Is a second Chernobyl possible? And what are people doing at that NPP now? A scientist answers important questions
"If you put cabbage and onions next to a pot, you won't get soup. It's the same with Chernobyl." We talked to scientist Yana Karslyan about everything you might not have understood about Chernobyl 40 years after the catastrophe.
Entrance to the Polessky State Radiation-Ecological Reserve — the Belarusian exclusion zone.
Why the remains of the exploded power unit were not simply encased in concrete and how people work there
Currently, the remains of the fourth power unit of the Chernobyl NPP, destroyed after the accident, are covered by a huge metal structure — the New Safe Confinement, or, as it is also called, the "Arch". It has been operational since 2019.
Why was more than 2 billion dollars spent on it? Why not just encase everything in concrete?
Yana explains:
“The fact that the power unit is destroyed does not mean that it can simply be covered with concrete – it needs control. In general, radioactive materials cannot be forgotten, because they constantly emit heat, radiation, and react to external factors such as humidity.”
The main component of concrete is water, which is a neutron moderator, meaning it slows down neutrons, which in turn helps them split uranium more efficiently. In such a case, the probability of a spontaneous chain reaction can increase.
“Also, we don't have materials that would be very cheap, so that everything could be poured in there and forgotten. Such materials must maintain stability for a long time in those extreme conditions, have good thermal conductivity, and not affect nuclear reactions.
The smoldering reactions under the sarcophagus cannot be stopped; they can only be controlled. This is what the current system helps with,” says Yana. This refers to the "Arch" being equipped with sensors to monitor the situation.
Yana Karslyan. Photo: "Shtodzian"
It might be surprising that people still work at the station. Is it really safe there?
"Compared to how it was before — yes, it's safe. Compared to a hypothetical remote island in Hawaii — no, because the radiation background at the station is still slightly elevated. In the resettlement zones, norms apply so that the annual radiation dose is less than 1 mSv per year, which is close to what people can get from natural background radiation somewhere high in the mountains, but still on the higher side of the norm."
Yana talks about the ALARA principle, which stands for "As Low As Reasonably Achievable" — meaning the lower the radiation level, the better, but within reasonable limits. Scientists do not strive to minimize the received radiation level if it requires too much human or financial resources. And if this principle is adhered to, one can speak of safety.
"If you put cabbage and onions next to a pot, you won't get soup. It's the same with Chernobyl"
What are people doing at the station now? Yana says that the "Arch" requires monitoring for safety, and this cannot be done without people. Work is underway to attract robots for such tasks, but the technology for this is still imperfect.
The scientist reflects: if she herself needed to go to the Chernobyl NPP for work, she would not be afraid, because the situation there is stable. But by the same ALARA principle, such trips are best avoided if the trip does not bring public benefit.
Due to Russian shelling, the Chernobyl NPP periodically loses electricity. What if the station is without electricity for a longer time? And what if there are no employees left there?
“This will not be a catastrophe or a second Chernobyl, but there will be another risk. Due to all those smoldering reactions, heat is constantly emitted there, and it needs to be removed. If this is not done, the movement of radioactive dust, which is the main problem there, can intensify.
View of the New Safe Confinement from Belarus.
You can't do anything with radioactive materials; those new isotopes we created there simply need to be left untouched and monitored so that they don't move on their own. Small migrations, i.e., particle movement within the zone, and small local increases in background radiation might occur, but this is a problem of local scale,” says Yana.
With the start of the full-scale war, another question arose. The territory around the station comes under shelling, and in February 2025, a Russian drone hit the "Arch". A fire started under the sarcophagus roof.
However, as they say at the Chernobyl NPP, the sarcophagus did not lose its functions. And Yana confirms that such incidents are not the worst thing:
“Such damage, of course, would be a problem, but it is not a second Chernobyl. The confinement itself would suffer, but the dust would not fly far and in all directions from it.”
And can the events of April 1986 be repeated at the station? Yana is confident that no:
“A new explosion is impossible. In 1986, an explosion occurred because people were conducting an experiment to check which conditions for the station's operation were safe, and they performed many specific actions for this purpose. It is not that simple to make an uncontrolled chain reaction probable.
If you put cabbage and onions next to a pot, you won't get soup on its own. It's the same with Chernobyl. For an explosion of the same scale as in 1986 to happen, a lot needs to be done.”
What dangerous isotopes remain
In recent years, much has been said about the danger of Americium-241. This is a radioactive isotope that forms through the decay of Plutonium-241 and is now accumulating in contaminated lands.
Yana explains that Americium-241 is an alpha emitter. Of the three types of radiation (alpha, beta, and gamma particles), alpha radiation causes the most damage if it gets inside. But at the same time, it is the easiest to protect against: while gamma rays partially pass through concrete, alpha particles can be stopped by a sheet of paper.
The amount of Americium, Yana says, is indeed increasing, but there is a nuance:
“This is not the only long-lived dangerous isotope there. And Americium is still an alpha-emitter, which does not pose a great threat if it is under the sarcophagus, because alpha particles do not pass through the sarcophagus.”
Building in the exclusion zone.
And yet a local catastrophe is still possible:
“There will be terrible trouble if the confinement collapses and alpha particles get out. But in such a terrible scenario, we will not worry about some specific isotope, because there are many dangerous isotopes there. And to destroy the confinement, a great force is needed, which in itself will be a problem.”
Americium is not cesium or strontium, which are easily incorporated into the body because they are natural. Americium is not natural; it is an element that people themselves created in reactors, and from an evolutionary point of view, this happened relatively recently. Therefore, nature does not know how to move it quickly through food chains; it is quite immobile, and its atomic nuclei are large themselves. If it enters a person, it stays there for a long time.”
The main problematic isotopes now and in the near future are Cesium-137 and Strontium-90. They also have high biological mobility because they are natural.
Americium-241 is not an isotope that easily spreads in the environment. But there is one dangerous exception – radioactive dust. If there is a fire in the contaminated zone or if there is drought and wind lifts dust into the air, those same alpha particles of Americium can be carried. People can inhale such dust and, as a result, carry Americium directly into their lungs.
Forget about Chernobyl? In 10 thousand years
The scientist believes that today we lack open data on the consequences of the Chernobyl NPP accident — there is little statistics and independent monitoring, but a lot of speculation.
"Chernobyl Way" in Vilnius, 2023.
What awaits the contaminated lands in the future? Yana speculates that humanity will only be able to completely put the Chernobyl accident in the past in 10 thousand years, when the half-life of plutonium passes, and the activity of other dangerous isotopes equals the natural radiation background. But the background in the contaminated zone will significantly improve in 300 years, as the half-life of Strontium-90 and Cesium-137 will occur.
The Belarusian zone, the Polessky State Radiation-Ecological Reserve, will not turn into a tourist paradise for a long time:
“This will be a zone that everyone will avoid. In my opinion, there is no need for tours there, and there is a risk in those trips, and these are not scare stories about cancer or death. It’s just that the body will receive an additional load due to the increased radiation background, and a person will need time to recover,” says Yana.
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