Ukraine’s Zaporizhzhia nuclear energy plant, the biggest in Europe, has provoked nervousness ever since Russian troops captured it barely two weeks into the 2022 invasion. However not too long ago, after three years of occupation and frequent close to misses that threatened radiological catastrophe, a promise of sunnier days abruptly popped into view, albeit briefly. In a 19 March name U.S. President Donald Trump and Ukrainian President Volodymyr Zelensky mentioned American safety and funding for Ukraine’s nuclear energy—and even possession, in response to a White Home abstract. Worldwide Atomic Power Company (IAEA) director Rafael Grossi upped the ante one week later, telling Reuters that Zaporizhzhia’s reactors may restart inside “months” of a ceasefireand the plant might be totally operational in a yr.
The promise of a speedy restart at Zaporizhzhia, which has six 950-megawatt reactors, shortly pale amid every day and lethal Russian assaults on Ukrainian cities. However the chief govt of EnergoatomUkraine’s nuclear energy utility, primarily endorsed Grossi’s timeline for a demilitarized state of affairs in an interview this monthat the same time as he acknowledged severe technical challenges together with deferred upkeep and a dearth of cooling water.
In reality, in response to Ukrainian, European and U.S.-based specialists interviewed by IEEE Spectrum, the challenges going through a Zaporizhzhia Nuclear Energy Plant (ZNPP) revival may go far deeper. These specialists say that Russia’s operation of the plant could have so badly broken it that repairs may take years and value billions of {dollars}. Explicit issues embrace potential tilting of the reactor buildings, and the integrity of the advanced and comparatively fragile steam turbines for the plant’s pressurized, light-water reactors.
Even when there’s a lasting cessation of hostilities, restarting ZNPP’s reactor-generator items could price greater than Ukraine is ready to spend. And at the least some Ukrainian vitality specialists say the nation ought to focus as a substitute on constructing smaller, decentralized energy crops.
Volodymyr Kudrytskyithe previous director of Ukraine’s energy grid operator, stated as a lot final month throughout a discussion board at MIT final month. Kudrytskyi stated huge nuclear energy crops focus an excessive amount of energy at just a few spots within the grid: “We’re ready to make use of this Soviet legacy to outlive, however this isn’t the best way ahead.”
Questionable Working Practices Might Have Broken the Plant
Since Russia’s full-scale invasion of Ukraine, ZNPP skilled a variety of unprecedented insults. Throughout its armed seizure in March 2022, Russian forces fired on the plant. That October, Russia started bombing the Ukrainian energy system. These assaults repeatedly disconnected ZNPP from Ukraine’s grid, forcing using diesel turbines to energy the pumps that flow into water over spent gas, maintaining it from overheating and doubtlessly melting down and releasing massive quantities of radiation.
Russia’s assaults have destroyed some gear and positioned pressure on others, however particular concern arises from unprecedented longterm working modes: sizzling shutdown and chilly shutdown.
ZNPP is the primary nuclear energy plant on the planet to persist in a situation of sizzling shutdown, by which the plant operates at minimal output. Sustained sizzling shutdown, for months on finish, violated ZNPP’s license. However Russian plant managers insisted that it supplied steam wanted to maintain important gear, such because the water therapy plant, in addition to heating for the close by metropolis of Enerhodar, additionally beneath Russian occupation.
Ukrainian and worldwide security specialists argued as a substitute that sizzling shutdown unnecessarily elevated the chance of an accident inflicting a regional disaster, since sizzling reactors soften down extra shortly after cooling techniques fail. Ukrainians noticed the improved danger as a type of nuclear blackmail, arguing that Russian forces may intentionally unleash a radiological incident in the event that they had been compelled to retreat from the realm.
In April 2024 the plant’s Russian administration lastly relented, putting the final working producing unit into chilly shutdown. Chilly shutdown is a safer mode for the plant, however, nonetheless, a number of facets of the chilly shutdown are extremely uncommon and are scary concern.
These considerations stem from a fancy mixture of chemistry and physics. Throughout chilly shutdown the cooling flows are low—almost stationary in some loops—and likewise comparatively cool, in some instances dropping under 35 °C.
The result’s a coolant with greater density. Ukrainian nuclear professional Georgiy Balakan says that high-density coolant places better mechanical load on the cooling pipes and the fragile tubes throughout the steam turbines. That elevated load, in flip, will increase pressure on the numerous welds, in addition to on the metal pipes themselves as a result of their metallic is much less ductile at decrease temperatures, in response to Balakan.
Low temperature and circulate, in the meantime, additionally affect boric acid that’s added to the first cooling water to control the reactor’s fission reactions, permitting boric acid to crystallize in delicate areas of the first circuit pipes and within the steam turbines. Efforts to purge crystals can then exacerbate harm. If the harm perforates the steam generator tubes, borated water can leak by way of and assault the secondary cooling circuits’ metal, which is of a decrease grade.
