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Today, in Ukraine, an international team of engineers
is racing to assemble
one of the most complex superstructures ever built.
It's the largest structure that will have moved on land.
An extraordinary 36,000-tonne, £1.2 billion mega dome.
Its job, to entomb the crumbling remains
of the Chernobyl nuclear reactor.
It's just fantastic. Really, really an amazing structure.
In 1986, the Chernobyl nuclear reactor exploded,
releasing 400 times more radiation than the Hiroshima bomb.
It was the world's worst nuclear disaster.
30 workers died. 50,000 people fled the nearest city.
And radioactive fallout turned an area larger than Lancashire
into a no-go zone.
30 years on, as scientists investigate
the true impact of the disaster...
It's given wildlife an opportunity to move back in,
for their numbers to increase.
..the shell of the nuclear reactor is collapsing.
Engineers must battle
to stop another escape of deadly radiation...
It is extremely dangerous.
Everything we touch, everything we do, it is completely crazy.
..fighting freezing weather and lethal radiation.
This is the inside story of the race to build Chernobyl's mega tomb.
These are the world's most uncomfortable boots.
But I think they preserve these just for occasional visitors.
Simon Evans is one of the world's most unusual bankers.
He is overseeing the funds for a project that will clean up
and make safe one of the most deadly places on earth.
The Chernobyl nuclear power plant in Ukraine.
If you spend too long in some parts of this building,
the radiation will kill you.
Don't stop, don't stop.
We are in the control room of Reactor 4,
where just over 30 years ago,
they conducted a safety test
on April 26, 1986,
and it went catastrophically wrong,
and there's the consequences we're all too familiar with.
At 1.23 in the morning inside this Soviet-built reactor,
a runaway nuclear reaction created a massive steam explosion.
The blast killed two workers,
and blew radioactive uranium fuel onto nearby buildings.
Radiation coming from this and the destroyed reactor
killed a further 28 people.
-'Soviet authorities have been trying
'to downplay the incident, claiming that there are
'only two dead and only 100...'
-'..reports coming out of the Soviet Union.
'We do know that a zone of deadly radiation has been released...'
The explosion sent 50 tonnes of nuclear fuel
high into the atmosphere.
The wind blew it across Europe.
Where it settled, it contaminated both the land and animals.
In the UK, sheep reared in parts of Wales and Cumbria
were declared unfit for human consumption.
Close to the reactor, the radioactive fallout
forced a third of a million people to evacuate their homes,
never to return.
It was and remains
the world's worst ever nuclear disaster.
HE SPEAKS RUSSIAN
After the dust settled,
the Soviet authorities faced a monumental problem.
Over 200 tonnes of radioactive material
remained inside the damaged reactor building.
Left unchecked, wind would blow the radioactive dust into the air.
Over the next six months,
workers battled extreme radiation
to seal the reactor inside a 300,000-tonne shelter
made from steel and concrete.
It was called the sarcophagus.
Once it was complete, the world breathed a sigh of relief.
Everything seemed safe.
But the engineers who built the sarcophagus
knew it was a temporary fix.
Today, 30 years after it was built, the shelter is falling apart.
This equipment monitors the stability
of the existing shelter, which is absolutely essential
to ensure that we know precisely what's going on here.
We know that it's way beyond its design life. It's crumbling.
We've already had a collapse in one part of the turbine hall
about two and a half years ago, with a very heavy snow load,
and you see some very major destruction and damage there.
This is the most radioactive area.
The hall that once contained the reactor.
The remains of nuclear fuel rods and the molten core of the reactor
give off so much radiation that visits here are limited to seconds.
Holes in the roof are clearly visible.
The collapse of the shelter itself over the old reactor hall
is the apocalyptic scenario which we must avoid.
Certainly, it would release
another major release of radiation into the environment.
The sarcophagus is a toxic time bomb.
Don't stop, Dermot.
To make the site safe,
today engineers need to entomb the crumbling sarcophagus
inside a completely new shelter.
There's just one problem with this idea.
The site is still too radioactive for builders to construct
a new cover directly over the old reactor.
So they have devised an ambitious scheme
to build a new shelter to one side of the reactor,
then move it into position.
This is their grand plan.
300 metres away from the reactor,
where radiation levels are low enough
for builders to work normally,
they will construct two halves of a giant steel arch
taller than Big Ben.
