Warnings of a possible attack at the Zaporizhzhia nuclear power plant in southeastern Ukraine have sent some nearby residents fleeing over the threat of nuclear catastrophe.
Ukrainian intelligence said Russia sent plant workers home Friday and could be planning an imminent attack. The facility has been under Russian control since March but continues to supply electricity to Ukraine.
Ukraine has blamed Russia for explosions there and said the Kremlin is using Europe's largest nuclear power plant for blackmail. Russian President Vladimir Putin, meanwhile, has accused Ukraine of shelling the plant. Both sides said the other could seek to deflect blame through a "false flag" operation.
So far, Ukraine's suspicions that Russia will act to remove Zaporizhzhia from Ukraine's power grid have not been borne out. But the situation remains tense: Fighting has prompted some nearby residents to leave, while others live under daily bombardment.
Rafael Mariano Grossi, director general of the International Atomic Energy Agency, warned Friday that escalation could lead to a severe nuclear accident. But the Zaporizhzhia facility is safer than the one at Chernobyl, the site of the world's worst nuclear accident in 1986, experts say.
Here's what to know about the Zaporizhzhia plant and the risks of fighting there.
Q: Where is Zaporizhzhia, and why is the plant important?
A: Ukraine has 15 functional nuclear reactors, which together supplied 51 percent of its electricity in 2020, according to the IAEA. The country has relied on nuclear power to decrease its energy dependence on Russia.
Six of the reactors are at Zaporizhzhia, on the edge of Enerhodar, a city in southeastern Ukraine about 140 miles from Crimea, the peninsula Russia annexed in 2014. It lies on the war's front line, on the Russia-controlled left bank of the Dnieper River; Ukrainian troops control the opposite side of the river.
Zaporizhzhia's reactors began operating between 1984 and 1995. Together, they can produce 5,700 megawatts of electricity at full capacity. The plant is a huge source of nuclear power for Ukraine: Before the war, it produced a fifth of Ukraine's electricity and nearly half of its nuclear energy.
Q: What's happened to the plant under Russian occupation?
A: Fears of a nuclear disaster at the plant have lingered since Russian forces seized the facility in early March after one of their projectiles set part of the complex on fire.
The fire was extinguished, and international monitors did not record a release of radioactive material. But it marked the first time fighting had broken out around an active nuclear power plant, feeding anxiety around the world.
The IAEA has seen sporadic interruptions in transmission of remote safeguards data from the plant. For months, the agency has called on Russia and Ukraine to allow its inspectors to visit the site. But logistical and political disputes have prevented that from happening.
Meanwhile, thousands of Ukrainian workers have continued to operate the power plant under difficult conditions. Two of the six reactors at Zaporizhzhia still provide power to the Ukrainian grid. But Grossi told the Associated Press in early August that supply chain interruptions could mean the plant isn't getting the equipment it needs.
Russia and Ukraine have each accused the other of attacking the site. International concern mounted in early August, when Russia and Ukraine traded blame for shelling on Zaporizhzhia that damaged parts of the plant. Ukrainian authorities said plant staff had restricted access to the on-site center meant to respond to emergencies.
The head of Energoatom, Ukraine's state nuclear power company, said this month that Russia had positioned rocket launchers and hundreds of soldiers at the site. Fighting around Zaporizhzhia picked up through August, leading a fresh wave of residents to evacuate nearby towns.
Q: What's the worst that could happen?
A: The chief concern: a nuclear meltdown.
Meltdowns occur when fuel in a reactor isn't being adequately cooled. Uranium in fuel rods can then melt and, if there are leaks in the containment building, cause radiation to be released into the environment.
The prospect of a nuclear accident holds particular resonance in Ukraine, the site of the 1986 Chernobyl disaster that led to the evacuation of hundreds of thousands of residents and sent radioactive material across Europe.
The reactors at Zaporizhzhia are protected by reinforced concrete shells, and a direct munitions hit on a reactor remains unlikely, said James Acton, co-director of the Nuclear Policy Program at the Carnegie Endowment for International Peace.
The biggest risk, he said, is that fighting cuts off the plant's electricity supply. Nuclear plants rely on electricity to keep cool - and Zaporizhzhia's external power supply has already been damaged by shelling.
After the Fukushima Daiichi accident in Japan in 2011, Ukraine bolstered safety measures, including around backup power generation. Each reactor at Zaporizhzhia has three backup diesel generators, according to Edwin Lyman, director of nuclear power safety at the Union of Concerned Scientists.
In peacetime, the likelihood of all of these cooling systems failing "would be very low," Acton said. "But in wartime, you could plausibly imagine a series of events that causes a major accident."
"Nuclear power plants are simply not designed to be in war zones," he added.
The biggest health and environmental danger comes from radiation. It's impossible to see or smell, and often, its effects aren't immediately perceptible. But it can remain a silent threat for years. Studies have linked radiation exposure to higher risk of developing cancer and other serious health conditions.
Grossi told the AP that each of the seven pillars of nuclear safety had been violated at the plant. If dangerous damage does occur, Acton said, the war could complicate the ability of emergency systems and personnel to respond.
A nuclear accident at Zaporizhzhia could spread radioactive material across much of Ukraine and possibly to other countries, according to a simulation this week by Ukraine's national weather service.
The worst-case scenario could be worse than the Fukushima disaster, analysts with Greenpeace International said in March - potentially leaving hundreds of miles of land around the plant uninhabitable.
It could also be risky to try to switch the plant from the Ukrainian to the Russian electrical grid, as Ukraine says Moscow intends to do. "If there were a problem at that moment, you'd be entirely reliant on diesel generators" to keep the plant cool, Acton said.
The situation has prompted warnings and a frenzy of diplomacy this month.
"Any potential damage to Zaporizhzhia is suicide," U.N. Secretary General António Guterres said Thursday, warning against any attempt to cut the facility's power and calling for an immediate cessation of hostilities.
U.S. officials are monitoring reports of damage to the plant, paying particular attention to power lines, a senior defense official said Friday. French President Emmanuel Macron called Putin on Friday to voice his concerns.
Both Ukraine and Russia have expressed willingness in recent days to facilitate an IAEA inspection of the site. But Russia has rejected calls from the United Nations to create a demilitarized zone around the Zaporizhzhia plant, arguing that Russian troops provided a "guarantee" there would not be a nuclear disaster there.
The Washington Post