Chernobyl Disaster

In the early morning hours of April 26, 1986, the Chernobyl nuclear power plant in Ukraine (formerly part of the Soviet Union) exploded, creating what has been described as the worst nuclear disaster the world has ever seen.

Even after many years of scientific research and government investigation, there are still many unanswered questions about the Chernobyl accident — especially regarding the long-term health impacts that the massive radiation leak will have on those who were exposed.

Where is Chernobyl?

Located about 81 miles (130 km) north of the city of Kiev, Ukraine, and about 12 miles (20 km) south of the border with Belarus, the four reactors at the Chernobyl Nuclear Power Plant were designed and built during the 1970s and 1980s. A manmade reservoir, roughly 8.5 square miles (22 sq. km) in size and fed by the Pripyat River, was created to provide cooling water for the reactor.

The nearest town to the power plant was the newly built city of Pripyat, which housed almost 50,000 people in 1986. A smaller town, Chornobyl, was home to about 12,000 residents. The remainder of the region was primarily farms and woodland.

What happened?

The day before the Chernobyl nuclear disaster, plant operators were preparing for a one-time shutdown to perform routine maintenance on reactor number 4. In violation of safety regulations, operators disabled plant equipment including the automatic shutdown mechanisms.

On April 26, when extremely hot nuclear fuel rods were lowered into cooling water, because of the reactors' design flaws — created more reactivity in the nuclear core of reactor number 4. The resultant power surge caused an immense explosion that detached the 1,000-ton plate covering the reactor core, releasing radiation into the atmosphere and cutting off the flow of coolant into the reactor.

A few seconds later, a second explosion of even greater power than the first blew the reactor building apart and spewed burning graphite and other parts of the reactor core around the plant, starting a number of intense fires around the damaged reactor and reactor number 3, which was still operating at the time of the explosions.

Radioactive fallout

The explosions killed two plant workers, who were the first of several workers to die within hours of the accident. For the next several days, as emergency crews tried desperately to contain the fires and radiation leaks, the death toll climbed as plant workers succumbed to acute radiation sickness.

On April 27, the residents of Pripyat were evacuated about 36 hours after the accident had occurred.

By that time, many were already complaining about vomiting, headaches and other signs of radiation sickness.

Health effects

Twenty-eight of the workers at Chernobyl died in the

...