The HBO miniseries Chernobyl has been released to critical acclaim, with Sky Atlantic tweeting on 23 May: “Chernobyl is officially the highest rated TV show of all time on IMDb. Thanks to everyone for watching and rating.”

As The Sun helpfully pointed out, Chernobyl is based on a ‘terrifying true story’ of arguably the worst nuclear power disaster ever and how the Soviet Union dealt with the catastrophe, and keep it secret from the world and its citizens. But how close were the makers of the show to the truth of Chernobyl? Or was fact separated from fiction?

What happened in Chernobyl?

The Chernobyl nuclear disaster took place on 26 April 1986 at 1.23am.

The plant was in the midst of a shutdown when there was a power surge, caused by control rods being inserted into the reactor. The mix of the overly hot fuel with the cooling water caused increased pressure and steam production, which spread through the entire core and caused an explosion. This was followed by a second explosion possibly caused by a build-up of hydrogen from zirconium steam explosions.

A radioactive plume of smoke and debris rose about a kilometre in the air and eventually spread across Europe. It was estimated this radiation was equivalent to 500 atomic bombs of the same level that were dropped on Hiroshima.

After a major operation involving firemen, evacuations of the town of Pripyat and the dumping of 5,000 tonnes of materials like boron carbide, lead, sand and clay, the reactor was eventually entombed in a steel and concrete sarcophagus to lock in the radiation.