* Did the Chernobyl explosion 40 years ago pose a threat to the Czech Republic?
Elevated radiation levels were detected here in April 1986, but their health effects were negligible. It is worth mentioning the psychological effects. The Czechoslovak regime at the time did not inform us about the accident. This led to a number of rumors that caused people stress. Fear is harmful to health. Even things that do not actually threaten us can manifest as anxiety and depression.
* What caused the Chernobyl accident?
Several TV series have been made about it, explaining the technical details of the accident minute by minute. What experiment the Soviets were conducting in Chernobyl, what systems they turned on, and what they turned off. Yet the political regime—which was perhaps the most important factor—is often overlooked. The key to understanding the accident lies in the atmosphere of the time. Let me explain with an analogy. If you drive drunk in the wrong direction on a highway, you can’t be surprised if you crash. You might have the best car or the worst car, but it’s just going to happen. But if you drive sober, pay attention, and follow the rules, you have a high chance that nothing will happen to you, even if you’re driving an old car. The Chernobyl reactor was a veteran; it was certainly not a modern car with airbags, parking assist, cruise control, and other safety features. If the operators had respected that and worked by the rules, nothing would have happened. But they used the reactor the wrong way, and the technology wasn’t robust enough to tolerate it.
* So, Soviet sloppiness and ignorance?
There’s a big difference in how we approach nuclear energy in the West. But we still have to remind ourselves that rules must be followed. Look at Czech roads—how many people drive cars that aren’t roadworthy, or speed… They think they can handle driving even after a night out with alcohol still in their system. In Chernobyl, they also told themselves that regulations could be circumvented and that they’d manage just fine. That attitude was a manifestation of the communist system. There is definitely no Soviet sloppiness in European nuclear energy; safety rules are strictly followed. The system is set up much better.
* Could the same thing happen at Temelín or Dukovany?
I’d have to be a science fiction writer to imagine a situation where such a massive release of radioactive substances into the environment would occur here as it did in Chernobyl. A hypothetical scenario could probably be devised, but practically speaking, I consider it nearly impossible.
* What is the difference between the Chernobyl reactor and the reactors we have in Temelín and Dukovany?
Absolutely fundamental—a generational difference. The Chernobyl reactor suffered from a number of design flaws inherent in the technology of that era. The reactors in Czech power plants are significantly more advanced; it’s a difference of decades.
* For example?
For example, in the reactor’s protective shell—the reactor vessel. You can think of it as a giant pot that can withstand extreme conditions, including high pressure and temperature. If a reactor accident were to occur, the shell would contain the radioactive material inside. In other words, the “pot” won’t overflow, even if you burn your lunch. Surrounding the vessel is also a so-called containment, which is a very durable reinforced concrete structure. Even if the “pot” were to fail in an accident, the containment would prevent radioactive materials from escaping into the environment. The Chernobyl reactor had none of this. The fission reaction therefore works the same way, but the technology for controlling it has advanced significantly over the past forty years.
* I read somewhere that while the reactor in Chernobyl was part of a power plant, its function was to produce plutonium for military purposes. Is that possible?
We’ll probably never know—the Soviets kept it secret. But it is true that the Chernobyl reactor type was very well suited for plutonium production.
* Could that also be done at Temelín or Dukovany?
It would be extremely difficult, but more importantly, it couldn’t be kept secret. We live under a different political system, and our reactors are also supervised by the International Atomic Energy Agency and the State Office for Nuclear Safety. There are seals on the reactor lids, and they are constantly monitored by cameras that record everything. Plus, inspectors visit the sites frequently.
* How does a nuclear power plant differ from a coal-fired power plant?
The basic principle is the same—to generate steam that drives a turbine. However, there are a number of differences between the two types of power plants. For example, a coal-fired power plant is much less efficient, and we must monitor chemical substances in its flue gases, such as sulfur and mercury. In a nuclear power plant, on the other hand, there are much stricter requirements for operational safety.
* In both cases, it’s essentially a boiler, but they’re heated by different fuels. In a coal-fired power plant, coal burns inside, but how is heat generated in a nuclear plant?
When you light a stove at home, burning wood or coal releases the energy stored in chemical bonds. Carbon is converted into carbon dioxide through combustion, generating heat. In a nuclear power plant, we go one step deeper into matter—during a chain reaction, we alter the bonds within the nuclei of uranium atoms. Their fission is much more efficient than burning matter, because nuclear bonds contain a much greater amount of energy—and are more concentrated—than chemical bonds.
* Everyone surely pictures the atomic bombings of Hiroshima and Nagasaki. How does that differ from the processes taking place in a nuclear reactor?
The principle is the same in both cases. The difference is that in a reactor, we control the fission, so it’s slow and steady. It can be compared to gasoline, which can either explode and cause a fire or power a car engine. The energy is simply either released all at once, or we use it more slowly and in a controlled manner.
* How do you control the chain reaction in a reactor?
From a single split uranium nucleus, two (or up to three) neutrons are emitted, splitting two more nuclei; four neutrons are emitted from those, splitting four more nuclei, and so on in a geometric progression. This is the principle behind the atomic bomb. In a reactor, however, we absorb some of the neutrons, so fission proceeds at a constant rate. So there is no explosion; the power output remains constant. This can be explained by comparing it to the COVID-19 pandemic.
* How?
Do you remember the so-called reproduction number that was reported on TV every day six years ago?
