Original subtitles

I was the first western scientist

invited to do scientific research with the Complex's expedition.

A small group of scientists who worked on forensic analysis

of the remains of the destroyed Reactor in Unit 4.

The Soviet Union was collapsing.

They took me to the plant kind of undercover.

They dressed me up in worker's clothing...

just under the radar.

Yes.

I thought it was just hey, let's take this American along kind of thing.

But no, it was get up, work, until you drop.

Pretty much every day.

People sometimes laugh at scientists,

but that's because they don't understand the sheer beauty of seeking the truth.

And that's what these people wanted.

This is where officials say, a crime was committed.

It's here that engineers conducted the experiment that led to the explosion.

The destroyed reactor is still hot,

very deep within what the Soviets call a sarcophagus,

a gigantic concrete tomb

where the radioactive material will be buried for centuries to come.

The structure of the sarcophagus was really

a combination of improvisation and brute force.

When it was complete the Soviet engineer said that the sarcophagus

was another triumph of Soviet engineering.

But inside the ruins of the reactor building

around 190 tons of uranium fuel remained unaccounted for.

The scientists were worried about what's called the critical mass coming together

and restarting a nuclear reaction.

They noticed on their neutron detectors a spike of neutrons

that led them to believe that a critical mass had indeed formed

and that a nuclear reaction had happened.

They were puzzled, they were worried. So, we gotta know where this fuel is.

Scientists from the Kurchatov Institute,

the Soviet Union's chief

research and development agency for nuclear energy

launched what became known as the Chernobyl Complex Expedition

to locate the fuel.

It was this eclectic almost rag-tagged group of scientists.

They were soft-spoken people, just trying to get to the bottom of things.

My job was to shoot. They told me what to shoot and I did it.

Sergey! Pull the water into the light.

Then we gave the plans to the scientists

who processed them and they studied them.

I mean they're getting dosed.

Everything is coated with varying degrees of contamination.

I mean, you don't want to stay in there.

My principle was, when the image starts to break down,

when radiation affected the sensors, then I knew it was dangerous in there.

My boss used to say, "The Soviet Radioactivity is the best.

You will grow chest hair. and it will strengthen your manhood!"

Although he is dead now.

Some of the fuel had been thrown out of the reactor core by the explosion.

But it was assumed that the rest remained inside Reactor number 4.

The supervisor told me: "Tomorrow you will come to the reactor."

"We will lay rails to lower the camera into the pipeline."

A tunnel had been carved on the cement to get through.

Water was coming in from the reactor cracks.

Of course, the water was radioactive.

My boot cover was torn and it filled with water, but I continued.

Later, when I checked my leg with a dosimeter,

the radiation level was skyrocketing.

My leg was radioactive for two weeks,

until layers of skin were removed.

Nobody had been inside the reactor vessel.

Anybody who went in there would have been exposed to very high fields of radiation.

They told me that underneath me there were 200 roentgens.

It's a lot, it's a lethal dose, if you stay there for three hours.

We put the camera on in the reactor pipeline.

But then it didn't go any further. It was stuck.

I ran and climbed in the reactor.

And I fixed the camera.

And we discovered something interesting.

That's when they noticed what core. It was no core.

There was nothing left inside the reactor.

And so, the immediate question was: "Where the hell did the fuel go?"

To help them locate the fuel, they would strap cameras to toy tanks.

Because they were the ones that could withstand the radiation in there.

Other more sophisticated robots failed.

They would have aerosol and air current detection methods.

And that's when the bigger picture started to emerge.

What happened was the core itself, the fuel and the graphite

basically were percolating through the floor of the reactor cavity.

The fuel melted through

and fell down onto the floor of the sub-reactor region.

There were holes that led to what are called steam distribution headers.

If flowed out the steam distribution headers and then two more floor

down pipes into the water that was there.

Roughly 75% of the fuel

ended up in the lower regions of the reactor building.

