The 25th of April 1986 was a day like another. In Kiev, a town with 25 million inhabitants, 130 kilometres south-east of the "Lenin power plant" in Chernobyl, the people had gone to work as usual, had come home tired, had eaten their supper and then gone off to bed to wake up the next morning to another normal working day just like the rest of the Europeans.
A nuclear accident, like it took place in the Ukraine on "a day like another", happens silently unpredictably and surprising. It doesn't only concern a few of us who live nearby. It concerns each and every one of us. Because nuclear radiation doesn't stop at the state boundaries, you can't run from it, you can't see it and you can't protect yourself from it by hiding in a cellar. Nuclear radiation outlives human beings.
354 reactors where in use all over the world that night delivering electricity but only one of them broke. The consequence was the biggest nuclear disaster that the world had ever known up till then. The "peaceful use of nuclear power" was regarded to be the biggest blessing during the first decades of the post war period. Clean and cheap electricity coming from clean power plants.
A lot of the power plants that were originally used for the production of nuclear weapons were rebuilt to serve a civil purpose. Safety was missed out. President Eisenhower called the project he introduced to the members of the United Nations in 1958 "atoms for peace". Some people had a different point of view: prospects of a "radiant future" was the tragically ambiguous comment of opponents of nuclear energy.
On the 25th of April 1986 nobody on the whole world thought of the possibility that a nuclear accident might occur within the next couple of hours. Is there anybody who thinks about the possibility that Chernobyl might be repeating itself today, on the 21st of April, perhaps somewhere in Mexico or maybe in the USA or in Bohunice in the Czech Republic or maybe only 50 kilometres away from us?
"Atom – radioactivity – fire" – these were the code words reporting the catastrophe in Chernobyl to the catastrophe centre in Moscow.
A series of human mistakes led to that what nobody expected: "The operating staff was so convinced of the plant's safety that they threw caution to the wind. Consequently various operating instructions were deliberately ignored!" stated the Soviet delegation in 1986 as cause for the accident to the International Atomic Energy Agency (IAEA) of the United Nations.
The operating personnel of reactor block 4 tested the worst case scenario on April the 25th 1986. They wanted to check if the diesel generators would switch themselves on in time and supply the plant with sufficient electricity in case of a loss of external electric power – an irony of destiny if you consider the consequences.
To simulate this "worst case" scenario the emergency cooling system in reactor block 4 was switched off. It was supposed to be switched on again at 11.10 pm but the operating personnel forgot to do so.
A series of unjustifiable safety-related decisions followed: the technicians lowered the reactor capacity far below the required level for the test, the amount of bubbles from within the coolant rose to a dangerous amount, further emergency systems were switched off and most of the control rods that are required for controlled nuclear fission were pulled out.
On April 26th 1986 the situation in reactor block 4 became "hypercritical": Released neutrons struck the atom centres of the uranium isotope 235 - the combustible of the reactor. High amounts of nuclear energy were released.
Within 4 seconds the reactor capacity was the fourfold of the normal operating capacity. An atomic explosion, similar to one of an atom bomb was about to happen. Uranium with a melting point of 1100 degrees Celsius became fluid. The water that was supposed to cool down the uranium bars evaporated.
A huge steam explosion blew up the containment of the reactor that was supposed to prevent the radiation from escaping. The lid with a weight of almost one thousand tons was blown off block 4. Burning debris fell on the other 3 reactor blocks and started fires at 30 locations in the neighbourhood.
The red-hot 7 meter tall block of graphite came in contact with the cooling water. Highly explosive carbon was the result, which produced more reactor debris in a second explosion 3 seconds later. On top of that radioactive dust was catapulted 1.5 km into the air.
That is how the nuclear explosion took place in the Ukrainian Chernobyl on the 26th of April 1986. Dr. Robert Gale, a physician who performed life saving bone marrow transplants on a lot of victims says: "More than 75.000 people died of cancer because of the nuclear accident, more than half of them were European."
"All in all, the accident could have been worse" is the opinion of the American atomic engineer Richard Webb "a quarter of the radioactive fission products got into the atmosphere. Would it have been three quarters, there would have been a catastrophe in the whole of Europe."