How will Ukraine’s nuclear power plants be managed safely amid war?

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Russia’s invasion of Ukraine presents an unprecedented challenge for the country’s electrical utilities: How to maintain safety of its 15 operating reactors amid the chaos of war.

“We’ve never had a situation where we’ve had an invading army in a country that has so many operating reactors,” said Bennett Ramberg, author of a Cold War-era book that examined nuclear power plants as potential military targets. In a commentary published earlier this month, he cautioned that if attacked, Ukraine’s facilities could become “radiological mines.”

“There are multiple modalities, in a war setting particularly, whereby your reactor could be disrupted, and you can have the core melt,” he told The Globe and Mail in an interview.

On Sunday, the International Atomic Energy Agency (IAEA) said it had been informed by Ukraine that missiles struck a radioactive-waste disposal site in Kyiv overnight, “but there were no reports of damage to the buildings or any indications of a radioactive release.” The IAEA also said it had been informed that an electrical transformer at another disposal facility near Kharkiv had been damaged, again with no reported radioactive releases.

Neither facility contained high-level radioactive waste, the IAEA added, although the waste could “still cause a serious radiological impact event.”

“These two incidents highlight the very real risk that facilities with radioactive material will suffer damage during the conflict, with potentially severe consequences for human health and the environment,” said Rafael Mariano Grossi, the IAEA’s director-general, who has issued repeated calls “for maximum restraint to avoid any action that could jeopardize plant safety” since the invasion began.

So far, there have been no reports of incidents at any of the country’s four operational plants. The State Nuclear Regulatory Inspectorate of Ukraine issues daily status updates: the latest, published Saturday, stated as usual that “there are no violations of [nuclear power plant] safe-operation limits and conditions” and that the “radioactive situation meets established norms.”

Energoatom, the company which operates the plants, said in a statement Sunday that there were enemy movements near some plants, presenting a high risk of shelling, but that the plants continued to operate safely.

Ukraine’s Zaporizhzhya, Rivne, Khmelnitsky and South Ukrainian stations collectively generate more than half of Ukraine’s electricity, according to the International Energy Agency. (Only France and Slovakia generate greater percentages of their electricity using nuclear power.) Russian forces reportedly seized control of the defunct Chernobyl plant, site of history’s worst nuclear disaster in 1986, on Thursday.

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Though divided on the probability of a major incident at one of Ukraine’s plants, Mr. Ramberg and other sources contacted by The Globe agreed on one key point: All deemed it exceedingly unlikely that Russian forces would deliberately target or sabotage one of Ukraine’s nuclear facilities.

Power plants have been targeted in past conflicts, sometimes to hamper military operations or impede war production, or else to damage civilian morale. But when nuclear facilities have been attacked, typically they were still under construction. Were one of Ukraine’s operating reactors to be bombed, Russia itself might well receive wind-borne radioactive debris.

But “stuff happens in war,” Mr. Ramberg added, raising the possibility of inadvertent damage.

According to a January report by The New York Times, at the height of the war against the Islamic State in Syria, in March, 2017, members of a U.S. special-operations unit bombed a large dam on the Euphrates River. The dam was on a “no-strike” list. (The Times reported that a U.S. BLU-109 “bunker buster” subsequently found at the site had failed to explode, but could have caused the dam to fail had it detonated.)

Mr. Ramberg noted also that during North Atlantic Treaty Organization bombing of Yugoslavia in 1999, the U.S. accidentally bombed China’s embassy in Belgrade.

“It’s an illustration of what happens when people do really stupid things,” he said.

Ed Lyman, an expert on nuclear-power safety and security at the Union of Concerned Scientists, also saw no motive for Russian forces to damage any part of the electricity system if they intend to occupy the country. He added, however, that should Ukrainian and Russian forces clash over control of nuclear facilities, inadvertent damage could result.

Sunil Nijhawan, a retired reactor safety expert, said the risk of a major incident at one of Ukraine’s plants during the invasion is low. Ukraine’s Russian-built reactors feature robust, thick concrete containment, backup power generators and other safeguards.

“The worst that would happen is that a reactor will trip,” he said, referring to a situation where a reactor automatically shuts down because of changed conditions. “And there are so many built-in systems there to keep it safe. There would have to be multiple other failures” for a serious incident to occur.

“I personally don’t think there’s an issue there.”

Nuclear power plants typically feature on-site water pools where spent fuel is stored. Mycle Schneider, a Paris-based nuclear consultant, said these pools represent large concentrations of radioactive material. They require water to be circulated constantly and added to periodically, otherwise the water will eventually boil off. Without cooling, the fuel could catch fire, resulting in severe radioactive releases into the atmosphere. Such a situation would typically take several days to develop, however.

“To me, spent-fuel fires are the most dangerous events,” he said.

As the invasion unfolds, it’s unclear how much staffing Ukraine’s plants will require to maintain safe operations. James Acton, a co-director of nuclear policy with the Carnegie Endowment for International Peace, wrote in a commentary Thursday that travelling to work may be dangerous for power-plant workers, which could compromise safe operations.

“Generally in emergencies, [nuclear power plants] can operate on skeleton crews,” Mr. Lyman said. “I can think of situations in the U.S. where plants have been flooded, cut off actually, the operators can’t get back and forth easily. So in emergency situations, they function. But longer term, it would likely be a concern.”

On Friday, Ukraine’s nuclear regulator reported elevated levels of gamma radiation within the Chernobyl Exclusion Zone. It attributed that to large numbers of heavy machinery moving through the area, disturbing soil. The IAEA said the readings “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.”

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