The reason why Chernobyl seems such a dire warning to so many people
around the world is the nuclear disaster that happened there
affected the entire planet.
I remember the first time going to the site itself.
It's a sinister place, because you can't help remembering
what happened there and how it affected hundreds of thousands
of people's lives.
Two miles from Chernobyl, the city of Pripyat, once home to 50,000
people, lies in ruins.
Vegetation is taking over.
There are trees that are growing into the upper floors
of the tower blocks.
A 1,000-square-mile exclusion zone has restricted access to the site
for the past 36 years.
WARNING SIREN
But that all changes on the 24th of February 2022...
..when Russia invades Ukraine in a bid to take back
the former Soviet republic.
An early strategic target is the Chernobyl nuclear power plant.
Russia was moving tanks through the zone,
and that raised radioactive dust.
Russia is really weaponising nuclear power plants in this war on Ukraine.
The story of Chernobyl is decades in the making.
It began when the emerging Soviet Union's nuclear power programme
threatened the world.
A Soviet dream that became a nightmare.
A disaster officials tried to cover up.
As a brave few battled to stop radiation spreading
across the globe.
Using top-secret Soviet documents...
..and hearing from those who risked everything...
..this is the story
of one of the world's worst nuclear accidents.
Early morning.
The Chernobyl nuclear power plant gets ready to carry out
a safety test on reactor number four.
Every nuclear power station has to undergo a series of tests.
And one of the safety tests that it needed to prove to continue
to operate was to test what would happen to the coolant system
if there was a power cut.
Engineers planned to switch off four of the pumps
to test their backup systems.
If there was a power cut and the emergency generators
didn't kick in, there would be a real problem.
The job was extremely difficult and complex, and demanded a lot...
A lot of concentration. A lot of experience.
It was kind of a routine test, but it was conducted in such a way
that that routine test turned into a terrible accident.
The Chernobyl disaster can be traced back to the 1960s,
when Ukraine was part of the USSR
and harnessing nuclear power was a major Soviet ambition.
NEWSREEL: A multi-stage rocket took off from a launching site in Russia.
The mid twentieth century was the height of the Cold War.
Rival superpowers
the Soviet Union and the USA are vying for technological...
..and military supremacy.
The USSR is determined to lead the world in harnessing nuclear power
and it pours vast resources into nuclear research.
Nuclear power was enormously important to the Soviet Union,
and scientists were these heroes of the Soviet Union.
And nuclear research was the flagship
of what Soviet science could offer.
Soviet leadership plans to build a vast nuclear power plant,
one which would dwarf any the world has ever seen.
The reason why they wanted to build such a large reactor, the biggest
in the world, they hoped, was national pride.
The Soviet Union at the time was engaged in a...
Not just an arms race with the United States,
but a cultural, political competition
to prove themselves that their system of government
and life was best.
The new plant is to be built in the Ukrainian wilderness,
60 miles north of the capital, Kyiv.
It's named after a nearby town,
Chernobyl.
Ukraine enjoyed a special status in the Soviet Union.
It was very important economically.
It also contained very important industries on its territory.
Coal-mining industries, of course, and many others.
A very important member of the union for political, strategic,
military reasons, economic reasons, especially.
It's on the borderlands, facing to the West.
It's also a showcase of Soviet modernity.
In the winter of 1970, the man chosen to build and run Chernobyl
arrives in northern Ukraine.
Despite having never worked with nuclear power,
34-year-old Viktor Brukhanov will be Chernobyl's first director.
Viktor Brukhanov was a young man when he was picked, surprisingly,
to take on the Chernobyl project.
He was electrical engineer.
He'd worked in a couple of power plants across the Soviet Union,
but this was his first nuclear power job.
Engineer Nikolai Steinberg worked on the project with Brukhanov.
His main deficiency was that he was never trained as a nuclear engineer.
The real reason he was picked was because the authorities thought
he was the man who would be able to master a very,
very complex, difficult task.
Construction of the huge power plant gets under way
in early spring 1970.
The first of six planned reactors will take seven years to build.
As the power plant grows, so does the city built to house its workers.
Pripyat is one of nine atomgrads, or atomic cities, in the USSR.
Each one is built from scratch for workers of the nuclear industry
and their families.
Pripyat was a city whose reason for existence was Chernobyl.
And in many ways it was a model Soviet city.
It was what the socialist city was supposed to be like.
The apartment buildings were very well-made.
The shops were stocked, which was quite unusual
in Soviet society, especially in the '70s.
Chernobyl's 5,000 workers and their families lived just two
miles from the power plant.
Seven years after work began,
Chernobyl's reactor number one is finally ready to be switched on.
Plant director Viktor Brukhanov is now at the helm of Chernobyl's
first reactor, and is charged with building five more.
But it won't be long before Chernobyl suffers
its first accident.
And the authorities are quick to cover it up.
Three nuclear reactors are now fully operational at Chernobyl.
The completion of a fourth will make this the largest nuclear power
station in the Soviet Union.
The Ukrainian city of Pripyat, built to house Chernobyl's workers,
is also flourishing.
In 12 years, it's grown from a wasteland
into a city of 50,000 people.
Although they live in a Soviet paradise,
the residents of Pripyat are unaware of the danger they're in.
The new Chernobyl power plant is already riddled with problems.
But it would take until 2020, when the Ukrainian government
released thousands of top secret documents, that Chernobyl's early
safety problems were made public.
One of them exposes how unsafe the power plant is becoming.
The report is dated from January 5th, 1983.
And according to this report,
between January 1978 to December 1982,
the Chernobyl nuclear power station experienced 27 accidents
and 87 equipment failures, including five accidents and 16 failures
in just 12 months of 1982.
One of the most serious accidents happens in late summer.
Chernobyl's number one reactor undergoes a routine safety test.
Nikolai Steinberg, head of turbines, is in his office
in the third reactor building.
Outside Nikolai's office runs a ventilation pipe
connected to reactor one.
The steam is part of a major radiation leak.
Reactor one is shut down.
Nikolai waits for a briefing on the incident from his bosses.
The cause of the accident is kept secret from Nikolai
and his colleagues.
One reason for the secrecy is down to the presence of the KGB,
the Soviet Union's secret police.
They're a constant presence at Chernobyl.
Well, the KGB's job would be partly to investigate
whether this was an act of sabotage or whether there was someone
who was simply negligent.
But also part of their job was to contain rumours and to prevent
the spread of panic.
The KGB investigation is more concerned with quashing rumours
than uncovering why the accident happened.
They do talk about the presence of distorted rumours that spread
by residents of the city of Pripyat.
And this is kind of a nightmare scenario for the Soviet authorities,
that rumours will spread.
None of this was reported in the press.
After the accident,
radiation is detected nine miles from the plant.
In some areas, the levels are hundreds of times
higher than normal.
But the residents of the nearby city of Pripyat are kept in the dark.
Despite the accident, Chernobyl continues to grow.
It's now 13 years since work began on the plant.
Managers are under orders to complete the fourth reactor
by the end of the year.
Engineers like Vladimir Kagan are feeling the pressure.
They were incentivised to get jobs done by a particular time.
And this meant bonuses.
This meant certain perks.
The people who were able to meet those deadlines,
they were rewarded, and that was part of the game.
