Chernobyl

ChernobylMIR

Chernobyl (11383710145)

Свято-Іллінська церква в Чорнобилі

Tabula VIII Europae

Černobyl, 18

Chernobyl refers to a catastrophic nuclear accident that occurred on April 26, 1986, at the Chernobyl Nuclear Power Plant in the city of Pripyat, then located in the Ukrainian SSR of the Soviet Union. The disaster is considered the worst nuclear power plant accident in history, both in terms of cost and casualties. It is one of only two nuclear energy accidents rated at seven—the maximum severity—on the International Nuclear Event Scale, the other being the Fukushima Daiichi nuclear disaster in Japan in 2011.

Background

The Chernobyl disaster occurred during a late-night safety test which simulated a power-failure and in which safety systems were deliberately turned off. A combination of inherent reactor design flaws, together with the reactor operators arranging the core in a manner contrary to the checklist for the test, eventually led to an uncontrolled reaction conditions. Water flashed into steam generating a destructive steam explosion and a subsequent open-air graphite fire. This fire produced considerable updrafts for about nine days that lofted plumes of fission products into the atmosphere, with fallout spreading over much of the western USSR and Europe.

Aftermath

The immediate aftermath of the Chernobyl disaster involved a massive emergency response effort, including firemen, engineers, military personnel, and miners, aimed at containing the spread of radioactivity. The accident prompted the evacuation and resettlement of over 350,000 people from the most severely contaminated areas of Belarus, Russia, and Ukraine. A large restricted area, known as the Chernobyl Exclusion Zone, was established to enclose the areas with the highest levels of radiation.

Long-term health effects, including cancer and other diseases, have been observed among the emergency workers and the populations of the affected areas. The United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) and other international bodies have conducted studies to monitor and evaluate the health and environmental impacts.

Reactor Design and Safety Features

The Chernobyl reactor, a RBMK-type (High Power Channel-type Reactor), had several design flaws and lacked adequate safety features. The RBMK design allowed for a positive void coefficient, meaning that the reactor's power could increase rapidly in certain conditions. This design, coupled with a lack of containment structure, significantly contributed to the severity of the accident.

Response and Containment

In the aftermath of the explosion, the Soviet government initiated a cleanup operation, involving the construction of a sarcophagus to enclose the damaged reactor and contain the radioactive materials. This structure, known as the Chernobyl Shelter, was completed in November 1986. In 2016, the New Safe Confinement, a larger dome designed to encase the original sarcophagus and the reactor building, was completed to further contain the radioactive materials and allow for the eventual dismantling of the old structures.

Legacy

The Chernobyl disaster had a profound impact on the global perception of nuclear power, leading to changes in safety protocols and regulations. It also significantly influenced the development of international nuclear safety standards and the establishment of the International Atomic Energy Agency's Convention on Nuclear Safety. The disaster has been the subject of numerous studies, documentaries, and a highly acclaimed television miniseries, which have contributed to the public's understanding of nuclear safety issues.

See Also

• Nuclear safety
• List of nuclear accidents and incidents
• Three Mile Island accident
• Fukushima Daiichi nuclear disaster

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