Overview

Globally, there have been at least 99 (civilian and military) recorded nuclear power plant accidents 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. Property damage costs include destruction of property, emergency response, environmental remediation, evacuation, lost product, fines, and court claims.^[2] Because nuclear power plants are large and complex accidents onsite tend to be relatively expensive.^[3]
The 1979 Three Mile Island accident in Pennsylvania was caused by a series of failures in secondary systems at the reactor, which allowed radioactive steam to escape and resulted in the partial core meltdown of one of two reactors at the site, making it the most significant accident in U.S. history.^[4]
The world's worst nuclear accident has been the 1986 Chernobyl disaster in the Ukraine, the only accident that has been rated as a level 7 event on the International Nuclear Event Scale.^[5] The accident occurred at the Chernobyl Nuclear Power Plant after an unsafe systems test led to a rupture of the reactor vessel and a series of explosions that destroyed reactor number four. The radiation plume spread to the surrounding city of Pripyat and covered extensive portions of Europe with traces of radioactivity, leaving reindeer in Northern Europe and sheep in portions of England unfit for human consumption. A 30 kilometres (19 mi) "Zone of alienation" has been formed around the reactor.^[6]
At least fifty-seven accidents have occurred since the Chernobyl disaster, and over 56 nuclear accidents have occurred in the USA. Relatively few accidents have involved fatalities.^[2]

Canada

Chalk River Laboratories

China

Nuclear power accidents in China

Date	Location	Description	Fatalities	Cost (in millions 2006 US$)
*

France

Nuclear power accidents in France

Date	Location	Description	Fatalities	Cost (in millions 2006 US$)
25 Jul 1979	Saclay, France	Radioactive fluids escape into drains designed for ordinary wastes, seeping into the local watershed at the Saclay BL3 Reactor	0	5
13 Mar 1980	Loir-et-Cher, France	A malfunctioning cooling system fuses fuel elements together at the Saint Laurent A2 reactor, ruining the fuel assembly and forcing an extended shutdown	0	22
14 Apr 1984	Bugey, France	Electrical cables fail at the command centre of the Bugey Nuclear Power Plant and force a complete shutdown of one reactor	0	2
22 May 1986	Normandy, France	A reprocessing plant at Le Hague malfunctions and exposes workers to unsafe levels of radiation and forces five to be hospitalised	0	5
12 Apr 1987	Tricastin, France	Tricastin fast breeder reactor leaks coolant, sodium and uranium hexachloride, injuring seven workers and contaminating water supplies	0	50
27 Dec 1999	Blayais, France	An unexpectedly strong storm floods the Blayais Nuclear Power Plant, forcing an emergency shutdown after injection pumps and containment safety systems fail from water damage	0	55
21 Jan 2002	Manche, France	Control systems and safety valves fail after improper installation of condensers, forcing a two-month shutdown	0	102
16 May 2005	Lorraine, France	Sub-standard electrical cables at the Cattenon-2 nuclear reactor cause a fire in an electricity funnel, damaging safety systems	0	12
13 Jul 2008	Tricastin, France	Dozens of litres of wastewater contaminated with uranium are accidentally poured on the ground and runoff into a nearby river	0	7
12 Aug 2009	Gravelines, France	Assembly system fails to properly eject spent fuel rods from the Gravelines Nuclear Power Plant, causing the fuel rods to jam and the reactor to shut down	0	2

Germany

Nuclear power accidents in Germany

Date	Location	Description	Fatalities	Cost (in millions 2006 US$)
4 May 1986	Hamm-Uentrop, Germany	Operator actions to dislodge damaged fuel elements at the thorium high-temperature reactor release excessive radiation to 4 km2 surrounding the facility	0	267
17 Dec 1987	Hesse, Germany	Stop valve fails at Biblis Nuclear Power Plant and contaminates local area	0	13
07 Dec 1975	Greifswald, East Germany	Electrical error at Greifswald Nuclear Power Plant causes a fire in the main trough and destroys control lines and the electric supply for 5 main coolant pumps (out of a total of 6) and induces a partial meltdown in bloc 1. Ultimately classified as INES 3. The incident was not reported to the public until 14 years after it occurred.	0	443
Nov 24, 1989	Greifswald, East Germany	A near core meltdown occurs at Greifswald Nuclear Power Plant. It's the fifth dangerous incident at the plant. Three out of six cooling water pumps were switched off for a test. A fourth pump broke down and control of the reactor was lost; 10 fuel elements were damaged. The accident was reportedly attributed to sticky relay contacts [8]

