Ukraine’s Nuclear Reactors Remain at Risk as One-Year Anniversary of War Looms

Protesters have been warning about the dangers of reactors in Ukraine since long before the Russian invasion. (2010 anti-nuclear protest in Kiev by Christian Ganzer/Wikimedia Commons)

Since the war began, the 15 Ukraine reactors situated at four sites, along with the defunct Chornobyl nuclear plant, have been at the center of media attention, once again bringing to light the inherent and extreme dangers of nuclear power plants at any time, let alone during an armed conflict. And, on a few occasions, all of those sites have also been in the crosshairs of actual fighting, most notably the six-reactor Zaporizhzhia nuclear power plant, the largest both in Ukraine and all of Europe.

Despite pleadings by the International Atomic Energy Agency and its director, Rafael Grossi, not to engage in combat close to the nuclear plants, no effective deterrent or peaceful protective measure has been found or implemented, even as the IAEA continues to urge the creation of safe zones around the nuclear sites.

Grossi and others insist that the nuclear plants themselves are not the problem. “It’s very simple, the problem in Ukraine and in Russia is they are at war. The problem is not nuclear energy,” he told the BBC in an interview.

Except that it IS the nuclear plants that are the problem. After all, if Ukraine was powered by renewables and not nuclear plants, this wouldn’t even be an issue. As an Austrian government briefing paper, collected under “Fairy tales by the nuclear lobby,” said: “A ‘successful’ attack on a nuclear power plant in densely populated Europe would have radiological and economic consequences far beyond those experienced after Chernobyl or Fukushima. So far, no terrorist attacks on wind turbines or solar panels have been reported.”

An attack or other precipitating events caused by the war in Ukraine, could still result in such a disaster. Sadly, with the war raging on, nothing has really changed since the February 24, 2022 invasion.

Since it’s the most dangerous, being the largest, and also the closest to the worst of the fighting, let’s take Zaporizhzhia as our test case.

There are approximately 200 different radioactive isotopes contained in any given nuclear reactor and its waste inventories. Zaporizhzhia houses at least 2,204 tons of highly radioactive waste within the reactors and the irradiated fuel pools, according to a March 2022 Greenpeace analysis, looking at 2017 figures, the latest data available. At least 855 tons of those wastes are in the pools. The quantities are so high because the reactors have been in operation for several decades. The first unit came on line in 1985, the sixth in 1996.

Among those 200 isotopes are iodine-131, which attacks the thyroid, cesium-134 that accumulates in muscle and strontium-90 which acts like calcium in the body and is easily incorporated into bone. Since all reactors also make plutonium-239 — with a half-life of 24,000 years — as part of the fission process, it, too, could be propelled into the environment. As an alpha-emitting particle, it is most dangerous when inhaled, attacking lungs, kidneys and other organs.

A control room at the Zaporizhzhia nuclear power plant. The condition — and fate — of workers there is uncertain, raising the risk of an accident. (Photo: IAEA Imagebank)

As we have written frequently at Beyond Nuclear since our first article appeared and the Russian war on Ukraine followed, there are a number of scenarios that could precipitate such a catastrophe. It could involve a full or partial reactor meltdown, an irradiated fuel pool fire or hydrogen explosion, or a breach of the radioactive waste storage casks.

The specific scenarios for this are described with essential detail and great clarity in the special section on “Nuclear Power and War” in the 2022 edition of the World Nuclear Industry Status Report.

“Unlike all other types of power plants, the safety of a nuclear power plant depends on continuously functioning cooling systems,” the WNISR authors write in the chapter introduction. “The physical reason for this is the radioactive decay of the fission products and transuranic elements produced by neutron capture on uranium. During this decay, considerable amounts of heat are generated, so-called decay heat. If it is not continuously removed by cooling, this leads to strong heat buildup, which can cause melting, fires, or other events that can cause major releases of radioactive materials. During operation and directly after a reactor shutdown, cooling requirements are particularly high.”

