In part two of our mini-series on nuclear energy, we'll explore the catastrophic Chernobyl Disaster, the incident that drastically changed public opinion on nuclear power.
We'll uncover the series of errors that led to this nuclear nightmare and its far-reaching impact on humanity and the future of energy.
[00:00:05] Hello, hello hello, and welcome to English Learning for Curious Minds, by Leonardo English.
[00:00:11] The show where you can listen to fascinating stories, and learn weird and wonderful things about the world at the same time as improving your English.
[00:00:20] I'm Alastair Budge, and today is part two of our three-part mini-series on nuclear power.
[00:00:27] In case you missed it, in part one we talked about early nuclear power, Dwight Eisenhower’s famous Atoms for Peace speech, and the early enthusiasm mixed with fear that much of the developed world had for nuclear power.
[00:00:43] In the next episode, part three, we are going to talk about the state of nuclear power today and tomorrow, now and in the future, and try to understand why some people believe it to be a key weapon in the fight against climate change while others still vehemently oppose it.
[00:01:03] And in today’s episode, part two, we are going to talk about the incident that has done more than any other to change public opinion on nuclear power: The Chernobyl Disaster.
[00:01:15] You can, of course, listen to this episode without having listened to the last one, but it will probably make a little more sense if you have listened to part one, so if you haven’t done so already, I’d recommend you press pause and listen to that one first.
[00:01:33] OK then, let’s get right into it and talk about the most deadly disaster in the history of nuclear power.
[00:01:42] If you were a kid growing up in the 1990s, like me, you might well have played the game SimCity. The game required you to build a city.
[00:01:54] You would choose where to place roads, residential areas, business areas, industrial areas, schools, and hospitals.
[00:02:03] As your city grew, you made more money, which you would then spend on building more infrastructure. And as your city developed and got richer, your city would modernise.
[00:02:17] Basic houses would become shining skyscrapers. Smoke-billowing factories would turn into high-tech business zones, and so on.
[00:02:29] And of course, you needed to plan your utilities. Water, transport, and electricity.
[00:02:37] There were certain types of power plants you could build: coal, wind, and nuclear.
[00:02:45] You had to balance your city’s need for power with where you were going to put the power plant, because if you put a coal-powered plant next to a residential area, nobody would want to live there.
[00:02:58] Nuclear power plants were good, but they were quite expensive to build and there was the threat of a tornado or earthquake that would damage the plant, causing the nearby area to be contaminated by nuclear waste and property values to plummet.
[00:03:17] If, like me, you spent hundreds of hours of your childhood playing this game, you will know firsthand why it was so addictive, and if you have never heard of it, just trust me, it was seriously good fun.
[00:03:32] Now, not such a long time before the first SimCity game was released, central planners in the USSR were playing their own, real-life and–of course–infinitely more complicated version.
[00:03:48] The USSR covered a whopping 22.4 million square km, 17% of the world’s total land area.
[00:03:59] It had an abundance of natural resources, coal, oil and natural gas, but the largest known deposits were in Siberia, in the eastern part of the country, while the majority of the population was in the west of the country.
[00:04:18] Nuclear power offered a convenient solution.
[00:04:23] A nuclear power plant could be placed anywhere, more or less.
[00:04:29] They need a lot of water, so they are typically placed near rivers, lakes, or seas. And they should ideally be placed away from populated areas, in case anything goes wrong, but with 22.4 million square kilometres, the USSR had plenty of options.
[00:04:49] The USSR was, in fact, the first country to successfully open a nuclear power plant, which it did in June of 1954, and by 1982 it had a total of 26 nuclear reactors across 10 different plants, which produced 6.5% of the country’s power.
[00:05:12] One of these was at the town of Pripyat, close to the town of Chernobyl, in northern Ukraine, which was then part of the Soviet Union.
[00:05:22] The plant at Chernobyl was home to four nuclear reactors, which had been built between 1977 and 1983.
[00:05:32] Now, as a quick and very superficial reminder of how a nuclear power plant works, there is a controlled nuclear fission reaction in the core of a reactor, which gives off huge amounts of heat, which boils water, which creates steam, which turns a turbine.
[00:05:52] The turbine is connected to a generator, which then converts the mechanical energy from the spinning turbine into electricity.
[00:06:02] The principle is the same as in an oil or gas power station; water is heated so that it boils, the steam turns a turbine, and a generator produces electricity.
[00:06:15] A core difference, however, is that the balance in a nuclear reactor is much more sensitive.
[00:06:25] In an oil or gas plant, if something goes wrong, the fuel supply can simply be cut off, stopping the reaction almost immediately.
[00:06:36] But in a nuclear reactor, the process is far more complex and can’t just be shut down with the flip of a switch.
[00:06:45] The nuclear fission reaction relies on a delicate balance of control rods, cooling systems, and a stable core temperature.
[00:06:56] The control rods absorb neutrons, which slow down or even stop the reaction when needed.
[00:07:04] These rods are carefully adjusted to control the rate of fission.
[00:07:11] The cooling system, meanwhile, ensures that the reactor doesn’t overheat, keeping the reaction in check and preventing the fuel rods from melting.
[00:07:23] This balance is critical.
[00:07:26] If anything disrupts it—whether it’s an issue with the control rods, a cooling failure, or operator error—the chain reaction can accelerate dangerously, leading to a buildup of heat and pressure.
[00:07:42] And if it goes too far, the consequences can be catastrophic.
[00:07:48] This is what made nuclear energy both powerful and, in the eyes of many, terrifying.
[00:07:56] While it offered a seemingly limitless supply of energy without the pollution of fossil fuels, it also demanded a level of precision and caution unlike any other energy source.
[00:08:09] And on the night of April the 26th, 1986, at the Chernobyl Nuclear Power Plant in northern Ukraine, this delicate balance was lost.
[00:08:21] It all began as a routine safety test designed to verify procedures in case of a power loss during an emergency shutdown.
