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In Ukraine, there’s no second Chernobyl disaster in the making — not yet

While there are reasons for concern, there is no need for panic.

An abandoned Ferris wheel in the ghost town of Pripyat, Ukraine, near the Chernobyl nuclear plant, on April 15, 2021.Efrem Lukatsky/Associated Press

As the battle for Ukraine enters its third week, the specter of Chernobyl, site of the world’s worst nuclear accident, returns to haunt us. A few hours after the Russian invasion started, early on Feb. 24, the Russian military occupied the Chernobyl exclusion zone, some 30 kilometers in radius, that houses the decommissioned power plant, nuclear fuel storage, and nuclear waste facilities. On March 9, Ukraine’s nuclear regulator informed the International Atomic Energy Agency that the Chernobyl power plant lost electricity and that the safe operation of the plant’s cooling system was in danger.

How high is the risk of another major nuclear accident under the circumstances? While there are reasons for concern, there is no need for panic.


The Chernobyl Nuclear Power Plant once operated four nuclear reactors. One of them became the site of the infamous nuclear accident in April 1986, when, due to a faulty reactor design and operator error, the reactor core melted down, causing explosions and sending radioactive plumes into the atmosphere for the winds to carry as far away as Scotland. The other three reactors were shut down in stages, with the last one taken offline in 2000. The spent nuclear fuel from the Chernobyl reactors, contained in more than 20,000 assemblies, has since been stored in special pools that require a constant circulation of cold water to keep the fuel from overheating.

The supply of water depends on the functioning of pumps, which in turn depend on electricity. When the main power supply goes out, there are backup diesel-powered generators. Those have now kicked in at Chernobyl, although the Ukrainian authorities said on Wednesday there was enough fuel for only 48 hours. Once that supply of power is no longer available, however, catastrophe is not imminent.


The Chernobyl fuel rods have been cooling for over 20 years and no longer generate the kind of energy that fresh reactor fuel would. So while, after some time, the water in the pool would heat up and evaporate, and after some more time the fuel would reach a high enough temperature to begin melting down, risking a radioactive release, this would take weeks, not hours or days. This time cushion should give staff the opportunity to refill the pools with water, even if from a firehose.

Of greater concern is the safe and secure operation of Ukraine’s functioning power plants, like the one at Zaporizhzhia, the largest in Europe, which has been shelled and has been occupied by Russian troops since March 5. The reactor cores and the spent fuel there are fresher and more volatile, which means the damage to the cooling system at that plant would be more dangerous. But the risks go beyond mere physics.

The safety and security systems of nuclear power plants and spent fuel facilities, robust though they are, were not designed with a full-scale and protracted war in mind. The personnel at the Chernobyl and Zaporizhzhia power plants have been effectively captives of the Russian military. They are operating under duress, worried about their lives and the lives of their families, all the while reporting to people who, it is safe to assume, know nothing about the safe operation of a nuclear facility. Even basic repairs or access to the necessary relief might become impossible due to the intense fighting surrounding the power plants.


In short, the attack on and capture of a civilian nuclear facility is unprecedented. It is a situation of crisis management, not preparedness. Beyond the compromised security of nuclear power plants in Ukraine, Russia’s actions dealt a profound blow to international nuclear governance. Moscow was one of the founders and most influential members of the IAEA, which is among the oldest and most revered international organizations ever established. The IAEA’s mandate is to promote safe and secure applications of peaceful nuclear energy and ensure that the peaceful atom is not diverted to military purposes.

Essentially, a major nuclear power and a stakeholder in the international nuclear order, the Russian Federation, has gone rogue, glibly breaking the rules it was once part of creating. It is a world none of us want to live in.

Mariana Budjeryn is a research associate with the Project on Managing the Atom at the Harvard Kennedy School Belfer Center. Her book “Inheriting the Bomb: The Collapse of the USSR and the Nuclear Disarmament of Ukraine” will be published later this year.