245: Chernobyl Part 2

Episode number two starts with some text on the screen to let us know we’re now at the Byelorussian Institute for Nuclear Energy in Minsk. It’s 8:30 AM on Saturday, April 26^th, 1986. So, that’s seven hours after the explosion.

Ulana Khomyuk, who is played by Emily Watson, gets woken up by her colleague, Misha. They’re the only ones there because it’s a Saturday…but they’re both workaholics, so they’re at work anyway.

Misha remarks how hot it is in the room and goes to open a window. A second after he does, the dosimeter alarm starts going off to indicate high radiation levels. He immediately closes the window.

A leak? The Americans?

Ulana opens the window quickly to gather a sample from the outside of the glass. She takes it into the lab where she tests it. The printer spits out a piece of paper that she takes back to her colleague.

It’s uranium decay. U-235. Reactor fuel. They call the closest nuclear power plant. It’s not them. What’s the next-closest? Chernobyl—but there’s no way it’s them, they’re 400 kilometers away and that’s too far to be leaking that kind of radiation. They’d have to be completely split open.

But, maybe they know something anyway. Ulana gives them a call. It rings. And rings. And rings.

Now, they’re concerned.

This scene is made up for the series, although there are elements of truth to it.

For example, in the first few shots we see a mural just before the text on the screen setting up the location as being at in the Byelorussian Institute for Nuclear Energy in Minsk. But that mural isn’t in Minsk. It’s actually at the Institute for Nuclear Research in Kyiv, in Ukraine and not Belarus.

That’s 530 kilometers, or 330 miles, away from Minsk.

So, it is a real mural—a beautiful mural—and it is tied to nuclear energy, so I can see why they’d want to include it in the series.

But one of the biggest changes in that first sequence comes from probably one of the biggest fictional elements in the entire series: Emily Watson’s character, Ulana Khomyuk. She’s a composite character.

So, of course, there couldn’t have been a way where she noticed uranium-235 because, well, she’s not a real person. Although, as we learned in our last episode, uranium-235 really is what they used to enrich the uranium-238 that was in the fuel rods for the reactor at Chernobyl. 

So, elements of truth.

If you haven’t already, there’s a great series of podcasts released by HBO with the writer of the miniseries, Craig Mazin. In that series, he talks about how and why he created the composite character of Ulana Khomyuk. In a nutshell, there were just too many real people—hundreds of scientists—who were trying to figure out what happened at Chernobyl. It’d be impossible to have hundreds of characters in the series and be able to keep track of who is who.

So, that’s why they made up the character of Ulana Khomyuk who they could turn into someone doing many of the real things those hundreds of scientists did…just in a way that’s a lot easier to keep track of as viewers.

Something else that’s worth pointing out is even if the specifics of the sequence we see in the opening of episode two isn’t entirely accurate to what really happened—the basic gist is true.

First, to clarify, the place where this is happening in the series is in modern-day Belarus. That’s an independent country now, although in 1986 it was part of the Soviet Union as Byleorussian SSR. The SSR stands for Soviet Socialist Republics—the same thing as in USSR, or the Union of Soviet Socialist Republics.

What I mean by the opening sequence being basically true is it is true the radiation from Chernobyl drifted into the country we now know as Belarus. In fact, most of it did. Some experts say that about 70% of the radiation from Chernobyl drifted into Belarus.

Of course, not all of that happened in the first seven hours like we see in the opening sequence, but nevertheless the impact of the Chernobyl accident on Belarus is an important part of the story.

And the mention of iodine-131 is also true.

Iodine-131 is a byproduct of nuclear fission in reactors like the one at Chernobyl. When there’s too much of it in the atmosphere, it’ll get absorbed into your thyroid gland thereby increasing the risk of thyroid cancer.

There are still studies being done on residents of Belarus due to their exposure of Chernobyl’s fallout. One of the studies, which I’ll link to on this episode’s page over at basedonatruestorypodcast.com, concluded that childhood exposure to internal iodine-131 as a result of the Chernobyl accident is tied to increased risk of neoplastic thyroid nodules.

