7 Disaster Nuclear Accidents which have occurred

Nuclear is one source of electricity generation. In the reactor Nuclear Power Plant (NPP) contained in a controlled chain reaction. This is what distinguishes it from an atomic bomb. However, although restrained, if a leak would be dangerous as well.
International Nuclear Event Scale (Ines) issued to determine the level of nuclear power plant accident disaster. Ines explained the importance scale of events in a variety of activities, including the use of radiation sources by industry and medical, as well as operation of nuclear installations and transport of radioactive material.
In the website of the international atomic agency, the IAEA, described the scale of disaster is divided into 7 levels. An event that incoming in level 1-3 is called the incident (incident). Whereas if you've entered the level of 4-7 called the accident (accident). Nuclear-related events at nuclear power plants that do not endanger the safety of so-called 'irregularities' and included in the classification scale / level 0.
Here is the level of catastrophic accidents and nuclear power plant event example:
Level 1 (anomaly). Exposure to radiation is above the threshold. There is a small problem with the component of security and minimal impact.
For instance occurs when there are violations of the operation of nuclear facilities.
Level 2 (the incident). Radiation exposure to the public up to 10 mSv. Radiation level in the operating area of ​​more than 50 mSv. There is a significant failure of safety-related conditions but no consequences.
For example occurred in Atucha, Argentina, in 2005. At that time workers in the nuclear reactor exposed to radiation that exceeds the threshold. Also occur in Cadarache, France, in 1993, when the spread of radioactive contamination in the environment by accident.
Level 2 nuclear power plant accidents disasters also occurred in Forsmark, Sweden, in 2006 when the security function damaged resulting in system failures at the nuclear power plant emergency energy supplies.
Level 3 (serious incident). Exposure to radiation ten times the safe limit worker. Not lethal, but the health impact.
For example occurred in Sellafield, England, in 2005. At that time there was a leak of radioactive material in large quantities in the installation. Occur also in Vandellos, Spain, in 1989. In that year there was an accident caused by fire resulting in loss of security systems at nuclear power stations.
Level 4 (accidents with local impact). Radioactive leak in small quantities. At least one person was killed by radiation. Fuel melt or damage the fuel, resulting in leakage of more than 0.1% core supply.
The accident occurred at level 4 Tokaimura, Japan, in 1999. When there are mistakes made by workers when mixing ingredients. As a result of an accident that left two workers dead and several others were exposed to radiation.
In addition, there is also in Saint Laurent des Eaux, France, in 1980. At that time in the reactor fuel line melted. But there was no leakage outside.
Level 5 (accident with a broader impact.) Radioactive leaks in limited numbers and thus require remedial action. Several people were killed by radiation. Some damage occurred in the reactor core. Leakage of large amounts of radiation in this installation, that's what allows the public to be exposed. This could arise from catastrophic accidents or fires.
The accident occurred at Windscale Pile England, in 1957. At that time the radioactive material leaked into the environment as a result of fire in the reactor core. Three Mile Island nuclear power plant, the United States, also experienced it in 1979, where some of the reactor core is damaged.
Level 6 (serious accidents). Radioactive leak in a large enough number of which require follow-handling.
Occur at nuclear power plants Kyshtym, Russia in 1957. Leakage of radioactive material in a fairly large number occur in the environment around nuclear power plants. This is because the waste tank explosion. Thousands of people exposed to this radiation.
Level 7 (major accident). With large amounts of radioactive leaks occurred so far-reaching impact on health and the environment. Because it takes the response and long-term action.
Experienced by the Chernobyl NPP, Ukraine, in 1986. At that time the number four reactor exploded. As a result there was a fire and radioactive leakage in large numbers. Environment and communities exposed to this radiation. Radioactive steam that contain iodine 131, cesium 137 and xenon that its volume 100 times the Hiroshima atomic bomb. Spread of radioactive steam into the Soviet Union, Eastern Europe, Western Europe and Northern Europe. Most of the people in Ukraine, Belarus and Russia were evacuated. At that time more than 336,000 people were displaced