[00:08:31] The purpose of this test was simple in theory but critical in practice.
[00:08:38] If there was an emergency shutdown, there were backup diesel generators that would kick in, but this wasn’t an automatic and instant process.
[00:08:49] It took 45 seconds or so.
[00:08:52] The nuclear scientists had calculated that there was enough residual energy in the reactor’s turbines to continue running and generating electricity for the cooling pumps while the backup generators started working.
[00:09:06] Of course, the cooling pumps needed to continue pumping water, because if they stopped working, the nuclear reactor could overheat uncontrollably.
[00:09:17] The scientists had calculated that this wouldn’t be an issue, they had proved it on paper, but they had never actually demonstrated it live, in the power plant.
[00:09:30] So this was the purpose of the test.
[00:09:33] They were proving that in the event of a complete power loss, the remaining energy in the turbines would buy them enough time until the backup diesel generators kicked in.
[00:09:46] So, this is what they did.
[00:09:49] The operators began by reducing the reactor’s power to a low level.
[00:09:55] This was part of the test’s procedure, intended to simulate what would happen if there were a sudden need to shut down the reactor.
[00:10:04] But as they did so, things started to go wrong.
[00:10:10] The power dropped to dangerously low levels—far lower than they had planned for, and much lower than what the reactor was designed to handle safely.
[00:10:20] In an attempt to bring the power up, the operators withdrew almost all of the control rods—rods that were essential for slowing down the nuclear reaction.
[00:10:32] This move put the reactor in a highly unstable state.
[00:10:38] At these low power levels, a gas called xenon started to build up in the reactor.
[00:10:45] This gas absorbed neutrons, which slowed the reaction down even more, making it harder for the operators to raise the power to a stable level.
[00:10:57] The operators, perhaps under pressure to complete the test, ignored the warning signs and continued with the procedure.
[00:11:06] By 1:23 a.m., they were ready to start the test.
[00:11:11] But the reactor was already in a volatile state, balanced precariously on the edge of control.
[00:11:20] At this critical moment, they pressed the button to initiate the emergency shutdown.
[00:11:27] The control rods, which were designed to slow the reaction by absorbing neutrons, were rapidly inserted back into the core.
[00:11:38] But there was a deadly flaw in the reactor’s design: the tips of these control rods were made of graphite, a material that actually increased reactivity rather than decreased it.
[00:11:52] Instead of shutting down the reaction, the insertion of the control rods created a sudden spike in power.
[00:12:01] Within seconds, the reactor’s power surged uncontrollably, reaching levels a hundred times higher than normal. The heat built up rapidly, and the pressure in the reactor core became immense.
[00:12:16] The cooling water turned to steam, building up pressure until the pipes burst.
[00:12:23] A series of huge explosions rocked the reactor, blowing off the thousand-tonne steel and concrete lid that protected the nuclear core from the outside world.
[00:12:35] The core was exposed, and a massive fire ignited, shooting radioactive material high into the air.
[00:12:44] Now it was a race against time to put out the fires threatening the rest of the power plant.
[00:12:52] Remember, the accident happened only at reactor number four, and there were three others. If the fires got to the other reactors, then they too would be threatened, and the entire plant could explode.
[00:13:08] At 1:45 a.m., 22 minutes after the explosion, the first batch of firefighters arrived on the scene.
[00:13:16] They rushed in to put out the fires, without proper protective equipment, thus inadvertently exposing themselves to incredibly dangerous levels of radiation.
[00:13:27] It was a fire like no other, and when the firefighters were unable to successfully extinguish it, the Soviet army was called in.
[00:13:38] With the core still melting at over 2,000 degrees Centigrade, helicopters dropped more than 5,000 tonnes of sand, lead and clay onto the reactor, in a bid to cover it.
[00:13:51] It didn’t work, and this huge, molten mass of radioactive material kept seeping through the reinforced concrete, inching closer to the huge water tanks below the reactor, which, under normal conditions, would pump water to cool the reactor.
[00:14:09] Now, if the melting radioactive material reached the water, it would spell even greater disaster.
[00:14:17] The water would immediately turn to steam, turning the plant into a huge pressure cooker and blowing even more radioactive material into the atmosphere.
[00:14:28] Fortunately, this crisis was averted by workers who waded into the water tanks and managed to find the tap to drain them, but in so doing exposing themselves to extremely dangerous levels of radiation.
[00:14:44] Now, for the first almost 48 hours after the explosion, there was no official word from Moscow, no public statement about what had happened.
[00:14:56] The residents of the closest town, Pripyat, had been evacuated, and an exclusion zone had been created around the plant, but there was no official word from the Soviet state.
[00:15:09] It wasn’t until 9 pm on April 28th that the announcement came, but it was short and fairly nondescript: there has been an accident, one of the reactors was damaged, we are helping anybody affected.
[00:15:25] But even before this announcement, there were suspicions outside the Soviet Union that something had happened.
[00:15:34] At a nuclear power plant in Forsmark, two hours north of Stockholm in Sweden, 1,300 kilometres from Chernobyl, scientists had noted higher than usual levels of radiation.
[00:15:48] Initially, they thought this must be some kind of mistake, but after further analysis, it was clear that it was not.
[00:15:57] Wind from the southeast was blowing radioactive material towards Sweden, and after consulting meteorological colleagues, it was concluded that this must have come from the Soviet Union.
[00:16:11] The usual diplomatic channels were followed, but Swedish diplomats reported that they had been told that there had not been any kind of nuclear test or malfunction at a nuclear plant.
[00:16:25] The Swedes said, in the most diplomatic way possible, “we don’t believe a word you’re saying”, and told their Soviet counterparts that they were going to file an official alert with the International Energy Agency.
[00:16:39] And shortly after came the official announcement from Moscow, yes, there had in fact been an accident.
[00:16:48] And not just any accident. The disaster at Chernobyl is to date–and one must hope it will remain–the worst and most expensive disaster in nuclear history.
