Nuclear Energy Brinkmanship in Ukraine

A battle of nerves and steel is raging at Europe's largest nuclear power plant, which Russia captured in March. Russian forces use the Zaporizhzhia plant as a safe haven for troops and equipment, including artillery that is shelling Ukrainian-held territory directly across the Dnipro River. Ukraine is launching a counteroffensive to retake occupied territory, including Zaporizhzhia. And, all the while, each blames the other as explosions rock the nuclear site.

According to a Reuters report today, Russia's Defense Department may order the plant to shut down, citing shelling damage to the plant's back-up support systems." Yesterday most plant workers were allegedly told not to come to work tomorrow, according to Ukranian intelligence, which warns the Russians may be planning a dangerous provocation."

The ongoing confrontation risks widespread death and contamination-including to the fertile Ukrainian breadbasket that helped feed the world until Russia's invasion. In a simulated fallout map produced by Ukraine's national weather service and posted Sunday, a radiation plume spreads northwest and reaches Poland and Lithuania within 72 hours.

In Ukraine, which endured the 1986 Chernobyl accident, fear of another nuclear disaster is fueling a debate over Zaporizhzhia's continued operation amidst the mayhem. Nikolai Steinberg, a former chief engineer at Chernobyl and member of the International Atomic Energy Agency's governing board, called running the plant a crime" in an email interview with IEEE Spectrum. That's because stopping would cool off the operating reactors, buying the beleaguered operators time to avert nuclear meltdowns if, say, shelling sparks a station-wide blackout.

Backers of Steinberg's position are urging Ukraine's nuclear regulatory agency to order a shutdown. (To date, plant operators have continued to respond to orders from Ukraine's grid operator.) But Ukraine's Ministry of Energy and nuclear power firm Energoatom say a broader risk calculus supports keeping the plant running. As Energoatom stated in June: Disconnection is impossible from a technical, security, economic, or political point of view." Factors cited to justify operation include the possibility that cooling the plant will make it easier for Russia to transfer its generation to its own grid, and the need for power exports to Europe that deliver revenue and political support.

Last month, Energoatom increased generation at Zaporizhzhia by ordering plant staff, working under Russian supervision, to start up a third reactor for the first time since the plant's 4 March capture. At the time the Minister of Energy was pushing Europe's grid regulators to rapidly expand capacity limits for Ukrainian electricity exports.

We are in a nightmare," is how Jan Haverkamp, a nuclear safety expert with Greenpeace International, described the quandary facing Ukraine and the world in an email to IEEE Spectrum. Haverkamp and other Western experts say ceasing power generation would be the wisest thing to do" under normal circumstances. Of course, adds Haverkamp, there's nothing normal about Zaporizhzhia's situation.

Nuclear Roulette

The debate over operating Zaporizhzhia boiled over when artillery shells started hitting the plant site late last month. Which side is responsible for that shelling remains contested, though Western security experts argue that Russia has more incentives to risk an accident. Equipment damaged in the attacks include:

• radiation sensors monitoring spent fuel;
• an air-separation unit that makes hydrogen gas used to cool the plant's turbine generators; and
• a substation connecting Zaporizhzhia to 750-kilovolt transmission lines.

The 5 August substation blast prompted one of Zaporizhzhia's three operating units to automatically shut down. It also left the plant with just one grid connection, compared with 7 preinvasion connections. That jeopardizes the entire plant, which uses grid power to cool all six of its reactors and spent fuel pools. Energoatom CEO Petro Kotin said it put Zaporizhzhia very close" to the situation that produced the 2011 Fukushima meltdowns.

Batteries and diesel backup generators are designed to power the plant's cooling systems for 10 days. But Haverkamp says an emergency situation or even meltdown" is possible well before then. Alleged corruption before Russia's invasion raises doubts about the reliability of Zaporizhzhia's backup systems. Haverkamp also cites the plant's exhausted and decimated" Ukrainian staff, and the possibility of a power struggle with their Russian occupiers over how to manage an emergency.

Ukraine's state nuclear-safety center projects that Zaporizhzhia's operating units could experience reactor damage in as little as 3 hours without power, according to a May 2022 assessment revealed last week by Kyiv-based MIND. Horrific consequences could follow. The agency that manages the Chernobyl Exclusion Zone projected last week that shells or rockets hitting Zaporizhzhia might unleash an accident 10 times worse than Chernobyl's. The agency stated that radioactive emissions could kill tens of thousands of people, displace 2 million, pollute an area three times the size of Ukraine, and create a long-term exclusion zone as large as 30,000 square kilometers.