They will mount them on two concrete runways,
running either side of the crumbling sarcophagus.
Then, they will slide the two halves of the arch together
to make one enormous structure.
Inside the ceiling of the arch,
they will attach two giant robotic cranes.
Next to the reactor, they will construct a nerve centre
to provide the power, ventilation and control systems for the arch.
Once complete, engineers will slide the vast arch over the reactor.
It will be the biggest structure ever moved across land.
Over time, the remotely controlled robot cranes inside the arch
will dismantle the old sarcophagus
and remove the remains of the exploded reactor...
..making the site safe.
It's a trailblazing scheme that will cost more than £1.2 billion.
It will be funded with grants from countries all over the world.
We're not really a normal bank.
We have over 40 international donors supporting our work,
representing the fact that it was an international accident
and it's an international solution to that problem.
THEY LAUGH AND CHAT INDISTINCTLY
Since 2010, up to 1,200 people have travelled in
to work at the Chernobyl site each day.
The ambitious project has attracted an international team of engineers.
When you have the choice between building a tunnel in Miami
or an arch in Chernobyl,
it seems strange to go, to choose to go to Chernobyl.
It's a complicated project,
because it's difficult to understand each other.
MAN GIVES INSTRUCTIONS IN OWN LANGUAGE
It's hard to find somebody who hasn't heard of Chernobyl.
You know, my kids, when they talk about what their dad does, you know,
they're like, "Oh, yeah, that's a pretty special project."
I had a very nice agency call me and they asked
if I was interested in Chernobyl.
And I laughed and I said,
"You're having a joke with me."
But after a few conversations,
I realised they were being serious,
and I thought, "This is a challenge."
The first stage of the operation is to construct the arch,
in two halves.
The frame will be made from 25,000 tonnes of steel tubes,
whilst the vast roof will be clad with stainless steel.
Ukraine's harsh climate will make building the arch
a formidable challenge.
The biggest problem we have is the weather.
It's the biggest, biggest problem on here.
For the winter period, we can lose three months,
four months of the year.
Winter temperatures here can plunge to -29 Celsius.
Today, we have the wind problem,
yesterday we had ice on the roof, so we could not work.
We lost a whole morning yesterday just through ice on the roof alone.
Ian's team must work 109 metres above the ground.
That's twice the height of Nelson's Column.
For this job, it's extremely dangerous.
The winds, the rains,
makes the surfaces that we're working on very slippy.
The roofers are all trained rope access technicians.
But in these conditions,
a momentary lapse of concentration could be fatal.
Some of the materials that we are using,
they can act like a kite, if you like.
You can imagine a sail in the air,
and the material is razor sharp, so it's very, very dangerous.
So, yes, we have to be very, very careful.
The extreme weather and heights aren't the only risks that
the team must battle.
Radiation is still streaming from the melted uranium fuel
in the destroyed reactor.
The uranium fuel gives off radiation in the form of gamma rays,
high energy photons.
Some of these pass through the walls and stream out
into the surrounding space.
Most pass straight through a human body.
But some interact, damaging cells...
..and fragmenting DNA. Which can cause cancer.
The dangers are very real.
Back in 1986, when the Chernobyl reactor exploded,
the blast blew open the pressure vessel holding the uranium fuel.
This exposed workers and firefighters to
high levels of radiation.
Engineer Nikolai Pazhentsov
was on duty in the reactor as the disaster unfolded.
Radiation burns skin,
and can prevent cells in the body dividing normally.
In the weeks following the disaster,
28 workers died from their exposure to radiation.
Every year, on the anniversary of the disaster,
the people of Slavutych,
the town where most Chernobyl workers now live,
remember those who lost their lives.
Viktor Ivkin was also working at the reactor that night.
Like many others, he received a large dose of radiation.
100 Roentgens is over 900 times the annual dose of radiation
a member of the public is allowed today.
Today, at the Chernobyl plant, the danger of radiation still exists.
95% of the uranium that was in the reactor before the explosion
is still there.
Close to the reactor,
the high number of gamma rays makes it too dangerous to work for
the long periods of time needed to construct the arch.
But the engineers have one thing on their side.
As the gamma rays leave the reactor,
they get further apart from each other.
And some are absorbed in the air.