[00:17:00] As you may know, it took decades to clean up, even today there is an exclusion zone around it, and one estimate puts the cost of the disaster at $700 billion dollars.
[00:17:15] The explosion itself was not so deadly, with only two engineers being killed in the blast, but a further 29 would die in the subsequent weeks, from a mixture of acute radiation sickness and burns sustained trying to put out the fires.
[00:17:34] At around 30 direct deaths, this would be a tragic but relatively unhistoric industrial accident.
[00:17:43] The reason Chernobyl is different is that it didn’t just affect the people working in the power plant, it didn’t just affect those in the nearby blast radius, it created a cloud of radioactive material that was blown across much of Europe, spreading silently across borders, with the result that higher than usual doses of radiation were measured in the United States, Canada, China and Japan.
[00:18:11] Although these levels were low, it showed how far radiation from a nuclear disaster could travel.
[00:18:18] And nuclear radiation, as you will know, is not good news. It can cause all sorts of irregularities, cancers, organ damage, and death.
[00:18:31] Now, the impact of Chernobyl, in terms of its human cost, is still hotly debated.
[00:18:38] An official United Nations report puts the estimated total deaths at 4,000, but other estimates are up to 16,000, and one even puts it at several hundred thousand, if you take into account everyone around the world who might have been exposed to higher-than-usual doses of radiation.
[00:18:59] The difference comes down to how you measure it, and what you define to be an acceptable dose of radiation. Lots of stuff we do in our daily lives exposes us to radiation, from going on an aeroplane to having an x-ray, so just because someone was exposed to some radiation from a nuclear disaster thousands of kilometres away, it doesn’t necessarily mean it will have any impact on their health.
[00:19:27] But, and it is a big but, the Chernobyl disaster was a huge disaster for the public perception of nuclear power.
[00:19:37] The public around the world had been told that nuclear power was safe, it was the way of the future.
[00:19:45] And then this reality was shattered, at least in the public’s mind.
[00:19:51] There were stories of radioactive clouds, genetic mutations, terrible cancers, sterility, and of course nobody wanted to live anywhere near a power plant that might explode and subject them to lethal levels of radiation.
[00:20:08] Perfectly understandably, across the world public support for new nuclear power plant construction plummeted.
[00:20:16] The year after the Chernobyl Disaster, Italy held a referendum on nuclear power, and Italians voted resoundingly against it, shutting down all nuclear power plants by 1990.
[00:20:30] It was also a major boon to the anti-nuclear Greens in Germany, increasing their share of the vote to 8.3% in the 1987 election.
[00:20:42] Interestingly enough, since the Chernobyl Disaster, Russia has in fact increased not just the total amount of energy that it gets from nuclear but also the percentage of its total energy needs that come from nuclear sources. In 1986 it was 12.5% of the country’s total power, but that number is now more than 20%.
[00:21:07] Russia is now the fourth largest nuclear producer in the world, after the United States, China and France.
[00:21:16] To the nuclear sceptics, this is a dangerous situation to be in and Russia, of all countries, should be acutely aware of what happens when nuclear power goes wrong.
[00:21:28] To the supporters of nuclear power, it is an admirable commitment to what is now a considerably safer power source, and one that is an important stepping stone to a carbon-free future.
[00:21:41] And that, my friends, is what we will talk about in much more detail in the next episode.
[00:21:48] OK then, that is it for today's episode on the Chernobyl Disaster.
[00:21:53] I hope it's been an interesting one, and that you've learnt something new.
[00:21:57] As a reminder, this is part two of our three-part mini-series, the last one was on early nuclear power and the next one will be on the future of nuclear energy.
[00:22:08] And if you want to get really deep into the theme of nuclear and atomic energy, and you are ready for a more destructive subject, we also made a three-part mini-series on the atomic bomb.
[00:22:20] That’s episodes 284, 285 and 286 if you haven’t listened to them already.
[00:22:27] You've been listening to English Learning for Curious Minds, by Leonardo English.
[00:22:32] I'm Alastair Budge, you stay safe, and I'll catch you in the next episode.
[00:00:05] Hello, hello hello, and welcome to English Learning for Curious Minds, by Leonardo English.
[00:00:11] The show where you can listen to fascinating stories, and learn weird and wonderful things about the world at the same time as improving your English.
[00:00:20] I'm Alastair Budge, and today is part two of our three-part mini-series on nuclear power.
[00:00:27] In case you missed it, in part one we talked about early nuclear power, Dwight Eisenhower’s famous Atoms for Peace speech, and the early enthusiasm mixed with fear that much of the developed world had for nuclear power.
[00:00:43] In the next episode, part three, we are going to talk about the state of nuclear power today and tomorrow, now and in the future, and try to understand why some people believe it to be a key weapon in the fight against climate change while others still vehemently oppose it.
[00:01:03] And in today’s episode, part two, we are going to talk about the incident that has done more than any other to change public opinion on nuclear power: The Chernobyl Disaster.
[00:01:15] You can, of course, listen to this episode without having listened to the last one, but it will probably make a little more sense if you have listened to part one, so if you haven’t done so already, I’d recommend you press pause and listen to that one first.
[00:01:33] OK then, let’s get right into it and talk about the most deadly disaster in the history of nuclear power.
[00:01:42] If you were a kid growing up in the 1990s, like me, you might well have played the game SimCity. The game required you to build a city.
[00:01:54] You would choose where to place roads, residential areas, business areas, industrial areas, schools, and hospitals.
[00:02:03] As your city grew, you made more money, which you would then spend on building more infrastructure. And as your city developed and got richer, your city would modernise.
[00:02:17] Basic houses would become shining skyscrapers. Smoke-billowing factories would turn into high-tech business zones, and so on.
[00:02:29] And of course, you needed to plan your utilities. Water, transport, and electricity.
