The Chernobyl accident: its causes and its consequences

The Chernobyl reactor accident occurred during the night of April 26th. Its exact causes were only known at the end of the month of August when an international conference, proposed by the Soviets, was held in Vienna. The Chernobyl reactor, which was moderated by graphite and cooled by water, had several weak points. A crew, which was carrying-out tests, cancelled six safety devices, some of which were essential. In these conditions, the reactor went out of control and this led to two explosions and a serious fire. The fire spread to the graphite and a part of the radioactivity in the reactor escaped into the atmosphere. The consequences of this accident which were well controlled by the authorities were serious in the neighbourhood of the reactor: 31 dead, 100 000 people evacuated and contaminated soil. The radioactive cloud resulting from the accident, pushed by the wind, travelled across Europe and provoked worry everywhere. In fact, the risks from such small doses of radioactivity are not significant; an evaluation of such risks is given in this article in comparison with the effects of small doses of chemical products which although they have analogous effects are considered as being inoffensive