Without getting too sidetracked with the medical side, that’s a tumor that can be cancerous. So, basically, the study on people who were children in Belarus at the time of the Chernobyl accident has proven to be linked to an increased risk of cancer later in life.

Going back to the series, as the series shifts back to Valery Legasov and Boris Shcherbina being pulled into the story to figure out what’s going on…we’re faced with something we’ve seen a little bit in the first episode, too.

I’m speaking about how the series mentions the dosimeter reading of 3.6 roentgen.

In the first episode we see this reading, but in the second episode we see that Legasov isn’t happy with this reading. What bothers him about this is that he knows 3.6 roentgen is the maximum amount the lower quality dosimeters will go. So, that’s not necessarily an accurate reading—it’s just as high as they’ll go.

That whole concept is true—the dosimeters they were using at first maxed out at 3.6 roentgen. As I was watching this episode in particular, I was confused about why the number was 3.6. That just seems so random…but once I researched it more, it made a lot more sense.

To understand this more, we have to understand what that unit of measurement even means—a roentgen.

It’s named after a person named Wilhelm Roentgen. He won the very first Nobel Prize in Physics in 1901 for his 1895 discovery of what we now know as X-rays. Then in 1928, his last name was adopted as the first international measurement for ionizing radiation like happens at a nuclear power plant. It’s worth pointing out that in 1998, after the timeline of our story today, that unit was redefined, so it’s not really used for ionizing radiation anymore.

Now if we do the math to figure out how many seconds there are per hour, that’d be 3,600. And that is why the dosimeters they used at first could only go up to 3.6 roentgen, because they were maxing out at 1,000 microroentgens per second. There are 1,000,000 microroentgen in one roentgen, so 3,600 seconds times 1,000 equals 3,600,000 microroentgen or…3.6 roentgen per hour.

So, what does that mean for safety though?

After all, radiation is something that occurs in nature and everywhere all around us to some degree, most of it coming from the sun. While there are a lot of different factors that can determine how safe levels are—not every person is the same, not all factors are the same—but generally speaking, 60 microroentgens per hour is safe.

That’s 0.00006 roentgen per hour.

120 microroentgens an hour starts to get into dangerous territory.

With that in mind, it makes sense that the dosimeters they had at Chernobyl were sensitive enough to detect up to 1,000 microroentgens per hour. After all, that’s way more than is safe!

That level is definitely not safe—and the readings they got, just like we see in the series, were maxing out the dosimeters.

A level 3.6 roentgens per hour is detecting levels that aren’t safe.

Of course, if we’re looking at what deadly means—it’d take about five hours of constant exposure to 500 roentgens per hour, or 500,000,000 microroentgen per hour, to prove fatal for a human.

So, no, 3.6 roentgens isn’t safe, but it’s also a far cry from a fatal amount of 500 roentgen.

And it kind of makes sense for that to be a maximum level when you think about 120 being considered a risk in everyday life—1,000 should be a big warning.

When they ran the dosimeter in the control room, it read 800 microroentgens per second. That’s a lot, but then they ran it in another part of the control room and it went past the maximum of 1,000 microroentgens that the dosimeter could read.

After the explosion on April 26, 1986, and after the dosimeters read 800 microroentgen in one part of the control room and then maxed out the dosimeter at 1,000 microroentgen in another part, Anatoly Dyatlov figured it might be about 5 roentgens per hour. That’s about 1,388 microroentgen per second.

If that was the case, it’d make sense why the dosimeter would max out. It’d also make sense why it wasn’t seen as an extreme emergency quite yet, because something the series doesn’t mention is that the operators at Chernobyl already had a documented plan for the maximum amount of radiation. That was 25 roentgen per hour, which is a little under 7,000 microroentgen per second. Even at that rate, they were technically allowed to be there—but just for a few hours, and only in an extreme emergency.

So maybe that’s why Anatoly Dyatlov didn’t consider it to be the emergency we now know it was. But that’s pure speculation on my part—it’s hard to know what goes on in someone’s mind.

