This Day in Chernobyl NPP History

Today is 26 years as Shelter Object was accepted for operation. It was constructed over ChNPP Unit 4 that had been destroyed by the beyond-design-basis accident. The State Commission’s Certificate on acceptance of the preserved Chernobyl NPP Unit No.4 for maintenance was signed on November 30, 1986.


The accident, happened at the Chernobyl NPP on April 26, 1986, by its scales and consequences has become the largest and the most severe catastrophe in the history of power energy. The explosion destroyed the reactor core, protective barriers and safety systems. By development of the 4th Unit destruction processes and by magnitude of its consequences the accident refers to the 7th level according to the International Nuclear Events Scale (INES).

The Shelter construction was started following the State Commission’s decision of May 22, 1986, on the long-term preservation of the fourth ChNPP Unit to prevent radionuclide release into the environment and reduce radiation impact on the ChNPP industrial site.

Over a short period of time eighteen options for the future Shelter design were elaborated. The one was selected that maximally used structures of the destroyed Power Unit. 90 thousand people was directly involved into the construction activities. In total about 200 thousand people was involved into the activities on the accident consequences liquidation within the ChNPP area during 1986-1987. 400 thousand cubic meters of concrete mix and 7,000 tones of metal structures were utilized for the Shelter construction.

The Shelter Object was constructed only within 206 days. It enabled in the shortest possible time to reduce the negative impact of the destroyed Power Unit on the environment, perform activities on remediation and commissioning of ChNPP Units No.1 and No.2 on the same year.