First Deputy Minister of Energy and Electrification of the USSR Regarding the accident at Reactor No 4 of the Chernobyl nuclear power plant URGENT REPORT On April 26 1986 at 1 21 o’clock as reactor No 4 of the Chernobyl nuclear power plant was taken into routine maintenance an explosion occurred in the upper part of the reactor compartment after it was shut down According to the director of the Chernobyl power plant as the result of the explosion the roof and parts of the reactor compartment wall panels collapsed as well as several roof panels of the turbine island and auxiliary systems of the reactor compartment The roof also caught on fire At 3 30 o’clock the fire was eliminated The personnel of the nuclear power plant are taking measures to cool down the reactor core It is the opinion of the Third Main Directorate of the Ministry of Health that special measures including the evacuation of the city are not necessary Nine members of the operational staff have been hospitalized as well as 25 members of the paramilitary fire brigade Measures are being taken to eliminate the consequences and investigate the incident Signed A N Makukhin Translated by Anna Melyakova for the National Security Archive