In nuclear energy, we refer to nuclear accident to those incidents that emit a certain level of radiation, which could harm public health. To determine the severity of an accident, an International Nuclear Event Scale (better known by its acronym INES) has been established.
Nuclear accidents are classified as nuclear accidents and incidents depending on the severity´s level. In this classification nuclear accidents and radioactive accidents are included. To understand the difference between these two types of accidents, a nuclear accident could be the failure of a reactor of a nuclear power plant and a radiation accident could be when pouring a radiation source to a river.
Despite the known nuclear accidents have occurred at nuclear power plants, they can also happen in other places where nuclear energy is used to work; for example hospitals or research laboratories.
Due to the secrecy of the governments and the companies that own the nuclear power plants, in certain cases, it is difficult to determine the severity or extent and repercussions that a given nuclear accident can entail. In addition to nuclear accidents in the civil field, nuclear tests have also been conducted in the military in different parts of the world. Obviously, with military secrecy it is practically impossible to know the real repercussions of these military trials.
Civilian nuclear accidents during the history of nuclear energy
Next, we briefly describe the main nuclear accidents worldwide in order of severity.
Nuclear Accident in the Chernobyl nuclear power plant, Ukraine - 1986
Level 7 on the INES scale, serious nuclear accident.
The Chernobyl nuclear accident is considered the worst nuclear accident in history.
In April 1986, during a series of tests in the Chernobyl nuclear reactor, a series of explosions occurred in the reactor core. The accident was due to a succession of human errors in the course of previously planned tests.
A cloud of radioactive material spilled from the reactor and fell over large areas around the plant, contaminating them heavily and making it necessary to evacuate and resettle some 336,000 people in other areas. Radioactive clouds also reached Eastern Europe, Finland and Scandinavia with gradually lower levels of pollution, which also affected Italy, France, Germany, Switzerland, Austria and the Balkans, to parts of the eastern coast of North America.
Nuclear accident in the Fukushima nuclear power plant, Japan - 2011
Level 7 on the INES scale, serious nuclear accident.
The Fukushima nuclear accident occurred in 2011 as a result of a series of natural events that seriously affected the plant. This is the second worst nuclear accident in history, after the Chernobyl nuclear accident.
Initially there was an earthquake of 8.9 degrees on the Richter scale near the northwest coast of Japan and a subsequent tsunami seriously affected the core cooling system of the nuclear reactor of the Japanese nuclear power plant in Fukushima.
Nuclear Accident in Mayak, Russia - 1957
Mayak is the name given to a known center nuclear facilities located between the cities of Kaslo and Kyshtym, in the province of Chelyabinsk, Russia.
It is one of the points of the planet with pollution by radioactive materials, although it is not that known because the Soviet authorities have been trying to hide during 30 years that nuclear leaks have been occurring.
Nuclear accident in Goiânia, Brazil - 1987
The Goiâna nuclear accident is classified in level 5 on the INES scale.
In September 1987 the city of Goiânia in Brazil had a radioactive contamination accident. Two men robbed a teletherapy device and they manipulated it. They extracted a cesium capsule from his protective housing what made it a radioactive cesium-137 source. The International Atomic Energy Agency (IAEA) highlighted that nuclear accident as one of the worst radiological incidents worldwide.
The nuclear accident in Goiânia was considered Level 5 on the INES scale. Residences and public places are severely polluted. Four people died and 28 suffered radiation burns. As part of decontamination process, several buildings were demolished and farmland was removed.
Nuclear accident in the Three Mile Island nuclear power plant, USA - 1979
The Three Mile Islant nuclear accident is classified in level 5 of the INES scale.
In March 1979, the nuclear power plant at Three Mile Island had a serious nuclear accident after the first year of operating. Misinterpretation of data caused serious errors in certain decisions of plant personnel. Although the core of the nuclear reactor was badly damaged, it had limited radioactive products escape outwards. The accident was classified as Level 5 on the International Nuclear Event Scale (INES).
1952 and 1958 - Nuclear accident in the nuclear power plant Chalk River, Canada
Nuclear accident at Windscale Pile, United Kingdom - 1957
Level 5 on the INES scale.
In October 1957, a nuclear accident occurs at the Windscale reactor number one, in Cumberland (now Sellafield, Cumbria). This incident became the worst nuclear accident in history of the United Kingdom classified at Level 5 of the INES scale.
The fire at the nuclear reactor led to the release of radioactive material into the surrounding area. The radiation could have caused about 240 cases of cancer. Nobody was evacuated from the affected area, but there was concern about the possible contamination of the milk.
The air ducts of the reactor outlet were sealed and the fuel cartridges were removed. The second nuclear reactor at the site was also closed, although it was undamaged by fire.
Level 4 on the INES scale.
In September 1999, there was a nuclear accident at the Tokaimura uranium fuel treatment plant, owned by the company JCO in Tokaimura. All signs pointed out that it was due to human error. The accident was classified as level 4 according to INES scale ("accident without significant off-site risk"), since the amounts of radiation released to the outside were very small, and within the limits and within the site. The damage produced in the equipment and biological barriers was significant, addition to worker exposure fatal.
Nuclear accident in the Saint Laurent des Eaux nuclear power plant, France - 1980
The worst nuclear accident in France occurred in the nuclear power plant Saint Laurent des Eaux next to the river Loire. It happened in March 1980. A failure in the cooling system caused the melting of a fuel channel in the Saint Laurent A2 reactor.
This nuclear accident was classified as Level 4 on the INES scale. No radioactive material was released outside the plant.
The INES scale or international scale of nuclear and radiological events (International Scale of Nuclear and Radiological Events) has been developed since 1989 by the IAEA, the international atomic energy agency, with the aim of classifying nuclear and radiological accidents and allowing The severity of nuclear or radiological accidents is immediately noticeable to the public, without referring to technical data that is more difficult to understand.
The INES scale applies to events associated with the transport, storage and use of radioactive materials or sources, regardless of whether the event occurs in an industrial plant or abroad (for example, during transport).
The INES scale includes 7 levels (plus a level 0 below the scale) and is divided into two parts: the incidents (from the 4th to the 7th level) and the failures (from the 1st to the 3rd). Level 0 is classified as a diversion. It is a logarithmic scale and, therefore, the passage from one level to another means an increase in damage of approximately ten times.
- The world's worst nuclear power disasters
- The international nuclear and radiological event scale. Widespread health and environmental effects. External release of a significant fraction of reactor core inventory
Last review: October 9, 2019