Dec. 12, 1952
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.
Oct. 7, 1957
AP Photo
Fire destroyed the core of a plutonium-producing reactor at Britain's Windscale nuclear complex, sending clouds of radioactivity into the atmosphere. Leaked radiation may have caused dozens of cancer deaths.
Winter 1957-'58
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.
Jan. 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.
Oct. 5, 1966
The core of an experimental reactor near Detroit, Mich., melted partially when a sodium cooling system failed.
Jan. 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.
Dec. 7, 1975
AP Photo
An accident occurred at the Lubmin nuclear power complex near Greifswald on the Baltic coast in 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.
March 28, 1979
AP Photo
America's worst nuclear accident occurred at the Three Mile Island plant near Harrisburg, Pa. A partial meltdown of one of the reactors forced the evacuation of residents after radioactive gas leaked into the atmosphere.
Aug. 7, 1979
Highly enriched uranium spewed out of a top-secret nuclear fuel plant in Tennessee. Around 1,000 people were contaminated with up to five times as much radiation as they would normally receive in a year.
Feb. 11, 1981
AP Photo
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 problem-ridden plant at Tsuruga, Japan.
Aug. 10, 1985
An explosion devastated the Shkotovo-22 ship repair facility which services Soviet navy nuclear-powered vessels. Ten people were killed and many died later from radiation exposure.
Jan. 6, 1986
One worker died and 100 were injured at a plant in Oklahoma when a cylinder of nuclear material burst after being improperly heated.
April 26, 1986
AP Photo
In the world's worst nuclear accident, an explosion and fire at the Chernobyl nuclear plant spewed radiation over much of Europe. Thirty-one people died in the immediate aftermath of the explosion.
March 24, 1992
Radioactive iodine and inert gases escaped into the atmosphere after a loss of pressure in a reactor channel at the Sosnovy Bor station near St. Petersburg in Russia.
November 1992
AP Photo
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.
November 1995
At Chernobyl, serious contamination occurred when fuel was being removed from one of the reactors. One person received the equivalent of a year's permitted radiation.
November 1995
Two to three tons of sodium leaked from the secondary cooling system of Japan's Monju prototype fast-breeder nuclear reactor in an accident.
March 1997
AP Photo
A fire and explosion at the state-run Power Reactor and Nuclear Fuel Development Corporation reprocessing plant at Tokaimura, Japan, contaminated at least 35 workers with minor radiation.
Sept. 30, 1999
Japan's worst nuclear accident occurred at a uranium processing plant in Tokaimura. The accidental reaction occurred while workers were processing uranium into fuel for nuclear power plants.