If we go back to the series, we’re at the point where we see Valery Legasov and Boris Shcherbina arriving at Chernobyl. We don’t see the specific time they arrive via helicopter, but we do see that they’ve been ordered to go there by Gorbachev himself. The way we see it depicted in the series, Shcherbina is the political leader of the committee digging into the accident while Legasov is the nuclear scientist to explain how nuclear reactors work to Shcherbina.

As we mentioned in the last episode, both Valery Legasov and Boris Shcherbina were real people. And the series is correct to explain their roles in investigating the Chernobyl accident.

Boris Shcherbina was, as the series suggests, a political leader. His official role at the time was as deputy prime minister in charge of energy for the government. He had a background in oil and gas. Something else to keep in mind was that in 1986, oil and gas were still making a lot more money for the Russian government than nuclear power was. Those two things are why the series is correct to show why Shcherbina wasn’t up on the nuclear side of energy.

That’s where the other man we see with him comes in: Valery Legasov.

Legasov’s role at the time was as first deputy to the director of the Kurchatov Institute of Atomic Energy.

In the morning hours of April 26^th, Shcherbina found out he was in charge of the commission to determine what happened at Chernobyl. After going back to Moscow—he had been in Siberia, which was part of his normal weekend routine to check on various construction sites he was overseeing—Shcherbina had a chat with his boss about the accident and rounded up some experts, one of them being Legasov, to fly to Pripyat.

Legasov found out he was a part of the committee, not from a phone call while he was at home like we see at the end of the first episode, but rather he was at a state meeting about atomic energy. In that meeting they mentioned the Chernobyl accident, but it didn’t seem to be a big deal. A little bit later, while the meeting was on break, Legasov found out he was being ordered to the airport as part of the state commission.

And it is true that Legasov and Shcherbina had a conversation on the flight to the accident zone. They talked about the nuclear industry as a whole as well as some other nuclear accidents—in particular the more recent partial meltdown of the reactor at Three Mile Island in Pennsylvania in the United States. That was in March of 1979, so relatively recent in the minds of another nuclear accident now in 1986.

One difference from how we see things happening in the series to reality is the way Shcherbina and Legasov approached Chernobyl. In the series we can see them flying in helicopters near the power plant. They’re close enough to where Legasov can see the core is exposed right away, although Shcherbina isn’t quite sure how he can tell that from the position they’re in. Legasov points out the ionizing radiation in the air as being how he knows.

In truth, Legasov, Shcherbina, and the rest of the state committee flew into Kyiv. That’s about 130 miles, or 209 kilometers, away from Chernobyl. When they landed in Kyiv, they took cars to the nearby city of Pripyat where they’d basically set up their base of operations for the investigation.

Oh, and its daytime in the series, but in truth they arrived in Pripyat around 8:00 PM, about an hour or so after the sun had gone down. With that said, though, the series is correct to show Legasov and the others seeing something not right from afar. Even before they got there, Legasov later commented on what it was like when they drove up to Pripyat, saying the sky near the plant had a deep crimson glow to it.

Things were worse than they originally thought.

Going back to the series, it’s April 27^th now, or 30 hours after the explosion. One of the first things they do is to figure out the real readings. Legasov doesn’t trust the number they received being at 3.6 roentgen because he knows that’s the maximum of the dosimeters they had—and also what he’s seen with his own eyes makes him think things are a lot worse than 3.6 roentgen.

To get the reading, we see them using a lead-lined truck with a high-range dosimeter. General Pikalov offers to drive the truck so no one else takes the risk. When he arrives, he tells Legasov and Shcherbina that the reading is not 3 roentgen—it’s 15,000.

General Pikalov is based on a real person who was there. The real Pikalov was in charge of the chemical warfare divisions of the military, so he was there to try to measure the radioactivity. And he did drive a truck like we see in the series to get a more accurate reading. It’s still not entirely accurate, but it’s enough to let everyone know they’re dealing with a lot more than they had initially thought.

From that, they determined the reaction was still happening—the reactor was still heating up. It wasn’t stable, it wasn’t cooling down. It was going to get worse if they didn’t do something.