By the end of December, reactor four is near completion.
Everything had to be finished by December.
That's when the bonuses were handed out.
But before it can become operational, the reactor must
undergo a critical safety test.
The turbine test that was the last remaining test
that was due to be done on the unit four reactor
hadn't been done by December.
Carrying out the test now will mean a delay.
The reactor might not be ready by the December deadline.
The decision on whether or not to go ahead with the test
falls to plant director Viktor Brukhanov.
So Brukhanov said, "OK, we'll sign it off and then we'll come back
and do it at a later date."
Despite the safety test not being carried out,
Brukhanov allows the reactor to enter service.
He was someone who was taking risks, he believed calculated risks.
He lacked really deep understanding of what he was running.
With reactor four online,
Brukhanov is now in charge of the Soviet Union's biggest
nuclear power plant.
Spring 1985.
Events in Moscow are about to put nuclear energy at the forefront
of Soviet politics.
The USSR has a new leader.
Mikhail Gorbachev's arrival heralds an era of transformation
in the Soviet Union.
He was seen as a new, different type of leader.
He had a meeting with Margaret Thatcher in December 1984.
They famously get on very well together.
There's a feeling, I think, that things are beginning to change
inside the Soviet Union.
He understood that the Soviet Union and Soviet economy especially
were in need of reforms, and he was willing to undertake
that project of reforming the Soviet Union to save it.
One of Gorbachev's first tasks
is to announce a plan to revive the economy,
made to an audience of 5,000 high-ranking party members.
Gorbachev presided over the party congress, and that congress adopted
a resolution to double the number of the nuclear reactors
that they would build in the next five-year plan.
So nuclear energy was supposed to be the solution, or at least part
of the solution of how to drag the Soviet economy
out of that stagnation.
In the audience is Chernobyl's director, Viktor Brukhanov.
He will be held personally responsible for helping meet
Gorbachev's ambitious goals.
So the pressure on the management was actually now becoming
even stronger, and the burden on their shoulders
was even heavier.
Chernobyl's four reactors, known as RBMK reactors,
are of a type unique to the Soviet Union.
The RBMK reactor was really advanced for its time,
much more so than Western reactors,
and this was because it could put out the most amount of power
for a reactor of its size.
This also meant that it was really cost-effective, which is why
they were able to build so many across the Soviet Union.
In total, 17 RBMK reactors are built.
All produce energy in the same way.
Effectively, the nuclear reactor is like a kettle.
It's generating steam by splitting uranium atoms to generate the heat.
The heat then is used to heat water.
The water is then turned into steam,
which turns turbines to generate electricity.
Reactor number four has been running for two years when the long-delayed
safety test is finally scheduled to take place.
The test will be overseen by deputy chief engineer Anatoly Dyatlov.
Dyatlov was one of the few people at the top
who was trained as a nuclear engineer.
He had quite an abrasive personality.
Dyatlov was very often feared.
And he was he was using a very harsh language
to deal with his subordinates.
The test will take place on Friday the 25th of April.
Dyatlov has briefed the staff,
and they know what's expected of them.
Everyone turned up expecting it to be a normal shift.
As it turned out, it didn't go that way.
And not everybody would make it home alive.
Early morning.
Engineers are preparing to carry out a safety test
on Chernobyl's reactor number four.
This particular safety test was designed to see what happened
when the cooling water pumps lost electrical power.
Engineers will switch off four of the pumps which cool the reactor
to test the backup system.
And it has to be done today.
It was the last day of the week before the start of a holiday season
in the Soviet Union.
They were under pressure to complete the task, to complete the shutdown
of their reactor before that holiday season.
Two miles away in Pripyat...
..Chernobyl workers and their families prepare for the upcoming
May Day holiday.
It's a normal spring day with lots of people being about.
This is late April in Ukraine.
It's beautiful weather.
Generally, the time when you felt summer is coming,
the spring has turned the corner. It's going to be warm and lovely.
Back at Chernobyl, inside the control room,
preparations for the test are under way.
It's a vast room - a giant, curving control panel,
strange paving flooring.
It would have been filled with smoke - everybody smoked at the time.
Overseeing the test,
Deputy Chief Engineer Anatoly Dyatlov.
So, Anatoly Dyatlov was probably the most feared person
at the facility.
If he was in the room, you had to listen to him
and do what he said, otherwise there'd be trouble.
The test is due to be carried out
by members of the plant's morning shift.
They've been trained on how to carry it out safely.
To operate the test,
the operators needed to lower the power output of the reactor.
This makes sense - if you're going to test the brakes on your bike,
you don't do it at 50mph, you do it at five.
Operators have been gradually powering down the reactor
since 1am.
By early afternoon, the power's been reduced to nearly three-quarters
of the reactor's normal power.
Inside the control room, the phone rings.
Partway through the day, the emergency grid controller
asked them to stop lowering the power.
The energy was needed.
300 miles away,
another nuclear reactor has had an emergency shut down.
Chernobyl must keep producing power.
Rather than say, "OK, we'll cut our losses and come back another day",
Dyatlov decided, "No, we'll carry on. We'll do it this evening."
For hours, the reactor continues to operate, but at a lower power.
The operators wait for the green light to carry out the test.
They had to hold the reactor at a mid-power level
for a longer period than was expected.
Inside the reactor, there's been a build-up of a dangerous gas
called Xenon.
No-one really realised that, while working at that lower power level,
the reactor was producing the chemical elements.
The so-called "poisoning" of the reactor was taking place.
Late in the evening, and the test still hasn't taken place.
Chernobyl produces power 24/7
and there are constant shift changes.
The day shift transitioned into the evening shift,
transitioned to the night shift.
There wasn't the information passed through
each of the operators from day to evening.
New people came - the graveyard shift.
People who thought that, by the time they come and start their shift,
the whole thing would be over.
So they were not prepared.
After a nine-hour delay, the control room is finally given the go-ahead
to carry out the test.
So it was the night shift that were conducting the test.
It actually started at about 11 o'clock.
Ordinarily, the control room was a quiet place,
especially at that time of night.
Because the turbine test was taking place,
it was filled with people.
There were more than 20 people in the room that night.
One of the operators working the night shift is Leonid Toptunov.
Leonid Toptunov was one of the four operators
that took over the operation of the reactor.
He was a young and very clearly talented engineer.
One of Toptunov's main jobs that night was to keep an eye on the power in the reactor.
The final steps to start the test are taken.
So, having been left in this low power state all day,
the reactor was extremely unstable.
The build-up of xenon gas inside the reactor
is causing it to behave erratically.
Because the operators were relatively untrained
and not prepared for the test, they didn't really notice the signs
that the reactor wasn't in a safe state.
Operators know that if all goes wrong,
there is a safety mechanism in place.
Inside the control room,
something happens that sets alarm bells ringing.
The power dropped really unexpectedly,
which was unexplainable to the operators at the time.
If the operators knew enough about the issues and problems,
they certainly would avoid the accident.
Once power began to fall in the reactor...
..it carried on falling, and it fell to disastrously low levels.
The reactor was now in serious danger.
Toptunov takes steps to raise the reactor's power level.
But, rather than bursting back into life,
the reactor's power only creeps up to a 16th of its maximum output.
