Current Table

Selected Examples of Historic Nuclear Events, as Classified by the INES Scale (1)


Level INES description Example Location Year
1 Anomaly Fast stop of the main circulation pumps
and simultaneous loss of their fly wheel
systems during reactor scram
Olkiluoto Nuclear Power Plant,  Finland 2008
    Exposure of two workers in the nuclear power plant beyond the dose constraints Rajasthan Nuclear Power Plant, India 2012
2 Incident Reactor trip due to high pressure in the reactor pressure vessel Laguna Verde Nuclear
Power Plant, Mexico
    Overexposure of a practitioner in interventional radiology exceeding the annual limit Paris, France 2013
3 Serious incident Release of iodine 131 into the environment from the radioelements production facility Fleurus, Belgium 2008
    Severe overexposure of a radiographer Lima, Peru 2012
4 Accident with local consequences Radioactive material in scrap metal facility resulted in acute exposure of scrap dealer New Delhi, India 2010
    Overexposure of four workers at an irradiation facility Stamboliysky, Bulgaria 2011
5 Accident with wider consequences Severe damage to the reactor core Three Mile Island Nuclear Power Plant, USA 1979
    Four people died after being overexposed from an abandoned and ruptured high activity source Goiania, Brazil  1987
6 Serious accident Significant release of radioactive material to the environment after the explosion of a high activity waste tank Kyshtym, Russian Federation 1957
7 Major accident Significant release of radioactive material to the environment resulting in widespread health and environmental effects  Chernobyl, Ukraine 1986
    Significant release of radioactive material to the environment resulting in widespread environmental effects Fukushima, Japan 2011

(1) International Nuclear and Radiological Event Scale.

Source: International Atomic Energy Agency. INES Flyer.

Rank Date Location Description Fatalities  In 2006 dollars
($ millions) (2)
1 April 26, 1986 Kiev, Ukraine 

Mishandled reactor safety test at Chernobyl
nuclear reactor causes steam explosion
and meltdown, necessitating the evacuation of
300,000 people from Kiev and dispersing
radioactive material across Europe

4,056 $6,700
2 March 28, 1979 Middletown, Pennsylvania,
United States
Equipment failures and operator error contribute to loss of coolant and partial core meltdown at Three Mile Island nuclear reactor 0 2,400
3 March 9, 1985 Athens, Alabama, United States Instrumentation systems malfunction during startup, convincing the Tennessee Valley Authority to suspend operations at all three Browns Ferry Units  0 1,830
4 February 22, 1977 Jaslovske Bohunice, Czechoslovakia  Mechanical failure during fuel loading causes severe corrosion of reactor and release of radioactivity into the plant area, necessitating total decommission  0 1,700
5 April 11, 1986 Plymouth, Massachusetts, United States Recurring equipment problems with instrumentation, vacuum breakers, instrument air system, and main transformer force emergency shutdown of Boston Edison’s Pilgrim nuclear facility 0 1,001
6 February 1, 2010 Montpelier, Vermont, United States Deteriorating underground pipes from the Vermont Yankee nuclear power plant leak radioactive tritium into groundwater supplies in Vermont, resulting in the eventual shutdown of the plant 0 700
7 December 26, 1985 Clay Station, California, United States Safety and control systems unexpectedly fail at Rancho Seco nuclear reactor, ultimately leading to the premature closure of the plant 0 672
8 November 24, 1989 Greifswald, East Germany Electrical error causes fire in the main trough that destroys control lines and 5 main coolant pumps and almost induces meltdown 0 443
9 March 31, 1987 Delta, Pennsylvania, United States Philadelphia Electric Company shuts down Peach Bottom units 2 and 3 due to cooling malfunctions and unexplained equipment problems 0 400
10 September 2, 1996 Crystal River, Florida, United States Balance-of-plant equipment malfunction forces Florida Power Corporation to shut down Crystal River Unit 3 and make extensive repairs 0 384
11 May 4, 1987 Kalpakkam, India Fast Breeder Test Reactor at Kalpakkam has to shut down due to the simultaneous occurrence of pump failures, faulty instrument signals, and turbine malfunctions that culminate in a refuelling accident that ruptures the reactor core with 23 fuel assembles, resulting in a two year shutdown 0 300
12 February 2, 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
13 May 4, 1986 Hamm-Uentrop, Germany Operator actions to dislodge damaged fuel rod at Experimental High Temperature Gas Reactor release excessive radiation to 4 square kilometers surrounding the facility 0 267
14 February 20, 1996 Waterford, Connecticut, United States Leaking valve forces Northeast Utilities Company to shut down Millstone Units 1 and 2, further inspection reveals multiple equipment failures 0 254
15 March 22, 1975 Browns Ferry, Alabama, United States Fire burns for seven hours and damages more than 1,600 control cables for three nuclear reactors, disabling core cooling systems 0 240
16 March 31, 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
17 December 19, 1987 Lycoming, New York, United States Fuel rod, waste storage, and water pumping malfunctions force Niagara Mohawk Power Corporation to shut down Nine Mile Point Unit 1 0 150
18 February 16, 2002 Oak Harbor, Ohio, United States Severe corrosion of control rod forces 24 month outage of Davis-Besse reactor 0 143
19 March 17, 1989 Lusby, Maryland, United States Inspections at Baltimore Gas & Electric’s Calvert Cliff Units 1 and 2 reveal cracks at pressurized heater sleeves, forcing extended shutdowns 0 120
20 September 15, 1984 Athens, Alabama, United States Safety violations, operator error, and design problems force 6 year outage at Browns Ferry Unit 2 0 110
20 August 27, 2009 St. Petersburg, Russia A cracked discharge accumulator and malfunctioning feed pump force the Leningrad Nuclear Power Plant reactor number 3 to close for extended repairs 0 110

(1) As of February 2011. Does not include the unfolding March 2011 incident in Japan.
(2) Total economic losses, including destruction of property, emergency response, environmental remediation, evacuation, lost product, fines, and court and insurance claims.

Source: Benjamin K. Sovacool, Contesting the Future of Nuclear Power: A Critical Global Assessment of Atomic Energy (London: World Scientific, 2011).