Twenty-five years after Chernobyl and following the recent Fukushima disaster in Japan, a listing of nuclear accidents that have occurred around the world
December 12, 1952
Partial meltdown of a reactor’s uranium core occurred at the Chalk River plant near Ottawa, Canada, due to the removal of four control rods. Millions of gallons of radioactive water were poured into the reactor. There were no injuries.
October 10, 1957
Fire destroyed the core of a plutonium-producing reactor at Britain’s Windscale nuclear complex (renamed Sellafield) sending clouds of radioactive substances into the atmosphere. The graphite core of the reactor caught fire, releasing substantial amounts of radioactive contamination into the surrounding area. The incident could have caused dozens of cancer deaths in the vicinity of Liverpool.
September 29, 1957
During the winter of 1957, near the town of Kyshtym, Russia, a cooling system in one of the tanks of a nuclear plant containing about 70–80 tonnes of liquid radioactive waste failed and was not repaired. The temperature in it started to rise, resulting in evaporation and a chemical explosion of the dried waste consisting mainly of ammonium nitrate and acetates. The explosion threw the 160-tonne heavy concrete lid into the air. There were no immediate casualties.
January 3, 1961
The SL1 or State Low Power Reactor Number 1 was a United States Army experimental reactor which underwent a steam explosion and meltdown on January 3, 1961, killing its three operators. The direct cause was improper withdrawal of the central control rod, responsible for absorbing neutrons in the poorly designed reactor core. The event is the only known fatal reactor accident in the United States.
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, Michigan, melted partially when a sodium cooling system failed. A zirconium plate at the bottom of a reactor vessel came loose during a test for full power. The plate blocked the flow of liquid sodium coolant, causing two fuel sub-assemblies to begin to melt. When radiation monitors sounded, operators shut down the reactor manually.
January 21, 1969
A coolant malfunction at an experimental underground reactor at Lucens Vad, Switzerland, led to partial core meltdown and massive radioactive contamination of the cavern, which was then sealed. The accident was caused by water condensation forming on some of the magnesium alloy fuel element components during shutdown, thereby corroding them. No workers were exposed to the radiation at the plant.
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 error started a fire. The fire in the main trough destroyed the electric supply and the control lines of five main coolant pumps. The fire was brought under control quickly. This incident was made known to the public only in 1989.
March 28, 1979
March 28, 1979
The Three Mile Island accident occurred near Harrisburg, Pennsylvania. It is considered to be America’s worst nuclear accident. Partial meltdown of one of the reactors (unit 2 -- a pressurised water reactor) forced the evacuation of residents after radioactive gas escaped into the atmosphere. It resulted in the release of 481 PBq (13 million curies) of radioactive gas, and less than 740 GBq (20 curies) of iodine-131. The mechanical failures were compounded by the initial failure of plant operators to recognise the situation as a loss-of-coolant accident due to inadequate training and human factors.
February 11, 1981
Eight workers were contaminated and more than 100,000 gallons of radioactive coolant fluid leaked at the Tennessee Valley Authority’s Sequoyah-1 plant in Tennessee, when an under-trained technician opened a valve at the plant.
April 25, 1981
Officials said around 45 workers were exposed to radioactivity during repairs to a plant at Tsuruga, Japan.
January 25, 1982
A steam generator pipe burst at the Ginna nuclear generating station, causing 15,000 gallons of radioactive coolant to leak and radioactive steam to be released into the atmosphere.
April 26, 1986
April 26, 1986
The world’s worst nuclear accident occurred after an explosion and fire at the Chernobyl nuclear power plant in Ukraine, causing the immediate death of 31 people. Hundreds of thousands of residents were moved from the area (between 1986 and 2000) and a similar number are believed to have suffered from the effects of radiation exposure.
March 24, 1992
At the Sosnovy Bor station near St Petersburg, Russia, radioactive iodine escaped into the atmosphere through a ruptured fuel channel. Loss of pressure in a reactor channel was the source of the accident.
In Forbach, France, three workers without protective clothing were contaminated after entering an electron accelerator irradiator used to treat granulated polytetrafluoroethylene (Teflon). Executives were jailed in 1993 for failing to take proper safety measures.
December 8, 1995
Around 700 kg of molten sodium leaked from the secondary cooling circuit of the Monju reactor, causing a fire. Although the accident itself did not result in a radiation leak, the sodium spill came very close to detonating Monju, a catastrophe which would have spilled plutonium into the environment.
Thirty-five workers were contaminated with minor radiation after a fire and explosion at Japan’s state-run Power Reactor and Nuclear Fuel Development Corporation reprocessing plant at Tokaimura, Japan.
September 30, 1999
Another accident at the uranium processing plant at the Tokaimura, Japan, plant exposed 55 workers to radiation. More than 300,000 people living near the plant were ordered to stay indoors. Workers had been mixing uranium with nitric acid to make nuclear fuel, but had used too much uranium which set off the accidental uncontrolled reaction.
February 16, 2002
Severe corrosion of a control rod forced the outage of the Davis-Besse reactor at Oak Harbour, Ohio, United States. Inspections found that an acid leak had nearly eaten through the reactor’s six-inch-thick steel cap. In September 2011, the Nuclear Regulatory Commission allowed it to resume operations.
August 9, 2004
An accident occurred in a building housing turbines for the Mihama 3 reactor in Japan. Hot water and steam leaked from a broken pipe killing four workers, and it resulted in seven others being injured. The accident was referred to as Japan’s worst nuclear power accident before the current crisis at the Fukushima nuclear power plant.
March 11, 2011
A cooling failure in four reactors following an earthquake, tsunami, multiple fires, and hydrogen explosions at the Fukushima nuclear power plant. People living within 10 km of the plant were evacuated from the site. Worldwide measurements of iodine-131 and caesium-137 indicate that the releases from Fukushima are of the same order of magnitude as the releases of those isotopes from the Chernobyl disaster in 1986. The International Atomic Energy Agency (IAEA) announced on March 27 that workers had been exposed to radiation at their ankles when standing in water in unit 3 of the plant. Tokyo Electric Power Company (TEPCO) confirmed the death of two workers due to the disaster.
Compiled by Aaron PereiraCourtesy: Infochange News & Features, May 2011