Ukraine’s Zaporizhzhia nuclear power plant, the most important 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 near misses that threatened radiological catastrophe, a promise of sunnier days immediately 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 power—and even possession, according to a White House summary. International Atomic Energy Agency (IAEA) director Rafael Grossi upped the ante one week later, telling Reuters that Zaporizhzhia’s reactors might restart within “months” of a ceasefire, and the plant might be totally operational in a 12 months.
The promise of a fast restart at Zaporizhzhia, which has six 950-megawatt reactors, rapidly pale amid every day and lethal Russian assaults on Ukrainian cities. Nonetheless the chief government of Energoatom, Ukraine’s nuclear energy utility, essentially endorsed Grossi’s timeline for a demilitarized scenario in an interview this month, whilst he acknowledged severe technical challenges together with deferred upkeep and a dearth of cooling water.
In truth, in keeping with Ukrainian, European and U.S.-based consultants interviewed by IEEE Spectrum, the challenges dealing with a Zaporizhzhia Nuclear Power Plant (ZNPP) revival might go far deeper. These consultants say that Russia’s operation of the plant could have so badly broken it that repairs might take years and value billions of {dollars}. Specific issues embrace potential tilting of the reactor buildings, and the integrity of the advanced and comparatively fragile steam mills for the plant’s pressurized, light-water reactors.
Even when there’s a lasting cessation of hostilities, restarting ZNPP’s reactor-generator models could value greater than Ukraine is ready to spend. And at the very least some Ukrainian vitality consultants say the nation ought to focus as a substitute on building smaller, decentralized power plants.
Volodymyr Kudrytskyi, the previous director of Ukraine’s power grid operator, stated as a lot final month during a forum at MIT last month. Kudrytskyi stated huge nuclear power plants focus an excessive amount of energy at a couple of spots within the grid: “We’re in a position to make use of this Soviet legacy to outlive, however this isn’t the best way ahead.”
Questionable Working Practices Could 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 power system. These assaults repeatedly disconnected ZNPP from Ukraine’s grid, forcing using diesel mills to energy the pumps that flow into water over spent fuel, holding it from overheating and probably melting down and releasing giant quantities of radiation.
Russia’s assaults have destroyed some tools and positioned pressure on others, however particular concern arises from unprecedented longterm working modes: hot shutdown and cold shutdown.
ZNPP is the primary nuclear power plant on the earth to persist in a situation of scorching shutdown, during which the plant operates at minimal output. Sustained scorching shutdown, for months on finish, violated ZNPP’s license. However Russian plant managers insisted that it supplied steam wanted to maintain essential tools, such because the water treatment plant, in addition to heating for the close by metropolis of Enerhodar, additionally underneath Russian occupation.
Ukrainian and worldwide security consultants argued as a substitute that scorching shutdown unnecessarily elevated the chance of an accident inflicting a regional disaster, since scorching reactors soften down extra rapidly after cooling programs fail. Ukrainians noticed the improved danger as a form of nuclear blackmail, arguing that Russian forces might intentionally unleash a radiological incident in the event that they had been pressured to retreat from the realm.
In April 2024 the plant’s Russian administration lastly relented, placing the last operating generating unit into cold shutdown. Chilly shutdown is a safer mode for the plant, however, nonetheless, a number of points of the chilly shutdown are extremely uncommon and are frightening 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 in addition comparatively cool, in some circumstances dropping beneath 35 °C.
The result’s a coolant with larger density. Ukrainian nuclear skilled Georgiy Balakan says that high-density coolant places better mechanical load on the cooling pipes and the fragile tubes inside the steam mills. 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 steel is much less ductile at decrease temperatures, in keeping with Balakan.