So for every 1,000 gamma rays passing through
a person standing 30 metres from the radioactive source...
..only about one will pass through a worker standing 300 metres away,
where they're building the arch.
Radiological engineer Nicolas Guilcher
measures the radiation across the site.
You can see...
A special unit checks the daily amount of radiation every
We provide everybody with dosimeters.
I have a French national dosimeters,
I have the Ukrainian national dosimeters, and then we
so have an electronic dosimeter that is our operational dosimeter.
The dosimeters ensure no worker receives too much radiation.
There is one further challenge that makes this already complex
project even tougher.
The crumbling reactor to their side could collapse at any moment.
In June 1986, two months after the disaster, Soviet engineers
began building the sarcophagus to enclose the ruined reactor.
The plan required 300,000 cubic metres of concrete
to buttress the damaged walls.
And giant steel beams to support the roof.
But the extreme radiation made it impossible to build
the sarcophagus to normal engineering standards.
Because all sarcophagus had no...building.
The sarcophagus had no proper foundations.
It simply rested on the ruins of the destroyed reactor.
Even as they built it, engineers knew its days were numbered.
Now, the 30 years are up.
If the roof of the sarcophagus collapses,
it will throw radioactive dust out into the atmosphere...
..where the wind could blow it towards the construction site.
If a worker inhales a radioactive fragment,
it could stay in the body, releasing radiation that could cause cancer.
Good morning, all.
So, this is jacking and lifting, so I will ask you all to not
stand under the load if you don't need to be under the load.
HE SPEAKS RUSSIAN
The team building the arch is in a race against time to complete
the job before the sarcophagus collapses.
As soon as you are ready...
Deputy construction manager Jean-Philippe Gardeur and the team
are gearing up to lift the second half of the arch to its full height.
Everything on this field is huge, it's enormous, you know?
We don't have small things.
Everything we touch, everything we do, is completely crazy.
Nice to hear this noise, eh?
It will take 40 huge jacks to raise this metal monster.
That's going to be very tight, that's for sure. But we'll see.
HE SPEAKS OWN LANGUAGE
Each jack has enough power to lift five jumbo jets.
-OK, guys. So, we start the jacking now.
OK. Let's continue.
HE SPEAKS OWN LANGUAGE
OK, perfect. OK.
Success. But the team can't afford to kick back and relax.
If the sarcophagus collapses before the arch is in place,
the fallout would contaminate both the arch and work site.
It would undo the years of work it took to clear up the
radioactive debris from the original disaster.
It's a nightmare scenario,
and the people here know better than anyone what the effects would be.
Two miles from the reactor lies the abandoned city of Pripyat.
50,000 people once lived here.
Many of them workers at the nuclear plant.
High levels of radioactive debris fell on this city.
It will be uninhabitable for hundreds of years.
Jean-Philippe must now join the two halves of the arch together
before winter sets in.
It will take 56 pairs of hydraulic pistons and over
a megawatt of power to pull the arch together.
The two parts of the arch are finally one. It's a major moment.
For the first time,
it's possible to see the vast scale of the new shelter.
Right now, it may look like nothing more than an empty hanger.
But before they slide the shelter over the reactor,
engineers will transform it into a living, breathing machine,
designed to tackle Chernobyl's long-term problems.
The radioactive debris inside the reactor will remain dangerous
for at least 20,000 years.
If engineers simply covered the reactor with the arch and did
nothing else, they would only be adding to the problem.
In time, many years from now, the arch would collapse,
and a future generation would need to build another, even bigger
one, to keep the reactor safe.
To stop this happening, engineers must fit out the arch with
trailblazing equipment designed to clear up the destroyed reactor.
Nicolas Caille is in charge of constructing the new shelter.
We have to provide tools to enable the construction.
We have to remove the sarcophagus built by the Russians,
so first of all,
we need to remove the roof over all the exploded reactor,
and then, after, they will have two break the concrete and at the
end, remove the fuel in the heart of the reactor.
It will take a long time.
Our arch is guaranteed for 100 years, so at the maximum,
they can take 100 years.
No-one has attempted to dismantle an exploded nuclear reactor before.
Radiation makes the job too dangerous for people.
The fuel that was there is still there, but when they start to
dismantle it, you're going to expose that fuel, and as it gets exposed,
the level of radiation will get much, much higher than it is today.
