Zaporizhzhia’s Future: Nuclear Peril or Promise?

Ukraine’s Zaporizhzhia nuclear energy 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 close to misses that threatened radiological catastrophe, a promise of sunnier days out of the blue 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 line with a White Home abstract. Worldwide Atomic Vitality Company (IAEA) director Rafael Grossi upped the ante one week later, telling Reuters that Zaporizhzhia’s reactors might restart inside “months” of a ceasefire, and the plant could possibly be absolutely operational in a yr.

The promise of a fast restart at Zaporizhzhia, which has six 950-megawatt reactors, shortly pale amid every day and lethal Russian assaults on Ukrainian cities. Nonetheless the chief government of Energoatom, Ukraine’s nuclear energy utility, basically endorsed Grossi’s timeline for a demilitarized state of affairs in an interview this month, whilst he acknowledged critical technical challenges together with deferred upkeep and a dearth of cooling water.

In truth, in line with Ukrainian, European and U.S.-based consultants interviewed by IEEE Spectrum, the challenges dealing with a Zaporizhzhia Nuclear Energy 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 price billions of {dollars}. Specific 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 items could price greater than Ukraine is ready to spend. And no less than some Ukrainian power consultants say the nation ought to focus as a substitute on constructing smaller, decentralized energy crops.

Volodymyr Kudrytskyi, the 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 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 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 energy 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 gas, conserving it from overheating and probably melting down and releasing massive quantities of radiation.

Russia’s assaults have destroyed some tools and positioned pressure on others, however particular concern arises from unprecedented longterm working modes: scorching shutdown and chilly shutdown.

ZNPP is the primary nuclear energy plant on the planet to persist in a situation of scorching shutdown, by 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 crucial tools, 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 consultants argued as a substitute 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 danger as a type of nuclear blackmail, arguing that Russian forces might intentionally unleash a radiological incident in the event that they had been compelled to retreat from the world.

In April 2024 the plant’s Russian administration lastly relented, inserting the final working producing unit into chilly shutdown. Chilly shutdown is a safer mode for the plant, however, nonetheless, a number of elements of the chilly shutdown are extremely uncommon and are upsetting 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 increased density. Ukrainian nuclear knowledgeable Georgiy Balakan says that high-density coolant places better mechanical load on the cooling pipes and the fragile tubes inside 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 steel is much less ductile at decrease temperatures, in line 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 turbines. Efforts to purge crystals can then exacerbate injury. If the injury perforates the steam generator tubes, borated water can leak by 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 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 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 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 embody 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 will not be 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 embody impairment a crucial 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 era and know-how conglomerate, drilled 11 wells on website. Withdrawing of floorwater is trigger for concern, in line with Aybars Gürpinar, a former prime security official on the Worldwide Atomic Vitality Company (IAEA). “Particularly when there may be important floor water extraction, settlement is all the time a chance,” wrote Gürpinar, now a marketing consultant primarily based in Vienna and Brussels, in an e 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, in line with a 2024 LinkedIn submit by Balakan. In 2011, Rosatom informed 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 manage the reactor and leaving them with out backup management.

In a press release to Spectrum, Rosatom asserted that: “No floor stage adjustments or indicators of subsidence have been noticed.”