Zaporizhzhia’s Future: Nuclear Peril or Promise?

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 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 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 might be totally operational in a 12 months.

The promise of a speedy 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, essentially endorsed Grossi’s timeline for a demilitarized scenario in an interview this month, at the same time as he acknowledged severe technical challenges together with deferred upkeep and a dearth of cooling water.

Actually, in keeping with Ukrainian, European and U.S.-based specialists interviewed by IEEE Spectrum, the challenges going through 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 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 might price 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 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 huge 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 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 power system. These assaults repeatedly disconnected ZNPP from Ukraine’s grid, forcing using diesel turbines to energy the pumps that flow into water over spent fuel, preserving it from overheating and probably melting down and releasing giant quantities of radiation.

Russia’s assaults have destroyed some tools 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, through 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 important tools, 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 sizzling shutdown unnecessarily elevated the chance of an accident inflicting a regional disaster, since sizzling reactors soften down extra rapidly after cooling methods fail. Ukrainians noticed the improved danger as a form 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, placing the last operating generating unit into cold shutdown. Chilly shutdown is a safer mode for the plant, however, nonetheless, a number of points 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—practically stationary in some loops—and likewise comparatively cool, in some circumstances dropping beneath 35 °C.

The result’s a coolant with greater density. Ukrainian nuclear skilled Georgiy Balakan says that high-density coolant places larger mechanical load on the cooling pipes and the fragile tubes throughout 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 keeping with Balakan.

Low temperature and move, 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 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 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 tools. “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 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 just isn’t 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 price practically $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 embrace impairment a important 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 keeping 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. 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, 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 vegetation.

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 regulate the reactor and leaving them with out backup management.

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