Chernobyl accident in 1986 is the largest in the history of nuclear energy before an explosion at the plant "Fukushima- 1", as for the number of injured people and for the people who suffered from consequences of the accident and of economic losses. About 200 000 people were evacuated from the areas of pollution. 30km exclusion zone was installed around Chernobyl. Four zones of destruction have been established according to degree of radiation exposure. The first zone is a zone of complete destruction of softwoods with partial damage of the hardwood (so-called Red Forest). The area of this zone is about 4.5 hectares. At night of the explosion at Power Unit 4, these trees were so heavily irradiated, so they became unnaturally red.
400 thousand cubic meters of concrete mix and 7,000 tons of steel were used for construction "Shelter" on the fourth power unit. It was built in the shortest amount of time - 206 days. 90 thousand people were involved to build the "Shelter". The unofficial name “sarcophagus” was given to the construction.
Now because of the danger of destroying the sarcophagus over the 4th reactor in Chernobyl people are working to transform the “Shelter” into an ecologically safe system. This work is going to finish in 2015. The new facility will be a strong steel structure of 108 m height and 150 m length, in which technological building and ancillary facilities will be situated.