[00:02:37] There were certain types of power plants you could build: coal, wind, and nuclear.
[00:02:45] You had to balance your city’s need for power with where you were going to put the power plant, because if you put a coal-powered plant next to a residential area, nobody would want to live there.
[00:02:58] Nuclear power plants were good, but they were quite expensive to build and there was the threat of a tornado or earthquake that would damage the plant, causing the nearby area to be contaminated by nuclear waste and property values to plummet.
[00:03:17] If, like me, you spent hundreds of hours of your childhood playing this game, you will know firsthand why it was so addictive, and if you have never heard of it, just trust me, it was seriously good fun.
[00:03:32] Now, not such a long time before the first SimCity game was released, central planners in the USSR were playing their own, real-life and–of course–infinitely more complicated version.
[00:03:48] The USSR covered a whopping 22.4 million square km, 17% of the world’s total land area.
[00:03:59] It had an abundance of natural resources, coal, oil and natural gas, but the largest known deposits were in Siberia, in the eastern part of the country, while the majority of the population was in the west of the country.
[00:04:18] Nuclear power offered a convenient solution.
[00:04:23] A nuclear power plant could be placed anywhere, more or less.
[00:04:29] They need a lot of water, so they are typically placed near rivers, lakes, or seas. And they should ideally be placed away from populated areas, in case anything goes wrong, but with 22.4 million square kilometres, the USSR had plenty of options.
[00:04:49] The USSR was, in fact, the first country to successfully open a nuclear power plant, which it did in June of 1954, and by 1982 it had a total of 26 nuclear reactors across 10 different plants, which produced 6.5% of the country’s power.
[00:05:12] One of these was at the town of Pripyat, close to the town of Chernobyl, in northern Ukraine, which was then part of the Soviet Union.
[00:05:22] The plant at Chernobyl was home to four nuclear reactors, which had been built between 1977 and 1983.
[00:05:32] Now, as a quick and very superficial reminder of how a nuclear power plant works, there is a controlled nuclear fission reaction in the core of a reactor, which gives off huge amounts of heat, which boils water, which creates steam, which turns a turbine.
[00:05:52] The turbine is connected to a generator, which then converts the mechanical energy from the spinning turbine into electricity.
[00:06:02] The principle is the same as in an oil or gas power station; water is heated so that it boils, the steam turns a turbine, and a generator produces electricity.
[00:06:15] A core difference, however, is that the balance in a nuclear reactor is much more sensitive.
[00:06:25] In an oil or gas plant, if something goes wrong, the fuel supply can simply be cut off, stopping the reaction almost immediately.
[00:06:36] But in a nuclear reactor, the process is far more complex and can’t just be shut down with the flip of a switch.
[00:06:45] The nuclear fission reaction relies on a delicate balance of control rods, cooling systems, and a stable core temperature.
[00:06:56] The control rods absorb neutrons, which slow down or even stop the reaction when needed.
[00:07:04] These rods are carefully adjusted to control the rate of fission.
[00:07:11] The cooling system, meanwhile, ensures that the reactor doesn’t overheat, keeping the reaction in check and preventing the fuel rods from melting.
[00:07:23] This balance is critical.
[00:07:26] If anything disrupts it—whether it’s an issue with the control rods, a cooling failure, or operator error—the chain reaction can accelerate dangerously, leading to a buildup of heat and pressure.
[00:07:42] And if it goes too far, the consequences can be catastrophic.
[00:07:48] This is what made nuclear energy both powerful and, in the eyes of many, terrifying.
[00:07:56] While it offered a seemingly limitless supply of energy without the pollution of fossil fuels, it also demanded a level of precision and caution unlike any other energy source.
[00:08:09] And on the night of April the 26th, 1986, at the Chernobyl Nuclear Power Plant in northern Ukraine, this delicate balance was lost.
[00:08:21] It all began as a routine safety test designed to verify procedures in case of a power loss during an emergency shutdown.
[00:08:31] The purpose of this test was simple in theory but critical in practice.
[00:08:38] If there was an emergency shutdown, there were backup diesel generators that would kick in, but this wasn’t an automatic and instant process.
[00:08:49] It took 45 seconds or so.
[00:08:52] The nuclear scientists had calculated that there was enough residual energy in the reactor’s turbines to continue running and generating electricity for the cooling pumps while the backup generators started working.
[00:09:06] Of course, the cooling pumps needed to continue pumping water, because if they stopped working, the nuclear reactor could overheat uncontrollably.
[00:09:17] The scientists had calculated that this wouldn’t be an issue, they had proved it on paper, but they had never actually demonstrated it live, in the power plant.
[00:09:30] So this was the purpose of the test.
[00:09:33] They were proving that in the event of a complete power loss, the remaining energy in the turbines would buy them enough time until the backup diesel generators kicked in.
[00:09:46] So, this is what they did.
[00:09:49] The operators began by reducing the reactor’s power to a low level.
[00:09:55] This was part of the test’s procedure, intended to simulate what would happen if there were a sudden need to shut down the reactor.
[00:10:04] But as they did so, things started to go wrong.
[00:10:10] The power dropped to dangerously low levels—far lower than they had planned for, and much lower than what the reactor was designed to handle safely.
[00:10:20] In an attempt to bring the power up, the operators withdrew almost all of the control rods—rods that were essential for slowing down the nuclear reaction.
[00:10:32] This move put the reactor in a highly unstable state.
[00:10:38] At these low power levels, a gas called xenon started to build up in the reactor.
[00:10:45] This gas absorbed neutrons, which slowed the reaction down even more, making it harder for the operators to raise the power to a stable level.
[00:10:57] The operators, perhaps under pressure to complete the test, ignored the warning signs and continued with the procedure.
[00:11:06] By 1:23 a.m., they were ready to start the test.
[00:11:11] But the reactor was already in a volatile state, balanced precariously on the edge of control.
[00:11:20] At this critical moment, they pressed the button to initiate the emergency shutdown.