Xenon gas has poisoned the reactor.
ALARM SOUNDS
The Xenon in the reactor
was reducing the activity to very, very, very low levels.
Toptunov can't increase the power to the level needed for the test.
People who were around him tried to help him.
Dyatlov, it seems, wants to carry on with the test regardless.
An argument reportedly breaks out between Dyatlov
and the shift foreman, Aleksandr Akimov.
They were seen having quite a heated conversation,
and it's fair to assume that it was Dyatlov saying,
"I want to go ahead",
and Akimov saying, "No, we should stop. It's not safe."
For nearly 24 hours,
engineers at Chernobyl's fourth nuclear reactor
have been attempting to carry out a safety test.
They were going to turn off the cooling system manually...
..and see what happened.
But, even before the test starts,
they're struggling to control the reactor.
An experiment was started.
It was already in an unstable state,
but the operators didn't exactly know
what was going on in the reactor.
Deputy Chief Engineer Anatoly Dyatlov insists
the test should go ahead.
Operators of Soviet reactors
were kind of used to not exactly following the guidelines,
partly because the guidelines were confusing,
but partly because it was quite difficult to operate
those particular reactors without doing a few things
that you shouldn't really do.
Operators - guys who were operating the controls -
said, "We should stop".
But Dyatlov just told them to get on with it.
The experiment was started at 1:23.
Four of the eight pumps that were putting cooling water
into the reactor,
the power was taken away.
When the coolant system was switched off,
that water was no longer coming up past the fuel rods quickly.
Any water that was in the system was boiled off.
The water was no longer being used to cool
the fuel rods, and it bubbled off into steam.
This kind of causes the nuclear reaction
to actually start to speed up.
So, with more boiling, more steam is produced,
the rate of fission increases.
Water then kept being pumped into the reactor
with the aim of cooling it down, had the opposite effect.
The more fission increases, the more steam is produced,
more bubbles, and it's a positive feedback.
It's a never-ending cycle until you get to a very dangerous,
unstable point in the reactor.
In Reactor 4's control room,
Leonid Toptunov is monitoring the reactor's power level.
A few seconds into the test, he's scared by what he sees.
As the reactor overheated Toptunov finally saw this.
He called across and said temperatures are just skyrocketing
inside the reactor.
With the reactor out of control, there's only one course of action.
The emergency button to shut the reactor down was hit.
The test had been running for just 36 seconds.
Instead of shutting down,
when that emergency button was pressed,
the power continued to increase.
It keeps perpetuating and keeps growing and growing and growing.
You have no water left in the reactor.
You have just steam.
The fuel channels ruptured.
The amount of steam increased.
You've got more heat, more power,
and a runaway reaction happens.
There's nothing that can be done at this point.
The Unit 4 reactor explodes.
First thought that crossed the mind of some of them was,
"OK, it is probably an earthquake."
They wouldn't have been prepared for what had happened
inside the reactor.
Two people die instantly in the explosion.
Others are now being exposed to lethal doses of radiation.
Inside a nearby fire station, the telephone rings.
The fight to save Chernobyl has begun.
With radiation pouring out of Chernobyl's number four reactor...
..the Soviet government does everything it can
to conceal the accident...
They couldn't control radiation,
so they were trying to control the information.
..with deadly consequences.
Nobody knows how many people died as a result of that delay.
A Soviet dream that became a nightmare.
A disaster officials tried to cover up
as a brave few battled to stop
radiation spreading across the globe.
Using top secret Soviet documents...
..and hearing from those who risked everything...
..this is the story of
one of the world's worst nuclear accidents.
Chernobyl Nuclear Power Plant -
Reactor Number 4 is on fire.
That was a picture worthy of Dante Inferno.
There had never been a fire like this before.
A long-overdue safety test on Reactor Number 4
has gone disastrously wrong.
What had once been a 17-storey building wasn't there any more.
It's clear the reactor's finished.
It's gone. It's in flames.
The firefighters' hoses are actually melting under the intense heat.
The asphalt under their feet was melting to...
..sucking their boots off.
The severe heat is the least of the firefighters' problems.
The firefighters who were first on scene reported tasting
a metallic taste in the air.
And this was essentially particles
of the nuclear fuel itself.
As firefighters contend with the radioactive inferno,
the man in charge inside the reactor's control room
is deputy chief engineer Anatoly Dyatlov.
Dyatlov and his colleagues in the control room are trying
to make sense of what's just happened.
The control panel is telling Dyatlov
there's no water in the reactor system.
That would be amazingly terrifying.
I can't imagine what that must have been like.
You have to have constant supply of very large amounts of water
to keep the reactor cool, or it will melt down.
Imagine losing water in your radiator in your car.
The engine overheats, the parts would...
..distort, it would seize.
The same thing happens within a nuclear power plant.
Dyatlov thinks his main priority at this stage is to protect
the reactor.
Dyatlov orders the gates of the coolant pipe valve to be opened
to get more water into the reactor.
One of the operatives from outside comes running in and he's got
what's called a nuclear tan -
his face is red and burned from exposure to radiation -
and he tells Dyatlov that the Unit 4 reactor has exploded.
It's up in flames, it's not there any more.
Dyatlov flat-out refuses to believe him.
He just... He can't acknowledge the possibility that something
so terrible has happened.
He was in a state of denial.
Just imagine you can be responsible for what happened.
And Dyatlov just carries on.
Even though the reactor he's trying to save no longer exists.
25 minutes after the explosion,
making his way to Chernobyl is the power plant's director,
Viktor Brukhanov.
Brukhanov receives a phone call at home and he's told there's
been an accident at the plant.
He's not told how serious it is,
so he doesn't really have a huge sense of urgency.
He actually takes the bus to the plant.
Engineer Nikolai Steinberg worked at Chernobyl under Brukhanov.
Brukhanov has been plant director here since construction started
in 1970, and he's been looking forward to the day Chernobyl
is completed and he will preside over the largest nuclear power plant
in the Soviet Union.
But now he sees the wreckage of the Unit 4 reactor glowing red.
One of his first thoughts that went through his mind was,
"This is prison."
He would be kept responsible,
and that sooner or later he would end in prison.
Part of the rules of the game within the Soviet managerial system
since Stalin's times, that the director would be always
certainly kept responsible for...
..for what happened.
He retreats to what's known as the bunker, a safe room,
as it were, underground.
Built at the height of the Cold War
as a shelter in case of nuclear attack by the West,
now it will act as a crisis centre
for the worst nuclear disaster in history.
Here, Brukhanov is soon joined by the power plant's
resident officer from the security services, the KGB.
They were the government watchdog, really, performing the role
of the nuclear regulator.
Serious questions need to be answered.
On the other side of the site,
the fire around Reactor 4 is still raging.
Fighting the fire was a constant danger but, of course,
the radiation was a much worse danger for them.
This huge fire would spray extremely radioactive material into the air.
The fuel itself, the uranium fuel, was getting blasted up onto the bits
of the roof that survived.
It's estimated that on parts of the destroyed roof,
radiation is 16 times stronger than a fatal dose.
The problem with radioactivity is that you can't see it.
You don't know you're being exposed to it until much later.
The firefighters are realising this is no normal fire.
Many are starting to vomit.
