Considered a risky and controversial design in the West, the Chernobyl plant began operation in 1977. Its fourth reactor, the one involved in the 1986 accident, came on line in 1983. The Chernobyl reactors used graphite to modify the nuclear reaction and water flowing around the channels holding the fuel elements for cooling. There was, however, no containment structure for these reactors.
It has been determined that a combination of design flaws and operating errors caused the 1986 disaster. During the early-morning test, the fuel elements in the reactor ruptured, causing an explosion that lifted the cover plate off the reactor and forced radioactive steam into the atmosphere in the form of a deadly radioactive cloud.
A secondary explosion then set the graphite afire, releasing more radioactivity as the fire raged for nine days. Estimates hold that the Chernobyl accident released one hundred times more radioactivity than the two atomic bombs dropped on Hiroshima and Nagasaki, Japan, in August 1945. Most of the radioactive fallout settled to the ground within a few miles of the site, but lighter amounts of radioactive material were carried by wind patterns as far as Scandinavia and to a lesser but measurable extent across the entire Northern Hemisphere.
The explosions and fire destroyed Reactor Four and led to the deaths of 30 workers by radiation exposure. More than 100 other workers suffered from radiation poisoning, all of whom recovered from the initial effects. Thousands more, however, were exposed to radiation, either from being in the immediate area or being sent there in response to the accident. By 4 May, more than 160,000 people living within 30 kilometers (18 miles) of the plant were evacuated. Another 210,000 residents outside that radius were later evacuated. The response to the accident in 1986 and 1987 involved about 200,000 people, some of whom received large doses of radiation. These and later responders have been referred to as "liquidators" in the Soviet literature involving the accident.
In later years another 400,000 helped with the cleanup, most receiving low dosages of radiation. In all, more than 1 million people were affected in some way by radiation, and the World Health Organization (WHO) has reported a statistically significant increase in the incidence of thyroid cancer in the affected areas. Scientists also expect an increase in the level of leukemia and congenital anomalies attributable to the accident, although they have not yet occurred with any great frequency.
What made the Chernobyl accident even worse was the Soviet government's lack of immediate candor about the crisis and its inability to respond in a more timely fashion. Unwilling to admit to such a catastrophe, the Soviet government at first tried to hide the effects of the explosions and fire; not until radioactivity sensors in Scandinavia and Western Europe began registering abnormally high readings did the Kremlin go public with the nuclear nightmare. Chernobyl also laid bare the inferiority of Soviet technology and the government's inability to react to the situation in a more efficacious fashion.
There will likely be a continuing debate over the long-term impact of the Chernobyl disaster. Soviet-era secrecy surrounding issues of health, particularly those involving environmental issues, will make it difficult to establish base data from which to calculate changes after 1986 that can be attributed to Chernobyl.
Daniel E. Spector
United Nations Development Program and United Nations Children's Fund. The Human Consequences of the Chernobyl Nuclear Accident: A Strategy for Recovery. New York: United Nations, 2002.