On 26 April 1986, one of the four reactors at the Chernobyl nuclear power station on the Ukraine-Belarus border (then part of the USSR) exploded during a routine systems test. The blast and subsequent fire that continued for 10 days discharged vast amounts of radioactive material into the atmosphere at levels 300 times greater than Hiroshima.

The catastrophe forced mass evacuations in the surrounding areas of Ukraine and Belarus as radioactive elements released from the fallout spread as far as Canada and the United States. It remains the most devastating nuclear disaster of all time.

In the first part of a special three-part documentary on the Chernobyl nuclear disaster, IBTimes UK spoke with Chernobyl plant workers, local residents and the Chernobyl liquidators (civil and military personnel who were called upon to deal with consequences of the disaster) about how the accident unfolded on that fateful day and how they remember the tragedy today.