One of the most famous incidents of its kind, the explosion of the Chernobyl reactor brought home the stark dangers of dealing with nuclear technology. On April 26th, 1986 tests were conducted in nuclear reactor 4 of the Chernobyl plant, 80 miles away from Kiev. These tests required parts of the security system to be shut down, which had disastrous consequences.Thanks to errors in the reactor design and misjudgement by personal, energy production levels shot up to ten times the normal level. The extreme pressures caused steam to starting escaping which built up to a massive explosion which blew the roof off the building, started a major fire and forming an atmospheric cloud which contained between 185 to 250 million curies of radioactive material.
The fire and explosion killed 31 people instantly and the presence of the radioactive cloud lead to Moscow evacuating over 135,000 people from within a 30km radius of the explosion. Ukrainian government figures show that 8,000 Ukrainians died as a result of their exposure to the radiation during the first cleanup operation. The eventual death toll from the explosion is estimated to be from 30,000 to 300,000 people. However, unofficial figures put that figure closer to 400,000. The government believes that up to seven million people have been affected by the accident.
The reactor is currently enclosed in a large concrete 'sarcophagus' which was built to allow the continuing operation of the other reactors in the plant. However, the structure is unsound and is in imminent danger of collapse, releasing a new cloud of radioactive dust into the atmosphere, due to the 200 tons of radioactive material that remains inside the reactor.
A new safe confinement structure is being developed, with plans to have it in place by 2011.