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 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 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 could possibly be totally operational in a yr.

The promise of a speedy restart at Zaporizhzhia, which has six 950-megawatt reactors, shortly pale amid day by 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, whilst 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 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}. Specific 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 might value greater than Ukraine is ready to spend. And no less than some Ukrainian vitality specialists say the nation ought to focus as a substitute 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 large nuclear power plants focus an excessive amount of energy at just a few spots within the grid: “We’re in a position to make use of this Soviet legacy to outlive, however this isn’t the best way 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, maintaining 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: hot shutdown and cold shutdown.

ZNPP is the primary nuclear power plant on the earth to persist in a situation of scorching shutdown, during 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 important gear, such because the water treatment plant, in addition to heating for the close by metropolis of Enerhodar, additionally underneath Russian occupation.

Ukrainian and worldwide security specialists argued as a substitute that scorching shutdown unnecessarily elevated the chance of an accident inflicting a regional disaster, since scorching reactors soften down extra shortly after cooling techniques 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 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 scary concern.

These issues stem from a fancy mixture of chemistry and physics. Throughout chilly shutdown the cooling flows are low—practically stationary in some loops—and likewise comparatively cool, in some instances dropping under 35 °C.

The result’s a coolant with increased density. Ukrainian nuclear professional Georgiy Balakan says that high-density coolant places larger 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 metallic 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 means 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 power was captured by Russian troops. Olga Maltseva/AFP/Getty Pictures

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 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 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 will not be 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 value 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 embody 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 expertise conglomerate, drilled 11 wells on website. Withdrawing of floorwater is trigger for concern, in accordance with Aybars Gürpinar, a former high security official on the International Atomic Energy Agency (IAEA). “Particularly when there may be vital floor water extraction, settlement is at all times a chance,” wrote Gürpinar, now a guide based mostly in Vienna and Brussels, in an e-mail to Spectrum.

Subsidence has precipitated 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, 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 crops.

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