Chernobyl Disaster in the Soviet Union

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Picture of the exploded Chernobyl reactor unit 4 after the accident of INES level 7 on April 26, 1986
Action in front of a market hall in Minsk for Chernobyl Day 2011
The protests in Minsk reminded that constructing an NPP in the most Chernobyl affected country is no good idea
Action on April 27, 2010 in front of the Parliament building in Helsinki
Poster announcing the Chernobyl theatre piece in Belarus 2014
Demonstration outside Ålands Lagting on Chernobyl Day 2009
Chalk slogans on the road connecting French EPR project and Chernobyl experiences (Network meeting in Bure, 2008)

On April 26, 1986 Chernobyl NPP unit 4 exploded. 500,000 people and 485 villages have been relocated, more than 500,000 victims suffered from this by then biggest atomic catastrophe in human history.


The nuclear power plant (NPP) was constructed in the former Soviet Union, situated in the Ukrainian village Chernobyl in distance of 16 kilometers to the town Prypiat close to the Belarusian border. When the accident happened in 1986 the Chernobyl NPP was composed of four reactors in operation and two more under construction. The construction of the concerned unit 4 had been planned in 1972 and completed in 1983.

"Official" accident scenario

There are different interpretations of the course of the accident in Chernobyl, including several conspiracy theories. The "official" scenario reads like this:

On April 25th a new emergency cooling system was to be tested.

Unit 4 of the Chernobyl NPP explodes on April 26th at 1.23 AM. At 7 AM 186 fire fighters combat the fire. A few hours after the explosion Prypiat is exposed to radiation 15,000 times the normal (normal: 12 millionth roentgen). In the evening the radiation is 600,000 times the normal. Emergency rescue services operating at the wrecked reactor are exposed to a lethal dose already after 15 minutes. No clearing up on the catastrophe. In Prypiat a flashing was seen; the official statement was "everything is under control". Gorbachev later commented: "It was even expected that the reactor could be operational again in May or June."

On April 27th 50,000 people are evacuated from Prypiat, lethal cancers had already been triggered in most of them. Units 1 and 2 were shut down. The mobilization of liquidators started.

An increased radiation is detected at Forsmark NPP in Sweden on April 28th. The origin is outside the nuclear plant. 60 hours after the explosion the Soviet Union still didn't provide a public statement. Swedish military aircrafts measure radiation in the air and determine the source of increased radiation is not located in their region. European and US satellites scan Soviet atomic sites and find the remains of the Chernobyl reactor three days after the explosion.

In the evening of April 28th IAEA and public are officially informed about the disaster for the first time. In the core of the reactor 1,200 tons of fuel are burning at more than 3,000 °C, a nuclear meltdown is going on. Radioactive gases are continuously released to the atmosphere; the wind direction dictates wide areas to be contaminated. Helicopters trying to extinguish the fire. In a height of 200 meters temperatures of 120-180 °C are effective. The radioactive exposure here mounts up to 1,000 roentgen; the lethal dose is reached after an operation of 30 minutes. On 28th of April 80 helicopters from Moscow are operating aiming on extinguishing the fire and sealing the reactor. Soldiers are dropping 80 kg sandbags from the helicopters into the fire. On the first day of operation 110 of these flight missions take place, 300 on the second one. Above the reactor the radiation is higher than 3,500 roentgen - 9 times the lethal dose. Some pilots flew 33 missions per day.

On May 1st 30 kilometers east of the reactor the trees are dying due to the high radiation; also further situated areas are concerned. The radioactive cloud reaches Kiev. Still the population hasn't been informed about the actual danger. A first note in a daily newspaper is downplaying the accident.

Radioactive cloud

The radioactive cloud moved more than 1,000 kilometers towards north crossing on 26th and 27th of April Belarus, the Baltic and Russia, and eventually reached Scandinavia on April 28th. Today the most affected country is Belarus. Most contamination occurred here, because the radioactive nuclides settled where it was raining when the cloud passed. Due to wind direction and rain 70 % of radioactivity deposited in Belarus. According to unverified sources the cloud was artificially dispersed with chemicals above Belarus to protect Moscow. 20 % of the area of Belarus have been radioactively contaminated.

First radiation victims

All radiation victims were treated in the 6th Moscow hospital. It was the only Soviet utility with the necessary special equipment. Symptoms of the radiation syndrome are: nausea, vomitus and diarrhea followed by a phase of adynamia; later for instance disintegration of bone marrow or burns can occur. Pilots often had been hospitalized after dizzy spells.

27 people immediately died close to the accident. But most victims were not aware of the dramatic art of their sickness. During the following 15 years only the very first victims had been recognized by authorities.

Impact on the Baltic Sea region

Although far from that water body, the disaster is until today the biggest Baltic Sea polluter. At the same time the Baltic Sea is also the marine area most affected by this accident classified as INES 7. The reason is the route the radioactive cloud traveled after the explosions in Chernobyl. It went to the north and caused a strong deposition of radioactive nuclides in the watershed of the Baltic Sea. Cesium-137 first dispersed directly onto sea surface. Radionuclides came from the entire drainage area and from surrounding terrestrial as well as coastal areas due to runoff, river discharges and coastal currents. The total input from Chernobyl to Baltic Sea accounts for about 4,100-5,100 TBq Cs-137 and 80 TBq Strontium-90 calculated on the basis of the year 1991. Half of the Chernobyl Cs-137 settled in the seabed. The strongest accumulation took place during the first 5-6 years. It is still an ongoing process. The majority of radioactivity is deposited in the Baltic Sea sediments.

Actions and events


  • lecture "The Reactor Catastrophe in Chernobyl"
    • Information about the Chernobyl site, basic facts of the accidents, rescue measurements, radiation doses, consequences of the catastrophe, lies of authorities and politicians, Chernobyl as a political symbol and conclusions. 62 slides with images of the accident and from Belarus (victims of the accident, liquidators, "empty villages", actions).
    • The slides are currently provided in German (smaller file)only, but the presentation can be held in English, too.
    • duration: some 2 hours
    • technical requirements: digital projector & screen, computer/laptop
    • contact: Falk Beyer, Falk AT nuclear-heritage DOT net[1]
  • theater group: Theatre Kryly Halopa
    • Since 2013 the theatre “Kryly Halopa” has started work on a documentary theatre project “Stories of Belarus”. The documentary theatre Chernobyl based on the authentic texts and documents, interviews and the fates of real people, technology verbatim and the most actual and contemporary topics of reality, is a genre that exists on the border of art and social analysis.


Guided tours to the nuclear exclusion zone of the catastrophe - caution! This article downplays the risks of radiation while scientific sounding data is mentioned without telling that any additional radiation dose is to be avoided. They don't speak about the alpha and beta radiation regular Geiger counters can't detect. Don't trust travel agencies promoting adventure trips to atomic disaster zones - there safety measures and advice will probably again underestimate the actual threats.

Media releases


Further information

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