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 just lately, after three years of occupation and frequent near 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 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 pale 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 severe technical challenges together with deferred upkeep and a dearth of cooling water.
In actual fact, in accordance with 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 might have so badly broken it that repairs might take years and value billions of {dollars}. Explicit issues embody potential tilting of the reactor buildings, and the integrity of the complicated 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 might value greater than Ukraine is ready to spend. And no less than some Ukrainian vitality specialists say the nation ought to focus as an alternative on building smaller, decentralized power plants.
Volodymyr Kudrytskyi, the previous director of Ukraine’s power grid operator, mentioned as a lot final month during a forum at MIT last month. Kudrytskyi mentioned massive nuclear power plants focus an excessive amount of energy at a number of spots within the grid: “We’re in a position to make use of this Soviet legacy to outlive, however this isn’t the way in which 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 mills to energy the pumps that flow into water over spent fuel, conserving 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 the earth to persist in a situation of scorching shutdown, wherein 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 gear, such because the water treatment plant, in addition to heating for the close by metropolis of Enerhodar, additionally beneath Russian occupation.
Ukrainian and worldwide security specialists argued as an alternative that scorching shutdown unnecessarily elevated the danger of an accident inflicting a regional disaster, since scorching reactors soften down extra shortly after cooling methods 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 facets of the chilly shutdown are extremely uncommon and are upsetting concern.
These considerations stem from a posh mixture of chemistry and physics. Throughout chilly shutdown the cooling flows are low—almost stationary in some loops—and likewise comparatively cool, in some circumstances dropping beneath 35 °C.
The result’s a coolant with increased density. Ukrainian nuclear skilled Georgiy Balakan says that high-density coolant places larger 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 accordance with Balakan.
Low temperature and stream, 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 mills. Efforts to purge crystals can then exacerbate injury. If the injury 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 Photos
Steam Leaks or Groundwater Extraction May 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 may function the water-chemical regime for a vast time,” he says.
Impartial specialists contacted by IEEE Spectrum affirmed Balakan’s evaluation. They embody a senior U.S. nuclear engineer conversant in 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 just 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 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 embody impairment a essential security system: the reactor management rods.
After the draining of the Kakhovka Reservoir eradicated ZNPP’s unique supply of cooling water, Rosatom, the Russian nuclear technology and expertise conglomerate, drilled 11 wells on web site. Withdrawing of floorwater is trigger for concern, in accordance with Aybars Gürpinar, a former prime security official on the International Atomic Energy Agency (IAEA). “Particularly when there’s vital floor water extraction, settlement is all the time a chance,” wrote Gürpinar, now a advisor primarily based in Vienna and Brussels, in an electronic mail to Spectrum.
Subsidence has brought about 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 informed then-President Dmitry Medvedev it had plans to repair the “progressing tilt” on the Balakovo and Kalinin energy vegetation.
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 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 injury is just one of many challenges to securely restarting ZNPP’s reactors. Final month, ZNPP’s Russian-appointed director Yuriy Chernichuk mentioned 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 instances extra warmth. Rosatom says it plans to faucet the Dnieper River for this goal.
Chernichuk went on to supply a laundry checklist of extra 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 employees; and
•Constructing transmission hyperlinks to Russia’s grid.
Chernichuk mentioned that “essentially the most lifelike choice” is to launch Models 2 and 6 first. Their reactors are loaded with Russian-produced gas, whereas different reactors include gas 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 Models 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 might stream to the U.S. if it might stress Russia to surrender the plant. Nevertheless, Zelensky has rejected U.S. possession.
Balakan tasks that Energoatom would want 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 injury just isn’t extreme.
However show-stoppers might nonetheless emerge. If the steam mills want intensive elements 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 accessible at any worth.
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