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Disaster: The Chernobyl Meltdown. Aired 12-1a ET

Aired May 18, 2026 - 12:00   ET

THIS IS A RUSH TRANSCRIPT. THIS COPY MAY NOT BE IN ITS FINAL FORM AND MAY BE UPDATED.

[00:00:41]

UNIDENTIFIED MALE: Forty years after Chernobyl, it's that specter of contamination from a nuclear catastrophe like we all saw in 1986, that the Kremlin taps into.

SALMA ABDELAZIZ, CNN CORRESPONDENT: Do you remember Chernobyl? Well, that nuclear power plant has been struck by a Russian drone, according to President Zelenskyy of Ukraine.

UNIDENTIFIED MALE: Are you kidding? Lobbing a missile into Chernobyl? What possessed you to do that?

UNIDENTIFIED MALE: Russia wants to issue that not so subtle threat that there could be a nuclear consequence to this conflict. And I think that's terrifying.

UNIDENTIFIED MALE: 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, buried deep within what the Soviets call a sarcophagus, a gigantic concrete tomb where the radioactive material will be buried for centuries to come.

ADAM HIGGINBOTHAM, AUTHOR "MIDNIGHT IN CHERNOBYL": The structure of the sarcophagus was really a combination of improvisation and brute force. When it was complete, the Soviet engineers said that the sarcophagus was another triumph of Soviet engineering.

But inside the ruins of the Rakta building, around 190 tons of uranium fuel remained unaccounted for.

ALEXANDER SICH, NUCLEAR ENGINEER: The scientists were worried about what's called a 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 got to know where this fuel is.

HIGGINBOTHAM: 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.

SICH: I was the first Western scientist invited to do scientific research with the complex expedition. It was this eclectic, almost ragtag group of scientists. They were soft spoken people just trying to get to the bottom of things.

UNIDENTIFIED MALE (through translation): My task was to film. They told me what to film and I did it.

(FOREIGN LANGUAGE)

SERGEY KOSHELEV, COMPLEX EXPEDITION VIDEOGRAPHER (through translation): Then we would give the footage to the scientists who would process it and study it.

[00:05:00]

SICH: I mean, they're getting dosed. Everything is coated with varying degrees of contamination. I mean, you don't want to stay in there.

[00:05:09]

KOSHELEV (through translation): My principle was, when the camera starts glitching. When the radiation on affects the camera sensors then I know it's dangerous there. As my boss used to say, Soviet radiation is the best in the world. It'll put hairs on your chest and boost your virility.

HIGGINBOTHAM: 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 no. 4.

KOSHELEV (through translation): The supervisor told me, tomorrow you're coming with us to the reactor block. We're going to install rails to lower the video camera into the reactor shaft.

A tunnel had been carved through the concrete, so we could get through. Water was seeping in from cracks in the reactor. Of course the water was radioactive. My boot cover tore and it filled with water, but I kept going.

Later when I checked my bare leg with a dosimeter, the radiation lever was off the scaled. My led was radioactive for about two weeks, until the layers of skin came off.

HIGGINBOTHAM: Nobody had been inside the reactor vessel. Anybody who went in there would have been exposed to very high fields of radiation.

KOSHELEV (through translation): We inserted the camera into the reactor shaft. But then it wouldn't go any further. It was stuck. So I ran over and climbed into the reactor and fixed the camera.

Then we discovered an interesting thing.

SICH: That's when they noticed what core? There was no core. There was nothing left inside the reactor. And so, the immediate question was, where the hell did the fuel go?

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.

It flowed out the steam distribution headers and two more floors down pipes into the water that was there. Roughly 75 percent 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 release which would cause damage. Thank God that never happened.

We later found out once the fuel broke through and spread out, it basically shut itself down, right? It just froze in place. And you can see that to 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.

[00:10:05]

HIGGINBOTHAM: A year after the accident, it had become clear that the Soviet authorities intended to lay the blame for what had happened almost entirely at the feet of the operators.

UNIDENTIFIED MALE: 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.

UNIDENTIFIED MALE: 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 overriding safety systems.

HIGGINBOTHAM: The judge made it clear that he wasn't going to listen to anything that contradicted the official version of events. It was effectively one of the final show trials of the Soviet Union.

(COMMERCIAL BREAK)

[00:15:00]

UNIDENTIFIED MALE: A chapter ended today and history's worst nuclear accident in Chernobyl in the Soviet Union, six Russian nuclear power plant officials who flouted safety regulations were held criminally responsible for the deaths of 36 people.

RAY RICHARDSON, CIA NUCLEAR ANALYST: They had to have a scapegoat and that became the operators.

UNIDENTIFIED MALE: The verdict was all six 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 year sentence for abuse of power.

NIKOLAI STEINBERG, NUCLEAR ENGINEER: Yes, they blame the operators. I was also an operator once. Overall, I worked at the station for almost 13 years before the accident.

UNIDENTIFIED MALE: 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.

UNIDENTIFIED MALE: 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.

