"Sometimes it happens in life that someone, somewhere, has to do something. Whether they want to or not."

Key points: At age 32, Jaan Krinal was forced to go to Chernobyl and clean the roof of the reactor

At age 32, Jaan Krinal was forced to go to Chernobyl and clean the roof of the reactor He says men were initially enthusiastic to help eliminate the radiation

He says men were initially enthusiastic to help eliminate the radiation One-third of the men of his town he served with in Chernobyl have died

When he left his wife and two children on May 7, 1986 and went to work, Jaan Krinal didn't know he would be one of those people.

The 32-year-old was working on a state-owned farm in Soviet-occupied Estonia.

Because he'd been forced to complete the Soviet military's retraining a year before, he was confused when officers surprised him at work and said he'd been called up again — immediately.

Jaan and 200 other men were taken to a nearby school. Once they'd walked through the door, no-one was allowed to leave.

The men's passports were seized before they were loaded onto buses and taken to a forest, where they were told to slip into brand new army uniforms.

"That's when I first questioned what's really going on here," Jaan recalls.

"The Chernobyl explosion that had happened just days before didn't even cross my mind.

"It had been briefly mentioned in one of the news bulletins in April.

"I do remember that when I heard it, I felt uneasy … but because everyone remained so calm, I thought, 'Well, I guess accidents can happen'".

Some civilians refused to leave the area despite the evacuation. ( Supplied: Eesti Tsernoboli Uhing )

When the officials finally revealed they were headed to Chernobyl, the men were almost relieved. They had initially feared they would be sent to fight in the USSR's bloody war in Afghanistan.

"I don't think anyone realised the danger we were about to be in," Jaan says.

"There was very little information about the disaster and all the official sources kept reassuring us, 'it's just a minor accident, nothing to worry about'."

Jaan says while it wasn't uncommon for Soviet authorities to use propaganda and routinely cover up events of public interest, he thinks not even those in charge immediately knew they were dealing with the planet's biggest nuclear catastrophe.

"To be honest, I think even the higher-ups didn't really know what had happened. They really did think we were going to be back from Chernobyl before too long," he says.

Two soldiers in front of a sign that reads "Chernobyl — the place of heroic efforts". ( Supplied: Eesti Tsernoboli Uhing )

Workers told radiation could have health benefits

It all happened fast.

Hundreds of men boarded a Ukraine-bound train on May 8. By the next evening, they were setting up camp on the edge of Chernobyl's exclusion zone.

They were just 30 kilometres away from the site of the world's worst nuclear disaster — the still-smouldering wreckage of a reactor torn apart by a series of explosions and spewing radiation in a plume across Europe.

Jaan was among the first group sent to clean up in the aftermath of the catastrophe.

Tasked with hosing down radiation on the houses in nearby villages, he was thrown into the thick of it.

Jaan Krinal (right) with four other men at their camp on the edge of Chernobyl's exclusion zone. ( Supplied: Jaan Krinal )

"I'd even say that the men were enthusiastic — let's get this done quickly and people can go back home," he says.

They mixed water with a "washing powder-like" substance and measured the radiation levels once the houses had been hosed down.

"The results were so good that we thought maybe we really can finish up in two weeks," he recalls.

"But one time, someone had an idea that we should return to a village that was hosed down a couple of days earlier and check the radiation levels again.

"The radiation had returned, if not to say it was worse."

Despite the apparent uselessness of the job, they continued to work 11-hour days without a day off until the end of June. After that, they had two days of downtime a month.

As the weeks rolled on, suspicions grew.

"We started to have doubts. But all the officers said, 'Why are you fretting, the radiation levels aren't that high."

In a cruel irony, the commanders told the men that being exposed to radiation would actually have health benefits.

"They joked that whoever has cancer can now get rid of it — because the radiation helps," Jaan says.

Men unaware of deadly reason behind roof time limit

By the end of September, whatever enthusiasm the men initially felt had faded.

