Nuclear accident at Chernobyl near Kiev (Ukraine) is the largest “technological catastrophe” in human history whose real effects are beginning to be discerned only after more than twenty years, transcending with its reality the most pessimistic predictions of scientists at that time.
The world's largest nuclear disaster occurred in 1986 when it came to a sudden outflow of water from the cooling system due to human negligence and deterioration of devices
Due to this, temperature increased from 600oC to 3000oC influencing the melting of a zirconium layer around the fuel. Water from the turbine came into contact with radioactive material, and overheated steam reacted with graphite, uranium and zirconium causing an explosion.

One thousand and seven hundred tons of graphite bricks around the fuel began to burn. Poor layer insulation caused emission of tons of radioactive material into the atmosphere for days.

Total scattered radioactive material was about 200 times bigger and stronger than the bombs that were dropped on Hiroshima and Nagasaki in 1945. It was first spread by the air flow to the north, endangering Sweden, Poland, Denmark and Norway, and then to the south, threatening Central Europe, Balkans, Italy and South France. Thus, almost whole Europe was contaminated with the radionuclides, whose amounts exceeded the allowed dose from 100 to 10,000 times.

The consequences were the following:

• total contaminated area of 160,000 km2 in the three republics of the former Soviet Union (Belarus, Ukraine, Russia);
• The river Techa was contaminated;
• Agricultural land was permanently destroyed to the extent of several hundred square kilometers;
• accident has affected a total of about 9 million people, out of which 2.5 million in Belarus, 3.5 million in Ukraine and 3 million in Russia;
• 400,000 people from these three republics left their homes forever;
• 270,000 people lived in contaminated areas.

Source: Ecological management, Natasa Petrovic