Rob Owen leads the team building a special robotic crane
that will dismantle the reactor... from inside the shelter.
It uses an ingenious system of wires to carry a platform
holding a robotic arm.
The arrangement of the wires is crucial.
If the platform was supported by vertical wires, it would swing.
But using three pairs of wires arranged in triangles,
and adding a heavy weight, makes it rigid.
It's not perfect, a strong side force could move the platform
and slacken in some of the wires.
But if the weight on the platform is heavy enough,
all the wires will stay tight.
And the platform will remain rigid enough to hold the robot arm
that will dismantle the sarcophagus.
We kind of had to really go back and study the design.
Would it work here? Could we make it big enough?
It had to be considerably larger
than anything that had ever been built.
But the idea was really intriguing, because of all the pluses.
To drill into walls or pull a beam,
the robotic arm needs to be able to push and pull horizontally.
We have the six wire ropes, and a lot of weight here,
as you can see on the bottom.
All the cables remain in tension.
It provides that stiffness that allows you to do pushing, pulling...
This quarter scale model demonstrates that the concept works.
But the only place large enough to test the full-size crane will
be in the arch itself.
In less than 16 months,
the team must slide the arch over the reactor.
But there's yet another major job they must complete before
Right next to the reactor, they must build the nerve centre that
will house the control systems for the arch.
And where trucks will collect
the broken down pieces of the old reactor.
It will be the entrance into the arch,
so the truck will enter below the arch and all the waste,
the deconstructed material, will go through that building,
out of that building, to be stored somewhere else.
The real challenges the location.
It's just ten, 20 metres from the exploded reactors.
This area is so close to the reactor that builders must wear extra
protection and working hours are limited.
It's too dangerous for people to work inside the crane cabs above
So operators drive them by remote control
from the safety of concrete sentry boxes.
I don't think 30 years ago there was a word in construction for safety.
It's increased... by tenfold, 100 fold.
Safety is much more important than it was before.
Back in 1986, the priority was to clean up the disaster...
..and people paid a heavy price.
After Chernobyl exploded, it burned for nine days,
spewing radioactive dust onto the surrounding countryside.
The Soviet authorities declared a 30km radius exclusion zone
around the reactor.
They drafted in 350,000 people to clean up the radiation.
They were called liquidators.
At the centre of the zone, they cleared the radioactive
debris from the roof of the exploded reactor.
Here, some only had 45 seconds to perform their task before
their dose of radiation became too great.
In the surrounding area,
they washed down surfaces to remove the radioactive dust.
They bulldozed and buried the most contaminated homes.
Along with over one million tonnes of contaminated soil and machinery.
Among liquidators was Ivan Martynenko.
GEIGER COUNTER RAPIDLY CLICKS
OFFICER GIVES COMMANDS IN RUSSIAN
The World Health Organization estimates that
around 2,200 liquidators have died or will die
as a result of the radiation they received.
Those guys are heroes.
They did tremendous work.
It could have spread and been much, much worse.
Today, the clean-up isn't finished.
It will take decades for the remote-controlled cranes
to dismantle the damaged reactor and dispose of its radioactive waste.
This creates another major design challenge for the engineers
building the arch.
It must last 100 years. The metallic structure cannot last 100 years.
You have to protect the structure and repaint it.
I mean, as a French, I take the example of the Eiffel Tower,
which is repainted every 7-10 years.
Moisture in the air will cause the steel to rust over time.
Painting the steel protects it.
But it will be impossible to repaint the steelwork once the arch
sits over the reactor.
As you can see, the steel structure has been painted in the factory.
This paint will last 15 years.
Unfortunately, we will not be able to renew it once the arch
will be in the final position, because the radiation
condition at that location are too severe for a painter.
But left unpainted, the arch will corrode.
To solve this problem,
they're engineering the arch to be an ingenious breathing structure.
The gap between the arch's exterior roof and interior ceiling
will be airtight.
This creates a vast enclosed space around the steelwork.
Powerful fans will suck in air from outside...
..channel it through massive dehumidifiers to remove moisture...
..then blow the dried air along 3.5km of aluminium ducts...
..into every corner of the enclosed space.
The ducts will constantly recirculate the dry air...
