How the Russians could make Chornobyl deadly again
Beneath a popular escape outside Kyiv rests Chornobyl-era radioactive sediments, raising fears that war could turn a hidden risk into a wider disaster.
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By JLP
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KYIV, Ukraine — Yana Antoniuk comes to the Kyiv Sea to relax several times each summer. She celebrated her graduation, birthdays, and bachelorette party here.
The Kyiv Sea has become her substitute for the real sea, since she hasn’t left the Kyiv region during the war.
Locals call the Kyiv Reservoir the ‘Kyiv Sea’ — it’s so vast that when you stand on one shore, you can’t see the other.
This seemingly peaceful spot hides a significant danger at the bottom.
The Kyiv Reservoir is part of the Dnipro River cascade, a water source for millions of people, and an ecosystem that stretches to the Black Sea across several countries. On April 26, 1986, 40 years ago, an explosion occurred at the Chornobyl Nuclear Power Plant.
After the reactor explosion, radioactive dust and particles rose into the air and were carried hundreds of kilometers away. What settled over the water fell into rivers and ended up in the Dnipro River cascade. The Pripyat River, which flows through the exclusion zone, carried the contamination directly into the Kyiv Reservoir. There, the particles settled to the bottom and remained there.
Official sources say there is no cause for concern as long as the sediment remains at the bottom. The main thing is to not disturb it.
But the war poses a particular threat to the stability of radioactive sediments.
For example, in 2024, Russia struck the Vyshhorod Hydroelectric Power Plant — the dam that directly holds back this reservoir.
If the dam of the Kyiv Reservoir collapses, radioactive particles will enter the water system and carry dangerous contaminants downstream along the Dnipro River, increasing the radiation risk to plants, animals, and millions of people.
Yana was born in Kyiv into a well-off family. Every summer, she and her family would go on vacation to Crimea and Odesa, in southern Ukraine. Not all Ukrainians had the opportunity to visit these resort areas, and many of them never got to see Crimea before its annexation.
Yana enjoyed sitting on the shore of the Black Sea, watching the sun set, and feeling the water tickle her heels. It felt like she owned the world during those peaceful moments.
The war cut Yana off from her favorite places along the Black Sea coast. After 2013, she never returned to Crimea, leaving behind places dear to her heart and countless friends. After 2022, she stopped traveling even to Odesa.
“I’m a very anxious person. I’m afraid of explosions, and it’s much easier for me to cope with things like that in the familiar surroundings of my home,” Yana said.
Yana’s desire for quiet getaways close to water never went away, though. As an accountant, she finds work exhausting. When she has the chance to take a few extra days off or a vacation, she gives her brain a break from the digital noise.
“I usually don’t even leave Kyiv; I go to the beaches here. But if I do manage to get away, the Kyiv Sea is truly the best place,” Yana said.
Yana had never wondered what lay hidden at the bottom of the Kyiv Reservoir.
The Chornobyl Nuclear Power Plant explosion, 40 years ago tomorrow, was the worst nuclear disaster in human history. A cloud of radioactive particles was released into the atmosphere, covering a significant part of Europe.
What settled in the water, rivers, and soil remains there to this day. The same applies to the Kyiv Reservoir, located just 80 miles from Chornobyl.
The IAEA recommends leaving the contaminated sediments undisturbed; keeping them in place is the only barrier between the accumulated radioactivity and the water used by millions of people downstream. This strategy holds until the first major disturbance: a flood, a prolonged drought, dredging, or something worse.
In other words, sediments that were lying at the bottom rise to the surface and dry out. Radioactive dust could then rise into the air, be washed into the water by rain, or seep into the soil. What was previously trapped underwater becomes accessible to the environment.
Professor Timothy Mousseau, who spent more than 25 years studying Chornobyl and the effects of radiation on biological organisms, lives thousands of kilometers away from this shore, but he has been thinking about exactly these kinds of risks for decades. Yana lives right nearby and knows almost nothing about them.
Even before the full-scale invasion, there were attempts to clean up the Kyiv Reservoir, not to improve the security of the area, but to ensure navigability.
Back then, an independent study by the French organization ACRO found that 28 million people downstream, who depend on the Dnipro for water and food, could face increased radiation risks if dredging continued. The work eventually stopped. But this precedent shows that even peaceful, planned intervention in these sediments is recognized by the international community as an unacceptable risk.
War introduces a far more violent kind of disturbance.
Mousseau and his team arrived in the exclusion zone in 2022, shortly after the area had been liberated by Ukrainian forces. He got a lab and house there, had equipment and ongoing studies. He believes that if you don’t show up regularly, nothing gets done.
“Many mines were laid underground throughout the area, including where we do our fieldwork. Being in this war zone was very scary, with the sirens going constantly and drones flying over,” Mousseau said.
And although Russian troops have physically withdrawn from the Chornobyl zone, they continue to pose a radiation threat to the Ukrainian population – if they attack the dam, it could be catastrophic.
Yana doesn’t really believe there’s much risk of a radiation threat, but just in case, she bought some iodine supplements to protect herself: “It won’t save me if they [the Russians] do decide to use nuclear weapons, but it makes me feel more at ease.”
Mousseau isn’t so optimistic.