India

Nuclear power accidents in India

Date	Location	Description	Fatalities	Cost (in millions 2006 US$)
4 May 1987	Kalpakkam, India	Fast Breeder Test Reactor at Kalpakkam refuelling accident that ruptures the reactor core, resulting in a two-year shutdown	0	300
10 Sep 1989	Tarapur, Maharashtra, India	Operators at the Tarapur Atomic Power Station find that the reactor had been leaking radioactive iodine at more than 700 times normal levels. Repairs to the reactor take more than a year	0	78 The on line hours of unit 1&2 in 1990 were 7772 and 7827 hrs (source IAEA PRIS. Repairs lasting more than one year from 10 Sep 1989 can not yield such on line hours.surely something is wrong.
13 May 1992	Tarapur, Maharashtra, India	A malfunctioning tube causes the Tarapur Atomic Power Station to release 12 curies of radioactivity	0	2
31 Mar 1993	Bulandshahr, Uttar Pradesh, India	The Narora Atomic Power Station suffers a fire at two of its steam turbine blades, damaging the heavy water reactor and almost leading to a meltdown	0	220 The cost data is not on comparable basis. 2400 or so US 2006 $s for TMI and 220 for NAPS unit 1 is wrong.
2 Feb 1995	Kota, Rajasthan, India	The Rajasthan Atomic Power Station leaks radioactive helium and heavy water into the Rana Pratap Sagar River, necessitating a two-year shutdown for repairs		280
22 Oct 2002	Kalpakkam, India	Almost 100 kg radioactive sodium at a fast breeder reactor leaks into a purification cabin, ruining a number of valves and operating systems	0	30

Japan

See also: Timeline of the Fukushima nuclear accidents

Nuclear power accidents in Japan

Date	Location	Description	Fatalities	Cost (in millions 2006 US$)
25 Jul 1979	Japan	Radioactive fluids escape into drains designed for ordinary wastes, seeping into the local watershed at the Saclay BL3 Reactor
1981	Japan	Almost 300 workers were exposed to excessive levels of radiation after a fuel rod ruptured during repairs at the Tsuruga Nuclear Power Plant.[9]
December 1995	Japan	The fast breeder Monju Nuclear Power Plant sodium leak.[9] State-run operator Donen was found to have concealed videotape footage that showed extensive damage to the reactor.
March 1997	Japan	The Tokaimura nuclear reprocessing plant fire and explosion, northeast of Tokyo. 37 workers were exposed to low doses of radiation. Donen later acknowledged it had initially suppressed information about the fire.
1999	Japan	A fuel loading system malfunctioned at a nuclear plant in the Fukui Prefecture and set off an uncontrolled nuclear reaction and explosion.[9]
September 1999	Japan	The criticality accident at the Tokai fuel fabrication facility.[9] Hundreds of people were exposed to radiation and two workers later died.[10]
2002	Japan	Two workers were exposed to a small amount of radiation and suffered minor burns during a fire at Onagawa Nuclear Power Station in northern Japan.[10]
9 August 2004	Japan	five workers were killed after a steam explosion at the Mihama-3 station; the subsequent investigation revealed a serious lack in systematic inspection in Japanese nuclear plants, which led to a massive inspection program.[11]
2006	Japan	A small amount of radioactive steam was released at the Fukushima Dai-ichi plant and it escaped the compound.[10]
16 July 2007	Japan	a severe earthquake (measuring 6.8 on the Richter scale) hit the region where Tokyo Electric's Kashiwazaki-Kariwa Nuclear Power Plant is located and radioactive water spilled into the Sea of Japan; as of March 2009, all of the reactors remain shut down for damage verification and repairs; the plant with seven units was the largest single nuclear power station in the world.[11]
2011	Japan	A magnitude 9.0 earthquake and associated tsunami triggered cooling problems at Fukushima 1 & 2 stations with several reactors. There were hydrogen explosions and a fire caused by overheating spent fuel rods. Some radioactivity was released. Some immediate injuries resulted.

Other Key Events

Description
2000 Japan Three Tokyo Electric Power Co. executives were forced to quit after the company in 1989 ordered an employee to edit out footage showing cracks in nuclear plant steam pipes in video being submitted to regulators.
August 2002 Japan A widespread falsification scandal starting in that led to the shut down of all Tokyo Electric Power Company’s 17 nuclear reactors; Tokyo Electric's officials had falsified inspection records and attempted to hide cracks in reactor vessel shrouds in 13 of its 17 units.[11]

Ukraine

Nuclear power accidents in Ukraine

Date	Location	Description	Fatalities	Cost (in millions 2006 US$)
26 Apr 1986	Pripyat, Ukraine	Steam explosion and meltdown (see Chernobyl disaster) necessitating the evacuation of 300,000 people from Pripyat and dispersing radioactive material across Europe (see Chernobyl disaster effects)	Fewer than 50 directly, Eventually as many as 4,000[12]	6700