..to make sure that the atmosphere in the enclosure remains dry
so the steelwork doesn't rust.
For the ventilation to work, the interior ceiling must be airtight.
We have some junctions here, so because of this gap,
we have to do a compressed sealant, which makes the air seal tight.
This cladding is stainless steel,
and it's designed for the purpose of containing any airborne
contaminated particles from escaping into the environment during
the dismantling of the reactor number four.
Before engineers slide the arch over the reactor...
..they must install the massive cranes 80 metres above the ground.
-Baptiste Briois is the engineer in charge.
-Up, up, up. High up. Steps.
Today, he has a 26-storey climb to the control room.
369. 369 steps.
Twice a day!
Everyone in position, everything is ready. We can start.
We can go. We can start.
The team is relying on 12 hydraulic jacks fixed near the top of
the arch to lift the 800-tonne crane into position.
Inside the jacks,
hydraulic jaws grip the wires attached to the crane
and slowly hoist them up.
It's coming closer and closer. I like it.
But just of the crane lifts off, they hit a glitch.
Is there...? Sorry, sorry.
Is it OK?
No, apparently have a little problem with the strain carousel.
The lifting wires are tangling.
I'll be back in a minute.
Working 90 metres above the ground,
it's a precarious operation wrestling the wires back into place.
It was very quick,
they are very efficient, so we can still finish today.
HE SPEAKS OWN LANGUAGE
Now, engineers can start tests on the full-scale crane.
-Now, we can lift.
-Yes. Yes, we can lift, yes.
Within the next few years,
these cranes will start dismantling the ruins of the Chernobyl reactor.
It will be the final step
in the long operation to make the site safe.
But the reactor is only one part of a wider problem.
During the disaster, large quantities of radioactive
material fell in the area around Chernobyl.
A 30km exclusion zone was set up around the reactor.
30 years on, it's still a restricted area.
But what does the future hold for this contaminated land?
Scientists make regular visits into the exclusion zone to study
the effects of the radioactive contamination.
Ecologist Mike Wood is investigating what types of animals live in
the zone, and if the levels of radiation effect where they live.
At the time of the accident,
depending on which direction the wind was blowing and whether
or not there was rainfall, you got different amounts of
radioactive fallout in different parts of the exclusion zone.
Mike is setting up camera traps in three different areas,
places with high, medium and low radioactive contamination.
The traps will photograph any large mammal
that moves in front of the lens.
We're hoping to be able to understand more about the way
in which the range of large mammal species that we see
is or is not influenced by the radiation levels.
By placing traps at 84 randomly chosen sites in each area,
Mike hopes to discover how many different species of large
mammals live in each place.
So when we put the cameras out,
we take a GPS reading of the location of the camera, and then we
can use hand-held GPS like this to be able to find the cameras again.
And then come and see what it's recorded.
So... Let's have a look at this.
The cameras reveal an astonishing variety of life.
So we can see that we've got an elk here.
And wild boar, as well.
We see quite a range of animals on most of the cameras
that we bring back in.
Red deer, wolves, lynx, Eurasian lynx,
and also European bison, as well.
In the high contamination areas,
and in the low contamination areas, there doesn't seem to be
a difference in the range of species that we see.
It appears that some animals are thriving in the exclusion zone.
But the animals might not have it all to themselves for long.
In the once abandoned town of Chernobyl, nine miles from the
reactor, radiation levels are low enough that some workers
constructing the shelter stay here for up to two weeks at a time.
And a Chinese company plans to take advantage of the cheap land
to install 25 square kilometres of solar panels
to once again generate electricity in the zone.
There are only 11 days to go before the team moves the arch.
We are coming to the end.
We're preparing for the skidding of the arch over the reactor.
At last, this huge thing is built
and it's going to move to where it should be.
For the engineers,
this is the last chance to make sure everything works.
There's a lot more activity,
because we now have many more tasks to complete.
All in the same period.
One job is crucial before they slide the arch.
They must open its enormous special doors.
To stop radioactive dust escaping from inside the arch...
..its end wall must form a perfect seal around the
old reactor building.
But parts of the sarcophagus stick out,
preventing the arch from sliding to its final position.
So engineers have equipped the arch with
tilting panels, like giant cat flaps
that they must raise.
And then lower into place when the arch is in position.