They can't go on any more. More firemen come in,
more firemen go on the roof. Same thing.
So there's a conveyor belt of people going up there
and exposing themselves.
In the bunker, Brukhanov is told
radiation readings at the plant are off the scale.
He refused to accept the high levels of radiation that were given to him.
Everyone describes Brukhanov to be really depressed at that time.
High levels meant...
actually, high level of responsibility for what happened.
Brukhanov had a very difficult phone call to make to Moscow.
It was convenient for him to believe that
"Maybe it's not as bad as we think it is."
Brukhanov orders water to be put into the system to save the reactor.
There was nothing to save any more.
Senior reactor control engineer Leonid Toptunov is the man
trying to fulfil this order.
Leonid Toptunov was a young engineer,
he was 25 years old and relatively inexperienced.
It's one of the reasons why he was on the night shift,
because that's where you gained your spurs, as it were.
It was only the third month that he was on that job.
It came with prestige,
it came with his high salary,
and so he was living... living his life dream.
Toptunov heads deep into the smouldering plant.
Radiation levels here are now 100,000 times higher than normal.
It could kill a person in just four minutes.
Five hours after an explosion at the Chernobyl Nuclear Power Plant.
In the daylight, it becomes clear this accident is catastrophic.
The reactor's nuclear core is exposed,
and sending smoke into the air.
Inside the smoke from the fire were particles
of nuclear fuel itself.
So the actual very radioactive material
inside of the reactor core
was emitted as smoke.
Toxic radiation thousands of times higher than normal background levels
is spreading far beyond the plant.
The town of Pripyat, two miles from the power plant.
It's a normal, normal day, a spring day with lots of people being about.
Among them was electrical engineer Vladimir Kagan.
There are lots of children about, weddings taking place.
And they, of course, are absolutely unaware of the catastrophe
that has already happened and of the danger that they're in.
At the power plant,
senior reactor control engineer Leonid Toptunov and his foremen
are on a doomed mission.
They're following orders to get water into the reactor system
to prevent nuclear meltdown.
If there's no reactor left, there is no point in actually
adding water to that area.
But the electrics have failed,
so they're doing the job manually.
That's where they got really hit by radiation.
Being very sick, already vomiting.
Despite this, the men refused to give up.
Their conduct after the explosion
is really, truly heroic.
That they are prepared to sacrifice
everything they've got, including their lives.
They turn on the valves, allow more water to flow into the reactor.
But, of course, it's all to no avail.
The reactor's not there any more.
But in the process, what they are doing is they're exposing themselves
to what turn out to be fatal levels of radiation.
In less than three weeks,
Toptunov would be dead.
At Pripyat Hospital,
the steady flow of plant workers and firefighters arriving
from Chernobyl is increasing.
They now had around 90 patients, all suffering from something
the doctors had never encountered before -
radiation sickness.
If you get a big dose of radiation,
it's got enough energy to damage DNA.
The reason it's called radiation sickness is because
one of the first symptoms is vomiting,
because the cells of this lining of your digestive system
replicate rapidly and they're vulnerable to radiation.
After the initial vomiting, other symptoms develop,
like hair loss, fever and radiation burns.
For some of them, it probably would have been palliative care,
because there wasn't much else you could do.
But even those patients who weren't beyond help
didn't get the treatment they needed.
Civilian hospitals in the Soviet Union are not prepared for the kind
of disaster that the Chernobyl explosion produces.
This is not just because they haven't got the resources
or they're underfunded.
They're not permitted to even accept the possibility that a disaster
like this could happen.
Nearly 10 hours after the accident.
Tanker trucks start spraying the streets of Pripyat.
This detergent is supposed to absorb the radioactive material
from Chernobyl that's already reached the town.
But the people of Pripyat, going about their Saturday morning,
have been told nothing about the accident.
The Soviet Union wanted to keep a lid on this.
They didn't want to tell anybody about that.
And that applied both to the West, but also to their own citizens.
They couldn't control radiation, so they were trying
to control the information.
There was a ring of steel imposed around Pripyat.
If anyone tried to leave the city, they wouldn't have had much joy.
They cut down almost immediately the telephone communication
between the city of Pripyat and the outside world.
The Soviet Union didn't do bad news.
Catastrophes, accidents,
nuclear disasters didn't happen in the Soviet Union.
They may happen abroad,
they may happen in capitalist countries,
but not in the Soviet Union.
To keep their totalitarian grip, the Soviet Communist government
need to maintain their apparent invincibility.
But word is starting to spread around Pripyat
about an accident at the plant.
The operators who worked there,
they were coming back and they were talking to their families.
Some people already knew that something bad happened.
The security services need to take action.
Secret documents reveal how they ensured silence.
The KGB reports that measures have been taken to prevent
the spread of information about the accident,
and dissemination of panic-causing rumours.
Panic is a euphemism for people learning the truth.
KGB was considered to be all-powerful organisation,
with ears and eyes everywhere.
It didn't take much to convince the population
that they had to be really very careful.
No-one is to find out what happened earlier that night at Chernobyl.
Moscow, more than 400 miles away
from the Chernobyl Nuclear Power Plant.
A report about the accident arrives for the leader
of the Soviet Union, Mikhail Gorbachev.
When Mikhail Gorbachev came to power in March of 1985,
he was quite different.
He was talking the talk of change and reform and opening up.
The introduction of glasnost -
or openness, as it is sometimes translated into English.
The state invited citizens' participation
in voicing their concern about problems in the economy,
in society, and how to overcome them.
Gorbachev really looked like a Western leader.
He talked and behaved like a Western leader.
And he was the man that Margaret Thatcher said
that she could do business with.
Despite Gorbachev's calls for honesty and openness,
when the report from Chernobyl arrives, it tells him virtually
nothing of what actually happened.
If you read that document, it looks like, yes, something bad happened,
but all the bad, mostly, was in the past, that the radiation
levels were low, manageable,
the fire extinguished.
Those who were reporting to him
were hoping that they could localise the incident.
This is a very famous Soviet euphemism
for not telling the whole truth.
We can deal with this without it getting to the very top,
and therefore all of us getting into a lot of trouble.
But the Chernobyl disaster is so huge
it would prove impossible to hide.
200 miles north of Chernobyl.
On the day that the Chernobyl disaster happened,
I was in Minsk, in Belarus.
I was in school.
I was only nine years old, but I remember that day well
because an extraordinary thing happened.
When I was sitting with the rest of my classmates in the classroom,
the door opened and my mum asked if she could take me home.
My father happened to work at the Institute of Nuclear Research
near Minsk.
The institute detected some extraordinary levels of radiation,
and my father telephoned my mum and asked her to bring me home,
close windows and clean our shoes.
With radiation continuing to pour out of the reactor, the government
in Moscow will be forced to act...
..but in Pripyat, life carries on as usual.
Then, a day and a half after the accident...
The residents of Pripyat were told the city was being evacuated.
They were given one hour to collect together some belongings,
a couple of days' worth of clothing, their identity papers,
and told to assemble at various points throughout the city
where buses had been laid on to take them away.
In just four hours, the entire population of Pripyat
would be evacuated.
This was much too late.
People had already been exposed to very large amounts of radiation.
Nobody knows how many people died as a result of that delay.