United Kingdom

Nuclear power accidents in the UK

Date	Location	Description	Fatalities	Cost (in millions 2006 US$)
8 Oct 1957	Windscale, UK	Fire ignites plutonium piles, contaminating surrounding dairy farms	33 estimated by UK government[13]	78
19 Apr 2005	Sellafield, UK	20 tonnes uranium and 160 kg plutonium leak from a cracked pipe at the Thorp nuclear fuel reprocessing plant	0	65

United States

Main article: Nuclear reactor accidents in the United States

Nuclear reactor accidents in the U.S.^[14][3]

Date	Location	Description	Fatalities	Cost (in millions 2006 US$)	INES rating
July 26, 1959	Simi Valley, California, USA	Partial core meltdown at Santa Susana Field Laboratory’s Sodium Reactor Experiment	0	32
January 3, 1961	Idaho Falls, Idaho, US	Explosion at National Reactor Testing Station	3	22
October 5, 1966	Monroe, Michigan, USA	Sodium cooling system malfunctions at Enrico Fermi demonstration breeder reactor causing partial core meltdown	0	19
July 16, 1971	Cordova, Illinois, USA	An electrician is electrocuted by a live cable at the Quad Cities Unit 1 reactor on the Mississippi River	1	1
August 11, 1973	Palisades, Michigan, USA	Steam generator leak causes manual shutdown of pressurized water reactor	0	10
March 22, 1975	Browns Ferry, Alabama, USA	Fire burns for seven hours and damages more than 1600 control cables for three nuclear reactors at Browns Ferry, disabling core cooling systems	0	240
November 5, 1975	Brownsville, Nebraska, USA	Hydrogen gas explosion damages the Cooper Nuclear Facility’s Boiling Water Reactor and an auxiliary building	0	13
June 10, 1977	Waterford, Connecticut, USA	Hydrogen gas explosion damages three buildings and forces shutdown of Millstone-1 Pressurized Water Reactor	0	15
February 4, 1979	Surry, Virginia, USA	Surry Unit 2 shut down in response to failing tube bundles in steam generators	0	12
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	2,400
November 22, 1980	San Clemente, California, USA	Worker cleaning breaker cubicles at San Onofre Pressurized Water Reactor contacts an energized line and is electrocuted	1	1
October 17, 1981	Buchanan, New York, USA	100,000 gallons of Hudson River water leaked into the Indian Point Energy Center Unit 2 containment building from the fan cooling unit, undetected by a safety device designed to detect hot water. The flooding, covering the first 9 feet of the reactor vessel, was discovered when technicians entered the building. Two pumps which should have removed the water were found to be inoperative. NRC proposed a $210,000 fine for the incident. [15]	0	-
February 26, 1982	San Clemente, California, USA	Southern California Company shuts down San Onofre Unit 1 out of concerns about earthquake	0	1
March 20, 1982	Lycoming, New York, USA	Recirculation system piping fails at Nine Mile Point Unit 1, forcing two year shutdown	0	45
March 25 1982	Buchanan, New York, USA	Damage to steam generator tubes and main generator resulting in a shut down Indian Point Energy Center Unit 3 for more than a year	0	56
June 18, 1982	Senaca, South Carolina, USA	Feedwater heat extraction line fails at Oconee 2 Pressurised Water Reactor, damaging thermal cooling system	0	10
February 12, 1983	Fork River, New Jersey, USA	Oyster Creek Nuclear Power Plant fails safety inspection, forced to shut down for repairs	0	32
February 26, 1983	Fort Pierce, Florida, USA	Damaged thermal shield and core barrel support at St Lucie Unit 1, necessitating 13-month shutdown	0	54
September 15, 1984	Athens, Alabama, US	Safety violations, operator error, and design problems force six year outage at Browns Ferry Unit 2	0	110
March 9, 1985	Athens, Alabama, US	Instrumentation systems malfunction during start-up, which led to suspension of operations at all three Browns Ferry Units	0	1,830
April 11, 1986	Plymouth, Massachusetts, US	Recurring equipment problems force emergency shutdown of Boston Edison’s Pilgrim Nuclear Power Plant	0	1,001
March 31, 1987	Delta, Pennsylvania, US	Peach Bottom units 2 and 3 shutdown due to cooling malfunctions and unexplained equipment problems	0	400
July 15, 1987	Burlington, Kansas, USA	Safety inspector dies from electrocution after contacting a mislabeled wire	1	1
December 19, 1987	Lycoming, New York, US	Malfunctions force Niagara Mohawk Power Corporation to shut down Nine Mile Point Unit 1	0	150
March 29, 1988	Burlington, Kansas, USA	A worker falls through an unmarked manhole and electrocutes himself when trying to escape	1	1