STEINBERG (through translation): I was called as a witness. I still don't understand whether I was called as a defense witness or a prosecution witness, I don't know. They asked some kind of technical question, I don't really remember. And that was it, I left the courtroom and drove off.

I had a feeling the accident was not just down to operator error. The operators did make mistakes, but it was obvious that the authorities were hiding something.

HIGGINBOTHAM: After leaving Chernobyl, Steinberg eventually became part of an independent commission that reopened the investigation into what had happened at Chernobyl.

STEINBERG (through translation): My friends had died. It didn't matter how much time passed, we had to conduct this investigation. The goal was clear, to establish the truth and restore justice.

HIGGINBOTHAM: 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.

STEINBERG (through translation): For us, two of three of the documents were fundamentally important. We needed the oscillogram data that would show exactly when the reactor began to run out of control and when the operators tried to stop it or shut it down. But the chief designer and the scientific director at the institute who designed and built the reactor did not give us their documents.

HIGGINBOTHAM: The KGB classified the real reasons for the causes of the Chernobyl accident. Any descent from the official line that the operators were responsible was essentially forbidden.

STEINBERG (through translation): Lawyers told us the documents we needed were also held by the Supreme Court who had conducted the investigation and held the trial. So I got in touch with the deputy chairman of the Supreme Court and he gave us the green light to access the documents.

We worked there and found the documents we needed. We went step by step. The work took a year and a half. The evidence was in the oscillogram data. It was clear that something extraordinary had happened. They actually shifted the data by six seconds.

[00:20:10]

And this allowed them to say that the operators were to blame.

UNIDENTIFIED FEMALE (through translation): So the data was falsified?

STEINBERG (through translation): Yes.

(COMMERCIAL BREAK)

HIGGINBOTHAM: The findings of Steinberg and the rest of the investigators finally brought to light the true causes of the disaster.

STEINBERG (through translation): We did it. We found all the supporting data and everything fell into place. It showed that the reactor ran out of control only after the operators tried to shut it down.

RICHARDSON: 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.

[00:25:10]

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 contain 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.

SICH: 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.

STEINBERG (through translation): The total number of parameters that an RBMK reactor operator must control is about 16,000. Just imagine keeping all of that information in your head. It was a problem.

RICHARDSON: The only way that the operators can control the reactor is with control rods. Insertion of the control rods tends to decrease the reactor power. Removal of control rods causes the reactor power to increase.

HIGGINBOTHAM: 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 accelerator on a car.

STEINBERG (through translation): During normal operation, there should be 26-30 control rods in the core.

HIGGINBOTHAM: The control rods are also used to shut down the RBMK reactor. RICHARDSON: The emergency shutdown function on the RBMK, also called the AZ-5 by Soviet terminology, was to shut the reactor down quickly in an emergency.

HIGGINBOTHAM: 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 safely shut down 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.

STEINBERG (through translation): Both the reactor designers and the leadership of the ministry who developed the RBMK reactors certainly knew about these defects long before the accident.

HIGGINBOTHAM: They'd begun to make progress on modifying the emergency shutdown system. And although the Chernobyl 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.

RICHARDSON: The operators were attempting a experiment to power the reactor when the offset power had been lost.

HIGGINBOTHAM: The midnight shift came in and they were told that they would conduct the experiment. They were not expecting to do this. They had not been familiarized with the test protocol.

[00:30:02]

HIGGINBOTHAM: The operators had great difficulty in bringing 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 four, 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.

(COMMERCIAL BREAK)

HIGGINBOTHAM: 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 1:23am.

[00:35:00]

IGOR KIRSHENBAUM, PLANT OPERATOR (through translation): There was silence for a few seconds, then there was a rumble, thunder, dust falling from the ceiling. RICHARDSON: 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.

HIGGINBOTHAM: But in this case, the core was already in such an unstable state, the slightest additional power fluctuation could initiate a runaway chain reaction.

RICHARDSON: The AZ-5 button that was pushed by the operators inserted all the control rods at once. Power shutter down at the top, the problem was the graphite caused the power to increase at the bottom of the reactor. You had a power surge at the bottom, the overall effect was disastrous.

KIRSHENBAUM (through translation): The power surge by a factor of 10,000 in 0.5 seconds. At that moment, the temperature reached up to 40,000 degrees.

RICHARDSON: It literally caused the reactor to explode, hence the building being destroyed.

HIGGINBOTHAM: It was as if when you stamped on the brakes of a speeding car, it accelerated instead of slowing down. The Soviet version of 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.

STEINBERG (through translation): The was a clear deliberate falsification. In fact everything was fine, all readings were stable until they pressed the shutdown button. No one could refute it anymore. We proved it absolutely clearly, pressing the brake led to the explosion.

KIRSHENBAUM (through translation): Truth is good, but those responsible have not been punished in any way. Others who were innocent went to prison. Let those who designed the reactor answer, why did it explode?

HIGGINBOTHAM: The operators in Unit 4 on the night of the accident did not know the potential consequences of triggering the emergency shutdown system.