With that said, though, the reading we see in the series is true. As you’ve probably figured out by now, the reading of 3.6 roentgen per hour was way off. Things were a lot worse than that. And the series is correct to give the number of 15,000. Although, it’s not like that was the number universally around the entire power plant.

In the series, when Shcherbina asks for an explanation of what the 15,000 number means, Legasov says it means the fire they’re watching with their own eyes is giving off nearly twice the radiation released by the bomb in Hiroshima. That’s every hour. Hour after hour, and at that point they’re 20 hours since the explosion so 40 bombs worth by now.

This example is made up for the series as a better way of describing what happened. A huge way we know this is because, quite simply, in 1986 we still didn’t even know exactly how much radiation the bombs in Hiroshima gave off. After all, that wasn’t a nuclear power plant. We know how powerful the bomb itself was, but we’re talking about radiation here…and that bomb was a surprise to a civilian population. They didn’t have dosimeters at the ready to determine how much radiation people were hit with.

In 2018, though, there were some tests done on a jawbone from someone who was in the attack and they found it to have absorbed 9.46 grays of radiation.

And again we’re hit with yet another form of measurement for radiation. Think of it kind of like how liquid can be measured in volume or in gallons…two measurements for the same amount of liquid. Okay, that’s not exactly a 1-to-1 example because if you’re a nuclear engineer you’ll know grays are measuring absorbed radiation compared to roentgen which measures ionized radiation…but for our purposes today, my point is merely that there are different ways to measure radiation in different ways.

Using a converter, I found 9.46 grays of radiation converts to 1,078,667,351 microroentgen, or 1,079 roentgen.

So, as far as my research is concerned that number doesn’t necessarily equate to 40 Hiroshima bombs—but at that point it almost doesn’t even matter what the specific numbers are. It’s not the survivable 3.6 roentgen per hour. It’s a number so high that it simply means if you’re in the area you’re going to die. Humans can’t survive anywhere near that kind of radiation. It’s the kind of deadly that kills humans many times over, the only thing at that point is just a matter of when you die as a result of the radiation.

And that right there brings to light something we see throughout the series that is very true: Most of these people working on figuring out and dealing with the Chernobyl accident were doing that knowing they were giving their lives doing so.

One of the books I used as a resource for this entire series is called Chernobyl Notebook by Grigoriy Medvedev. His book offers some of the few first-hand accounts and have been used as a source for many people since then. In his book, Medvedev recounts someone who made that sacrifice.

Here’s a quote from his book:

“Making a preliminary assessment of the situation and the actions of the operating personnel after the explosion, we can say that the turbine operators in the turbine hall, the firemen on the roof, and the electricians headed by Aleksandr Grigoryevich Lelechenko, deputy chief of the electrical shop, displayed unconditional heroism and self-sacrifice. These people prevented development of the disaster both inside and outside the turbine hall and thus saved the entire plant.

“Aleksandr Grigoryevich Lelechenko, protecting the young electricians from going unnecessarily into the zone of high radiation, himself went into the electrolysis space three times in order to turn off the flow of hydrogen to the emergency generators. When we take into account that the electrolysis space was alongside the pile of debris, and fragments of fuel and reactor graphite were everywhere, and the radioactivity was between 5,000 and 15,000 roentgens per hour, one can get an idea of how highly moral and heroic this 50-year-old man was when he deliberately shielded young lives behind his own. And then in radioactive water up to his knees, he studied the condition of the switchboxes, trying to supply voltage to the feedwater pumps…

His total exposure dose was 2,500 rads, enough to kill him five times. But after he had received first aid (they injected physiological solution into his vein) at the medical station in Pripyat, Lelechenko rushed back to the unit and worked there several more hours.

He died a terrible painful death in Kiev.”

With that quote, we get an idea of just one person who sacrificed their own life to try and stop the damage from getting even worse. It’s worth pointing out, though, that while Medvedev said in his book they gave their lives to save the entire plant, if we were to look at the entire story through a lens of history we know that isn’t always the case. Not that it was on purpose, but sometimes the actions they took actually made things worse.

One example of this is something we don’t see in the series at all, even though it relates to things we’ve seen already in the series.

