Original subtitles

- [Male Narrator] Our history is no more than a series

of incredible events.

Each one of us can influence its course.

The tiniest of our decisions can influence

the future of mankind.

To know the past is to anticipate the future.

April 26, 1986 at 1:03 in the morning,

Engineer Anatoly Dyatlov gives the order

to start a test in the Chernobyl nuclear plant.

25 minutes later, firefighters are

struggling to extinguish an enormous fire

in the very core of the plant's reactor number four.

(dramatic music)

On May 5, 1986, three engineers sacrifice their lives

when they dive into radioactive water to prevent

the cataclysmic explosion of the plant.

These three, intimately connected events,

are key moments in one of the most tragic

industrial accidents in history, the Chernobyl disaster.

Let's see why.

Energy, which allows us to move around,

to keep warm, to communicate.

(gentle music)

In our time, control of energy resources,

mastery of production techniques and the impact

on the environment are major issues.

The history of energy is linked to that of man.

The determination to control it and understand it

is one of the cornerstones of our civilization.

400,000 years ago, at the dawn of humanity,

prehistoric man discovers it without knowing

what it really is.

It can take a number of forms.

It has many faces.

Muscular energy, either human or animal,

to move around or carry things.

Mechanical energy, which uses forces such as gravity.

Thermal energy, which can turn fuel into heat.

Hydraulic, which by channeling water,

revolutionized transport and agriculture.

Wind, which uses its power to turn windmills

or drive ships.

In the 19th century, the Industrial Revolution

made it possible to understand a basic principle:

all energy production is in fact a transformation.

For example, coal contains energy.

When you burn it, the energy escapes.

This thermal energy heats water,

which in turn becomes steam.

This steam can then turn into mechanical energy

by working pistons or into electrical energy

using an alternator.

Energy cannot be created or destroyed,

it is transferred.

Like a mighty river, you can channel it,

tame it, use it, but you can also

lose control of it and then be flooded or drowned.

In 1898, husband and wife scientists Pierre

and Marie Curie discover radium,

an element that glows in the dark

and appears to produce infinite energy.

It's potential is enormous.

One gram of radium contains enough energy

to turn a ton of water into steam.

It is one of the earliest discoveries

that will lead to the development of this energy

that is both powerful and dangerous, nuclear energy.

- [Female Narrator] Welcome, to the memory of humanity.

(energetic music)

Here, we can control time, analyze and compare

billions of events, and alter them to rewrite

history endlessly.

For example, let's dive into the core of a nuclear

reactor to understand how it works.

A classic power plant works by burning a fuel,

whereas a nuclear reactor draws its energies from atoms.

When an atom is split, it releases

an enormous amount of energy,

energy that will split other atoms

in a chain reaction that can become a veritable bomb.

Under control, it is a formidable source of energy.

The nuclear plant turns all this energy

into steam, which then works

turbines to produce electricity.

To work, a reactor needs a raw material,

generally uranium.

Purified and refined, these materials become

tiny 10-gram pellets, each able to release

the equivalent of a ton of coal.

This combustible is placed in the core

of the nuclear reactor, which is itself contained

within a gas-tight vessel.

The whole is insulated within a solid concrete

structure known as the containment building.

This is supposed to contain any potential leaks.

Elements of vital importance, the control rods,

in an emergency, these rods are thrust

into the core of the reactor.

Their mission, to stop the chain reaction.

In theory, with all these safety measures,

accidents cannot happen.

However, the Chernobyl plant is rather unusual.

It has no confinement enclosure, and there are

no pressure sensors within the reactor core itself.

If there's a problem, nobody really knows what's happening.

The whole thing is monitored remotely from a control

room from which all orders are issued.

A misreading or a poor decision taken in this room,

and the reactor can dangerously overheat.

- [Male Narrator] The Soviet Union, Ukraine, April 25, 1986

Lenin Nuclear Plant, 11 miles north

of the city of Chernobyl.

It's a special night in the plant.

