Chronology

1986

25-26 April. Safety test takes place at Chernobyl nuclear power plant, Ukraine.

26 April (1.38 a.m.). An explosion destroys the fourth reactor.

27 April (2.00 p.m.). Evacuation of Pripyat begins.

28 April. Tass announces the accident to the world.

29 April. First news item is published in the Soviet press.

1 May. May Day celebrations take place as planned in Kiev, Minsk, and other cities.

2 May. Politburo members Ryzhkov and Ligachev visit Chernobyl. A 30 kilometre zone around the reactor is designated for evacuation.

10 May. The fourth reactor is "capped" with sand and boron, and leakages of radiation end.

May-June. Military reservists brought to Chernobyl to lead the clean-up operation.

August. The Soviet Report on the causes of the accident is presented to the International Atomic Energy Agency in Vienna.

December. A concrete roof ("sarcophagus") is completed over the fourth reactor.

1987

July. Chernobyl director and five plant operators are found guilty of gross negligence at a trial held mostly in camera in the town of Chernobyl.

1989

February. The first maps highlighting radiation fallout from Chernobyl are published in the Soviet press.

1991

April. On the fifth anniversary of Chernobyl there are mass demonstrations in Kiev and Minsk. The world press focuses on the event, highlighting new evacuations, alleged sicknesses in contaminated zones, and the continuing operation of Soviet RBMK reactors, including those at Chernobyl.

1992

March. The Ukrainian government reports that cracks have appeared in the sarcophagus. An international competition is to be held for a design for a replacement roof.