Remember back when Anatoly Dyatlov was in the control room soon after the explosion? Well, as the firefighters were working to extinguish the fire in the turbine hall, Dyaltov had the radiation measured. Of course, the dosimeter showed a value of 3.6 roentgen per hour. It maxed out.

A little later, Dyatlov then decided it’d be safer for any non-essential personnel to go to a different building. He didn’t think things were as bad as they were, but he wanted to be safe. It was Reactor #4 that had the emergency, after all, so he ordered everyone to go to the closest safe reactor nearby. They went to Reactor #3.

And to make it even safer for them, he ordered the ventilation in Reactor #4 to be turned off so they could crank the ventilation in Reactor #3 into high gear.

That wouldn’t be a bad idea if the situation was as Dyatlov thought—but the fact was that Reactor #4 had exploded. So, by turning up the ventilation in Reactor #3, they were basically pumping in the radioactive air from outside that Reactor #4 was spewing into the air.

And that is an example of how someone makes what they think is the best decision at the time, but in reality it ends up making things even worse.

If we go back to where we are in the timeline of the series, we see a lot happening on April 27^th, the day after the explosion. Since they know it’s a big deal, one of the first things we see them trying to do as a resolution is to dump a ton of…well…according to the series, it’s actually 5,000 tons of boron and sand.

We see the first helicopter trying to deliver its load of boron and sand over the exposed core simply fall apart in the sky.

The basic idea of dropping things on the reactor is true, although there is more to the story we don’t see in the series.

For example, in the series we see Legasov asking Shcherbina for the 5,000 tons of boron and sand. In truth, Shcherbina had the idea to use clay and boron. Legasov asked for 2,000 tons of lead, but he also was the first to admit that probably wouldn’t be enough—this was a bad situation to the level he’d never dealt with before.

So, in the end, Shcherbina ordered 6,000 tons of boron, sand, clay, and lead that they planned on dropping onto the open reactor from helicopters. And there was at least one helicopter that crashed in the process—although I couldn’t find anything in my research to suggest the helicopter just fell apart in the sky like we see in the series. In fact, there’s video footage of a helicopter crashing as it dropped its contents at Chernobyl—but that was because it got too close to a construction crane, it clipped it and went down. It’s not like it fell apart on its own because of the radiation. I’ll include a link to that in the resources for this episode if you want to watch that.

The purpose for dropping these items wasn’t random. Sand would suffocate the fire. Lead lowered the graphite from the exploded core that was still burning. And if you remember from the first episode, boron was in the control rods to absorb neutrons to slow the nuclear chain reaction—so dropping that with clay would help slow any continuing reaction from getting worse and worse.

Something else we don’t see in the series was that there were people who didn’t like this idea. For example, someone who isn’t in the series at all was Valentyn Fedulenko, who was considered an expert on RBMK reactors. Legasov was a nuclear expert, but not necessarily very experienced with RBMK reactors. In fact, he didn’t have any experience with them. When he found out he was on the committee for the Chernobyl accident, his first reaction was to grab any technical info on RBMK reactors and talk to people he knew that had worked with them to get a better idea of the specifics on how they worked.

While Legasov was a nuclear expert, Fedulenko was considered the top expert on RBMK reactors specifically. When he arrived in Pripyat on April 27^th, he didn’t like the idea of dropping sand, clay and lead on the reactor. A big reason for this was because he knew the reactor’s lid had been blown off—but the way it landed was to leave the core partially exposed. He didn’t think the helicopters could accurately drop their load onto the partially exposed reactor core.

But, it happened anyway. By the time April 28^th rolled around, 300 tons of materials had been dropped. Another 750 tons on April 29^th. Another 1,500 tons on April 30^th. Another 1,900 tons on May 1^st.

We’re getting a little ahead of the series timeline here, but with purpose because the amount of material dropped to smother the core ended up becoming an issue itself. They couldn’t just keep doing that because it was so much weight that they thought maybe the reactor would collapse on itself to lower levels of the unit. 

So, that’s why they stopped dumping material onto the reactor. But that didn’t fix the issue.

