The true story of Chernobyl's 'suicide squad': The 3 men willing to die to save millions.

The Chernobyl catastrophe is considered the worst nuclear accident in history.

At 1:23 am on 26 April 1986, a safety test at the Chernobyl Power Plant in Ukraine set off two explosions to the equivalent of 400 nuclear bombs.

Two workers were instantly killed and 29 more passed away in the following months.

The release of HBO’s five-part series, Chernobyl, has put the nuclear disaster back in the public eye as it recounts the aftermath of the tragedy in great detail.

You can watch the official trailer for Chernobyl, right here. Post continues after video.

Researchers remain divided on how fatal the Chernobyl disaster ultimately was. The World Health Organisation estimates that 30,000 deaths can be attributed to Chernobyl. However, the Chernobyl Union of Ukraine, a non-government organisation, estimates the death toll to be 734,000, with most due to related cancers.

But this toll could have been exponentially higher, had it not been for three brave men who volunteered for a job that many considered certain death. The mission later earned them the nickname ‘the suicide squad’.

The second explosion.

There was risk of a second explosion, that would have been even more devastating than the first.

Five days after Soviet authorities believed the disaster was contained, the alarming discovery was made in early May that Unit 4’s core reactor was continuing to melt down.

Under the reactor was a gigantic pool of water, serving as a coolant for the power plant. Dividing the pool and the melting reactor was a thick slab of concrete. But as the core continued to melt, the concrete was burning, seeing the molten of radioactive metal proceed towards the water.

If the two touched, it would have left unimaginable damage.

According to journalist Stephen McGinty for The Scotsman: “This would trigger a nuclear explosion that, so Soviet physicists calculated, would vaporise the fuel in the three other reactors, level 200 square kilometres, destroy Kiev, contaminate the water supply used by 30 million people and render northern Ukraine uninhabitable for more than a century.”

Firefighters launched a mission that pumped some of the water out, but gallons of radioactive water remained.

Three men, plant-workers who were on site, volunteered to dive into the radio-contaminated water to find the valves that would drain the rest of the pool and prevent a second explosion. It was considered a suicide mission. Officials reportedly even promised that if they didn’t survive, their families would be provided for.

Andrew Leatherbarrow, author of book Chernobyl 01:23:40, wrote: “The men entered the basement in wetsuits, radioactive water up to their knees, in a corridor stuffed with myriad pipes and valves… it was like finding a needle in a haystack.”

The men were successful in finding the valves and subsequently drain out the water, managing to complete the job before the molten of radioactive metal touched the water. Their brave acts saved potentially millions of lives.

Who were the three men?

The heroic men were named as mechanical engineer Alexei Ananenko, senior engineer Valeri Bespalov and shift supervisor Boris Baranov.

Ananeko said to Soviet media in 1986, "Everyone at the Chernobyl NPS (nuclear power station) was watching this operation."

"When the searchlight beam fell on a pipe, we were joyous: The pipe led to the valves. We heard the rush of water out of the tank. And in a few more minutes we were being embraced by the guys."

Ananeko recalled being told by his boss that he could refuse the hazardous assignment.

"But how could I do that when I was the only person on the shift who knew where the valves were located," the mechanical engineer responded.

It was widely reported in the decades since the disaster that the men had succumb to acute radiation syndrome. But in fact, the three men survived.

As of 2015, it is understood that that two of the men, Ananenko and Bespalov remain alive. Boris Baranov, the shift supervisor, passed away in 2005 from a heart attack.

According to The Trumpet, Ananenko, Bespalov, and posthumously Boris Baranov, were presented state awards by Ukrainian President Petro Poroshenko for their bravery.

Read more:

The Chernobyl nuclear disaster was the worst in history. Here are 4 things you didn't know.

The Chernobyl miners faced certain death to dig a tunnel. In the end, they didn't need to.

The real life faces and stories behind Chernobyl, HBO's gripping new miniseries.