Olena Pareniuk, a senior nuclear safety expert at Ukraine's National Academy of Sciences, told Ukrainian Radio last week that Zaporizhzhia could yield the world's first magnitude-8 nuclear accident. Chernobyl and Fukushima were sevens.

Hence, the call to suspend power generation. According to the state nuclear-safety center's expert assessment, reviewed by Spectrum, moving all reactors to a cold stop" would extend the delay between full power loss and core damage from 3 hours to 27 hours. Stifling the nuclear reactions that produce energy would allow short-lived fission products in the reactors to dissipate, reducing the harm caused by radioactive emissions. The overall risk would decrease," says Ed Lyman, director of nuclear power safety at the Union of Concerned Scientists. He says proactive shutdown makes sense, just as nuclear plants in the United States do when hurricanes head their way.

The agency stated that radioactive emissions could kill tens of thousands of people, displace 2 million, pollute an area three times the size of Ukraine, and create a long-term exclusion zone as large as 30,000 square kilometers.

Reports suggest that Ukraine's nuclear regulator may be moving toward ordering a cold stop during the occupation, heeding counsel from the agency's advisory board. On 4 August, the board recommended a cold stop requirement for two of the plant's four off-line units whose turbine halls appear to be occupied by Russian weapons.

However, at least one member of the board, state nuclear-safety-center representative Viktor Shenderovych, proposed stopping all six units. That call is supported by Georgiy Balakan, a former special advisory to the president of Energoatom, who worked with two independent groups of Ukrainian experts to fashion the world's first industry-grade risk assessments of nuclear power operation under hostilities.

The independent calculations were performed using standard industry codes and Energoatom's probabilistic risk models of Zaporizhzhia, developed with participation of U.S. national laboratories. And they look at risk across the site rather than just individual units, so they can spot larger accidents that happen when one event disrupts multiple systems. The analyses, reviewed in a recent LinkedIn post, project that common-cause" failures from military action significantly increase the probability of reactor core damage when multiple units are operating.

Demilitarizing Zaporizhzhia

In a 16 August statement to Spectrum, Energoatom CEO Petro Kotin rejected calls to stop nuclear generation, arguing that they play into Russia's hands.

Kotin claims that stopping Zaporizhzhia's internal power generation may cause an emergency" by making it more reliant on off-site power. But his primary argument is that a shutdown would facilitate Russia's apparent plans to permanently annex the plant, along with the rest of occupied southeastern Ukraine. He notes that Russian state nuclear power giant Rosatom has acknowledged that it has staff at the plant, saying they provide technical, consulting, communications, and other assistance." Sergey Kiriyenko, the Kremlin's point man for Russian-occupied Ukraine, led Rosatom from 2005 to 2016.

Ukraine was connected to Russia's grid until the invasion, when it disconnected and quickly synchronized instead with Europe's grid. But Crimea, occupied since 2014, remains on the Russian grid. Kotin claims that shutdown is a prerequisite for switching Zaporizhzhia (and the intervening southeastern lines to Crimea) back to Russia's grid.

A Ukrainian expert contacted by Spectrum counters that claim, however. He states that if Zaporizhzhia keeps running it can power its own systems while the regional grid is realigned. It creates some risk, but Russia's forces have proven their willingness to endanger lives for months.

Ukrainian President Volodymyr Zelenskyy says only restoration of full Ukrainian control can guarantee its safety. He has also called for new sanctions against Russia that target Rosatom, which remains largely unscathed. Last week 42 nations including the United States, Canada, Turkey, and most European states endorsed Zelenskyy's call for Russia to immediately withdraw from the Zaporizhzhia plant. Not surprisingly, Russia rejected that call. Its Security Council representative explained that Russian forces must stay to protect against provocations and terrorist attacks."

Nuclear safety experts such as Haverkamp at Greenpeace International endorse United Nations secretary general Antonio Guterres's proposed solution: Russian withdrawal coupled with creation of a demilitarized zone around the plant. The problem is finding a neutral international body to take charge. The most obvious choice, the International Atomic Energy Agency, is viewed with suspicion by Ukraine. Many IAEA staffers spent their careers at Rosatom, including the agency's deputy director.

Haverkamp is sympathetic: I am not really sure whether the IAEA can deliver that, as locked in [as] they are with Rosatom and Russia."