This also means that even when the reactors are shut down, as at least four have been at Zaporizhzhia, they are not out of danger. And the fuel pools present the greatest threat, as the radioactive waste inventory they contain is more radioactive than the fresh fuel before it is loaded into the reactor.

But it need not take a full blown attack to cause at least some of these disastrous outcomes. It could be as simple as a loss of power, or human error. We have already seen frequent bombardments of the electrical grid leading to loss of power and thereby causing immense suffering among the general population of Ukraine, now in the thick of winter and struggling to find heat, water and food. But such a loss of power can also be fatal to a nuclear power plant.

Reliant on an external source of electricity to cool the reactors and pump water into the fuel pools, workers must turn to onsite power when offsite power is cut. This is usually sourced from backup diesel generators that don’t always work and require a steady supply of fuel. Eventually, both fuel and time can run out.

“Without cooling, the water in the reactor core (and spent fuel pool) begins to heat,” explains the Greenpeace report.

“In the case of an operational reactor the heating is rapid. The water reaches boiling point and begins to evaporate, and the hot nuclear reactor fuel assemblies are at risk of being exposed to air which then would lead to a thermal reaction of the nuclear fuel assembly cladding and reactor core fuel melt.

“In the case of nuclear fuel in the spent fuel pool, the highly exothermic chemical reaction is called a runaway zirconium oxidation reaction or autocatalytic ignition, with resultant release of a very large volume of radioactivity.”

These massive amounts of radioactivity released into the environment by such a disaster can disperse with the winds and deposit through rainfall, persisting and remaining dangerous for many decades or even indefinitely.

The casks, stored unprotected outside are cooled passively, meaning they do not require an external source of power. But they represent an inviting target. If a bombing attack or a direct hit using a shaped charge or bunker buster-type weapon breaches both the outer and inner cask containment, the helium coolant is exposed to oxygen. All that is then needed is an ignition source and hydrogen explosions result, releasing and dispersing the radioactive inventory from the cask or multiple casks.

The workforce at Zaporizhzhia is especially vulnerable, given the plant has been under Russian occupation since March 4, 2022. While obtaining reliable information is challenging, grim stories have emerged that suggest gross mistreatment of — and even violence toward — the plant workers. Ukrainian authorities say many workers have failed to return to work, perhaps having fled the area with their families, leaving the reactors understaffed. Others may not be able to access the site if war is raging around it.

These fears have been articulated by IAEA officials who are in place at Zaporizhzhia currently. “The reduced ZNPP staffing levels combined with psychological stress due to the on-going military conflict and the absence of family members who fled the area have created an unprecedented situation that no NPP staff should have to endure,” said IAEA chief, Rafael Grossi of the conditions.

All of these stress factors make human error more likely, a key factor in the meltdowns at both Three Mile Island and Chornobyl.

An accidental or deliberate missile strike or bombardment that completely destroys one or more of the reactors and their fuel pools could cause the most catastrophic consequences given the explosive power of such an action and the conflagration that would result. While an accidental strike is more or less inevitable in the chaos of war, the outcome, whether accidental or deliberate, could be the same. It is of course hard to imagine what possible benefit there could be for either side in deliberately attacking and destroying a nuclear power plant. Nevertheless, that is precisely what each side has accused the other of attempting to do.

Explosions of the kind that happened at the stricken Fukushima-Daiichi nuclear power plant (pictured) remain a very real risk at Zaporizhzhia or at Ukraine’s other three nuclear power plants. (Still of news footage via YouTube)

Were that to happen, a fatal strike on one reactor, leading to a major meltdown and lethal radiation levels, could force the evacuation of the workforce. But abandoning the site could lead to a cascade of meltdowns at the other five reactors, making the disaster infinitely worse.