[00:11:27] The control rods, which were designed to slow the reaction by absorbing neutrons, were rapidly inserted back into the core.
[00:11:38] But there was a deadly flaw in the reactor’s design: the tips of these control rods were made of graphite, a material that actually increased reactivity rather than decreased it.
[00:11:52] Instead of shutting down the reaction, the insertion of the control rods created a sudden spike in power.
[00:12:01] Within seconds, the reactor’s power surged uncontrollably, reaching levels a hundred times higher than normal. The heat built up rapidly, and the pressure in the reactor core became immense.
[00:12:16] The cooling water turned to steam, building up pressure until the pipes burst.
[00:12:23] A series of huge explosions rocked the reactor, blowing off the thousand-tonne steel and concrete lid that protected the nuclear core from the outside world.
[00:12:35] The core was exposed, and a massive fire ignited, shooting radioactive material high into the air.
[00:12:44] Now it was a race against time to put out the fires threatening the rest of the power plant.
[00:12:52] Remember, the accident happened only at reactor number four, and there were three others. If the fires got to the other reactors, then they too would be threatened, and the entire plant could explode.
[00:13:08] At 1:45 a.m., 22 minutes after the explosion, the first batch of firefighters arrived on the scene.
[00:13:16] They rushed in to put out the fires, without proper protective equipment, thus inadvertently exposing themselves to incredibly dangerous levels of radiation.
[00:13:27] It was a fire like no other, and when the firefighters were unable to successfully extinguish it, the Soviet army was called in.
[00:13:38] With the core still melting at over 2,000 degrees Centigrade, helicopters dropped more than 5,000 tonnes of sand, lead and clay onto the reactor, in a bid to cover it.
[00:13:51] It didn’t work, and this huge, molten mass of radioactive material kept seeping through the reinforced concrete, inching closer to the huge water tanks below the reactor, which, under normal conditions, would pump water to cool the reactor.
[00:14:09] Now, if the melting radioactive material reached the water, it would spell even greater disaster.
[00:14:17] The water would immediately turn to steam, turning the plant into a huge pressure cooker and blowing even more radioactive material into the atmosphere.
[00:14:28] Fortunately, this crisis was averted by workers who waded into the water tanks and managed to find the tap to drain them, but in so doing exposing themselves to extremely dangerous levels of radiation.
[00:14:44] Now, for the first almost 48 hours after the explosion, there was no official word from Moscow, no public statement about what had happened.
[00:14:56] The residents of the closest town, Pripyat, had been evacuated, and an exclusion zone had been created around the plant, but there was no official word from the Soviet state.
[00:15:09] It wasn’t until 9 pm on April 28th that the announcement came, but it was short and fairly nondescript: there has been an accident, one of the reactors was damaged, we are helping anybody affected.
[00:15:25] But even before this announcement, there were suspicions outside the Soviet Union that something had happened.
[00:15:34] At a nuclear power plant in Forsmark, two hours north of Stockholm in Sweden, 1,300 kilometres from Chernobyl, scientists had noted higher than usual levels of radiation.
[00:15:48] Initially, they thought this must be some kind of mistake, but after further analysis, it was clear that it was not.
[00:15:57] Wind from the southeast was blowing radioactive material towards Sweden, and after consulting meteorological colleagues, it was concluded that this must have come from the Soviet Union.
[00:16:11] The usual diplomatic channels were followed, but Swedish diplomats reported that they had been told that there had not been any kind of nuclear test or malfunction at a nuclear plant.
[00:16:25] The Swedes said, in the most diplomatic way possible, “we don’t believe a word you’re saying”, and told their Soviet counterparts that they were going to file an official alert with the International Energy Agency.
[00:16:39] And shortly after came the official announcement from Moscow, yes, there had in fact been an accident.
[00:16:48] And not just any accident. The disaster at Chernobyl is to date–and one must hope it will remain–the worst and most expensive disaster in nuclear history.
[00:17:00] As you may know, it took decades to clean up, even today there is an exclusion zone around it, and one estimate puts the cost of the disaster at $700 billion dollars.
[00:17:15] The explosion itself was not so deadly, with only two engineers being killed in the blast, but a further 29 would die in the subsequent weeks, from a mixture of acute radiation sickness and burns sustained trying to put out the fires.
[00:17:34] At around 30 direct deaths, this would be a tragic but relatively unhistoric industrial accident.
[00:17:43] The reason Chernobyl is different is that it didn’t just affect the people working in the power plant, it didn’t just affect those in the nearby blast radius, it created a cloud of radioactive material that was blown across much of Europe, spreading silently across borders, with the result that higher than usual doses of radiation were measured in the United States, Canada, China and Japan.
[00:18:11] Although these levels were low, it showed how far radiation from a nuclear disaster could travel.
[00:18:18] And nuclear radiation, as you will know, is not good news. It can cause all sorts of irregularities, cancers, organ damage, and death.
[00:18:31] Now, the impact of Chernobyl, in terms of its human cost, is still hotly debated.
[00:18:38] An official United Nations report puts the estimated total deaths at 4,000, but other estimates are up to 16,000, and one even puts it at several hundred thousand, if you take into account everyone around the world who might have been exposed to higher-than-usual doses of radiation.
[00:18:59] The difference comes down to how you measure it, and what you define to be an acceptable dose of radiation. Lots of stuff we do in our daily lives exposes us to radiation, from going on an aeroplane to having an x-ray, so just because someone was exposed to some radiation from a nuclear disaster thousands of kilometres away, it doesn’t necessarily mean it will have any impact on their health.
[00:19:27] But, and it is a big but, the Chernobyl disaster was a huge disaster for the public perception of nuclear power.
[00:19:37] The public around the world had been told that nuclear power was safe, it was the way of the future.
[00:19:45] And then this reality was shattered, at least in the public’s mind.
