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There are renewed concerns over the safety of the Zaporizhzhia nuclear plant, the largest in Europe, which was seized by Russian troops early in the war.
President Volodymyr Zelenskyy on Wednesday (July 5) said the Russians have placed what appear to be explosives on the roofs of several power units at the plant, perhaps intending to fake an attack and blame Ukraine for it.
And a spokesperson for the Kremlin accused Ukraine of planning to sabotage the plant, and claimed Russia had taken steps to ward off the threat.
Chess legend and Russian opposition leader Garry Kasparov said on Twitter there was “increasing chatter that Russians may blow up the Zaporizhzhia nuclear plant in coming days”.
The International Atomic Energy Agency (IAEA), the United Nations nuclear watchdog, said on Wednesday that it had so far not seen any indications of mines or explosives, but “with military tension and activities increasing in the region…our experts must be able to verify the facts on the ground”.
Zaporizhzhia is the administrative centre of the Ukrainian oblast of the same name, located to the southeast of the country on the banks of the Dnipro river as it winds its way to the Black Sea.
The plant in Zaporizhzhia, one of four nuclear power stations in Ukraine, was built through the 1980s by the erstwhile Soviet Union. The plant at Zaporizhzhia has six reactors (there are a total of 15 in Ukraine), which can together produce about 5,700 MW of electricity. Before the beginning of the war, about half of Ukraine’s power demand was served by nuclear energy.
Russian forces attacked the plant in the night of March 3, 2022, and took control of it relatively easily. Since then, Russia and Ukraine have repeatedly accused one another of endangering the plant, running the risk of a major nuclear accident.
Amid the sporadic fighting, the situation escalated dangerously in August 2022 with increased shelling and mortar attacks, which the two armies blamed on each other. As the world watched nervously, buildings inside the nuclear complex were hit, though no significant damage was reported. Radiation levels around the site were stable, which meant there was no leakage.
In mid-August, the external power supply line to the complex was disrupted due to the fighting, and the station had to fall back temporarily on emergency generators.
While there is no major fighting around Zaporizhzhia currently, Zelenskyy resurrected the spectre of a nuclear disaster on July 1, telling a joint press conference with Spain’s Prime Minister Pedro Sánchez that Russia was “technically ready to provoke a local explosion at the station, which could lead to a [radiation] release”, according to reports.
In previous days, Ukraine’s military intelligence directorate (GUR) had said the Kremlin had approved a plan to blow up the power station and Russia had begun cutting troops at the site, and the Ukrainians had held nuclear disaster response drills in the area.
This is the first time that a nuclear installation has been caught in a military conflict, that too one that is in operation. There is no doubt that the situation is extremely volatile, and the possibility of something going horribly wrong remains open.
That said, it is also true that modern nuclear reactors are built to withstand considerable shock and impact. They have several layers of reinforced steel and concrete, and also elaborate fire security systems. Most modern reactors can survive earthquakes of magnitude 8 or higher. They are also designed to shut down automatically when they sense major natural hazards.
The Zaporizhzhia reactors are said to be quite safe. Gunfire or even shelling is unlikely to cause much harm or result in a nuclear accident. However, it is unclear how the reactors would face up to attacks by missiles, or powerful bombs of the kind the Ukrainians have referred to.
Also, buildings and water pools used for storing used and unused nuclear fuel are not as sturdily built as the reactors themselves, and can suffer significant damage in heavy fighting.
It stands to reason that neither of the parties would be so reckless so as to directly bomb the reactor to trigger a nuclear explosion. But again, no one really knows the Russian leadership’s assessment of the aborted rebellion by the chief of the Wagner mercenary group, Yevgeny Prigozhin, and its impact on the war — and what steps President Putin might contemplate in response.
Loss of electricity is the more realistic danger that has already visited the Zaporizhzhia station briefly. Since February 2022, there have been seven instances of complete power loss from external sources, forcing the plant to rely on temporary emergency diesel generators for electricity, according to the IAEA.
Last week, a 330 kV backup line to the plant was energised, which can supply power in case the main 750 kV power line is damaged or becomes unavailable, the IAEA said.
Nuclear plants have to depend on external electricity for a variety of needs, including the operation of water pumping systems to keep the reactors cool.
Cooling systems are critical to the safe operation of nuclear reactors, which see temperatures in the range of thousands of degree Celsius. To keep water pumping through the reactors, an external power supply is needed.
Nuclear stations have elaborate back-up generators in case of disruption of power. But these generators can supply electricity only for a limited time. And nuclear reactors, even if they are shut down, can take days, sometimes weeks, to cool down. A non-functional cooling system can lead to the reactor melting, or exploding, under tremendous heat, resulting in uncontrolled release of nuclear radiation.
This is what happened in the Fukushima disaster of 2011. The reactors were not damaged by the massive earthquake and tsunami. In fact, they automatically shut down their operations, as designed. But the regular power supply, as well as the backup generators, had failed due to rain, storm and flooding, rendering the cooling system non-functional.
The Fukushima disaster had prompted a discussion on installing ‘passive’ systems that would not be dependent on power supply, not just for cooling but also for other crucial safety features. An example, in the case of cooling systems, could be a water pumping facility relying on gravity.
The Zaporizhzhia nuclear station is reported to have some of these ‘passive’ systems as well, but it is not clear how effective they might be in case of a prolonged power outage.
Is there a possibility of human intervention of a non-military nature as well?
There is always the possibility of inadvertent, potentially disastrous errors by overworked or stressed-out engineers. Nuclear stations usually allow for some redundancy in their staffing to account for the stressful nature of the job, and to ensure very high safety standards. The Chernobyl disaster of 1986, the worst nuclear accident in history, is understood to have been triggered by a human error.
There are other threats as well. Rogue elements could try to utilise the war situation to steal nuclear material from the site. Ukraine is a signatory to the Nuclear Non-Proliferation Treaty as a non-nuclear weapons state. Each of its nuclear facilities is under IAEA safeguards. That means every bit of nuclear material and fuel, every kilogram of uranium and every gram of plutonium, has to be accounted for and reported.
But the region is in chaos, and rogue elements can try to use nuclear material to make dirty bombs, or to sell it in the illegal international nuclear market. It is not clear, for example, where all the fighters of the mercenary Wagner army are as of now.