SICH: The Soviets believed that their system was so superior that no mistake could ever be made, that their technology was beyond reproach.

HIGGINBOTHAM: The reactor had been designed by people at 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 operator in Ukraine, then they were going to be the ones who took the fall. RICHARDSON: 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 their operation.

[00:40:02]

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

HIGGINBOTHAM: 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.

UNIDENTIFIED MALE (through translation): Chernobyl is a great tragedy for our people, but it is not the greatest one. Because as long as we do not have our own state, Chernobyl has existed, exists and will continue to exist.

UNIDENTIFIED MALE: Good evening. Eleven Soviet republics agreed to form a new Commonwealth of Independent States today and consigned the Soviet Union to history.

MATTHEW CHANCE, CNN CHIEF GLOBAL AFFAIRS CORRESPONDENT: The Soviet Union saw itself as a great empire and in one day, that all came crashing down.

UNIDENTIFIED MALE: With 11 signatures and a round of applause, the Soviet Union had ceased to exist.

CHANCE: There was chaos. People lost their jobs, didn't have any food. It was deeply humiliating for many Russians, for millions of Russians.

MIKHAIL GORBACHEV, FORMER PRESIDENT OF THE SOVIET UNION (through translation): This is the first time we have encountered the formidable power of nuclear energy when it is out of control.

WYATT ANDREWS, CBS MOSCOW CORRESPONDENT: Gorbachev said he thought the Chernobyl accident was the ultimate cause of 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.

HIGGINBOTHAM: The breakup of the Soviet Union created the independent Ukrainian government as well. For Putin, the collapse of the Soviet Union, in his words, was the greatest geopolitical catastrophe of the 20th century.

(COMMERCIAL BREAK)

[00:46:38] RICHARDSON: The Soviets initial attempt to try to cover over the destroyed reactor building. It was leaky, it was not as structurally strong as it could have been.

UNIDENTIFIED MALE: It's way beyond its design life. It's crumbling. We've already had to collapse one part of the turbine, all of the very heavy snow load.

RICHARDSON: Because of these concerns, Ukraine and western donors got together and created a structure to cover over the entire building, very large structure called the New Safe Confinement.

CHANCE: 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. Construction was a long and arduous process and it ended six years later in 2016.

Ukraine, unlike the Soviet Union, very much wants to be part of the international community and not an insular state. The current Russia under Vladimir Putin is much more Soviet like. It is an imperialist, expansionist regime.

I was standing on a roof doing a live shot on CNN. Ukrainians who resist. Oh, I tell you what, I just heard a big bang right here behind me. I thought we shouldn't have done the live shot here. It was quite shocking that Russia had decided to send its forces into Kyiv, into Ukraine. And the first explosions of that conflict were being heard.

There was a profound sense that we're at an historic inflection point that things had changed from that moment on.

KIM BRUNHUBER, CNN ANCHOR: 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. Military advisor says staff members are held hostage.

UNIDENTIFIED MALE: There's a potentially dangerous military confrontation around that nuclear reactor that could kick up all sorts of horrific radioactive material and cause that massive catastrophe to repeat itself all over again.

[00:50:06]

CHANCE: 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 the 1986 calamity at Chernobyl, shortly afterwards the Ukrainians took back the Chernobyl exclusion zone.

The Russians found they had to fight for every square inch of the territory they were going to capture.

UNIDENTIFIED FEMALE: You're looking at footage that shows a Russian drone with a high explosive warhead striking the shelter that covers the fourth unit of the Chernobyl Nuclear Power Plant, sparking a fire that was later contained.

SICH: Are you kidding? Lobbing a missile into Chernobyl, what possessed you to do that?

(COMMERCIAL BREAK)

[00:55:13]

CHANCE: The strike on the New Safe Confinement structure underlines the nuclear threat throughout the whole Ukraine conflict that it could cause another Chernobyl , another nuclear disaster, and that would be catastrophic.

OLENA MOKHNYK, FORMER PRIPYAT RESIDENT: When we left Chernobyl, I was a 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 invasion in 2022, we left Ukraine and moved to Luxembourg, and now they are here.

I hoped better for my kids, but it didn't happen. I always teach my children, be adaptable and be resilient. And Ukrainians prove to be resilient.

KIRSHENBAUM (through translation): We were all psychologically affected by this accident. Our lives were divided before the accident and after the accident.

STEINBERG (through translation): Well, we believed in our government, we believed in our science, but we didn't understand the dangers.

CHANCE: 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've got little scars on their necks where they've had operation on their thyroid glands to take out parts of the thyroid because they've become cancerous.

MOKHNYK: I remember quite often I would hear that person died, friend or neighbor or colleague, just young people. It was radiation, but doctors would not mention that so it was silent war.

SICH: What to take from the story of Chernobyl?

RICHARDSON: Oh, that's a hard one. What would I say?

SICH: To maintain open societies that can provide checks and balances to the pride that comes with having huge complex technologies.

RICHARDSON: 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.

HIGGINBOTHAM: I think that 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.

ANDREWS: 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.