Zaporizhzhia’s Future: Nuclear Peril or Promise?

Ukraine’s Zaporizhzhia nuclear energy plant, the biggest in Europe, has provoked nervousness 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 all of the sudden 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 accordance 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 may restart inside “months” of a ceasefire, and the plant could possibly be absolutely operational in a 12 months.

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

In actual fact, in accordance with Ukrainian, European and U.S.-based consultants interviewed by IEEE Spectrum, the challenges going through a Zaporizhzhia Nuclear Energy Plant (ZNPP) revival may go far deeper. These consultants say that Russia’s operation of the plant could have so badly broken it that repairs may take years and price billions of {dollars}. Explicit issues embrace 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 a minimum of some Ukrainian vitality consultants 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 huge nuclear energy vegetation 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 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 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, maintaining 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: sizzling shutdown and chilly shutdown.

ZNPP is the primary nuclear energy plant on this planet to persist in a situation of sizzling shutdown, by 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 offered steam wanted to maintain important tools, such because the water remedy plant, in addition to heating for the close by metropolis of Enerhodar, additionally underneath Russian occupation.

Ukrainian and worldwide security consultants argued as an alternative that sizzling shutdown unnecessarily elevated the danger of an accident inflicting a regional disaster, since sizzling reactors soften down extra rapidly after cooling methods fail. Ukrainians noticed the improved threat as a type of nuclear blackmail, arguing that Russian forces may intentionally unleash a radiological incident in the event that they had been compelled to retreat from the realm.

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 frightening 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 under 35 °C.

The result’s a coolant with greater 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 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 circulation, 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 harm. If the harm 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 power was captured by Russian troops. Olga Maltseva/AFP/Getty Photographs

Steam Leaks or Groundwater Extraction May 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 limiteless time,” he says.

Unbiased consultants contacted by IEEE Spectrum affirmed Balakan’s evaluation. They embrace 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 isn’t 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 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 important 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 technology and expertise conglomerate, drilled 11 wells on web site. Withdrawing of floorwater is trigger for concern, in accordance with Aybars Gürpinar, a former high security official on the Worldwide Atomic Vitality Company (IAEA). “Particularly when there’s important floor water extraction, settlement is at all times a chance,” wrote Gürpinar, now a marketing consultant 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. Practically 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, in accordance with a 2024 LinkedIn submit 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 may 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 may 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 degree modifications or indicators of subsidence have been noticed.”