As a result of the explosion, the 4th Power Unit was considerably destroyed as a structural system. The reactor structure was destroyed completely; roof of the reactor central hall (CH) and drum separators’ premises, as well as of the north group of main circulation pumps, collapsed and spread out. The upper floors of deaerator stack were destroyed completely.

The accident at the 4th Unit of Chornobyl NPP is classified according to the International Nuclear Events Scale (INES) as the accident of the seventh (the highest) level.