They thought that they could have a critical mass coming together

to restart reactions.

So you have these great energies released which would cause damage.

Thank God, that never happen.

We later found out

once the fuel broke through and spread out, it basically shuts itself down.

It just froze in place. And you can see that, this day.

If you're going to be working in the kind of environment

that the Complex Expedition was...

you really have to be dedicated.

Dedicated to getting to the truth.

The Soviet Union was not about truth.

A year after the accident,

it had become clear that the Soviets authorities intended to lay the blame

for what had happened almost entirely at the feet of the operators.

In a makeshift courtroom in a building in the center of Chernobyl,

six men went on trial today charged with safety violations

that caused history's worst nuclear accident.

The defendants face up to 12 years in jail, if they are convicted.

The courtroom was packed with

workers from the power plant and families of the victims.

The defendants are accused of allowing unauthorized experiments at the plant,

ignoring basic operating procedures and overwriting safety systems.

The judge made it clear that he wasn't gonna listen to anything

that contradicted the official version of the events.

It was effectively one of the final show trials of the Soviet Union.

A chapter ended today in history's worst nuclear accident

in Chernobyl in the Soviet Union.

Six Russian nuclear power plant officials who defied safety regulations

were held criminally responsible for the deaths of 36 people.

They had to have a scapegoat. And that became the operators.

The verdict was all six are guilty of varying degrees of criminal negligence.

Viktor Bryukhanov the former plant director

10 years in a labor camp for gross violations of safety rules,

including a concurrent five years sentence for abuse of power.

Yes, they blamed the operators. I was an operator once too.

Overall, I worked at the station almost 13 years before the accident.

The trial has been closed to foreign journalists

And no detailed reports have appeared in Soviet media,

So it's not known whether or how the accused defended themselves.

On the opening day,

one of the defendants suggested some of the blame lay with the reactor design.

But that's the only thing that's been said publicly in their defense.

They called me as a witness.

I still don't know if I was called, as a defense witness

or as a prosecution witness.

I don't know.

They asked about a technical issue, I don't remember exactly.

And that was it. I left the room.

I had the feeling

that the accident was not only due to operator error.

The operators made mistakes.

but it was obvious that the authorities were hiding something.

After leaving Chernobyl,

Steinberg eventually became part of an independent commission

that reopened the investigation into what had happened at Chernobyl.

My friends were dead.

It didn't matter how much time passed, we had to do research.

The goal was clear.

Let's find the truth, and restore justice.

Data about the performance of the reactor during the accident was being recorded.

But in the immediate aftermath,

all the documentation and data from the plant was seized

and returned to Moscow and classified.

For us, two or three of the documents were very important.

We needed the pulsograms, which would show

when the reactor started to get out of control

and when the operators tried to deactivate it.

But the designer and the director of the institute

who designed and built the reactor

didn't give us their documents.

The KGB classified the real reasons for the causes of the Chernobyl accident.

Any dissent from the official line

that the operators were responsible was essentially forbidden.

The lawyers said that the documents we needed

are also at the The Supreme Court,

which was conducted the investigation and the trial.

I spoke with the vice president of the Supreme Court

and he gave us access to the documents.

There we found the documents we needed.

We took it step by step. The work took a year and a half.

The evidence was found in the oscillogram data.

It was clear that something unusual had happened.

They moved the data by six seconds.

This allowed them to say that the operators were at fault.

- So the data was fake? - Yes.

The findings of Steinberg and the rest of the investigators

finally brought to light the true causes of the disaster.

We did it.

We found all the data and everything fell into place.

They showed that the reactor got out of control

since the operators tried to deactivate it.

The new information tended to

shift the focus of responsibility from operator actions

to fundamental design flaws in the reactor itself.

The Chernobyl power station used RBMK type reactors

that was uniquely Soviet technology.

There was nothing like that produced in the West.

RBMK type reactors are very large reactors, that is large physically.

