About 200,000 people had to be permanently relocated after the disaster.
Initially, the plant's operators simply dumped the nuclear waste into a nearby river, before a storage facility for that waste opened in 1953.
The storage facility began to overheat, and a cooler was soon added, but it was poorly constructed.
Soviet nuclear knowledge had many holes, so it was impossible to know whether some decisions made in the construction were safe.
As it turned out, many of those decisions seriously compromised the plant's facility.
Those numbers are a subject of debate, however, as the Soviet Union did much to cover up the extent of the damage.
The World Health Organization reported the actual number of deaths related to Chernobyl was about 9,000.
The Chernobyl nuclear accident is widely regarded as the worst accident in the history of nuclear power.
It is the only nuclear accident that has been classified a "major accident" by the International Atomic Energy Agency.
During a routine test, the plant's safety systems were turned off to prevent any interruptions of power to the reactor.
The reactor was supposed to be powered down to 25 percent of capacity, but this is when the problems began.
The exact number of fatalities is hard to come by because the British government attempted to cover up how serious the fire had been.