[00:19:51] There were stories of radioactive clouds, genetic mutations, terrible cancers, sterility, and of course nobody wanted to live anywhere near a power plant that might explode and subject them to lethal levels of radiation.
[00:20:08] Perfectly understandably, across the world public support for new nuclear power plant construction plummeted.
[00:20:16] The year after the Chernobyl Disaster, Italy held a referendum on nuclear power, and Italians voted resoundingly against it, shutting down all nuclear power plants by 1990.
[00:20:30] It was also a major boon to the anti-nuclear Greens in Germany, increasing their share of the vote to 8.3% in the 1987 election.
[00:20:42] Interestingly enough, since the Chernobyl Disaster, Russia has in fact increased not just the total amount of energy that it gets from nuclear but also the percentage of its total energy needs that come from nuclear sources. In 1986 it was 12.5% of the country’s total power, but that number is now more than 20%.
[00:21:07] Russia is now the fourth largest nuclear producer in the world, after the United States, China and France.
[00:21:16] To the nuclear sceptics, this is a dangerous situation to be in and Russia, of all countries, should be acutely aware of what happens when nuclear power goes wrong.
[00:21:28] To the supporters of nuclear power, it is an admirable commitment to what is now a considerably safer power source, and one that is an important stepping stone to a carbon-free future.
[00:21:41] And that, my friends, is what we will talk about in much more detail in the next episode.
[00:21:48] OK then, that is it for today's episode on the Chernobyl Disaster.
[00:21:53] I hope it's been an interesting one, and that you've learnt something new.
[00:21:57] As a reminder, this is part two of our three-part mini-series, the last one was on early nuclear power and the next one will be on the future of nuclear energy.
[00:22:08] And if you want to get really deep into the theme of nuclear and atomic energy, and you are ready for a more destructive subject, we also made a three-part mini-series on the atomic bomb.
[00:22:20] That’s episodes 284, 285 and 286 if you haven’t listened to them already.
[00:22:27] You've been listening to English Learning for Curious Minds, by Leonardo English.
[00:22:32] I'm Alastair Budge, you stay safe, and I'll catch you in the next episode.
[00:00:05] Hello, hello hello, and welcome to English Learning for Curious Minds, by Leonardo English.
[00:00:11] The show where you can listen to fascinating stories, and learn weird and wonderful things about the world at the same time as improving your English.
[00:00:20] I'm Alastair Budge, and today is part two of our three-part mini-series on nuclear power.
[00:00:27] In case you missed it, in part one we talked about early nuclear power, Dwight Eisenhower’s famous Atoms for Peace speech, and the early enthusiasm mixed with fear that much of the developed world had for nuclear power.
[00:00:43] In the next episode, part three, we are going to talk about the state of nuclear power today and tomorrow, now and in the future, and try to understand why some people believe it to be a key weapon in the fight against climate change while others still vehemently oppose it.
[00:01:03] And in today’s episode, part two, we are going to talk about the incident that has done more than any other to change public opinion on nuclear power: The Chernobyl Disaster.
[00:01:15] You can, of course, listen to this episode without having listened to the last one, but it will probably make a little more sense if you have listened to part one, so if you haven’t done so already, I’d recommend you press pause and listen to that one first.
[00:01:33] OK then, let’s get right into it and talk about the most deadly disaster in the history of nuclear power.
[00:01:42] If you were a kid growing up in the 1990s, like me, you might well have played the game SimCity. The game required you to build a city.
[00:01:54] You would choose where to place roads, residential areas, business areas, industrial areas, schools, and hospitals.
[00:02:03] As your city grew, you made more money, which you would then spend on building more infrastructure. And as your city developed and got richer, your city would modernise.
[00:02:17] Basic houses would become shining skyscrapers. Smoke-billowing factories would turn into high-tech business zones, and so on.
[00:02:29] And of course, you needed to plan your utilities. Water, transport, and electricity.
[00:02:37] There were certain types of power plants you could build: coal, wind, and nuclear.
[00:02:45] You had to balance your city’s need for power with where you were going to put the power plant, because if you put a coal-powered plant next to a residential area, nobody would want to live there.
[00:02:58] Nuclear power plants were good, but they were quite expensive to build and there was the threat of a tornado or earthquake that would damage the plant, causing the nearby area to be contaminated by nuclear waste and property values to plummet.
[00:03:17] If, like me, you spent hundreds of hours of your childhood playing this game, you will know firsthand why it was so addictive, and if you have never heard of it, just trust me, it was seriously good fun.
[00:03:32] Now, not such a long time before the first SimCity game was released, central planners in the USSR were playing their own, real-life and–of course–infinitely more complicated version.
[00:03:48] The USSR covered a whopping 22.4 million square km, 17% of the world’s total land area.
[00:03:59] It had an abundance of natural resources, coal, oil and natural gas, but the largest known deposits were in Siberia, in the eastern part of the country, while the majority of the population was in the west of the country.
[00:04:18] Nuclear power offered a convenient solution.
[00:04:23] A nuclear power plant could be placed anywhere, more or less.
[00:04:29] They need a lot of water, so they are typically placed near rivers, lakes, or seas. And they should ideally be placed away from populated areas, in case anything goes wrong, but with 22.4 million square kilometres, the USSR had plenty of options.
[00:04:49] The USSR was, in fact, the first country to successfully open a nuclear power plant, which it did in June of 1954, and by 1982 it had a total of 26 nuclear reactors across 10 different plants, which produced 6.5% of the country’s power.
[00:05:12] One of these was at the town of Pripyat, close to the town of Chernobyl, in northern Ukraine, which was then part of the Soviet Union.
[00:05:22] The plant at Chernobyl was home to four nuclear reactors, which had been built between 1977 and 1983.
[00:05:32] Now, as a quick and very superficial reminder of how a nuclear power plant works, there is a controlled nuclear fission reaction in the core of a reactor, which gives off huge amounts of heat, which boils water, which creates steam, which turns a turbine.