As Pripyat began to empty,
a helicopter is taking off on a special mission.
It was pretty quickly clear that spraying water into the reactor
was not going to put out these fires.
So they decided that they would have to smother the fire.
And the only way to do that was to bring in helicopters.
Each helicopter has to lift a small portion of the 50,000 bags
of sand it's estimated will be needed to drop them
into the reactor core.
These were military trained helicopter pilots,
so they knew what they were doing.
They were very skilled.
And, of course, they were very brave.
Captain Alexander Maruhin flew alongside other helicopter pilots
who were trying to put out the fire.
It was a very risky undertaking.
They had to fly low because they were dropping material
into a space something like five metres wide.
So the lower they were, the better chance they had of success.
But, of course, the lower they were,
the more radiation they're exposed to.
And they were allowed to fly over just for a few seconds
so that hopefully they didn't get too much radiation.
But they had to do it again and again and again.
Workers at a nuclear power plant north of Stockholm in Sweden
went into work.
On their way, walking to work, there was some rain.
They had to pass through the testing area designed to make sure
they didn't take any radiation out after they'd been at work.
They were setting off the alarm bells as they walked in.
The Swedes didn't know to start with.
Why should workers coming in to work
in a nuclear power plant in the morning set off the alarm?
The radioactivity that was emitted into the atmosphere at Chernobyl,
it didn't form a single cloud that sat over the countryside
and just poured radioactivity down,
it was spread out across a vast part of Europe.
And so any time that it did rain, there was a chance
that radioactivity would come from the sky
and fall onto the ground.
In Sweden, engineers check the power plant for a radiation leak.
They find no problems.
They knew it wasn't from their reactor.
They worked out where the wind had come from,
and they realised it came from the south.
And it very quickly became clear that something had happened
in the Soviet Union.
Despite the Soviets' best efforts to hide Chernobyl,
the accident is impossible to conceal any longer.
Three days after the toxic nuclear smoke started to be released
by Reactor 4 at Chernobyl,
Radio Moscow broadcast this statement.
There's sort of a 20-second report that something has happened
at the Chernobyl power plant,
but there's no... There's nothing concrete that's telling people
anything that they really need to know.
Despite the danger, life in the Soviet Union
carries on as normal.
The May Day parades were coming up very soon in Ukraine
and across the rest of the Soviet Union.
There's tens of thousands of people on the street celebrating,
and exposing themselves to potentially deadly radiation.
Risking the lives and risking the health
of populations, including children,
was considered to be acceptable.
Five days after the catastrophic accident
at the Chernobyl Nuclear Power Plant,
it's May Day.
1st of May was a major holiday in the Soviet Union.
It was the Labour Day, as it is in this country,
but, of course, in the Soviet Union, it had enormous political
significance because the Soviet Union is the state of the workers,
the state of the labourers.
It was a day off, no matter which day of the week it was.
It was the day when you celebrated socialism.
So there were military parades,
people's parades. Everybody was out on the street.
And this is generally a happy occasion.
May Day parades are also taking place throughout the USSR,
including the towns and cities much closer to Chernobyl.
There was a very strong argument for cancelling the May Day parade
in Kyiv in particular.
Kyiv is 100 kilometres from Chernobyl.
It was experiencing very high levels of radiation.
Secret KGB documents reveal how little concern the authorities had
about the danger of holding the celebrations.
You probably would assume that the report,
especially three days after the accident,
would deal exclusively with Chernobyl,
that that would be the main preoccupation.
Well, in reality, the report is about something else.
The major Soviet holiday was coming up, and they were there to assure
that there would be no sign of dissent.
That was one of the tasks of the KGB.
They just didn't change their mode of operation,
Chernobyl or no Chernobyl, radiation or no radiation.
It does have a slightly unfortunate choice of words where it leads
by saying that the preparations for the celebrations
are taking place in an exceptionally healthy
political situation in the republic, which may be so,
but "healthy" is not something that applies to the area
at this particular moment.
Cancelling the May Day celebrations, it would have sent a clear message
that something was clearly up, both at home and abroad.
Gorbachev couldn't allow that to happen.
It's one of the more controversial decisions of his career.
But as the celebrations continued, the wind direction changed.
Prevailing winds and the weather systems
were moving the radiation cloud away from Ukraine,
across Belarus...
..and into Russia.
Within the Soviet Union,
all states are supposed to be equal, but clearly
some were more equal than others.
And at the top of the tree was always Russia.
It was the seat of government.
It was where many of the leaders came from.
It was the most powerful, the richest state
within the Soviet Union, and it needed to be protected.
Reportedly, a top secret operation named Cyclone begins.
It sounds like something out of a sci-fi movie, or...
It sounds ridiculous, but it actually happened.
Military airplanes loaded with silver iodide took to the skies
and chased those clouds moving from Ukraine in the direction
of the Russian Republic
and shot the clouds - literally shot the clouds -
with silver iodide capsules to make it rain.
It rained over Belarus and the rain brought down the radioactive fallout
matter onto the ground and onto the people who lived there,
several hundred thousands of people.
They became victims of the radioactive rain.
In many respects, Belarus is a forgotten victim of Chernobyl.
It suffered extensive damage,
its economy was ruined for many years.
And a large part of this, or a contributory part of this,
is the fact that huge areas of its productive farmland,
forests, became irradiated.
One of the main areas of contamination I've worked in
in the east of Belarus
has levels of radioactive caesium
that is almost the same as what you see in Chernobyl.
The Soviet Union needed help, and it would arrive
through back channels.
Over 6,000 miles from Chernobyl,
at the University of California,
a bone marrow transplant specialist, Dr Robert Gale, was getting ready
to fly to Moscow.
And I got a call in the middle of the night from
Ambassador Anatoly Dobrynin,
who said that Mr Gorbachev had asked him to ask me
to come to Moscow.
I grabbed my toothbrush and hopped on the next flight.
The flight was empty.
I mean, there was me and the pilot and two stewardesses.
You know, most people with any common sense
were headed the other way.
We have to remember that in April 1986,
the Cold War is still very much on.
The fact that the Soviets accepted help from the Americans does suggest
that by that point they realised that the situation was serious.
I was spirited off the plane and into a limousine
and taken directly to the hospital.
Dr Gale arrives at Hospital Number Six in Moscow.
Here, the Chernobyl firefighters and workers who received the highest
doses of radiation are being treated.
Their bone marrow -
stuff in our bones that produces the red blood cells
and white blood cells and platelets -
has been irreversibly destroyed,
so they're going to die of infection or bleeding.
Dr Gale had a pioneering solution to help these patients.
Well, there are hormones that stimulate your bone marrow.
And my colleagues and I at UCLA
had molecularly cloned those hormones.
Drug companies were in the process of developing this as a treatment.
So you would give this hormone to some cancer patient
who got chemotherapy,
and this would make their bone marrow recover.
Now, we had given these hormones to mice and dogs
and even monkeys,
but we haven't given it to humans before.
Of course, the Politburo said no.
They said, "Well, we don't want Soviet citizens to be guinea pigs."
I came up with an idea, which was,
"Why don't you inject this into me
"so these firefighters won't be the first?"
Dr Gale and his Russian counterpart at Hospital Six
both took doses of the untested hormones.
