On this day in 1986, the world's worst nuclear accident to date occurs at the Chernobyl nuclear plant near Kiev in Ukraine. The full toll from this disaster is still being tallied, but experts believe that thousands of people died and as many as 70,000 suffered severe poisoning. In addition, a large area of land may not be livable for as much as 150 years. The 18-mile radius around Chernobyl was home to almost 150,000 people who had to be permanently relocated.
The Soviet Union built the Chernobyl plant, which had four 1,000-megawatt reactors, in the town of Pripyat. At the time of the explosion, it was one of the largest and oldest nuclear power plants in the world. The explosion and subsequent meltdown of one reactor was a catastrophic event that directly affected hundreds of thousands of people. Still, the Soviet government kept its own people and the rest of the world in the dark about the accident until days later.
At first, the Soviet government only asked for advice on how to fight graphite fires and acknowledged the death of two people. It soon became apparent, however, that the Soviets were covering up a major accident and had ignored their responsibility to warn both their own people and surrounding nations. Two days after the explosion, Swedish authorities began measuring dangerously high levels of radioactivity in their atmosphere.
Years later, the full story was finally released. Workers at the plant were performing tests on the system. They shut off the emergency safety systems and the cooling system, against established regulations, in preparation for the tests. Even when warning signs of dangerous overheating began to appear, the workers failed to stop the test. Xenon gases built up and at 1:23 a.m. the first explosion rocked the reactor. A total of three explosions eventually blew the 1,000-ton steel top right off of the reactor.
A huge fireball erupted into the sky. Flames shot 1,000 feet into the air for two days, as the entire reactor began to melt down. Radioactive material was thrown into the air like fireworks. Although firefighting was futile, Pripyat's 40,000 people were not evacuated until 36 hours after the explosion. Potentially lethal rain fell as the fires continued for eight days. Dikes were built at the Pripyat River to contain damage from contaminated water run-off and the people of Kiev were warned to stay indoors as a radioactive cloud headed their way.
On May 9, workers began encasing the reactor in concrete. Later, Hans Blix of the International Atomic Energy Agency confirmed that approximately 200 people were directly exposed and that 31 had died immediately at Chernobyl. The clean-up effort and the general radioactive exposure in the region, however, would prove to be even more deadly. Some reports estimate that as many as 4,000 clean-up workers died from radiation poisoning. Birth defects among people living in the area have increased dramatically. Thyroid cancer has increased tenfold in Ukraine since the accident.