A core that was 14 meters in diameter and 7 meters high.

This is extremely large compared to reactors in the West,

which have a diameter of maybe 3 or 4 meters.

The RBMK reactors had nearly 1,700 fuel channels

that contained the uranium fuel that produces heat.

That's used to boil water to make steam to make electricity.

This core is so large it's almost like having two reactors in one,

one at the top and one at the bottom.

One side of the reactor couldn't speak to the other side of the reactor

so it forced the operators to keep careful watch over this.

The total number of parameters

which must be controlled by an RBMK reactor operator

is about 16,000.

Imagine having all of this information in your mind.

It was a problem.

The only way that the operators could control the reactor is with control rods.

Insertion of the control rods tend to decrease the reactor power.

Removal of the control rods causes the reactor power to increase.

The control rods are used by the operators

to fine tune the level of the chain reaction taking place.

So it's really like having brakes and an accelerator on a car.

Normally, there should be 26-30 control rods in the core.

The control rods are also used to shut down the RBMK reactor.

The emergency shutdown function on the RBMK, also called AZ-5 by the Soviet terminology,

was to shut the reactor down quickly in an emergency.

The AZ-5 system was designed to insert almost all of the remaining control rods

into the core at the same time.

And it was intended simply to bring the reactor into a safety shutdown state.

During tests in 1983,

nuclear engineers at another RBMK plant in Ignalina had discovered

that there was a disturbing anomaly about the way the AZ-5 system worked.

With a very low number of control rods inserted into the core of the reactor,

when the emergency shutdown system was activated

it could induce a runaway reaction

leading to a meltdown and an explosion of the core.

The reactor designers and the ministry officials

who developed the RBMK reactors

they knew about these defects long before the accident.

They've began to make progress on

modifying the emergency shutdown system

and although the Chernobyl number 4 Unit was on the list

as due for those modifications, they decided that they would just save it

until the next scheduled maintenance shutdown to make the fixes.

Information about this fault did not make its way down to the level of the individual operators.

The operators were attempting an experiment

to power the reactor when the offsite power have been lost.

The midnight shift came in...

and they were told that they would conduct the experiment.

They were not expecting to do this.

They have not been familiarized with the test protocol.

The operators had great difficulty bringing the reactor up to a power level

that would make the test possible.

They had withdrawn an equivalent of 203 of the 211 control rods

from the core of Reactor number 4,

making the reactor as unstable as it was possible to be.

And very sensitive to any further changes in control.

By the time the test actually began,

the reactor was like a loaded gun just waiting for someone to pull the trigger.

In the test protocol, the completion of the test

was marked by the operators pressing the AZ-5 button

to release the control rods to shut the reactor down.

They pressed the AZ-5 button at 1:23 AM.

Silence prevailed for a few seconds.

Then there was a noise. A humming sound.

Dust was falling from the ceiling.

It was a design flaw of the control rods that ultimately caused the explosion.

The control rods are made of boron,

which is a material that reduces the reaction rate in the reactor.

Unlike most reactors underneath those rods was sections of graphite

which tend to increase the reaction rate.

If the rods were completely withdrawn,

then this graphite was pulled into the core.

Under normal circumstances, this graphite would never cause a problem.

But in this case the core was already in such an unstable state

that the slightest additional power fluctuation

could initiate a runaway chain reaction.

The AZ-5 button that was pushed by the operators

inserted all of the control rods at once.

The problem was the graphite caused

the power to increase at the bottom of the reactor.

Power is shutting down at the top, but you had a power surge at the bottom.

The overall effect was disastrous.

A power increase by ten thousand times in 0.5 seconds.

At that moment, the temperature reached 40,000 degrees.

It literally caused the reactor to explode.

Hence the building being destroyed.

It was as if when you stamped on the brakes of a speeding car

it accelerated instead of slowing down.

