Risks to Ukraine’s Nuclear Power Plants Are Small—but Not Zero

On Thursday, invading Russian forces seized the Chernobyl nuclear plant in northern Ukraine near the Belarus border. The site of the infamous meltdown in the spring of 1986 is the scene of an ongoing environmental crisis. Soil and water remains poisoned by radioactive contaminants, and nuclear material is still being cleaned up inside a containment structure built over the remains of a damaged reactor. But as the fighting continues, there are perhaps bigger nuclear risks emanating from Ukraine: the many active reactors spread elsewhere across the country.

Ukraine’s aging power plants, packed with reactors, cooling systems, turbines, and other key components, require careful maintenance and monitoring that can be disrupted during wartime. They also risk being damaged by a stray missile or artillery shell, especially if the invasion drags on. While experts believe the Russian military would not deliberately target a nuclear plant, a potentially disastrous mistake—one that could harm millions of Ukranians and also neighboring Russians—is not impossible.

“That’s certainly something I would think the Russians would make an effort to avoid doing, not only because they don’t want to contaminate the country they’re trying to occupy—but, also, Ukraine needs electricity from those plants,” says Ed Lyman, Senior Global Security Scientist at the Union of Concerned Scientists and co-author of the book Fukushima: The Story of a Nuclear Disaster.

Rafael Mariano Grossi, the director general of the International Atomic Energy Agency, urged “maximum restraint” on Friday to avoid jeopardizing the safety of Ukraine’s nuclear plants. The agency is “gravely concerned” by the unprecedented situation of a large conflict occurring in such close proximity to reactors, according to their statement.

Ukraine has one of the world’s largest nuclear fleets, with four power plants and 15 reactors that produce about half of the country’s power. The massive 6-reactor Zaporizhzhya plant in the southeastern part of Ukraine lies just 120 miles from the Donbas region, where the government has been in conflict with Russia-backed separatists since 2014. Energoatom, the utility that runs Ukraine’s nuclear reactors, announced in a statement on Friday that two of those six reactors had been powered down, disconnected from the grid, and put in “reserve.” So far, all are reportedly operating normally.

For nuclear experts, the primary concern is not that missiles are likely to rain down on a nuclear facility, but instead involves the basics of keeping reactors running with adequate staff and safety protocols in the middle of a warzone. Power plants themselves need electricity, and an exploding missile could inadvertently trigger a power outage. Or, a cyberattack on the electricity grid could cause one. And if backup generators fail for any reason, that could disrupt a reactor’s cooling system, leading to a meltdown. That’s when the heat produced by the core of a reactor begins to exceed its ability to be cooled. The temperature rises uncontrollably, and eventually, components start to melt, leading to the release of radioactive fuel, and possibly fires or explosions.

Those risks could be compounded by staffing problems as the situation in the country grows more chaotic. “Let’s say all the staff say, ‘This is it, we’ve got to get out of here, I’m taking my family to Poland.’ How do you operate the reactor at that point?” asks M.V. Ramana, a nuclear policy expert at the University of British Columbia. (At Chernobyl, the Ukrainian government has accused the Russian military of “detaining” staff who are monitoring the waste site.)


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