Ordinary Ukrainians were turning out to defend Europe’s largest nuclear power plant from a Russian takeover on Wednesday as the International Atomic Energy Agency convened an emergency meeting with the hope of creating safe zones around the embattled country’s nuclear reactors.

The International Atomic Energy Agency announced it would convene the meeting as fighting closes in on the Zaporozhe plant in southern Ukraine, which sits on the Dneper River city of Enerhodar and lies astride Russian’s main invasions lines from the East and the Black Sea.

Energoatom, Ukraine’s state nuclear power plant operator, has asked the IAEA, a body of the United Nations, to intervene by enforcing a 30-kilometer buffer around its four operational nuclear power plants to keep them free from a strike by Russian forces, which launched a major war in Ukraine last Thursday.

In a statement to the World Nuclear Association, Energoatom said that columns of military equipment and forces have been moving near its nuclear power plants, with “shells exploding near the nuclear power plant” adding that “this can lead to highly undesirable threats across the planet.”

As of Tuesday, six of Ukraine’s 15 functioning nuclear reactors had been disconnected from the power grid in order reduce cooling needs, Ukraine’s state nuclear regulator said. All the country’s reactors – providing more than half of Ukraine’s electricity – were built by while Ukraine was still a Soviet republic, and all are past their original retirement ages.

Control of the Zaporozhe plant has hung in the balance for days. As early as Monday, Russia’s ministry of defense claimed it controlled the territory surrounding the plant, and that plant staff were “working to maintain the facility and control the nuclear environment.” The remarks were carried by the official RBC Russian newswire, which has now been blocked in the west.

But Energoatom roundly denied that claim in a statement to the WNA, calling it “false.” For its part, the IAEA told the Washington Post that “additional information” from Energoatom had established that Russian troops were “operational” near the plant but hadn’t yet entered it.

By Wednesday, numerous Twitter accounts and Radio Liberty reported that largely unarmed civilians had turned out on highways surrounded Enerhodar in an effort to thwart a brewing Russian attack.

“I continue to follow developments in Ukraine very closely and with grave concern,” IAEA director general Rafael Grossi said in a statement. “An accident involving the nuclear facilities in Ukraine would have severe consequences for public health and the environment.”

Aside from the gigantic Zaporozhe, Ukraine operates three other nuclear power plants: the South Ukraine in the country’s center, and the Rivne and the Khmelnytskyi both in Ukraine’s far western region.

While a direct attack meant to actually destroy Ukraine’s nuclear reactors appears to be unlikely in the eyes of experts, taking control of nuclear energy sources is a clear strategic aim of the Russian invaders.

“To put it simply, nuclear power plants are not designed for war zones,” James Acton, a nuclear analyst at the Carnegie Endowment for International Peace, said in a recent report. Ukraine’s reactors could, he added, “become targets in a war that will, in any case, disrupt their operations.”

Dangers at Chernobyl

The looming possibility of an accidental Russian strike on a nuclear reactor has preoccupied the world since Friday, when Russian troops rolled into Chernobyl, site of the world’s worst nuclear accident in 1986, and home to spent nuclear fuel storage facilities. The last of Chernobyl’s remaining three reactors was shut down in 2000 and it is now undergoing a massive decommissioning and decontamination effort.

The Chernobyl site is surrounded by a highly irradiated exclusion zone – an area the size of Luxembourg from which more than 150,000 people were evacuated in the days after the plant’s No 4 reactor exploded. Though the area is largely devoid of people, it nonetheless requires constant radiation monitoring and will remain dangerous for thousands of years.

The personnel at the decommissioned plant, who oversee the spent fuel, have not been relieved since the Russians took over, Reuters has reported, citing the IAEA and Ukraine’s nuclear regulator. Ukraine has said that Chernobyl staff are hostages, while Russia has asserted that they remained voluntarily.