The Soviet version of the events was that the accident began to occur

and then in a panic

the operators pressed the AZ-5 button in order to try and shut down the reactor.

It was a clear and deliberate falsification.

Everything was fine, all indications were stable

until they pressed the button.

They couldn't deny it anymore! We have clearly proven it.

The brake led to the explosion.

The truth is good.

But those responsible weren't punished in any way.

And innocent people went to prison.

Let them answer, those who designed the reactor.

Why did it explode?

The operators in Unit 4 on the night of the accident

not know the potential consequences of triggering the emergency shut down system.

The Soviets believed that their system was so superior

that no mistake could ever be made, that their technology was beyond reproach.

The reactor had been designed

by people of the pinnacle of the Soviet scientific state.

So if it came to a choice between making these people culpable for this catastrophe

and laying the blame at the feet of some lowly reactor operators in Ukraine,

then, they would gonna be the ones who took the fall.

The design flaws set them up for failure.

When the perfect storm of the circumstances, the actions

and the design problems came together, it was almost inevitable.

The nature of the Soviet system was such that denial, secrecy

and cover up was endemic to their way of operation.

The truth is, Chernobyl is more of a metaphor

for the failure of the Soviet system than it is of a reactor safety story.

The increasing reporting about what had really happened...

and information about the failures of the design of the reactor...

finally revealed to citizens of the USSR

that the Soviet Union did not in fact lead the world in high technology.

The dramatic failures of the Chernobyl accident

undermined one of the last sources of Soviet pride.

Chernobyl is a tragedy for our people, but not the greatest!

Because as long as we don't have our own state,

Chernobyl existed, exists and will continue to exist.

Good evening. Eleven Soviet republics

agreed to form a new commonwealth of independent states, today

and consign the Soviet Union to history.

The Soviet Union saw herself as a great empire

and one day that all came crushing down.

With 11 signatures and a round of applause,

The Soviet Union had cease to exists.

There was chaos. People lost their jobs, didn't had any food.

It was deeply humiliating for many Russians, for millions of Russians.

This is the first time we've met,

the terrible power of the nuclear energy

when it gets out of control.

Gorbachev said he thought the Chernobyl accident

was the ultimate cause of the the collapse of the Soviet Union.

Because huge numbers of people, especially in Ukraine,

began to realize the Communist party protected itself,

it didn't protect us.

The Soviet's initial attempt to try to cover over the destroyed reactor building

was a hastily engineered structure that they built in the summer of 1986.

It was leaky, it was not as structurally

strong as it could have been.

It's way beyond it's designed life, it's crumbling.

We've already had a collapse in one part of the turbine hall with a very heavy snow load.

We see some very, very major structural damage there.

If it had collapsed, it could have stirred up some of the radioactive debris and caused

additional release of some of the radioactive material that was within it.

Because of these concerns, Ukraine and Western donors got together

and created a structure to cover over the entire building.

A very large structure called the New Safe Confinement.

Construction began on the New Safe Confinement in 2010.

A massive international effort.

Something like 40 countries and organizations played a role

in funding and designing that structure.

It was hugely expensive as well, best part of two billion dollars.

This is actually one of the most ambitious projects in the history of engineering.

It is twice the length of a 747 airplane.

It is the largest movable land based structure ever built.

The New Safe Confinement

was actually built to be mobile and was built off to the side of the reactor

and moved on rails over the original building.

Over these pins we put the Teflon pads.

And basically, if you put a lot of them,

you make your own sliding way for the skid shoes to slide on.

Construction on the New Safe Confinement was a long and arduous process.

And it ended six years later in 2016.

It's a big step for safety,

and Ukraine and Europe will be much safer now.

Ukraine, unlike the Soviet Union,

very much wants to be part of the international community

and not an insular state.

I was standing on a roof doing a live shot on CNN.

The Ukrainians who resist...

I tell you what, I just heard a big bang right here behind me.

I told you we shouldn't have done the live shot here.

