M.V. Ramana. Nuclear Power: Economic, Safety, Health, and Environmental Issues of Near-Term Technologies, Annual Review of Environment and Resources, 2009, 34, p. 136.
  3. ^ Arm, Stuart T. (2010). "Nuclear Energy: A Vital Component of Our Energy Future" (PDF). Chemical Engineering Progress. New York, NY: American Institute of Chemical Engineers: 27–34. ISSN 0360-7275. OCLC 1929453. Retrieved 2010-07-26. {{cite journal}}: Unknown parameter |month= ignored (help)
  4. ^ a b c d e Benjamin K. Sovacool. A Critical Evaluation of Nuclear Power and Renewable Electricity in Asia Journal of Contemporary Asia, Vol. 40, No. 3, August 2010, pp. 393–400.
  5. ^ a b Medical management of radiation accidents pp. 299 & 303.
  6. ^ a b c Strengthening the Safety of Radiation Sources p. 15. Cite error: The named reference "rad" was defined multiple times with different content (see the help page).
  7. ^ a b Lost Iridium-192 Source
  8. ^ a b The Radiological Accident in Goiania p. 2.
  9. ^ a b c d Pallava Bagla. "Radiation Accident a 'Wake-Up Call' For India's Scientific Community" Science, Vol. 328, 7 May 2010, p. 679.
  10. ^ a b c Benjamin K. Sovacool. A preliminary assessment of major energy accidents, 1907–2007, Energy Policy 36 (2008), pp. 1802-1820.
  11. ^ Research Report #20. United Kingdom: University of East Anglia. 1994. {{cite book}}: |journal= ignored (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)
  12. ^ Hirschberg et al, Paul Scherrer Institut, 1996; in: IAEA, Sustainable Development and Nuclear Power, 1997
  13. ^ Severe Accidents in the Energy Sector, Paul Scherrer Institut, 2001.
  14. ^ "Senator Reid tells America coal makes them sick". 2008-07-10. Retrieved 2009-05-18.
  15. ^ "Deadly power plants? Study fuels debate". 2004-06-09. Retrieved 2009-05-18.
  16. ^ Scientific American, December 13, 2007"Coal Ash Is More Radioactive than Nuclear Waste". 2009-05-18. Retrieved 2009-05-18.
  17. ^ Benjamin K. Sovacool (2009). The Accidental Century - Prominent Energy Accidents in the Last 100 Years
  18. ^ a b c Timeline: Nuclear plant accidents BBC News, 11 July 2006.
  19. ^ Samuel Upton Newtan. Nuclear War I and Other Major Nuclear Disasters of the 20th Century 2007, pp. 237–240.
  20. ^ The Worst Nuclear Disasters
  21. ^ [1]
  22. ^ [2]
  23. ^ "Road container 'leaked radiation'". BBC News. February 17, 2006.
  24. ^ [3]
  25. ^ Benjamin K. Sovacool. A Critical Evaluation of Nuclear Power and Renewable Electricity in Asia, Journal of Contemporary Asia, Vol. 40, No. 3, August 2010, p. 381.
  26. ^ Jungk, Robert. Brighter than a Thousand Suns. 1956. p.194
  27. ^ IAEA BULLETIN, 41/3/1999
  28. ^ [4]
  29. ^ The radiological accident in Lilo, Georgia, WHO/REMPAN, 2002
  30. ^ [5]
  31. ^ [6]
  32. ^ [7]
  33. ^ [8]
  34. ^ [9]
  35. ^ [10]
  36. ^ [11]
  37. ^ [12]
  38. ^ [13]
  39. ^ As of 2006
  40. ^ Criterion for Preparation and Evaluation of Radiological Emergency Response Plans and Preparedness in support of Nuclear Power Plants
  41. ^ NRC Information Notice 2000-09
  42. ^ NRC Event Number 42348
  43. ^ NRC Event Number 40405
  44. ^ ref NRC Event Number 37193
  45. ^ NRC Event Number 37337
  46. ^ NRC Event Number 35915
  47. ^ NRC Commission Paper SECY 96-076
  48. ^ NRC Information Notice 91-64
  49. ^ NRC Information Notice 90-25
  50. ^ NRC Information Notice 85-80
  51. ^ NRC Generic Letter GL-82008
  52. ^ NRC Generic Letter GL-82011
  53. ^ NUREG-0909 and NUREG-0916 both seem to be missing from the NRC web site

External links

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