Our blood counts went up the next morning.
We were the guinea pigs and we got permission.
We had about 204 people in the hospital
with radiation sickness.
29 of them died.
So we were able to rescue more than 90%.
Six days after the accident, an exclusion zone is set up
around the Chernobyl Nuclear Power Plant.
The higher-ups decided that maybe, after all, they ought to evacuate
people from 100 or so other villages in the surrounding areas.
So they created this 20-mile exclusion zone around the reactor,
and that remains in place to this day.
But the exclusion zone is not the only area
that has suffered radioactive fallout.
The radioactive cloud from the Chernobyl nuclear reactor
has now spread across the whole of Britain,
according to official readings.
In the UK, the May bank holiday weekend is getting under way.
Radiation spread with the winds.
Any parcel of air that had gone over Chernobyl during the ten days
when it was burning was radioactive.
And some of it just spread across the North Sea
and started raining out over Scotland and Wales.
People started to be told that they shouldn't go out in the rain.
People wouldn't harvest vegetables from their allotments
because they were frightened.
This is in the UK, not just around the corner from the reactor.
So people were very worried.
The authorities were very worried.
It was, I remember, a really scary time when it was going on.
CHILDREN LAUGH
The whole of Europe was frightened by what might happen.
A deadly clean-up operation begins.
The rule really was that the job had to be done.
The liquidators were really the heroes of the story of Chernobyl.
A shocking tragedy adds to the death toll.
And war threatens the safety of Chernobyl once more.
The unthinkable of attacking nuclear power stations has happened.
A Soviet dream that became a nightmare.
A disaster officials tried to cover up...
..as a brave few battled to stop radiation
spreading across the globe.
Using top secret Soviet documents
and hearing from those, who risked everything...
..this is the story of one of the world's worst nuclear accidents.
It's been eight days
since Chernobyl's fourth nuclear reactor exploded.
The core of the reactor is smouldering,
releasing large amounts of radioactive material
into the atmosphere.
Helicopters battled to stop this deadly radiation escaping
from the molten core.
The temperatures,
which we are led to believe were in excess of 2,000 Kelvin,
would annihilate anything that came into that vicinity.
So, the way to use that is to think about how we can use the heat
to melt a structure that would act as a neutron absorber.
A number of different things were tried.
It was decided to dump a lot of sand on top of the reactor core.
Temperature and radiation levels are rising.
There was a need to think about other types of element
to encase that fallout.
Lead and a rare element called boron are added to the sand.
Up to 200 drops are made every day.
They were tasked with going on what they call "bombing runs",
filling up sandbags and dropping them
through quite a narrow hole in the roof onto the reactor below.
It's incredibly dangerous work.
The entire time, the people in the helicopter were receiving
quite a high dose of radioactivity.
The reactor is leaking radiation
that's up to ten times above a lethal dose.
One of the pilots who flew over the disaster site
is Soviet Captain Alexander Maruhin.
In total, 5,000 tonnes of materials are dropped onto the reactor.
Nine days after the disaster, the temperature begins to fall
and the radiation leak suddenly drops by 99%.
But by then, the radiation leak outside the plant is huge.
Large areas of Ukraine are now highly radioactive.
The Soviet Government announced an ambitious clean-up operation.
Thousands of people are drafted in to Chernobyl
from across the Soviet Union.
Most of those were young men and they were given a job to do
without really being told the full consequences of...
..of what they were undertaking.
They become known as liquidators.
Liquidators was a Russian term to describe the people
who were engaged in the clean-up,
mostly soldiers and other military people, many of them conscripts,
brought in to do the dirty work.
Ultimately, around 600,000 people were involved
in this liquidation campaign.
This is a high-risk operation.
Working in and around the disaster site,
the liquidators risk being exposed to high levels of radiation.
2,000 roentgen is 10,000 times higher than background radiation
and many liquidators like Vladimir Kagan are sent into areas like this
with little or no safety equipment.
The liquidators were definitely inadequately equipped
for the dangers that they were facing.
The rule really was that the job had to be done,
and if there wasn't the safety equipment,
then people simply weren't given it.
Many liquidators travel miles from Chernobyl.
They move from village to village, searching for radiation hot spots.
The release of radiation from the Chernobyl disaster was so intense
that anything that came into that vicinity would've been irradiated.
Many towns and villages were affected by radiation.
Where a building was infected, it was sprayed with a decontaminant.
It was a viscous liquid that caused...
..any radiation to adhere to the side of the building.
So, the building itself became a kind of...
Almost flypaper, where irradiated material was stuck to it.
In other places, where the radiation levels were even higher,
bulldozers were sent in and entire villages were completely flattened.
Abandoned homes are searched.
Cars are collected.
Anything registering high levels of radiation is removed and buried.
Then, some liquidators are sent on a bleak search and destroy operation.
GUNSHOTS
You needed to remove all the livestock
and much of the wildlife as well because it was radioactive.
GUNSHOTS
They went into towns, villages, found animals -
pet dogs, cats - and shot them.
It's terrible, soul-destroying work.
As the clean-up operation continues,
helicopter pilot Alexander Maruhin is recruited for a special mission.
Harmful levels of radiation are detected
up to 19 miles from the disaster site.
During one flight over this contaminated countryside,
Alexander makes a surprise discovery.
Their cows are likely producing milk that's highly radioactive.
In the aftermath of the disaster,
over 100,000 people are taken to hospital for examination.
If radioactive iodine gets into the food chain,
and particularly into milk,
almost all of it goes to this small thyroid gland in our neck,
and so they got really very, very high doses of radiation
to their thyroid gland.
Across the vast radioactive landscape,
many people fear that they've been poisoned.
They didn't know what physical damage they'd suffered,
whether they had radiological symptoms,
whether they were suffering more cancers than you would've expected.
They feared it.
Soviet authorities face a dilemma.
Chernobyl used to produce 10% of Ukraine's electricity
and that power is still needed.
Despite the huge dangers involved,
it's decided the three working reactors must be switched back on.
Before Chernobyl can begin producing power again,
two things must happen -
highly radioactive material has to be disposed of
and the destroyed reactor must be enclosed.
This was...
..easier said than done
because nothing like this had ever happened before
and nobody had the experience of building a containment device
to prevent further radiation escaping.
An ambitious plan is drawn up.
A large metal structure will be built called the Sarcophagus.
It was essentially a series of flat-packed slabs of concrete
and steel built off-site, put together,
moved into position around what was left of the reactor building,
and then, assembled.
This turned out to be probably
the world's largest prefabricated building.
The walls of the Sarcophagus are built,
but next to the exposed reactor is a roof
covered in highly radioactive material.
Before operators can go back to work, this has to be cleared.
They tried using robotic vehicles, automated vehicles,
but it didn't work.
Essentially, the radioactivity fried the circuits of those robots
and they died.
It became very clear very quickly
the only solution was to use humans to do this work.
And in a grim piece of Soviet irony, they became known as biorobots.
SHOUTING
Soldiers were sent up to clear off the debris from the roof
back into the reactor hall.
They were incredibly brave cos they faced something
that was, to them, a terrible danger.
Radiation levels on the roof are extreme.
Liquidators are given strict time limits.