[00:05:52] The turbine is connected to a generator, which then converts the mechanical energy from the spinning turbine into electricity.
[00:06:02] The principle is the same as in an oil or gas power station; water is heated so that it boils, the steam turns a turbine, and a generator produces electricity.
[00:06:15] A core difference, however, is that the balance in a nuclear reactor is much more sensitive.
[00:06:25] In an oil or gas plant, if something goes wrong, the fuel supply can simply be cut off, stopping the reaction almost immediately.
[00:06:36] But in a nuclear reactor, the process is far more complex and can’t just be shut down with the flip of a switch.
[00:06:45] The nuclear fission reaction relies on a delicate balance of control rods, cooling systems, and a stable core temperature.
[00:06:56] The control rods absorb neutrons, which slow down or even stop the reaction when needed.
[00:07:04] These rods are carefully adjusted to control the rate of fission.
[00:07:11] The cooling system, meanwhile, ensures that the reactor doesn’t overheat, keeping the reaction in check and preventing the fuel rods from melting.
[00:07:23] This balance is critical.
[00:07:26] If anything disrupts it—whether it’s an issue with the control rods, a cooling failure, or operator error—the chain reaction can accelerate dangerously, leading to a buildup of heat and pressure.
[00:07:42] And if it goes too far, the consequences can be catastrophic.
[00:07:48] This is what made nuclear energy both powerful and, in the eyes of many, terrifying.
[00:07:56] While it offered a seemingly limitless supply of energy without the pollution of fossil fuels, it also demanded a level of precision and caution unlike any other energy source.
[00:08:09] And on the night of April the 26th, 1986, at the Chernobyl Nuclear Power Plant in northern Ukraine, this delicate balance was lost.
[00:08:21] It all began as a routine safety test designed to verify procedures in case of a power loss during an emergency shutdown.
[00:08:31] The purpose of this test was simple in theory but critical in practice.
[00:08:38] If there was an emergency shutdown, there were backup diesel generators that would kick in, but this wasn’t an automatic and instant process.
[00:08:49] It took 45 seconds or so.
[00:08:52] The nuclear scientists had calculated that there was enough residual energy in the reactor’s turbines to continue running and generating electricity for the cooling pumps while the backup generators started working.
[00:09:06] Of course, the cooling pumps needed to continue pumping water, because if they stopped working, the nuclear reactor could overheat uncontrollably.
[00:09:17] The scientists had calculated that this wouldn’t be an issue, they had proved it on paper, but they had never actually demonstrated it live, in the power plant.
[00:09:30] So this was the purpose of the test.
[00:09:33] They were proving that in the event of a complete power loss, the remaining energy in the turbines would buy them enough time until the backup diesel generators kicked in.
[00:09:46] So, this is what they did.
[00:09:49] The operators began by reducing the reactor’s power to a low level.
[00:09:55] This was part of the test’s procedure, intended to simulate what would happen if there were a sudden need to shut down the reactor.
[00:10:04] But as they did so, things started to go wrong.
[00:10:10] The power dropped to dangerously low levels—far lower than they had planned for, and much lower than what the reactor was designed to handle safely.
[00:10:20] In an attempt to bring the power up, the operators withdrew almost all of the control rods—rods that were essential for slowing down the nuclear reaction.
[00:10:32] This move put the reactor in a highly unstable state.
[00:10:38] At these low power levels, a gas called xenon started to build up in the reactor.
[00:10:45] This gas absorbed neutrons, which slowed the reaction down even more, making it harder for the operators to raise the power to a stable level.
[00:10:57] The operators, perhaps under pressure to complete the test, ignored the warning signs and continued with the procedure.
[00:11:06] By 1:23 a.m., they were ready to start the test.
[00:11:11] But the reactor was already in a volatile state, balanced precariously on the edge of control.
[00:11:20] At this critical moment, they pressed the button to initiate the emergency shutdown.
[00:11:27] The control rods, which were designed to slow the reaction by absorbing neutrons, were rapidly inserted back into the core.
[00:11:38] But there was a deadly flaw in the reactor’s design: the tips of these control rods were made of graphite, a material that actually increased reactivity rather than decreased it.
[00:11:52] Instead of shutting down the reaction, the insertion of the control rods created a sudden spike in power.
[00:12:01] Within seconds, the reactor’s power surged uncontrollably, reaching levels a hundred times higher than normal. The heat built up rapidly, and the pressure in the reactor core became immense.
[00:12:16] The cooling water turned to steam, building up pressure until the pipes burst.
[00:12:23] A series of huge explosions rocked the reactor, blowing off the thousand-tonne steel and concrete lid that protected the nuclear core from the outside world.
[00:12:35] The core was exposed, and a massive fire ignited, shooting radioactive material high into the air.
[00:12:44] Now it was a race against time to put out the fires threatening the rest of the power plant.
[00:12:52] Remember, the accident happened only at reactor number four, and there were three others. If the fires got to the other reactors, then they too would be threatened, and the entire plant could explode.
[00:13:08] At 1:45 a.m., 22 minutes after the explosion, the first batch of firefighters arrived on the scene.
[00:13:16] They rushed in to put out the fires, without proper protective equipment, thus inadvertently exposing themselves to incredibly dangerous levels of radiation.
[00:13:27] It was a fire like no other, and when the firefighters were unable to successfully extinguish it, the Soviet army was called in.
[00:13:38] With the core still melting at over 2,000 degrees Centigrade, helicopters dropped more than 5,000 tonnes of sand, lead and clay onto the reactor, in a bid to cover it.
[00:13:51] It didn’t work, and this huge, molten mass of radioactive material kept seeping through the reinforced concrete, inching closer to the huge water tanks below the reactor, which, under normal conditions, would pump water to cool the reactor.
[00:14:09] Now, if the melting radioactive material reached the water, it would spell even greater disaster.