September 10, 1988	Surry, Virginia, USA	Refuelling cavity seal fails and destroys internal pipe system at Surry Unit 2, forcing 12-month outage	0	9
March 5, 1989	Tonopah, Arizona, USA	Atmospheric dump valves fail at Palo Verde Unit 1, leading to main transformer fire and emergency shutdown	0	14
March 17, 1989	Lusby, Maryland, US	Inspections at Calvert Cliff Units 1 and 2 reveal cracks at pressurized heater sleeves, forcing extended shutdowns	0	120
November 17, 1991	Scriba, New York, USA	Safety and fire problems force shut down of the FitzPatrick nuclear reactor for 13 months	0	5
April 21, 1992	Southport, North Carolina, USA	NRC forces shut down of Brunswick Units 1 and 2 after emergency diesel generators fail	0	2
February 3, 1993	Bay City, Texas, USA	Auxiliary feed-water pumps fail at South Texas Project Units 1 and 2, prompting rapid shutdown of both reactors	0	3
February 27, 1993	Buchanan, New York, USA	New York Power Authority shuts down Indian Point Energy Center Unit 3 after AMSAC system fails	0	2
March 2, 1993	Soddy-Daisy, Tennessee, USA	Equipment failures and broken pipes cause shut down of Sequoyah Unit 1	0	3
December 25, 1993	Newport, Michigan, USA	Shut down of Fermi Unit 2 after main turbine experienced major failure due to improper maintenance	0	67
14 January 1995	Wiscasset, Maine, USA	Steam generator tubes unexpectedly crack at Maine Yankee nuclear reactor; shut down of the facility for a year	0	62
May 16, 1995	Salem, New Jersey, USA	Ventilation systems fail at Salem Units 1 and 2	0	34
February 20, 1996	Waterford, Connecticut, US	Leaking valve forces shutdown Millstone Nuclear Power Plant Units 1 and 2, multiple equipment failures found	0	254
September 2, 1996	Crystal River, Florida, US	Balance-of-plant equipment malfunction forces shutdown and extensive repairs at Crystal River Unit 3	0	384
September 5, 1996	Clinton, Illinois, USA	Reactor recirculation pump fails, prompting shut down of Clinton boiling water reactor	0	38
September 20, 1996	Senaca, Illinois, USA	Service water system fails and results in closure of LaSalle Units 1 and 2 for more than 2 years	0	71
September 9, 1997	Bridgman, Michigan, USA	Ice condenser containment systems fail at Cook Units 1 and 2	0	11
May 25, 1999	Waterford, Connecticut, USA	Steam leak in feed-water heater causes manual shutdown and damage to control board annunicator at the Millstone Nuclear Power Plant	0	7
September 29, 1999	Lower Alloways Creek, New Jersey, USA	Major Freon leak at Hope Creek Nuclear Facility causes ventilation train chiller to trip, releasing toxic gas and damaging the colling system	0	2
February 16, 2002	Oak Harbor, Ohio, US	Severe corrosion of control rod forces 24-month outage of Davis-Besse reactor	0	143
January 15, 2003	Bridgman, Michigan, USA	A fault in the main transformer at the Donald C. Cook nuclear power plant causes a fire that damages the main generator and back-up turbines	0	10
June 16, 2005	Braidwood, Illinois, USA	Exelon’s Braidwood nuclear station leaks tritium and contaminates local water supplies	0	41
August 4, 2005	Buchanan, New York, USA	Entergy’s Indian Point Energy Center Nuclear Plant leaks tritium and strontium into underground lakes from 1974 to 2005		30
March 6, 2006	Erwin, Tennessee, USA	Nuclear fuel services plant spills 35 litres of highly enriched uranium, necessitating 7-month shutdown	0	98
January 7, 2010	Buchanan, New York, USA	NRC inspectors reported that an estimated 600,000 gallons of mildly radioactive steam was intentionally vented after an automatic shutdown of Indian Point Energy Center Unit 2. The levels of tritium in the steam were below those allowable by NRC safety standards.[16]	0	-
February 1, 2010	Montpelier, Vermont, US	Deteriorating underground pipes from the Vermont Yankee Nuclear Power Plant leak radioactive tritium into groundwater supplies	0	700

This list is incomplete; please help to expand it.

Nuclear safety

Main article: Nuclear safety

Internationally the International Atomic Energy Agency "works for the safe, secure and peaceful uses of nuclear science and technology."^{[citation needed]} Many nations utilizing nuclear power have special institutions overseeing and regulating nuclear safety.
Civilian nuclear safety in the U.S. is regulated by the Nuclear Regulatory Commission (NRC). The safety of nuclear plants and materials controlled by the U.S. government for research, weapons production, and those powering naval vessels is not governed by the NRC.^[17][18]
In the UK nuclear safety is regulated by the Office for Nuclear Regulation (ONR) and the Defence Nuclear Safety Regulator (DNSR).