Ukraine on Sunday began shutting down the last operating reactor at the Zaporizhzhya nuclear power plant, after concluding that its continued operation could be a precursor to a nuclear meltdown at Europe’s largest nuclear power facility.
The United States and the International Atomic Energy Agency had been urging the move for weeks, and its inspectors only gained access to the facility a week ago. While a direct military strike on a reactor center could result in an accident, the risk is greatly diminished if the plant is not operating. Russian soldiers still occupy the factory, and there have been reports of workers operating the facility at gunpoint. But there have also been ongoing disagreements over who is bombing the facility, and whether to cut off the outside power that keeps important cooling systems running.
The move aims to put the last six operating reactors in a relatively safe state as battles rage around the facility in southern Ukraine. But it also means that if the plant is again cut off from external power, as it has at least twice in the past three weeks, it will need to rely on diesel generators to run the safety equipment. Generators may run out of fuel.
“A decision was made to shut down power unit No. 6 and transfer it to the safest state – cold shutdown,” the Ukrainian nuclear organization Energoatom said in a statement.
The Biden administration has been urging Ukrainian authorities to take this step for weeks, in both public and private statements. But US officials said the Ukrainians were hesitant. The plant, which is fully operational, provided about a fifth of Ukraine’s electricity supply. And there is a fear that Russia, once shut down, may seek ways to connect it to Russia’s network, rather than Ukraine’s.
But by Friday, it was clear there was little choice. And for a while, the power to the plant was completely cut off, including the usual power sources to run the cooling systems. It seemed unlikely that it would be fully restored, and Ukrainian officials argued that Russia was seeking a disaster that could then be blamed on Ukrainian factory managers.
“The bombing around the Zaporizhia nuclear plant must stop,” said Rafael Mariano Grossi, director general of the International Atomic Energy Agency, who visited the plant last week and left two full-time inspectors behind.
Grossi’s agency said two observers at the plant had been informed of the move and noted that restoring a backup power line to the complex meant it had “the electricity it needs to cool the reactor and other safety functions.”
Last week’s bombing cut off transmission lines that supply external power to the plant – which is occupied by Russian forces but operated by Ukrainian engineers – Disconnected from the Ukrainian national electricity grid. Petro Kotin, President of Energoatom, said in an interview that Ukrainian engineers used the plant’s only active reactor to power the plant’s safety and cooling systems because that was more reliable than using diesel generators.
The station has since been reconnected to the national grid. This allowed the engineers to begin shutting down the active reactor, keeping it in a safer state than if it were “hot” or actively producing power. The remaining five reactors are already in the process of cycling.
But the plant is far from the forest. The company’s statement noted that the risk of further damage to power lines “remains high,” and that if the plant has to rely on generators to perform critical cooling functions, the length of time it can operate is “limited by the technological resource and the amount of diesel fuel available.”
The shutdown of all reactors also means that a major source of electricity will not be available for a country already worried about the coming winter. Before the war, the power plant provided 20 percent of Ukraine’s electricity. But energy officials said the damage to transmission lines that carried electricity away from the plant was so extensive during the war that it was unlikely to provide a reliable source of power, they said.
International concern is growing about the safety of the plant as it has been repeatedly bombed over the past month. Russian forces turned the sprawling complex into a fortress, parked military equipment near the reactors and stationed hundreds of soldiers at the station.