Nuclear power plants cannot be abandoned by their workforce. This became readily apparent during the March 2011 Fukushima Daiichi nuclear disaster in Japan. As workers lost control of three of the units, leading to explosions, soaring radiation levels and eventually meltdowns, Tepco had wanted to withdraw its workforce to protect their safety. Naoto Kan, the prime minister at the time (who has subsequently become an outspoken opponent of nuclear power), insisted that at least a sacrificial skeleton crew remained.

Allowing the disaster to worsen by abandoning the site, could have raised radiation levels in the environment so high, the neighboring crew at the Fukushima-Daiini nuclear power plant 7.5 miles away would have had to evacuate, leaving those four reactors untended. A cascading such set of disasters might eventually have led to Kan’s greatest fear — the evacuation of Tokyo, something he described as meaning, to him, the end of Japan as a nation. Instead, the Daiini workers were able to get the reactors there into cold shutdown within two days of the Daiichi accident.

In the event of a major radioactive release resulting from any of these scenarios, what would the health consequences be?

Let’s put this in context. When Chornobyl Unit 4 exploded in 1986, it was a single unit reactor that had been operating for two years. At least 200 million curies were released, contaminating 40% of the landmass in Europe (outside of Ukraine, Belarus and Russia).

Today, the Chornobyl Exclusion Zone extends to 1,000 square miles— an area deemed unsafe for human habitation for the foreseeable future.

Why is the Zone so large and why will it remain dangerous for so long? The kinds of radioactive isotopes released, as described earlier, not only entered the bodies of those people around at the time of the disaster. They were deposited in fallout, contaminating the soil and groundwater and ultimately the food chain. Thus, the exposures, and the harm, will continue down generations where people remain exposed.

The Chornobyl fallout map, which reveals how some countries got more heavily dosed than others, even far away from the source of the accident.

Resulting health impacts include damage not only to the heart, lungs, thyroid, kidneys and other organs, but issues with sight as well as increases in childhood leukemias and damage to DNA. Birth defects remain a common outcome among families exposed to the Chornobyl fallout.

Furthermore, the radioactive cloud dispersed not only across Ukraine, Belarus and Russia, where the effects were felt the worst, but also into much of Western Europe. Thus, radiation persists among plants, wildlife and fungi. Mushrooms and wild boar in parts of Germany remain too radioactive for consumption even today. Reindeer in Lapland equally so. Sheep in parts of England and Wales were also kept off the market until 2012.

This is in marked contrast to the effects of a nuclear weapon attack, with horrific immediate consequences but radiation levels that dissipate quickly. People live in Hiroshima and Nagasaki today. No one should live in the Chornobyl Exclusion Zone, (although some, mostly elderly people, choose to).

This is not to downplay or minimize in any way the horrors and immorality of an attack using nuclear weapons. But it is simply to point out that the after-effects of a nuclear power plant accident tend to be — but should not be — minimized in comparison. It is worth noting that the amount of radioactivity released by the Chornobyl disaster corresponds to approximately 200 times that of Hiroshima and Nagasaki combined.

How far radiation from another nuclear power plant disaster in Ukraine would spread depends on the direction of the wind and on where precipitation occurs. What is striking about the Chornobyl fallout map is just how selective and seemingly random it is once we are beyond the borders of the former Soviet Union. Austria got heavily dosed, for example, its immediate neighbors less so. Sweden, Norway and Finland suffered major hotspots while Denmark was largely spared.

As we ponder this in the context of the perils of war, we must also remember that war just makes this outcome more likely. A major nuclear disaster is still possible — and even probable — on a daily basis at any nuclear power plant anywhere and at any time. Loss of power and human error remain key causes, along with violent weather events — occurrences that will continue to become more frequent and more severe as the climate crisis worsens. Sabotage and terrorism are an ever-present possibility as well.

This means that striving for the unrealistic goal, as the IAEA does, of ensuring nuclear reactors are not caught up in a war zone, doesn’t make us all that much safer. Only the complete elimination of nuclear power as an energy source will achieve that.

This first appeared on Beyond Nuclear.

Linda Pentz Gunter is the editor and curator of and the international specialist at Beyond Nuclear.