Sealing the small remaining gap with a flexible plastic membrane.
Just as the team gets set to raise the heaviest panel, a winter
blizzard strikes, threatening to shut down the operation.
The icy temperatures could freeze the machinery.
We have six tilting panels and the largest one is 320 tonnes.
At the location where they will be located, it is not possible
to send a person to close these tilting panels, to operate them.
So we have designed a system of hydraulic jacks,
a system of winches to close these panels remotely.
It takes four hours to winch the massive cat flap open.
Seven years after work began to build the 36,000-tonne shelter,
the day finally arrives when the team will attempt to slide it
over the reactor.
It will be the largest structure ever moved across land.
We are almost at the end, and, yes, we are under pressure.
It's a great challenge, because of the size.
I'm also thinking about myself.
I have already a lot of white hair,
and the sooner it will be finished, the better it will be for me.
When you come here, you look at the distance between the reactor and the
arch, you're thinking, wow, this is going to be a couple of days' work.
Moving this massive structure will be no simple task.
The obvious way to move a monster arch would be on wheels.
But that won't work here.
The arch is so heavy that it would overload the wheel bearings...
..which would fracture, leaving the structure stranded.
So instead of wheels...
..engineers will use 116 steel feet known as skid shoes.
These will slide on Teflon pads placed on top of the rails.
It's a typical example of a Teflon pad with the two holes in it.
Over these, we put the Teflon pad, right solid.
And basically, if you put a lot of them,
you make your own sliding way for the skid shoes to slide on.
This nonstick surface, also used on frying pans, will help the
stainless steel feet of the arch to slide with very little friction.
To push the arch, engineers will fit each leg with hydraulic pistons.
These move a pair of wedges that grip the steel rail.
Powerful pumps will then extend the pistons to push the arch forward.
More than 200 pistons must work in perfect unison
to slowly slide the arch towards the reactor.
This is a one-off skidding.
I mean, you can't go back,
so you should be sure that you have not forgotten anything.
HE GIVES INSTRUCTIONS
This is the critical manoeuvre everyone
has been working towards for seven years.
There's the confirmation that we are ready. OK.
HE GIVES INSTRUCTIONS
We can go.
-On y va.
-On y va. OK.
The pistons fire up. 2,000 tonnes of force pushes against the arch.
And they're off.
The vast structure, as heavy as 3.5 Eiffel Towers,
slides towards the reactor at around ten metres an hour.
It's crucial that both sides of the arch move at the same speed.
If you move one side faster than the other, you will get bending
in the arch, which can lead to damage of the arch.
And if we go too far from each other, then you see the
deviation between the two gets too high, and then we have to adjust.
In the screen, all the upper skid shoes are the North.
These are the South, so we can select the upper skid shoes
and move forward to correct the readings we get on the system.
For the South, 383.
-OK. OK, thank you.
-What is that?
Ten? Is the difficult part of it.
You've got so much data, you have to act correctly and quickly.
The closer they get to the reactor,
the more difficult the operation becomes.
Sliding the arch over its walls will be tight.
People will follow the sliding itself of the arch.
80, 90 people will be involved.
We have a lot of watchmen, because our clearance is very limited.
The clearance that we have is quite tight. It's 50 centimetres.
-What could go wrong during the skidding?
Everything should be fine.
But just as the arch approaches the reactor, they run into trouble.
It gets caught on a barbed wire fence.
THEY SPEAK IN OWN LANGUAGE
The radiation here is high. So they must act fast.
There is two rebar we are attaching to the arch.
So we're sending somebody with a saw to remove these rebar.
To be sure that we are not damaging the arch.
With the wire removed...
..there's one last task before the final push.
They must lower one of the panels or it could jam on an old chimney.
If the arch is too close to the end, it will hit the chimney,
so we have to tilt it before,
and then we can restart it again and finish it tonight.
Oh, Vitaly! Yes!
The panel clears the chimney...
..and the final push begins.
After 33 hours of pushing,
the arch is finally in position over the reactor.
It's a feeling of pride. We've achieved something great. It's a big
step for safety. And Ukraine and Europe will be much safer now.
It has taken 18 years of planning, seven years of construction,
and a unique international collaboration.
But 30 years after the world's worst nuclear accident,
Chernobyl is finally a much safer place for generations to come.