Chernobyl disaster

Chernobyl disaster

Reactor 4 of the Chernobyl Nuclear Power Plant, near Pripyat in the Ukrainian SSR, exploded on 26 April 1986.1

The Soviet government set up a 10-kilometre exclusion zone 36 hours after the accident, initially evacuating around 49,000 people. The Exclusion Zone was originally a 30 km radius around the plant and was later enlarged to about 2600 square km.2,3

The first hours of 26 April 1986

  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.5,6

  2. A new commander takes charge

    Major Leonid Telyatnikov arrived at 01:47 and officially took scene command from Pravyk, who had been the de-facto site commander until then.7

  3. Pravyk reports by radio

    At 02:01 Pravyk reported over the radio an explosion in the reactor compartment of unit four.8

  1. Reactor 4 explodes1

    The accident

    Reactor 4 of the Chernobyl Nuclear Power Plant exploded on 26 April 1986.

  2. First Soviet announcement1,9

    Response

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

  3. First Soviet news conference1,10

    Response

    Shcherbina gave the first Soviet news conference on the disaster, admitting people near the plant had been exposed to radiation for 36 hours before evacuation.

  4. The reactor fire ends11

    The accident

    The fire inside reactor 4 burned until 10 May 1986.

  5. Sarcophagus design begins12

    Response

    Design of the sarcophagus started 24 days after the disaster, and construction ran from June to late November.

  6. Politburo hears the findings13

    Response

    In a Politburo session chaired by Gorbachev, Shcherbina presented the commission's findings, blaming both the Chernobyl staff and the design of RBMK reactors.

  7. Reactor no. 1 decommissioned14

    Aftermath

    Reactor no. 1 was decommissioned as part of a deal between the Ukrainian government and international organizations.

  8. Shelter Fund established15

    Aftermath

    The Chernobyl Shelter Fund was established at the G8 summit in Denver.

  9. Roof section collapses16

    Aftermath

    A 600 square metre section of the turbine-building roof collapsed next to the sarcophagus, causing a new release of radioactivity.

  10. Forest fires in the zone17

    Aftermath

    Forest fires spread through 20,000 ha of the exclusion zone.

The first days at Chernobyl, step by step

The first days at Chernobyl: from the explosion to the first announcement6,9

Move through the moments, from the explosion to the first official announcement6,9

What happened6

Background18

26 April 1986, 1:23:45 a.m.6

Reactor 4 of the Chernobyl Nuclear Power Plant exploded, exposing the uranium core.5,6

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

26 April, 01:476,7

Major Leonid Telyatnikov arrived and officially took scene command.7

The first firefighters on the scene were under Lieutenant Volodymyr Pravyk, the de-facto site commander until then.7,20

26 April, 02:016,8

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

Pravyk was commander of the fire brigade's third watch and a lieutenant in the MVD.21

Evening of 26 April22

The investigative commission arrived at the plant.22

The commission was headed by Valery Legasov.22

Late on the night of 26 April23

Boris Shcherbina, who had been in Siberia, arrived in Chernobyl almost a full day after the explosions.23

Shcherbina headed the government commission; Legasov was put in charge of containing the radiation when the team reached Pripyat.24

27 April, 10:00 a.m.25

At a joint meeting, Shcherbina and the commission announced they would evacuate nearby residents the same day.25

Shcherbina was then Deputy Chairman of the Council of Ministers.26

36 hours after the accident2

A 10-kilometre exclusion zone was set up and around 49,000 people were initially evacuated.2

Shcherbina later admitted that people near the plant had been exposed to radiation for 36 hours before evacuation.10

Before the first official announcement9,27

Elevated radiation levels were detected in Sweden.27

Until then, the Soviet government had not publicly acknowledged the disaster.27

28 April, 21:029

A 20-second announcement on the TV programme Vremya was the first official Soviet announcement of a nuclear accident.9

The Soviet Union admitted the accident only after Sweden suggested it would alert the IAEA.28

Chernobyl Nuclear Power Plant4

Pripyat29

Kyiv30

Forsmark Nuclear Power Plant31

10-kilometre exclusion zone2

Close up: the Chernobyl Nuclear Power Plant and Pripyat4,29

Wider view: the Chernobyl plant, Kyiv and the Forsmark Nuclear Power Plant4,30,31