It indicated how many other people a single infected person had infected. When it was greater than one, the pandemic was spreading; when it was less than one, it was subsiding. In an atomic bomb, the reproduction number is greater than one. This leads to a sharp increase in the number of “infected” people, and thus to an increase in the energy released and an explosion. In a nuclear reactor, we keep the reproduction number at one. The number of uranium nuclei split therefore remains almost the same, and with it, the power output.
* How much uranium is consumed at Temelín each year?
Each of the two units contains about 92 tons of fuel, of which about a quarter is used annually. We would need about a million times more coal to produce the same amount of power.
* In a car, we have a steering wheel, brakes, and an accelerator. How is a reactor controlled?
The basis is control rods, which absorb neutrons and thus slow down nuclear fission as needed. Conversely, when we need to increase power, we pull the rods out. We also have other control elements to ensure safe reactor operation. For example, boric acid, which also absorbs neutrons. Its quantity in the reactor determines how fission proceeds. Reactor output can also be controlled by the pressure and temperature of the so-called secondary circuit.
* What is this about?
The primary circuit, in which heat is generated by uranium fission, is the reactor itself. It heats the secondary circuit, where hot steam is produced to drive the turbine. This is connected to the tertiary circuit, which is linked to the cooling towers.
* So what is rising from them is not smoke from burning uranium? I ask this with deliberate exaggeration. Pure water vapor rises from the towers. Since all three circuits of the power plant are separated, the water does not come into contact with the uranium at all. In addition, the uranium is welded in zirconium tubes, so the fuel is completely separated from the external environment. Radiation is constantly measured everywhere.
* Does any radiation escape from the power plant?
Completely negligible, far below the level at which it could endanger anyone. This leads to absurd situations. When some time ago, wastewater from the Japanese Fukushima power plant was discharged into the ocean, thanks to the high sensitivity of the instruments, the radioactivity in it could be measured. There was less than the standard for baby water. And there was still a lot of hype around it.
* France currently produces about 75% of its energy from nuclear power, Germany 0%. What proportion of nuclear power would be reasonable for the Czech Republic? We have about 40% and it would like to increase significantly. It is good to see it every year in January and February, when we have the highest consumption. We would need three to six new reactors, especially if we want to give up coal.
* So get closer to France?
Yes, because thanks to nuclear power, it produces the least greenhouse gases in energy production. In Europe, it is a winner in this sense.
* So in connection with the Green Deal, can we expect a nuclear renaissance, despite Chernobyl?
Yes, and it is already happening. New nuclear power plants are being built in China today. I think we will succeed in Europe too, even if we are still making mistakes. A nuclear renaissance is on the horizon, for two reasons. The first was the Russian invasion of Ukraine four years ago, which raised the prices of oil and gas. Moreover, it has become clear that Europe does not want and cannot rely on Russian gas, even from a security perspective. The second reason is the ongoing crisis in the Iranian Strait of Hormuz, which has further increased oil prices. Incidentally, France realized this after the first oil crisis in 1973. It built so many nuclear power plants precisely to reduce its dependence on oil. Today, it has the cheapest electricity. Thanks to this, many French people heat their homes with electricity, which contributes to cleaner air.
* What was the impact of the Chernobyl accident on nuclear power?
It was also because of it that in 1992 the then Czechoslovak government decided to build Temelín with only two units. According to the original project, it was supposed to have four. But when you stop developing nuclear power, you have to get energy from elsewhere, which has serious consequences. In the Ústí nad Labem, Karlovy Vary and Ostrava regions, coal mining and its burning in power plants reduced the quality of life and life expectancy. The question is how much the slowdown in nuclear power contributed to this. How many deaths did it cause? It's a bad calculation, but we need to be aware of the principle.
* So do we miss the two unfinished Temelín units? Certainly, if only because if we had them today, we wouldn't have to burn so much coal thanks to ecologically clean nuclear energy. Europe is calling for decarbonization today and we would be in a better situation. Nuclear energy produces extremely few greenhouse gases in its life cycle and is better in this respect than, for example, solar power plants. With four Temelín units, we would also have a more stable and safer energy network, less dependent on Russia. We could export more nuclear electricity, which would result in a better environment throughout Europe. Coal would not have to be burned in Poland, for example.
* What did Chernobyl do elsewhere?
A number of countries renounced nuclear energy after the accident. Germany shut down its last three nuclear power plants in April 2023.
* German politicians are already saying today that this was a mistake.
Yes, because if nuclear power had continued to operate in Germany as a zero-emission technology, it would have saved greenhouse gases. German nuclear power plants produced about the same amount of energy as Czech coal-fired power plants. Their closure increased the environmental burden of energy production in other countries, which the Germans now have to import.
* So if Chernobyl had not happened, would we have cleaner and cheaper electricity in Europe today?
Wouldn't we be solving the problem of unreliable and expensive solar panels and windmills spreading all over the landscape? I don't think so. We would have renewable sources anyway. There would just be a larger share of nuclear and perhaps a smaller share of carbon-intensive sources, and the price would also be lower. Nuclear energy is technologically complex, so the state will always be involved in its operation. The decentralization of renewable sources would therefore come about in the same way. Today, it is also developing in France, which has a high share of nuclear power. Energy cannot be based solely on nuclear power; wind turbines and solar panels also have a place in the so-called energy mix. It is a reasonable combination, and it would have come about even without Chernobyl. But the accident was also good for something, even if it is said incorrectly.
* For what?
It was reflected in the increase in safety requirements for nuclear power plants. The shock from Chernobyl led to a significant improvement in many things. People only learn when something bad happens. The shock from Chernobyl led to a significant improvement in many things. People only learn when something bad happens.