In the control room, everybody is at his post.

Anatoly Dyatlov, assistant chief engineer,

is supervising operations.

(dramatic music)

For the first time, they're going to test

the working of reactor number four in the case

of a power cut.

For the requirements of the test, the cooling

alarm systems need to be disconnected

and the power of the reactor reduced.

23:10, the power of the reactor is reduced

to 700 megawatts, as planned.

The test can begin.

Half-past midnight, Anatoly Dyatlov and his

managers disagree on procedure.

One of them gets an extremely important manipulation wrong.

The reactor's control rods go in too deeply.

The power then drops rapidly to 30 megawatts.

Six minutes later, the reactor dies.

Its rate was far too low.

Suddenly, the pressure rises.

Because there's no sensor, nobody in the control

room is able to spot the danger.

38 minutes past midnight.

The reactor is producing hardly any energy.

Anatoly Dyatlov orders the control rods

to be removed and to restart the reactor.

This is directly against safety regulations.

The team protests in vain but obey orders.

42 minutes past midnight, the power of the reactor

rises but struggles to go above 200 megawatts.

This is not enough.

1:03, despite the malfunctions, and against the advice

of his team, Anatoly Dyatlov starts the test.

At the same moment, within the core of the reactor,

a hot point forms and concentrates.

Nobody can see it.

1:21, the emergency system calls for the immediate

shutdown of the reactor.

1:23 and four seconds, the test begins, despite everything.

At the same moment, a worker sees the lid

of the reactor rising because of the pressure.

1:23 and 40 seconds, Foreman Akimov decides

to trigger the emergency shutdown process himself

and lowers the control rods, but the heat

has distorted the guide tubes.

The rods only go down five feet instead of 20.

It's too late.

1:23 and 44 seconds, they hear the first explosions.

The reactor core is out of control.

Its power is multiplied by 100 in a few seconds.

The bottom of the reactor explodes and turns

into radioactive magma.

(dramatic music)

A few seconds later, an enormous explosion

sends the 1,400-ton lid hurtling into the air.

Reactor number four of the Chernobyl plant

has just exploded.

- [Female Narrator] The price to pay.

The Chernobyl disaster is classified as level seven

on the scale of nuclear accidents.

The only other accident of equal gravity

is that of Fukushima in Japan in 2011.

It corresponds to a major accident followed by massive,

long-lasting pollution, leading to serious

consequences on public health.

However, the history of civil nuclear power

still includes nearly 30 accidents of lesser

gravity, sometimes going as far as the fusion

of the reactor core, as was the case

at Three Mile Island in the United States in 1979.

So the danger is real.

Accidents more numerous than one imagines.

And yet, nuclear energy has no monopoly on pollution.

Between gigantic oil spills and chemical plant

explosions, the impact of human activity

on the environment is greater and greater.

The history of energy may be linked to that of man,

but it's also linked to that of pollution.

That is the price we pay for maintaining our way of life.

Pollution is degrading a natural environment

by introducing foreign materials in too large a quantity.

On exploding, reactor four holds 50 tons

of nuclear fuel into the atmosphere.

The tragedy is only just beginning.

(dramatic music)

(fire crackling)

- [Male Narrator] The inferno.

Flaming debris falls onto the plant,

sparking some 30 fires.

Radiation illuminates the sky with red and blue light.

Deadly radioactive dust spreads everywhere.

On the site of the explosion itself,

at the core of the reactor, surviving workers

try to save what they can.

They evacuate the injured, cut power supplies,

get the pumps working again.

All of them will be irremediably irradiated.

In vain, because at this point, nobody is

able to stop the chain reaction in reactor four.

However, just next to it, reactor three is still operating.

The fire could eventually reach it.

At 1:28, four minutes after the explosion,

the first firefighters arrive on the scene.

They have no protection against the radiation.

Rapidly succumbing to nausea and vomiting,

our front-line heroes battle hand-to-hand

with the monster.