If we go back to the series, things get bad enough that radiation levels are detected as far as Sweden.

That happened, and a lot of people think the detection of the radiation by surrounding countries ultimately would become a big reason why the Soviet Union couldn’t hid everything.

Even though people like Shcherbina, Legasov and others knew about the accident soon after it happened, most of the world outside the Soviet Union didn’t know anything at all had happened until the morning of April 28^th. There was a sensor at Sweden’s Forsmark Nuclear Power Plant that detected higher than usual radiation.

At first, they thought it was a mistake. Maybe a broken detector. Maybe it was a leak on-site. They evacuated their 600 or so staff members as they tried to figure out what was going on. Soon they figured out it wasn’t internal.

But if it was external, what could it be? Maybe a nuclear bomb. Would that mean war had broken out? What could that mean!?

By the evening of April 28^th, it wasn’t just Sweden that had detected elevated radiation. Finland and Norway were also getting similar readings. Okay, so it’s not nuclear war. It’s something else. But everyone has done internal testing and it’s not them…these readings are coming from somewhere else. As that alerted them to there being an issue, ultimately that would lead to the Soviet Union being forced to admit there was an accident at Chernobyl.

If we go back to the series, one of the other major plot points we see happens when the entire city of Pripyat is evacuated. That happened, although there is more to the story than we see in the HBO miniseries.

Starting at midnight on April 27^th, buses started to arrive in the city of Pripyat with the idea they’d be evacuating civilians. Things were still in a bit of flux—no one knew it’d be a permanent evacuation.

On April 27^th, 1986 at about 1:00 PM, there was an announcement broadcast the city of Pripyat. Here’s an excerpt from that announcement:

[ PLAY 20 SECONDS OF THE CLIP ]

Now, I don’t speak Russian, so I’ll admit that I had to use a translator for this…but that announcement says something like:

“Attention! Attention! The City Council informs you that in connection with the accident at the Chernobyl atomic power station, unfavorable radiation conditions are developing in the city of Pripyat. The Communist Party, its officials and the armed forces are taking necessary steps to fight this. Nevertheless, in order to ensure complete safety for residents, children first and foremost, it has become necessary to carry out a temporary evacuation of the city’s residents to nearby settlements of Kyiv oblast. For that purpose, buses will be provided to every residence today, April 27, beginning at 14:00 hours, under the supervision of police officers and representatives of the city executive committee. It is recommended that people take documents, absolutely necessary items and food products to meet immediate needs. All houses will be guarded by the police during the evacuation period. Comrades, on leaving your dwellings temporarily, please do not forget to close windows, switch off electrical and gas appliances and turn off water taps. Please remain calm, organized and orderly of this short-term evacuation.”

We know from history this announcement was repeated multiple times to residents in the city right before they were to supposed to evacuate. Some sources I saw mentioned giving the residents two hours while others mentioned them having less than an hour. In ether case, there wasn’t much time.

Can you imagine? What would you do if there was an announcement like that where you live? This was a Saturday, so imagine you’re out on the town during the weekend and you hear that being broadcast.

What would you do? Would you believe it at first? Would the first thing you do be to rush home and pack all the belongings you’ll need for the rest of your life? I know I wouldn’t. I’d wonder what’s going on. Should we do what it’s saying? Why is that being said? What in the world is going on?

What we don’t know from history is just how much everyone understood the seriousness of what it meant. How could they know this was evacuating their homes forever? Nothing about this announcement suggested they’d be leaving Pripyat to never return—quite the opposite, actually.

For the most part, the series is correct to show there wasn’t a huge issue with the evacuation. Most people just did what they were told. Did they understand it? No, not necessarily. But they didn’t need to understand. They did what they were told and, looking at it from a historical lens, we know that worked out for their best to leave the radioactive area near and around Chernobyl.

If we go back into the series, at the end of the second episode we see the next attempt to slow the heat from continuing to rise. This comes in the form of trying to release water from tanks before the heated sand—basically a lava-like material at that point—hits the tanks. If they don’t, the lava hitting the tank will instantly heat it up so fast it’ll cause a thermal explosion that’ll destroy the remaining reactors at Chernobyl and release so much radioactive material that millions of people will probably die and entire regions like Byleorussia and Ukraine will be completely uninhabitable for at least 100 years.