[00:14:17] The water would immediately turn to steam, turning the plant into a huge pressure cooker and blowing even more radioactive material into the atmosphere.
[00:14:28] Fortunately, this crisis was averted by workers who waded into the water tanks and managed to find the tap to drain them, but in so doing exposing themselves to extremely dangerous levels of radiation.
[00:14:44] Now, for the first almost 48 hours after the explosion, there was no official word from Moscow, no public statement about what had happened.
[00:14:56] The residents of the closest town, Pripyat, had been evacuated, and an exclusion zone had been created around the plant, but there was no official word from the Soviet state.
[00:15:09] It wasn’t until 9 pm on April 28th that the announcement came, but it was short and fairly nondescript: there has been an accident, one of the reactors was damaged, we are helping anybody affected.
[00:15:25] But even before this announcement, there were suspicions outside the Soviet Union that something had happened.
[00:15:34] At a nuclear power plant in Forsmark, two hours north of Stockholm in Sweden, 1,300 kilometres from Chernobyl, scientists had noted higher than usual levels of radiation.
[00:15:48] Initially, they thought this must be some kind of mistake, but after further analysis, it was clear that it was not.
[00:15:57] Wind from the southeast was blowing radioactive material towards Sweden, and after consulting meteorological colleagues, it was concluded that this must have come from the Soviet Union.
[00:16:11] The usual diplomatic channels were followed, but Swedish diplomats reported that they had been told that there had not been any kind of nuclear test or malfunction at a nuclear plant.
[00:16:25] The Swedes said, in the most diplomatic way possible, “we don’t believe a word you’re saying”, and told their Soviet counterparts that they were going to file an official alert with the International Energy Agency.
[00:16:39] And shortly after came the official announcement from Moscow, yes, there had in fact been an accident.
[00:16:48] And not just any accident. The disaster at Chernobyl is to date–and one must hope it will remain–the worst and most expensive disaster in nuclear history.
[00:17:00] As you may know, it took decades to clean up, even today there is an exclusion zone around it, and one estimate puts the cost of the disaster at $700 billion dollars.
[00:17:15] The explosion itself was not so deadly, with only two engineers being killed in the blast, but a further 29 would die in the subsequent weeks, from a mixture of acute radiation sickness and burns sustained trying to put out the fires.
[00:17:34] At around 30 direct deaths, this would be a tragic but relatively unhistoric industrial accident.
[00:17:43] The reason Chernobyl is different is that it didn’t just affect the people working in the power plant, it didn’t just affect those in the nearby blast radius, it created a cloud of radioactive material that was blown across much of Europe, spreading silently across borders, with the result that higher than usual doses of radiation were measured in the United States, Canada, China and Japan.
[00:18:11] Although these levels were low, it showed how far radiation from a nuclear disaster could travel.
[00:18:18] And nuclear radiation, as you will know, is not good news. It can cause all sorts of irregularities, cancers, organ damage, and death.
[00:18:31] Now, the impact of Chernobyl, in terms of its human cost, is still hotly debated.
[00:18:38] An official United Nations report puts the estimated total deaths at 4,000, but other estimates are up to 16,000, and one even puts it at several hundred thousand, if you take into account everyone around the world who might have been exposed to higher-than-usual doses of radiation.
[00:18:59] The difference comes down to how you measure it, and what you define to be an acceptable dose of radiation. Lots of stuff we do in our daily lives exposes us to radiation, from going on an aeroplane to having an x-ray, so just because someone was exposed to some radiation from a nuclear disaster thousands of kilometres away, it doesn’t necessarily mean it will have any impact on their health.
[00:19:27] But, and it is a big but, the Chernobyl disaster was a huge disaster for the public perception of nuclear power.
[00:19:37] The public around the world had been told that nuclear power was safe, it was the way of the future.
[00:19:45] And then this reality was shattered, at least in the public’s mind.
[00:19:51] There were stories of radioactive clouds, genetic mutations, terrible cancers, sterility, and of course nobody wanted to live anywhere near a power plant that might explode and subject them to lethal levels of radiation.
[00:20:08] Perfectly understandably, across the world public support for new nuclear power plant construction plummeted.
[00:20:16] The year after the Chernobyl Disaster, Italy held a referendum on nuclear power, and Italians voted resoundingly against it, shutting down all nuclear power plants by 1990.
[00:20:30] It was also a major boon to the anti-nuclear Greens in Germany, increasing their share of the vote to 8.3% in the 1987 election.
[00:20:42] Interestingly enough, since the Chernobyl Disaster, Russia has in fact increased not just the total amount of energy that it gets from nuclear but also the percentage of its total energy needs that come from nuclear sources. In 1986 it was 12.5% of the country’s total power, but that number is now more than 20%.
[00:21:07] Russia is now the fourth largest nuclear producer in the world, after the United States, China and France.
[00:21:16] To the nuclear sceptics, this is a dangerous situation to be in and Russia, of all countries, should be acutely aware of what happens when nuclear power goes wrong.
[00:21:28] To the supporters of nuclear power, it is an admirable commitment to what is now a considerably safer power source, and one that is an important stepping stone to a carbon-free future.
[00:21:41] And that, my friends, is what we will talk about in much more detail in the next episode.
[00:21:48] OK then, that is it for today's episode on the Chernobyl Disaster.
[00:21:53] I hope it's been an interesting one, and that you've learnt something new.
[00:21:57] As a reminder, this is part two of our three-part mini-series, the last one was on early nuclear power and the next one will be on the future of nuclear energy.
[00:22:08] And if you want to get really deep into the theme of nuclear and atomic energy, and you are ready for a more destructive subject, we also made a three-part mini-series on the atomic bomb.
[00:22:20] That’s episodes 284, 285 and 286 if you haven’t listened to them already.
[00:22:27] You've been listening to English Learning for Curious Minds, by Leonardo English.
[00:22:32] I'm Alastair Budge, you stay safe, and I'll catch you in the next episode.