Within 90 seconds,
they could receive an entire year's dose of radiation.
Most of the dose they got was...
You can't control with suits and respirators.
There is an additional risk from inhalation of radioactivity.
There's an additional risk if you get contamination on your body.
They were getting an external gamma dose rate risk,
which goes through any suit that you can imagine.
Nearly 4,000 people braved the roof to clear this deadly material.
These people were following orders
and they had to do what they were being told to do.
The fear of suffering radiation sickness drove many
to use unorthodox ways that they believed would protect them.
Some drank vodka.
Others took even more dangerous and futile measures.
Five months after the explosion,
the roof's radioactive material has been cleared.
The Chernobyl power plant's three working reactors
can now be switched back on.
The liquidators raise a flag to celebrate.
But within 24 hours, disaster would strike again.
As the Sarcophagus neared completion,
a military helicopter was flying over the Sarcophagus,
pouring decontamination into the reactor just to...
As a final cleansing operation, as it were.
These four victims add to Chernobyl's death toll.
And six months after the explosion,
now, over 18,000 people have been admitted to hospital.
In late November, the Sarcophagus is sealed.
They managed to put up the entire erection in around about 250 days,
which is quite remarkable.
The radiation leak has finally been stopped.
The world breathes a sigh of relief.
We're assured it's now completely safe to be here
just a few hundred yards away from reactor number 4.
When the concrete entombment was finished,
the level of radiation went down by several thousand folds.
The summer of 1987, Chernobyl makes headlines once more.
12 miles from the disaster site,
inside this building, a trial is taking place.
The trial became known as a so-called open trial
in the closed zone because they conducted it in Chernobyl.
No-one could admit that the system could fail
because the system was everything.
So, the government can't accept that responsibility.
It's got to be someone else's fault.
In the dock are six people, including Anatoly Dyatlov,
who was in charge on the night of the disaster,
chief engineer Nikolai Fomin
and Chernobyl's plant director Viktor Bryukhanov.
Bryukhanov knew quite well that
sooner or later he would end in prison.
That was part of the unwritten rules of the game.
Within the Soviet managerial system,
the director would be always kept responsible for...for what happened.
For many, the verdict in this trial is a foregone conclusion.
The authorities have made up their mind who was responsible
but there needed to be some form of public acceptance
and show of trial and retribution.
As authorities prepare to pin the blame,
secret KGB documents now reveal
they knew these people weren't responsible.
Chernobyl's style of reactor had major design flaws.
This document states that in 1987 there were 66 emergency shutdowns
at nuclear power facilities across Ukraine,
which seems to be really very high.
80% of these shutdowns are associated with
design and process equipment.
It tells me straight away that the design is...
..arguably not fit for what its purpose would be.
Rather than admit Soviet design was at fault,
witnesses are called to try and pin the blame on those on trial.
The verdict is announced.
All are found guilty of violating safety measures.
Dyatlov, Bryukhanov and Fomin receive the maximum sentence -
ten years hard labour.
Five years after the Chernobyl disaster
and its impact is still being felt.
It has severely damaged the stability of the Soviet Union.
Chernobyl became a catalyst for the independence movement
that had been growing, I think, quite slowly,
but had been calling for more autonomy for the republics.
In Ukraine, the first issues related to Chernobyl was the demand -
"Tell us the truth about Chernobyl.
"Show us the map of the fallout."
It's impossible to imagine Ukraine's road to independence
without mobilisation around Chernobyl.
Disillusioned with how the Chernobyl disaster has been handled,
the Ukrainian people declare their independence.
It's the beginning of the end of the Soviet Union.
But in the rush towards independence,
the human cost of Chernobyl is forgotten.
Many of the liquidators, those who cleared up the disaster,
are suffering terribly.
The official death toll stands at just 31.
But those who were at the disaster site tell a very different story.
Even for those, who didn't receive a fatal dose of radiation,
there is still a huge price to pay.
People's fear of what might happen to them because of the radiation.
You think the radiation is going to do harm for you,
so you don't take it as good care of yourself as you might.
You might drink more, you might smoke more,
you might live more dangerously.
And so, those factors in the lives of the liquidators
have been much more important
than the radiation dose that they received.
By the mid 90's, for those living in areas
contaminated by high levels of radiation,
there's a growing health crisis.
I started becoming interested in Chernobyl,
when my boss, who was one of the premier pathologists,
came back from Belarus.
He was...he was visibly shaken.
We have seen an increase in thyroid cancer...
..in about 7,000 children.
Everyone was a child at the time of the accident.
We predict there'll be probably
an excess of 16,000 thyroid cancer cases
but that will be spread over a long period of time,
so over the next 50 years.
Most of us were expecting to see far more different types of cancer
from exposure to radiation.
It is possible there may still be an increase
but we would've started to see something by now,
if it was going to be a big increase.
The exact number of deaths caused by the radiation will never be known
but the UN estimates it could be as high as 4,000.
The city just two miles from the disaster site
remains a haunted wasteland.
Without human interference, nature is reclaiming the area.
But at Chernobyl, there's a growing problem
that threatens to raise radiation levels once more.
Inside the Sarcophagus, it was essentially continually raining.
It was because of the heat difference
between the inside of the Sarcophagus and the outside.
So, everything inside of the reactor building,
inside of the Sarcophagus, was corroding really very badly,
including the fuel itself, which, when it corrodes,
it creates radioactive dust.
The Sarcophagus is falling apart.
A lot of it was built,
so that it was propped up basically like a house of cards.
It was really never built to last.
Sooner or later, it was going to collapse.
Workers explore Reactor 4's building
and discover corrosion in many areas.
Recognising the threat Chernobyl still poses,
45 countries, including the United States,
Russia and the United Kingdom,
all donate towards a new safe confinement shelter.
The overall plan was something like 2.1 billion
and 1.5 billion of that was for
the design and construction of the new safe confinement.
Work finally starts on the new structure in 2010,
but it takes another six years,
until it's ready to be placed over the old Sarcophagus.
It was decided that the best solution was an arch
that could be built some distance away
with relatively low levels of radiation exposure,
and then, slid over the facility, once it's completed.
This is to be the largest movable, land-based structure ever built.
Sliding something three times the weight of the Eiffel Tower
with millimetric precision over several days.
The longest slide we did in one day was about 18 metres
and it had to slide 300 metres,
so that gives you an idea of how long it took.
And it was slide, stop, check, slide, stop, check it every time.
As soon as we got to slide over the confinement,
we had to interface with the old structures.
We encountered tremendous challenges
in terms of the radiological risk there.
The worst was places, where workers could work
for about five minutes a day in terms of sealing the old structure
because the radiation levels were so high.
At times, we had doubts
whether we'd actually ever get over the finishing line.
The shelter is finally in position.
As the new confinement structure is sealed into place,
radiation levels fall by 90%.
The lifetime of the new safe confinement is 100 years.
The design life is 100 years.
I have every expectation that it will actually last
considerably longer than that.
Reactor 4 is now safer than it has ever been
and the teams start the long and difficult task
of deactivating the remaining reactors.
But six years on,
the contained Chernobyl plant is about to face another catastrophe.
Once the invasion happened,
people realised that the invasion route,
one of them at least, towards the capital Kyiv,
lay through the Exclusion Zone.
