Chernobyl disaster summary

Recent nuclear tragedy in Fukushima, Japan, reminded many of the similar disaster that shook the Europe over 20 years ago. The Chernobyl nuclear power plant is located in Ukraine near the city of Prypiat and within a close proximity to the administrative border with Belarus and Dnieper River.

At the time of the accident, the plant had four working reactors. It was considered the worst nuclear power plant crisis in history, being one of only two classified as a level 7 event on the International Nuclear Event Scale. The other incident is Fukushima nuclear disaster.

The Chernobyl crisis occurred on April 26, 1986, when operators of the power plant ran a test on an electric control system at the reactor number four. There was a sudden power output surge which prompted an attempt of emergency shutdown. Unfortunately, a more extreme spike in power output occurred, which led to a reactor vessel rupture and a series of explosions. One person was killed immediately and a second died in hospital soon after as a result of injuries received.

The accident destroyed the Chernobyl 4 reactor, killing 30 operators and firemen within three months and several further deaths later. Another person is reported to have died at the time from a coronary thrombosis. Acute radiation syndrome was originally diagnosed in 237 people on-site and involved with the clean-up and it was later confirmed in 134 cases. Of these, 28 people died as a result of syndrome within a few weeks of the accident.

Reactor explosion and radioaktive smoke over Europe
The Chernobyl disaster happened because of a combination of basic engineering deficiencies in the reactor and faulty actions of the operators. The safety systems had been switched off and the reactor was being operated under improper unstable conditions. Such situation allowed an uncontrollable power surges to occur, leading to a series of explosions and consequent fires that severely damaged the reactor building.

These events exposed the graphite moderator of the reactor to air, causing it to ignite. The resulting fire sent a plume of highly radioactive smoke fallout into the atmosphere and over an extensive geographical area, including Pripyat. The plume drifted over large parts of the western Soviet Union and Europe. The reactor was soon completely destroyed. The battle to contain the contamination and avert a greater catastrophe ultimately involved over 500,000 workers and cost an estimated 18 billion rubles, crippling the Soviet economy.

From 1986 to 2000 around 350,400 people were evacuated and resettled from the most severely contaminated areas of Belarus, Russia, and Ukraine. According to official post-Soviet data about 60% of the fallout landed in Belarus. Chernobyl reactor four is now enclosed in a large concrete shelter which was erected quickly to allow continuing operation of the other reactors at the plant.

Next: Chernobyl disaster health effects