As many developed a cough, concerns grew about whether they were being lied to about the radiation being harmless. The respirators the men were given wouldn't stay on because of the heat and were used until they got holes in them.

Later they found they should have been replaced every day.

The respirators failed to stay on in the heat. ( Supplied: Jaan Krinal )

Despite their growing fears, the men were reluctant to confide in each other.

"Sometimes I think that maybe we didn't even want to talk about it or think about it," Jaan says.

Then, a shimmer of hope emerged — in the unlikeliest of situations.

A rumour had it that the very last leg of the assignment was going on the roof of the reactor to clean up as much debris as possible.

Humans were going to be given a task that remote-control robots had previously attempted, but failed. The machines simply stopped working due to the unprecedented levels of radiation.

The aerial view of the decimated reactor four. ( Reuters: YK/AS )

"When they told us, 'You have to go to the roof', we thought, 'Oh, this means we can go home soon'," he says.

On the day, he changed his army uniform for a protective suit, glasses and a gas mask, and a metal groin guard.

"We were all lined up and told, 'who doesn't want to go on the roof, step forward'. But only a couple of us did," he says.

"There was no mass rejection. Most people went up there.

"It had to be done. We couldn't just leave it. I think everyone realised the longer the reactor would have stayed open, the more dangerous it would have become."

An actor in HBO's series Chernobyl (left) and real life workers cleaning up the roof of Reactor No. 4. ( Supplied: IMDB/Igor Kostin )

Jaan was shown on a small screen exactly which piece of debris he had to pick up with a shovel and throw off the roof of the reactor, but strictly warned against going too close to the edge.

He had two minutes to complete the assignment — a bell would ring to tell him when to run back.

The two-minute timeframe was to limit exposure to radiation, which could kill a man.

But this wasn't communicated to the men at the time.

"It was like being in the army, where no-one explains anything. You get an order, you go, and you do it. It's a demand," he says.

Jaan says the roof-cleaning scene depicted in HBO's mini-series Chernobyl mirrored real life events.

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He says he'll never forget those two minutes standing over the edge of an open nuclear reactor, shovelling radioactive graphite.

Perhaps it was the adrenaline — perhaps the fear — that made him go blank.

"Once I got on the roof, it looked completely different from what was shown on the screen. I just grabbed whatever piece of debris I could," he says.

"When I got there, adrenaline was pumping so hard that I thought I'll turn the roof upside down.

"I didn't even think about what will happen to me. I had no time. I think it was a survival instinct."

Chernobyl veterans dying of cancer, suicide

Jaan (third right) visited Chernobyl again. ( Supplied: Jaan Krinal )

By early October, Jaan was back in Estonia. He is 65 years old now and retired.

When the Soviet Union collapsed in 1991, he helped establish the Estonian Taxation Office.

The same year, he was sent to a hospital in Hiroshima, the Japanese city hit by a nuclear bomb at the end of World War II, where he was checked for radiation.

Jaan was found to be healthy during a visit to a hospital in Hiroshima in 1991. ( Supplied: Jaan Krinal )

While he was found to be healthy, he has since been pained to see many of the men he served with in Chernobyl die.

A staggering one-third of the men of his town who went to Chernobyl have died.

The average age of death has been 52.

"Over the past couple of years, just a couple of us have died. But not too long ago it was around 10 men a year," he says.

"There have been cancers. There have been suicides too, but thankfully not too many."

Jaan is the head of the Chernobyl veterans' union in his home town, Parnu.

He's visited Chernobyl twice with other veterans, in 2006 and 2011.

"It's fascinating what nature can do if people leave it be. The town [of Pripyat] has overgrown with trees," he says.

But he hopes tourists won't start flocking to the ghost city.

"I hope they'll never start sending large groups of tourists there. It's still a dangerous zone," he says.

He hasn't seen the mini-series, but welcomes the attention Chernobyl disaster is getting — he thinks it acts as a warning to the human kind.

"See what one mistake can do and how many people if affects — millions."