Low temperature and stream, in the meantime, additionally influence boric acid that’s added to the first cooling water to manage the reactor’s fission reactions, permitting boric acid to crystallize in delicate areas of the first circuit pipes and within the steam mills. 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 power was captured by Russian troops. Olga Maltseva/AFP/Getty Pictures
Steam Leaks or Groundwater Extraction Might Doom Plant
Russian officers controlling ZNPP have reported a collection of leaks to IAEA observers, together with steam generator leaks in half of its energy models. 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 tools. “The Russians acted as if they might function the water-chemical regime for a vast time,” he says.
Unbiased consultants 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 is just not approved to talk to the press.
Steam-generator points can shutter a nuclear plant for good. That situation performed out in California in 2013 when utility Southern California Edisonscrapped its only nuclear power plant after botched steam generator repairs that value almost $2 billion ($2.7 billion in 2025 {dollars}).
One other set of probably pricey 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 essential security system: the reactor management rods.
After the draining of the Kakhovka Reservoir eradicated ZNPP’s authentic supply of cooling water, Rosatom, the Russian nuclear era and expertise conglomerate, drilled 11 wells on web site. Withdrawing of floorwater is trigger for concern, in keeping with Aybars Gürpinar, a former prime security official on the International Atomic Energy Agency (IAEA). “Particularly when there’s important floor water extraction, settlement is at all times a chance,” wrote Gürpinar, now a advisor based mostly in Vienna and Brussels, in an e mail to Spectrum.
Subsidence has brought on a number of costly complications for Soviet-designed VVER-1000 reactors, together with ZNPP’s. Almost 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, according to a 2024 LinkedIn post by Balakan. In 2011, Rosatom advised then-President Dmitry Medvedev it had plans to repair the “progressing tilt” on the Balakovo and Kalinin energy crops.
Gürpinar says tilting might crack ZNPP’s concrete base and intrude with reactor management rods, slowing their gravity-driven drop into the reactor to squelch fission reactions throughout station blackouts. He says the rods might even get “caught,” forcing operators to depend on boric acid to regulate the reactor and leaving them with out backup management.
In an announcement to Spectrum, Rosatom asserted that: “No floor stage 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 securely restarting ZNPP’s reactors. Final month, ZNPP’s Russian-appointed director Yuriy Chernichuk stated in an interview for Rosatom’s corporate magazine that job one is shoring up the cooling water provide, as a result of restarting reactors will generate hundreds of occasions extra warmth. Rosatom says it plans to faucet the Dnieper River for this goal.
Chernichuk went on to supply a laundry checklist of further challenges, together with:
•Repairing or changing upgraded Western tools topic to worldwide sanctions;
•Securing working licenses from Russia’s nuclear regulator, since Ukrainian unit licenses start to run out this 12 months;
•Rebuilding personnel from ZNPP’s present skeleton workers; and
•Constructing transmission hyperlinks to Russia’s grid.
Chernichuk stated that “essentially the most real looking choice” is to launch Items 2 and 6 first. Their reactors are loaded with Russian-produced gasoline, whereas different reactors comprise gasoline produced by U.S.-based Westinghouse, for which Rosatom has neither license nor expertise.
If Ukraine reclaims the plant, Energoatom may extra simply handle its points. It might begin with Items 1 and three, which have more energizing gasoline. Energoatom additionally higher understands ZNPP’s tools, and it has entry to Western gear and experience.
Comparable benefits might stream to the U.S. if it might stress Russia to surrender the plant. Nonetheless, Zelensky has rejected U.S. possession.
Balakan initiatives that Energoatom would want one 12 months to restart only one energy unit in a best-case situation the place ZNPP is “underneath full management of Ukraine” and tools harm is just not extreme.
However show-stoppers might nonetheless emerge. If the steam mills want in depth components or alternative, it may not make sense to proceed—new steam mills might value over $1-billion per unit, judging by the expertise of Southern California Edison. “They’re not solely costly. They’re very difficult gadgets and so they’re laborious to repair,” says the U.S. skilled who spoke with Spectrum.
Sadly, solely Russian companies manufacture the steam mills employed at ZNPP. And people may not be obtainable at any value.
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