Chernobyl Nuclear Accident

1. What was the extent of the Chernobyl accident?

Deposition of 137 Cs in Europe as a result of the Chernobyl accident

The Chernobyl accident is the most serious accident in the history of the nuclear industry. Indeed, the explosions that ruptured one of the reactors of the Chernobyl nuclear power plant and the consequent fire that started on the 26 April 1986 and continued for 10 days resulted in an unprecedented release of radioactive materials into the environment.

The cloud from the burning reactor spread many types of radioactive materials, especially iodine-131 and caesium-137, over much of Europe. Because radioactive iodine disintegrates rapidly, it largely disappeared within the first few weeks of the accident. Radioactive caesium however is still measurable in soils and some foodstuffs in many parts of Europe. The greatest concentrations of contamination occurred over large areas of the Soviet Union surrounding the reactor in what are now the countries of Belarus, the Russian Federation and Ukraine.

Since the accident, 600 000 people have been involved in emergency, recovery, containment, and cleaning operations although only a small proportion of them have been exposed to dangerous levels of radiation. Those who received the highest doses of radiation were the emergency workers and personnel that were on-site during the first days of the accident (approximately 1000 people).

More than five million people live in areas of Belarus, Russia and Ukraine that are significantly ¹ contaminated with caesium-137 from the Chernobyl accident. 400 000 of these people lived in very contaminated areas classified as “areas of strict control” by Soviet authorities. Within this region, the area closest to the Chernobyl power plant was most heavily contaminated and has been designated as the “Exclusion Zone”. The 116 000 people who lived there were evacuated in the spring and summer of 1986 to non-contaminated areas, and 220 000 more were relocated in the following years. More...