Ukraine’s Zaporizhzhia nuclear power plant, the most important in Europe, has provoked anxiousness ever since Russian troops captured it barely two weeks into the 2022 invasion. However just lately, 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 may very well be totally operational in a yr.
The promise of a fast restart at Zaporizhzhia, which has six 950-megawatt reactors, shortly light amid each day and lethal Russian assaults on Ukrainian cities. Nonetheless the chief govt of Energoatom, Ukraine’s nuclear energy utility, essentially endorsed Grossi’s timeline for a demilitarized scenario in an interview this month, whilst he acknowledged critical technical challenges together with deferred upkeep and a dearth of cooling water.
In actual fact, based on Ukrainian, European and U.S.-based specialists interviewed by IEEE Spectrum, the challenges dealing with a Zaporizhzhia Nuclear Power Plant (ZNPP) revival might go far deeper. These specialists say that Russia’s operation of the plant could have so badly broken it that repairs might take years and price billions of {dollars}. Explicit issues embody 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 models could value greater than Ukraine is ready to spend. And at the least some Ukrainian power specialists 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 massive nuclear power plants focus an excessive amount of energy at just a few 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 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 power system. These assaults repeatedly disconnected ZNPP from Ukraine’s grid, forcing the usage of diesel turbines 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 gear 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 this planet to persist in a situation of sizzling shutdown, during 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 essential gear, 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 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 threat 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 features 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 in addition comparatively cool, in some circumstances dropping beneath 35 °C.
The result’s a coolant with greater density. Ukrainian nuclear knowledgeable Georgiy Balakan says that high-density coolant places higher mechanical load on the cooling pipes and the fragile tubes throughout the steam turbines. That elevated load, in flip, will increase pressure on the various welds, in addition to on the metal pipes themselves as a result of their metallic is much less ductile at decrease temperatures, based on Balakan.
Low temperature and movement, in the meantime, additionally impression 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 injury. If the injury perforates the steam generator tubes, borated water can leak by means 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 sequence 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 gear. “The Russians acted as if they might function the water-chemical regime for a vast time,” he says.
Unbiased specialists contacted by IEEE Spectrum affirmed Balakan’s evaluation. They embody a senior U.S. nuclear engineer accustomed to 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 shouldn’t be approved 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 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 expensive points stem from the operators’ shift to groundwater for cooling following the demolition of the Kakhovka Dam in June 2023. Potential implications embody 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 know-how conglomerate, drilled 11 wells on website. Withdrawing of floorwater is trigger for concern, based on Aybars Gürpinar, a former prime security official on the International Atomic Energy Agency (IAEA). “Particularly when there’s important floor water extraction, settlement is all the time a risk,” wrote Gürpinar, now a advisor based mostly in Vienna and Brussels, in an e-mail to Spectrum.
Subsidence has induced 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 location’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 intervene 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 manage the reactor and leaving them with out backup management.
In a press release to Spectrum, Rosatom asserted that: “No floor degree adjustments or indicators of subsidence have been noticed.”
Restarting the Reactors Would Require Fixing A number of Issues
Addressing structural injury 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 1000’s of instances 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 Models 2 and 6 first. Their reactors are loaded with Russian-produced gasoline, whereas different reactors include gasoline produced by U.S.-based Westinghouse, for which Rosatom has neither license nor expertise.
If Ukraine reclaims the plant, Energoatom would possibly extra simply tackle its points. It might begin with Models 1 and three, which have more energizing gasoline. Energoatom additionally higher understands ZNPP’s gear, and it has entry to Western gear and experience.
Comparable benefits might movement to the U.S. if it might strain Russia to surrender the plant. Nonetheless, Zelensky has rejected U.S. possession.
Balakan tasks that Energoatom would wish one yr to restart only one energy unit in a best-case state of affairs the place ZNPP is “underneath full management of Ukraine” and gear injury shouldn’t be extreme.
However show-stoppers might nonetheless emerge. If the steam turbines want in depth elements or substitute, it may not make sense to proceed—new steam turbines 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 arduous to repair,” says the U.S. knowledgeable who spoke with Spectrum.
Sadly, solely Russian corporations manufacture the steam turbines employed at ZNPP. And people may not be out there at any worth.
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