“If the dam were destroyed or damaged, that would dramatically increase the water flow from the Chornobyl region, stir up the sediments, and have the possibility of moving these radioactive sediments closer to Kyiv,” Mousseau said.
The stronger and faster the current, the more contaminated silt it can transport hundreds of kilometers in a short time.
This is exactly how, after 1986, traces of cesium and strontium reached as far as the Black Sea — the river and the current did their job.
In 2023, a very similar incident had already occurred: two explosions destroyed the Kakhovka Dam — a three-kilometer-long hydraulic structure on the Dnipro River in southern Ukraine. Nearly 90 percent of the reservoir was emptied, and the flood destroyed entire towns, left hundreds of thousands of people without drinking water, and killed tens of thousands of tons of fish.
When the reservoir emptied, sediments containing 83,000 tons of heavy metals, including lead, cadmium, and nickel, accumulated over decades rose to the surface. At the time, scientists compared the consequences of the dam’s collapse to the 1986 Chornobyl nuclear disaster.
But in the end, the Kakhovka dam did not contain Chornobyl-level sediment. The Kyiv Reservoir, however, does.
“People make use of the river to irrigate agricultural fields, for drinking water, and to recharge aquifers. The potential for increased radioactivity in agricultural products — the wheat and other crops — is a concern,” Mousseau said.
Some of the radioactive particles will settle again, but in new places, far from the exclusion zone. Some will enter the soil, and from there, into plants, into animals, into food. Ultimately, they will end up in humans, causing a slow accumulation of radiation exposure. For years, this may not be noticeable.
When cesium enters the body, it is distributed throughout all soft tissues, particularly in the muscles. Strontium accumulates in the bones and teeth, where it remains for years. Both emit radiation from within constantly, at low levels.
Over time, it increases the risk of cancer — primarily thyroid cancer, leukemia, and bone marrow cancer — the same conditions that emerged following the Chornobyl nuclear disaster. Children face a higher risk than adults because their cells divide more rapidly. For pregnant women, there is a risk to the fetus.
At the moment, no one is claiming that a disaster is inevitable, but there is a critical lack of data and research.
“We have insufficient information. It has not been sufficiently studied,” Mousseau said.
“Unfortunately, we got used to risks. But you can never know too much and relax.”
Yana tries not to think about the potential dangers. She says that if there were a real danger here, people would have been warned.
Until then, she’ll keep going to the Kyiv Reservoir for her vacations, since there are no safer alternatives for her.
In fact, Yana will probably go there again this summer to relax.
The water will look just as calm as it always does.
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“Thank you for your work. I read every essay from the Counter Offensive. It is one of the few news sources that I subscribe to, that is because I find it to be a honest open dialogue about Ukraine and how Ukrainians are managing their new lives brought about by russia invading.”
By JLP
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NEWS OF THE DAY:
By Oleksandra Poda
Good morning to readers; Kyiv remains in Ukrainian hands.
UKRAINE AND RUSSIA EXCHANGED 193 WAR PRISONERS: On Friday, Ukraine and Russia carried out an exchange of prisoners of war. There were 193 soldiers from each side, some of whom were wounded. Zelenskyy stated that most had been illegally detained in Chechnya. The exchange also included the return of 1,200 unidentified bodies to Ukraine. The United States and the UAE acted as mediators.
Prisoner exchanges remain the only specific result of the negotiation process between Ukraine and Russia. This is the second exchange in April, following the ‘175-for-175’ exchange on April 11.
PRINCE HARRY TESTS AI DRONES FOR MINE CLEARANCE: The UK’s Prince Harry made a surprise visit to Kyiv and met with mine clearance teams near Bucha, a suburb of Kyiv, on Friday. Wearing a VR headset, he operated an AI drone to detect mines and tested robots designed to defuse them. At the Kyiv Security Forum, he urged Putin to stop, and said Washington must intensify its efforts to achieve peace.
23% of Ukraine’s territory is contaminated with mines. It is the most heavily mined country in Europe.
ZELENSKYY VISITS AZERBAIJAN FOR THE FIRST TIME SINCE 2022: On April 25, Zelensky arrived in Azerbaijan on his first visit to Baku since the start of the full-scale invasion.
Azerbaijan is a key energy partner for the EU as an alternative to Russian gas, but has a complicated relationship with Russia following the downing of the AZAL plane in 2024.
CAT OF CONFLICT:
Oleksandra’s daughter played chess with the cat. It looks like the cat won the game.
Stay safe out there.
Best,
Oleksandra
 | A guest post by
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When I was 10, I received a book on ecology and have been a keen environmentalist ever since. My father worked for the Atomic Energy Board in South Africa, so I learned about radioactive substances at a young age. Although my childhood was unconventional, I had many opportunities to learn about our world. I even learned a little about war, from the conflicts in Mozambique and Angola!
Great report! It never ceases to amaze me how most people don't understand the danger of nuclear fallout, or that it will continue to be dangerous for literally hundreds of years. That lady should stay as far away as she can get from that lake. One suggestion, perhaps you should have mentioned the radioactive half life of the radioactive materials there. The poor people of Pripyat had zero clue that they were living next to a death trap, and a most horrible one at that.