Chernobyl disaster

The Test and the Explosion, Hour by Hour

Reactor 4 of the Chernobyl Nuclear Power Plant exploded on 26 April 1986. This page follows the first hours of that day and the morning after, using only what the record states.1

The test and the explosion, hour by hour

  1. Reactor 4 explodes4

    At 1:23 am the No. 4 reactor of the Chernobyl Nuclear Power Plant near Pripyat exploded, exposing the uranium core.5

    Anatoly Dyatlov had supervised a test at Unit 4 that day. Aleksandr Akimov was in charge of the night shift, and Leonid Toptunov was the senior reactor control engineer.18,19

  2. Major Telyatnikov takes command

    Major Leonid Telyatnikov arrived and officially took scene command from Pravyk, who had been the de-facto site commander until then.7

    The first firefighters on the scene were under Lieutenant Volodymyr Pravyk.20

  3. Pravyk reports the explosion

    Pravyk reported over the radio an explosion in the reactor compartment of unit four.8

  4. Evacuation announced

    At a joint meeting at 10:00 a.m. on 27 April, Shcherbina and the commission announced they would evacuate nearby residents the same day.25

  5. The first official announcement

    A 20-second announcement on the TV programme Vremya at 21:02 on 28 April was the first official Soviet announcement of a nuclear accident.9