Zaporizhzhia’s Future: Nuclear Peril or Promise?

Ukraine’s Zaporizhzhia nuclear energy plant, the biggest in Europe, has provoked anxiousness ever since Russian troops captured it barely two weeks into the 2022 invasion. However lately, after three years of occupation and frequent close to misses that threatened radiological catastrophe, a promise of sunnier days instantly 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 keeping with a White Home abstract. Worldwide Atomic Power 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 might be totally 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 govt of Energoatom, Ukraine’s nuclear energy utility, basically endorsed Grossi’s timeline for a demilitarized situation in an interview this month, whilst he acknowledged critical technical challenges together with deferred upkeep and a dearth of cooling water.

In truth, in keeping with Ukrainian, European and U.S.-based specialists interviewed by IEEE Spectrum, the challenges going through a Zaporizhzhia Nuclear Energy 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 value billions of {dollars}. Explicit issues embody potential tilting of the reactor buildings, and the integrity of the complicated 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 value greater than Ukraine is ready to spend. And a minimum of some Ukrainian vitality specialists say the nation ought to focus as an alternative on constructing smaller, decentralized energy vegetation.

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 large nuclear energy vegetation 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, preserving 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: scorching shutdown and chilly shutdown.

ZNPP is the primary nuclear energy plant on the planet 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 crucial 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 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 type of nuclear blackmail, arguing that Russian forces might intentionally unleash a radiological incident in the event that they have been pressured 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 elements 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 in addition comparatively cool, in some instances dropping under 35 °C.

The result’s a coolant with larger density. Ukrainian nuclear skilled 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 steel is much less ductile at decrease temperatures, in keeping with Balakan.

Low temperature and circulate, in the meantime, additionally influence 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 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 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 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 a limiteless time,” he says.

Impartial specialists 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 is just not licensed 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 solely nuclear energy plant after botched steam generator repairs that value 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 expertise conglomerate, drilled 11 wells on website. Withdrawing of floorwater is trigger for concern, in keeping with Aybars Gürpinar, a former high security official on the Worldwide Atomic Power Company (IAEA). “Particularly when there’s vital floor water extraction, settlement is all the time a risk,” wrote Gürpinar, now a marketing consultant 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. 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 keeping with a 2024 LinkedIn publish by Balakan. In 2011, Rosatom advised 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 regulate 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.”