A partial meltdown of a reactor's uranium core at the Chalk River plant near Ottawa, Canada, resulted after the accidental removal of four control rods. Although millions of gallons of radioactive water poured into the reactor, there were no injuries.
Fire destroyed the core of a plutonium-producing reactor at Britain's Windscale nuclear complex - since renamed Sellafield - sending clouds of radioactivity into the atmosphere. An official report said the leaked radiation could have caused dozens of cancer deaths in the vicinity of Liverpool.
A serious accident occurred during the winter of 1957-58 near the town of Kyshtym in the Urals. A Russian scientist who first reported the disaster estimated that hundreds died from radiation sickness.
January 3, 1961
Three technicians died at a U.S. plant in Idaho Falls in an accident at an experimental reactor.
July 4, 1961
The captain and seven crew members died when radiation spread through the Soviet Union's first nuclear-powered submarine. A pipe in the control system of one of the two reactors had ruptured.
October 5, 1966
The core of an experimental reactor near Detroit, Mich., melted partially when a sodium cooling system failed.
January 21, 1969
A coolant malfunction from an experimental underground reactor at Lucens Vad, Switzerland, releases a large amount of radiation into a cave, which was then sealed.
December 7, 1975
At the Lubmin nuclear power complex on the Baltic coast in the former East Germany, a short-circuit caused by an electrician's mistake started a fire. Some news reports said there was almost a meltdown of the reactor core.
The worst nuclear accident in the United States occurred when a small amount of radiation was released from a partial meltdown at the Three Mile Island nuclear power plant near Harrisburg, Pa. Almost 150,000 people were evacuated after the accident, which was attributed to human error and mechanical failure.
February 11, 1981
Eight workers are contaminated when more than 100,000 gallons of radioactive coolant fluid leaks into the contaminant building of the Tennessee Valley Authority's Sequoyah 1 plant in Tennessee.
April 25, 1981
Officials said around 45 workers were exposed to radioactivity during repairs to a plant at Tsuruga, Japan.
The world's worst nuclear disaster occurred at Ukraine's Chernobyl No. 4 reactor, which exposed large areas of Europe to radiation as it drifted across the continent. At least 31 people died during the accident and an estimated thousands have died since. The current evacuation zone is nearly 2,000 square miles.
March 24, 1992
At the Sosnovy Bor station near St. Petersburg, Russia, radioactive iodine escaped into the atmosphere. A loss of pressure in a reactor channel was the source of the accident.
In France's most serious nuclear accident, three workers were contaminated after entering a nuclear particle accelerator in Forbach without protective clothing. Executives were jailed in 1993 for failing to take proper safety measures.
Two to three tons of sodium accidentally leaked from the secondary cooling system of Japan's Monju prototype fast-breeder nuclear reactor.
The state-run Power Reactor and Nuclear Fuel Development Corporation reprocessing plant at Tokaimura, Japan, contaminated at least 35 workers with minor radiation after a fire and explosion occurred.
A fire and explosion at the state-run Power Reactor and Nuclear Fuel Development Corporation reprocessing plant at Tokaimura contaminated at least 35 workers with radiation and killing two in Japan's worst nuclear accident to date. Workers had been mixing uranium with nitric acid to make nuclear fuel, but had used too much uranium and set off the accidental uncontrolled reaction.
February 16, 2002
Severe corrosion of reactor vessel head forces 24-month outage of Davis-Besse reactor in Ohio.
April 10, 2003
Collapse of fuel rods at Hungary's Paks Nuclear Power Plant unit 2 during its corrosion cleaning led to leakage of radioactive gases. It remained inactive for 18 months.
August 9, 2004
Steam explosion at Japan's Mihama Nuclear Power Plant kills 4 workers and injures 7 more.
March 11, 2011
A tsunami flooded and damaged the Fukushima Daiichi nuclear power plant's 3 active reactors, drowning two workers. Loss of backup electrical power led to overheating, meltdowns, and evacuations. This accident is the second worst on record.
September 12, 2011
One person was killed and four injured, one seriously, in a blast at the France's Marcoule Nuclear Site. The explosion took place in a furnace used to melt metallic waste.
A second, but smaller, nuclear accident took place Fukushima Daiichi facility when approximately 300 tonnes (330 tons) of irradiated water used in ongoing cooling operations in reactors 1, 2, and 3 was discharged into the landscape
August 8, 2019
A radiation accident at the State Central Navy Testing Range at Nyonoksa, near Severodvinsk, Russia. Five military and civilian specialists were killed.