It was shocking that Russia had decided to send its forces

into Kiev, into Ukraine.

And the first explosions of that conflict were being heard.

Russian forces are said to have taken control

of the Chernobyl power plant in northern Ukraine,

the site of the world's worst nuclear disaster.

A military advisor says staff members are held hostage.

The potentially dangerous military confruntation

around that nuclear reactor,

that could kick up all sorts of horrific radioactive materials

and cause that massive catastrophe to repeat itself all over again.

The Russian soldiers plowed across the exclusion zone.

They dug trenches in the forest which is an extraordinary thing to do.

The amount of contamination absorbed by those soldiers is pretty shocking.

They will undoubtedly, suffer health consequences.

Of exactly the same kind that was suffered in Ukraine

post 1986 calamity at Chernobyl.

The Soviet Kremlin had an utter disregard for the liquidators

for the firefighters of Chernobyl.

In the same way, the Russian Kremlin

had an apparent disregard for the welfare of the soldiers.

Shortly afterwards, the Ukrainians took back the Chernobyl exclusion zone.

The Russians found they had to fight for every square centimeter

of the territory they were going to capture.

You're looking at footage that shows a Russian drone

with a high explosive warhead striking the shelter

that covers the 4th Unit of the Chernobyl nuclear power plant,

sparking a fire that was later contained.

Are you kidding? Lobbing a missile into Chernobyl?

What possessed you to do that?

The strike on the New Safe Confinement structure, underlines the nuclear threath

throughout the whole Ukraine conflict.

It could cause another Chernobyl, another nuclear disaster.

And that would be catastrophic.

Chernobyl remains the worst nuclear accident in history.

Around 200,000 people were relocated as a result of the catastrophe.

The area around the power plant is likely to remain uninhabitable for at least 20,000 years.

When we left Chernobyl, I was child, but I was put in a situation

that not even some adults can live through.

It feels that the situation repeats itself,

that we again are forced to leave our home.

When the Russians started the invasion in 2022,

we left Ukraine and moved to Luxembourg, and now we are here.

I hoped for better for my kids, but it didn't happen.

I always teach my children, be adaptable!

And be resilient!

And Ukrainians have proved to be resilient.

What can Chernobyl teach us in the context of the current war?

Each of these horrible acts

teaches the consequences of error.

Both are a huge sadness, a huge disaster

and a huge loss for every country.

We were all affected psychologically from the accident.

Our lives were separated, before and after the accident.

We believed in our government, in our science.

We believed that everything would go well.

But we didn't understand the risks.

I think the legacy of Chernobyl,

40 years on, isn't just in the minds of people.

The scars are physical as well.

These radioactive toxins

caused a huge spike in thyroid cancer.

And you can go to Ukraine today,

and you can see people who were around in 1986 when the catastrophe happened.

They have got little scars on their necks where they had operation on their thyroid glands

to take out parts of the thyroid because they become cancerous.

I remember quite often I would hear that that person died,

a friend or neighbor, or colleague just young people.

It was radiation but doctors wouldn't mention that.

So it was a silent war.

What to take from the story of Chernobyl?

That's a hard one.

What would I say?

To maintain open societies...

that can provide checks and balances

to the pride that comes with having huge, complex technologies.

If I were to give a lesson for my grandchildren,

tell the truth, no matter how bad the situation is

it can only be made worse by lying and being untruthful.

I think the Chernobyl story, is arguably more relevant than ever...

given that the causes of the accident lie in a government and a society

that had completely lost touch with what the truth really was.

Thirty-one operators and plant workers died in the immediate aftermath of the Chernobyl disaster.

Approximately 600,000 personnel were involved in the cleanup operation.

Thousands have died, but the true number will never be known.

One of the things that I think we all learned is

when the regime is serving itself rather than the people,

that's when power evaporates.

That's the moral binder, the truth.

Performance: Stella Sarigoule