The Chernobyl Reactor Incident

On April 25, 1986, Russian engineers and scientists begin preliminary tests on Chernobyl power plant's 4th reactor. What they didn't realize was that they were about to cause a meltdown that would kill them instantly and would have severe consequences that would extend even to the present day.

The test was conducted in order to create a sufficient supply of energy to prevent overheating in the event of a shutdown. In order to do this properly, several alterations in the generator's magnetic fields had to be made, requiring the engineers to lower the power output to unstable levels. In order to control the experiment, the automatic control system was shut down. After some work, stability was reached at very low power outputs. Unfortunately, manual control of the water pressure wasn't maintained. The reactor began to create excess heat. Without the automatic control, the control rods couldn't be reinserted in time; a deadly chain reaction had begun.

Within a matter of 3-4 seconds, the reactor went from 5% output to 100 times its normal level. The water in the reactor flash-boiled, creating an explosion that leveled thousands of tons of concrete and steel, including the housing for the reactor. The steam carried almost 70% of the nuclear material out of the reactor into the surrounding environment.

Several thousand volunteers died on the scene, and it is estimated that 7,000 to 10,000 volunteers died in total, considering short and long-term effects. Thousands of miles from the scene, the birth defect rate became double the world average.

It is also estimated that 150,000 were put at risk for thyroid cancer, and over 800,000 children were put at risk of contracting leukemia. 2 million acres of land (1/5 of the usable farmland in the Ukraine) was, and still is, completely unusable.

It remains difficult to determine the scope of the disaster; radiation resulting from the event was detected all over the globe. It is estimated that it may cost up to $400 billion and will take up to 200 years to correct the damage done to the area, and to compensate those affected by the meltdown. 

The Chernobyl site and plant

The damaged Chernobyl unit 4 reactor building

References:

http://en.wikipedia.org/wiki/Chernobyl_disaster 

http://seriousaccidents.com/legal-articles/what-happened-at-chernobyl/ 

http://hyperphysics.phy-astr.gsu.edu/Hbase/nucene/cherno.html