Despite pouring tons of water onto the reactor,

they cannot put out this invincible fire.

However, the other seats of fire

are progressively controlled.

In the end, their sacrifice saves reactor three

and prevents a fresh explosion.

(fire roaring)

Taken to the hospital at once,

their skin turned black.

They all die within a few weeks.

For their sacrifice, they will receive

the order of Heroes of the Nation.

(somber music)

- [Female Narrator] Save or perish.

The word irradiation means the exposure,

deliberately or accidentally, of a body to rays.

In strong doses, irradiation burns the skin,

destroys the nervous system and causes multiple cancers.

Actually, we are all permanently exposed,

whether it's for a simple chest X-ray

or during a flight in a plane, but fortunately,

to infinitely tiny doses.

(ominous music)

At Chernobyl, personnel and firefighters were

exposed to 30,000 times the fatal dose.

Not everyone knows the risks associated

with radioactivity, but one thing is sure,

once they were on the scene, despite vomiting

and burns, they did their duty to the end.

This sense of sacrifice, where the interests

of others is important, to the point of putting

oneself in danger to save them, is to be found

in a number of professions: firefighters,

policeman, rescue workers, soldiers, but it can

also manifest itself in any one of us

in emergency situations.

It has often happened that a great number

of human beings only owe their survival

to a tiny handful of people.

The firefighters of Chernobyl sacrificed themselves

to prevent the worst, but is all danger avoided?

- [Male Narrator] Morning of April 26th,

death is all around, invisible.

In the town of Pripyat, on the edge of the plant,

45,000 people begin their day as if nothing has happened.

Without knowing it, they are swimming in an atmosphere

saturated with deadly radiation.

Plenty of rumors are circulating about a fire

at the plant, but it can't be very serious

because no alarm has been raised.

(tense music)

Then, during the day, soldiers appear,

a worrying aspect.

They move around the town in protective equipment.

At the beginning of the afternoon,

the radiation norm has been exceeded by a wide margin,

more than 15,000 times acceptable dose.

By evening, it is 600,000 times.

36 hours after the explosion, the evacuation finally begins.

More than 1,000 buses head towards the town.

The residents have two hours to pack.

By the evening of April 27th, the town is

cleared of its inhabitants.

Only soldiers and scientists, ordered to evaluate

the accident, remain.

They all run a huge danger because the accident

is far from over.

The reactor core is still magma infusion.

Temperature, 5,400 degrees Fahrenheit.

Highly radioactive gasses are leaking out.

The radioactive cloud has already reached Sweden,

and the international community is getting

concerned by what is happening in the Soviet Union.

By any means, they have to stop

this radioactive hemorrhaging.

So, they improvise.

In turn, hundreds of helicopters fly

over the plant, to drop bags of sand and lead

into the gaping hole.

In this way, 5,000 tons are poured in

to limit the discharge.

600 pilots are irradiated.

Except that this plug has an undesirable effect.

It raises the heat in the reactor.

At any moment, radioactive magma may break

through the concrete slab and fall

into the basements of the plant,

and that would be an even more terrible disaster

because the basements are swimming in water,

in particular, that poured in by the firefighters

to extinguish the blaze.

5,400 degrees Fahrenheit of radioactive magma

suddenly plunged into 20,000 tons of water,

a thermonuclear bomb 80 times more powerful

than that dropped on Hiroshima during the Second World War.

The city of Kiev would be razed.

All life would be destroyed within a radius of 200 miles.

Only one solution to avoid the worst:

dive into the plant's basements,

swim through a radioactive soup,

find the drain sluices in the dark

and operate them manually.

(somber music)

Three of the plant's workers volunteer:

Valeri Bezpalov, Alexei Ananenko

and Boris Baranov.

The first two know exactly where the sluices are.

The third accompanies them with a torch

to guide them through the murky waters.

They are fully aware of the risks.

They remain in the gloom for an hour,

an hour to accomplish their heroic task.

They will die in the following weeks.