Russia was moving tanks and heavy equipment through the zone
and that raised radioactive dust.
JOURNALIST: Ukraine is under attack.
It has been since the early hours of the morning.
JOURNALIST: Russia pouring troops and tanks
into the Chernobyl Exclusion Zone.
At the end of February, Russia invades Ukraine.
Around Chernobyl, the Ukrainian army prepares to fight.
The spectre of another nuclear disaster
strikes fear around the world.
Chernobyl is this word that is associated with such great horror,
and the thought that that might suddenly not be safe
was a huge cause for concern.
As Russia invades, Ukraine tries to establish Chernobyl
and other nuclear power plants as no-go areas.
The Ukrainian authorities were begging
the International Atomic Energy Agency to negotiate a deal,
in which there would be a 30km exclusion zone.
The area that would be prohibited for any kind of military actions
and any kind of military operations.
Their pleas fall on deaf ears.
Without any agreement in place,
Chernobyl and all the staff, who work there, remain a target.
There's still a lot of people working on the Chernobyl site.
A lot of scientists are needed.
There's a lot of administrators that are needed.
There's a lot of maintenance people that are needed.
It's about 2,500 people that are there.
They're going in and out on a daily basis.
The main task to the people working on the site is really
just to make sure that the place stays as safe as it possibly can,
checking the spent fuel, making sure that there's no damage
to any of the containers and so on.
Within hours of the invasion,
Russian and Ukrainian forces battle outside the nuclear power plant.
I think that really struck a deep chord and provoked deep fear
that something might once again go wrong in Chernobyl.
The Chernobyl plant is now in the hands of the Russians.
It was actually reported that a shell had hit one of the containers,
housing the nuclear waste.
And a spike was recorded in radiation levels.
In some areas, the indicators are showing
that the radiation level went ten times up.
What happened was that Russia was moving tanks
and heavy equipment through the zone...
..and that raised radioactive dust.
The rise in radiation levels is relatively low...
..but it's a frightening reminder of what could happen.
Any nuclear power plant is strategically important.
There's the psychological impact of it,
of being able to capture something that will hit the headlines.
The Russians have now control over this area,
where there was a disaster that happened.
What's going to happen next?
Just 13 hours after the invasion begins,
Russian forces take over Chernobyl.
200 workers are taken hostage.
The Russians then force them to maintain and run the site,
which was challenging because...
..they can't really work seven days a week, 24 hours a day.
However professional or however well trained you are,
if you're working under duress,
or if you're working in difficult circumstances,
or if you're not getting enough rest,
there is a risk you may start to make mistakes.
I don't think the taking of the people hostage
necessarily was the scary bit.
If they kicked them all out or they killed them,
then that would've been even more scary.
The workers are held hostage for the next 13 days.
Then, the situation at Chernobyl worsens.
On the 9th of March, the power went down on the Chernobyl site.
Now, that was significant because the power is needed
to keep the air conditioning systems going
inside the containment buildings,
where a lot of the spent nuclear fuel is being stored.
More than 30 years have gone into making this place safe,
but if the systems they've put in place are no longer able to function properly,
then people would obviously be worried
about the potential consequences.
The loss of power could lead to a radiation leak.
If the heat builds up, the water that's surrounding
the spent nuclear fuel will begin to evaporate.
And that evaporated water will pick up radiation
and radioactive isotopes from the spent fuel rods
and put them into the atmosphere in the containment area.
It would increase the danger in the area
and the danger of highly radioactive isotopes
escaping into the atmosphere, if that got vented.
Information leaks out that the Russian soldiers don't understand
the danger the Chernobyl plant holds.
They won't have been briefed of the hazards in Chernobyl.
In fact, there are reports to suggest
that many of them had never even heard of the Chernobyl disaster.
With every passing day,
there's a growing fear about what's happening inside the plant.
Suddenly, all monitoring systems
and all communications to the outside world are cut.
Once you cut-off communication, you can hope that everything's OK.
You know that there are systems there,
but ultimately, you do not know what's happening.
Communication is absolutely key.
Once you lose your situational awareness,
then one's mind starts to run riot.
And when you're looking at a potential nuclear disaster
and there is no information going any way...
..people obviously start thinking about what the implications are.
And because it's nuclear, one is looking at the worst case scenario.
After five days, Chernobyl is reconnected to the power grid.
When we realised that actually Chernobyl was back up and running,
the power was running, people were there,
the flow of information was happening,
that was a huge relief.
The workers have been held hostage for three weeks.
Conditions inside the plant are deteriorating.
It seems unlikely to me that...
..that Chernobyl had three or four weeks of food already backed up.
We know that the Russian army has got no food.
So, no doubt, they were on meagre rations
with people holding guns over their head
and not knowing what was happening tomorrow.
I mean, absolutely horrific.
There were reports of people having to sleep on chairs
or in their offices or whatever.
This is not a place, which is meant for people to stay there
for days and days and days.
The hostages have now exceeded 15 days at the plant.
The maximum time allowed to keep radiation exposure to safe levels.
If the war means that those levels have not been observed
or adhered to, then there are potentially consequences
for the people, who are working at the site
and may have had more exposure than they should have.
Word gets out that Russian soldiers,
digging trenches around Chernobyl, could be falling sick.
They won't have understood the threats from the radiation.
So, they're sitting there breathing in the smoke
with radioactive particles in it,
the dust that their armoured vehicles and their wheeled vehicles
are kicking up with radioactive isotopes in it
and not knowing that these are potentially causing them harm.
They probably still don't know that these are causing them harm.
And I suspect the Ukrainian scientists haven't told them.
JOURNALIST: Russian troops have now pulled out
of the heavily contaminated Chernobyl nuclear site.
After 24 days of captivity,
the hostages are finally released
and replacement workers are allowed to enter the site.
It was a relief. Things were starting to get back to normal.
But it's a reminder that
in order for the safety procedures to function properly,
people need to be allowed to go in and out,
not kept there in circumstances,
which must've been at times terrifying.
The Russian targeting of Chernobyl has highlighted
the potentially devastating role of nuclear installations in wartime.
The last time that we had a large-scale war in Europe
was the Second World War.
This was not a Europe, where there were nuclear power stations.
And I think the return of 20th century war,
combined with this technology
that was supposed to be part of a peaceful future
has really scared people.
Russia is really weaponising nuclear power plants in this war on Ukraine.
What is happening in Ukraine today is a warning to the world as a whole
about the danger of the nuclear power
that normally we didn't think about and didn't talk about.
And that's what happens once the war arrives.
The unthinkable of attacking nuclear power stations has happened
and we must make sure that it doesn't happen in future.
Chernobyl's deadly legacy began over 30 years ago...
..and will continue long into the future.
The Chernobyl reactors today are a stark reminder of what happens,
when you don't think things through,
when you don't have a plan for what to do when something goes wrong,
particularly, when we're talking about radioactive materials
that could have severe health consequences.
Those materials are now there.
They may still be there for another 30 years, maybe 300 more years.
Today, it symbolises different things for different people.
It has been a symbol of the danger that the nuclear power brings along,
but also, a symbol of the war and Russian aggression.
So, Chernobyl really means different things
but none of those things is actually good or positive.