Whatever their circumstances, the IAEA insists they need rest and should be rotated out for a fresh, alert group of technicians. The Chernobyl specialists are charged with overseeing 20,000 spent nuclear fuel assemblies that are currently stored in open pools – that look like exactly that: swimming pools. These fuel rods are eventually to be moved to a more protective, double-walled dry storage canisters designed to last 100 years. In the meantime, the pools – like reactors – require close observation and fresh supplies of cooling water. Whether that will happen now is open to question.

On the day the Russians took Chernobyl, radiation levels picked up by sensors in the exclusion zone appeared to rise significantly, though the Ukrainian regulator reported they were still with safe levels for the area. The IAEA has said there has been no damaged to Chernobyl infrastructure – which includes an enormous steel protective dome over the remains of the Number 4 reactor – and the agency posited that the radiation spikes were caused by Russian tanks and other heavy armor churning up irradiated soil during the siege.

The fragile web that keeps Zaporozhe’s reactors going

Based on troop movements, the Zaporozhe plant is the next most vulnerable to the Russian invasion. Located 225 kilometers up the Dnepr River from the Black Sea, the plant runs six reactors, three of which Ukrainian regulators say have been taken off the grid. It is the largest nuclear power plant in Europe.

While most reactor vessels – those built by the Soviets included – are rated to sustain impacts as devastating as a direct hit by a jumbo jet, the infrastructure that keeps them going is painfully vulnerable to stray missiles and other common military mishaps, experts say.

Most vulnerable are the spent nuclear fuel storage pools, which are used to store irradiated fuel onsite at most nuclear power plants throughout the world – Zaporozhe included.

Because the pools reside in structures that are less robust that the well-constructed vessels designed to protect reactor cores, a strike from errant ordinance could interrupt the circulation of cold water needed to keep the spent fuel cool. Should that happen, Ukraine might soon be facing some of the dangers the Fukushima plant experienced in 2011.

“One particularly serious risk is that a direct attack might drain the pools in which spent fuel is stored, often in large amounts,” Carnegie’s Acton said. “Without cooling, this fuel could melt, releasing very large quantities of radioactivity.“

Yet other dangers arise from the vulnerably of reactor cooling systems. The reactors at  Zaporozhe, use electricity from the Ukrainian grid to power their coolant systems in the event they are forced to shut down. If those power lines are severed, diesel backup generators would kick in to keep the reactors cool. Each of Zaporozhe’s reactors has three such generators, each with about a week’s worth of fuel.

But after that, in circumstances or war, replenishing fuel supplies could become difficult, if not impossible. Again, the example of Fukushima – whose backup diesel generators were snuffed out by an influx of seawater – provides a troubling roadmap for what could come.

All of this could happen whether or not Ukrainian nuclear workers can even get to work. As Acton observes: “For Ukrainian nuclear power plant staff, merely traveling to work may be a dangerous act—making it potentially challenging to ensure the reactor can be operated safely.”

“In the event of an accident” he added, “backup personnel, such as firefighters, may not be able to reach the plant—not least because they could be involved in civilian relief efforts.”The IAEA said Sunday that missiles hit the site of a radioactive waste disposal facility in Kyiv overnight, but there were no reports of damage to the building or any indications of a release of radioactive materials, Grossi said in his statement. Staff at the facility were forced to take shelter during the night.

The incident came a day after an electrical transformer at a similar facility near the northeastern city of Kharkiv had been damaged, but there were no reports of a radioactive release. “Such facilities typically hold disused radioactive sources and other low-level waste from hospitals and industry,” the IAEA said.

According to Mycle Schneider, a Paris-based consultant and a member of the International Panel on Fissile Material, the world has entered unprecedented territory with the Russian war on Ukraine.

“We’ve never seen a full-scale war in a country that operates nuclear facilities,” he told the Washington Post.

Bellona will endeavor to update its readers on the state of Ukraine’s nuclear facilities as more information becomes available.