An workplace constructing on the Zaporizhzhia nuclear energy plant in southern Ukraine was photographed on 14 June, 2023, 15 months after the ability was captured by Russian troops. Olga Maltseva/AFP/Getty Photographs
Steam Leaks or Groundwater Extraction May Doom Plant
Russian officers controlling ZNPP have reported a sequence of leaks to IAEA observerstogether with steam generator leaks in half of its energy items. Balakan, a former particular advisor to the president of Energoatom, the Ukrainian nuclear utility, calls these telltale indicators of the bodily and chemical assault on the plant’s gear. “The Russians acted as if they might function the water-chemical regime for an infinite time,” he says.
Unbiased specialists contacted by IEEE Spectrum affirmed Balakan’s evaluation. They embrace a senior U.S. nuclear engineer acquainted with Soviet-design reactors, who spoke to Spectrum on situation of anonymity as a result of they feared retribution from nationwide authorities, and a Ukrainian engineer who isn’t licensed to talk to the press.
Steam-generator points can shutter a nuclear plant for good. That state of affairs performed out in California in 2013 when utility Southern California Edisonscrapped its solely nuclear energy plant after botched steam generator repairs that price almost $2 billion ($2.7 billion in 2025 {dollars}).
One other set of doubtless expensive points stem from the operators’ shift to groundwater for cooling following the demolition of the Kakhovka Dam in June 2023. Potential implications embrace impairment a important security system: the reactor management rods.
After the draining of the Kakhovka Reservoir eradicated ZNPP’s authentic supply of cooling water, Rosatomthe Russian nuclear technology and expertise conglomerate, drilled 11 wells on web site. Withdrawing of groundwater is trigger for concern, in response to Aybars Gürpinara former high security official on the Worldwide Atomic Power Company (IAEA). “Particularly when there may be vital floor water extraction, settlement is at all times a chance,” wrote Gürpinar, now a guide based mostly in Vienna and Brussels, in an e-mail to Spectrum.
Subsidence has prompted a number of costly complications for Soviet-designed VVER-1000 reactors, together with ZNPP’s. Practically 20 years in the past Energoatom needed to connect counterweights to arrest tilting of a number of reactor buildings settling into the positioning’s sandy soil, in response to a 2024 LinkedIn put up by Balakan. In 2011, Rosatom instructed then-President Dmitry Medvedev it had plans to repair the “progressing tilt” on the Balakovo and Kalinin energy crops.
Gürpinar says tilting may crack ZNPP’s concrete base and intervene with reactor management rods, slowing their gravity-driven drop into the reactor to squelch fission reactions throughout station blackouts. He says the rods may even get “caught,” forcing operators to depend on boric acid to manage the reactor and leaving them with out backup management.
In a press release to Spectrum, Rosatom asserted that: “No floor degree modifications or indicators of subsidence have been noticed.”
Restarting the Reactors Would Require Fixing A number of Issues
Addressing structural harm is just one of many challenges to soundly restarting ZNPP’s reactors. Final month, ZNPP’s Russian-appointed director Yuriy Chernichuk stated in an interview for Rosatom’s company journal that job one is shoring up the cooling water provide, as a result of restarting reactors will generate 1000’s of occasions extra warmth. Rosatom says it plans to faucet the Dnieper River for this goal.
Chernichuk went on to offer a laundry record of further challenges, together with:
•Repairing or changing upgraded Western gear topic to worldwide sanctions;
•Securing working licenses from Russia’s nuclear regulator, since Ukrainian unit licenses start to run out this yr;
•Rebuilding personnel from ZNPP’s present skeleton workers; and
•Constructing transmission hyperlinks to Russia’s grid.
Chernichuk stated that “essentially the most practical choice” is to launch Items 2 and 6 first. Their reactors are loaded with Russian-produced gas, whereas different reactors comprise gas produced by U.S.-based Westinghousefor which Rosatom has neither license nor expertise.
If Ukraine reclaims the plant, Energoatom may extra simply handle its points. It may begin with Items 1 and three, which have brisker gas. Energoatom additionally higher understands ZNPP’s gear, and it has entry to Western gear and experience.
Comparable benefits may circulate to the U.S. if it may strain Russia to surrender the plant. Nevertheless, Zelensky has rejected U.S. possession.
Balakan initiatives that Energoatom would wish one yr to restart only one energy unit in a best-case state of affairs the place ZNPP is “beneath full management of Ukraine” and gear harm isn’t extreme.
However show-stoppers may nonetheless emerge. If the steam turbines want intensive elements or alternative, it may not make sense to proceed—new steam turbines may price over $1-billion per unit, judging by the expertise of Southern California Edison. “They’re not solely costly. They’re very sophisticated devices they usually’re exhausting to repair,” says the U.S. professional who spoke with Spectrum.
Sadly, solely Russian companies manufacture the steam turbines employed at ZNPP. And people may not be accessible at any worth.
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