To avoid this, they have to open the valves and release the water before the lava gets there. But the men who do that will be exposed to so much radiation they’ll likely die. According to the series, the three men who volunteer for this are Ananenko, Bezpalov and Baranov.

That whole scenario is true, even down to the names of the three men who were sent to try and avoid this disaster…but because the TV series shows more of this in the third episode, we’ll talk more about them in our next episode as well.

One thing we don’t see in the series at all is that the boron they dumped along with the sand didn’t make it to the core. The purpose was exactly what the series shows, to use a mixture of sand and boron. The sand to help smother the fires and boron to absorb the neutrons to halt the continuing heat generated by the ongoing fission reaction.

But next to none of that boron even made it to the core, so it was kind of pointless. The reason we don’t see that mentioned in the series, though, is because at the time they didn’t know that. We only know that now looking at the event through a historical lens.

That’s just another example of how they tried to do the right thing, but what they tried doing ended up only making things worse.

One thing they did know though, was the detection of ruthenium. That’s a chemical element that belongs to the platinum group on the periodic table, atomic number 44. The reason that’s important is because they found the ruthenium was melting. And because they knew the melting point for ruthenium is 2,250 degrees Celcius—or about 4,000 degrees Fahrenheit—that means the fires near the core were at least that hot.

There are actually pictures and footage of the molten lava-like substance they managed to get, and I’ll include links to those in the resources links for this series.

That basically meant they had a nuclear meltdown on their hands.

Now, I know a nuclear meltdown is something we’re all familiar with…by that, I mean it’s a term we’ve probably all heard. But if you’re like me and not a nuclear engineer, what exactly does that mean?

To understand that, we have to have some basic knowledge about how a nuclear reactor works. We talked about that in the last episode. So, in that episode we learned about parts like a control rod and the uranium used as nuclear fuel.

To build on that knowledge, a nuclear meltdown occurs when the core gets so hot that the uranium melts. When it does that, it can burn through any casing and fall to the bottom of the reactor. Then, as it continues to get hotter and hotter, it’ll turn into the molten lava-like material they talk about in the series. That’s what can burn through any of the protective layers in the reactor and, eventually, hit the ground itself.

Once it does that, the only thing left is the earth itself. Everything, including the water in the ground get contaminated by the radioactive molten uranium.

These days there’s usually a layer of metallic alloy beneath the reactor to catch things before they get to the earth below. That’s an safety feature added in the wake of the Chernobyl accident.

That means at Chernobyl, there was no extra safety feature in case of a meltdown. There was just a water reservoir that was used for the emergency cooling pumps. That water was what they were concerned about. The moment the meltdown hit that, it’d start a new chain reaction of destruction. The water would instantly heat up, turning it into steam in an explosion that would hit the other three reactors at Chernobyl. Doing that would mean the nuclear fuel in those reactors would vaporize.

That’s the explosion they were trying to avoid.

The series is correct to show that some of the Soviet scientists working on the Chernobyl accident gave estimates that the potential explosion would basically flatten 200 square kilometers—that’s about 77 square miles—poison all the water in the area, killing who knows how many of the 30 million people who used it as drinking water and render Byelorussia and Ukraine uninhabitable.

Of course, thankfully we can look back on this event through a historical lens to know that did not happen. So that means it’s all speculation on how terrible it could have been.

But that’s what they were afraid of happening.

To avoid that, they needed to release the water from that reservoir. The challenge to that is just what we see in the series: The valves for that have to be turned by hand. Those valves were in the basement. And that basement was flooded with what was now radioactive water.

That brings us back to the three men who volunteered to turn the valves: Alexei Ananenko, Valery Bezpalov and Alexandrovich Baranov.

And that story is something we learn more about in episode three of the miniseries, so we’ll do that as we pick up next time where we’re leaving off about the true story behind episode number three of HBO’s Chernobyl!