By Ramin Skibba, Gregory Barber
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 remain 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 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 coauthor of the book Fukushima: The Story of a Nuclear Disaster.
The Chernobyl plant, known as a “first-generation” reactor, used graphite as a “moderator,” to slow neutrons down and facilitate fission chain reactions. But graphite burns, and when the graphite began to smolder, it helped spread radioactive material into the air. After the catastrophe, that design was phased out worldwide. Now, in the Ukraine and elsewhere, most nuclear plants have “pressurized water reactors,” which use water rather than graphite. But while the newer water reactors are safer, risks remain if plant operators can’t keep the coolant system going, since water heated by the fuel rods needs to be replaced by cool water.
“If the cooling system doesn’t work, that is a prescription for disaster,” says Bob Rosner, a physicist at the University of Chicago and former chair of the Bulletin of the Atomic Scientists’ Science and Security Board. He recalls the 2011 Fukushima Daiichi disaster in Japan, when the reactors there were cut off from the electric grid by a 9.0-magnitude earthquake offshore. Then the subsequent tsunami knocked out emergency diesel generators. Some backup battery power remained, but eventually that ran out too. With the reactors no longer able to run their coolant pumps, much of the uncovered nuclear fuel then melted.
It doesn’t help that Ukraine’s nuclear plants are getting old, Rosner says. Most were built in the 1980s, dating back to the Soviet era; the only reactors the country has closed are Chernobyl’s. In particular, the Rivne reactors northwest of Kyiv are close to or past the typical 40-year age limit. (In the US, plant operators can often get their license extended for another 20 years, following inspections and any necessary maintenance.) When considering a plant’s safety risks, the critical thing to pay attention to is a reactor’s containment vessel, which contains the nuclear fuel. That’s usually made of steel, but after many years of neutron bombardment, the steel becomes brittle and can crack. Older reactors, like most of those in Ukraine, need constant surveillance for that reason, Rosner says.
According to the State Nuclear Regulatory Inspectorate of Ukraine, on Friday, new readings from the automated radiation monitoring system in the Chernobyl area detected higher gamma ray radiation measurements than normal, up to 9.46 microsieverts per hour. The gamma rays could be the emissions from radioactive materials, Rosner says. They may have been caused by heavy military vehicles stirring up contaminated soil, according to the IAEA statement released Friday. Still, agency officials wrote in their statement, the radiation levels “are low and remain within the operational range measured in the Exclusion Zone since it was established, and therefore do not pose any danger to the public.” In contrast, the SNRI statement says that “control levels of gamma radiation dose rate in the Exclusion zone were exceeded.”
Ukraine faces plenty of nuclear risks even if Russia never deploys nuclear weapons, as Vladimir Putin has threatened. “What’s going on horrifies me,” Rosner says. “I’m not so worried about the reactors; I worry about the people, the Ukrainians.”