May 6th, the core of the reactor infusion

finally falls through the slab.

It reaches the basements of the plant.

Fortunately, there is no longer any water

to trigger an explosion.

- [Female Narrator] We have just reached a turning point.

A turning point is a key event, a crossroads

in our history where the world swings

one way or the other.

Faced with the imminent danger of an apocalyptic

nuclear explosion, three men volunteer.

They know it's a suicide mission.

What would have happened if nobody had gone

to open the sluices?

In the worst scenario, dozens of tons

of radioactive magma, at several thousand degrees,

would have come into contact with 20,000 cubic meters

of water in a confined space, a gigantic pressure

cooker, but without any safety valve.

The explosion, estimated at 50 to 80 times

that of Hiroshima, would certainly have razed

the city of Kiev and exterminated all life

within a radius of 200 miles.

Moreover, it would've reduced all the forces

responsible for fighting the accident to nothing,

nobody left to stop the flow of radiation,

the contamination would've been cataclysmic,

affecting the regions water reserves,

contaminating the soil for centuries.

Human life would no longer have been viable,

except at the price of cancers and genetic deformity.

Central Europe would've become a vast no-man's land,

a lost territory of desolate lands.

Our world of today would have a radically different face.

- [Male Narrator] The worst has been avoided,

but the situation remains extremely grave.

In a radius of 20 miles around the plant,

the earth, the water, the plants, the animals,

everything is polluted and highly radioactive.

(tense music)

To clean up this vast zone, 600,000 men

are employed to wash away the layer of dust,

level houses, bury waste, slaughter animals.

They call them the liquidators of Chernobyl,

and they are fighting the invisible enemy.

To prevent the radioactive magma from descending

further and contaminating the groundwater,

an access tunnel is dug.

Objective, construct a new concrete slab

underneath the reactor.

10,000 men work shifts night and day

to dig this tunnel.

Irradiated, a quarter of them will die

before the age of 40.

(man coughing)

Cleaning the plant itself is extremely dangerous.

The smallest debris is sufficiently radioactive

to kill a man within an hour.

So they send in remote-controlled robots.

However, these break down because the radiation is too high.

Only men can do what has to be done.

Rotating every 45 seconds, equipped with simple

lead protection, those they will call the bio-robots

fight at the risk of their lives to clear the debris.

After these cleanup operations, a concrete

sarcophagus can finally be built around reactor number four.

It is left to later generations to deal

with the time bomb that is sealed within.

In our time, a gigantic construction site

is underway at Chernobyl.

To renew the confinement to the reactor,

they are building a formidable arch consisting

of 30,000 tons of steel and standing 100 meters high.

Lifespan of this new protection, around 100 years.

And then?

But that is another story.

- [Female Narrator] Life always finds a way.

(pulsating music)

The Chernobyl region was cleaned up over a radius

of 20 miles from the plant then closed and fenced off.

Today, it is simply known by the name Zone.

Signs prohibit access and warn of the danger

of radioactivity.

The Chernobyl disaster was devastating for the human

populations but also for the local wildlife.

Animals that were not killed by the radiation

were slaughtered by the liquidators.

For a long time it was thought that this zone

was lost for centuries.

Everything appeared dead, frozen in time.

But, as always, life evolved and adapted.

Certain animals, better protected against radiation

than others, survived and have reproduced.

Today, species that are unique in the world

have appeared in this zone, abandoned by man,

sometimes with deformities or strange colors of fur,

but life is well and truly there.

And in the end, the biodiversity can be compared

to that of a nature reserve.

Billions of years ago, life conquered

the then sterile earth.

It has resisted bombardment by meteorites,

ice ages and major extinctions.

However, despite all these assaults, little by little,

life has always got the upper hand,

whatever its form, however much time it took.

Life is not fragile, it is tenacious.

It was here before man and will be here after him.

The only fragile thing is us.

The only thing in danger is our environment,

the very thing that allows the human species to exist.