Russia’s war in Ukraine

Backup diesel generators were “immediately activated” at the Zaporizhzhia nuclear power plant on Thursday to avert a “radiation disaster,” Ukrainian President Volodymyr Zelensky said.

“Today, for the first time in history, the Zaporizhzhia nuclear power plant stopped,” Zelensky said in his nightly address Thursday.

“The emergency protection of the power units worked — after the last working line of the plant’s power return to the Ukrainian power system was damaged by Russian shelling,” he said.

CNN is unable to verify who is responsible for the shelling, as both sides have accused the other.

There were originally four power lines supplying electricity to the plant; three were out of action due to the ongoing fighting around the facility. The last remaining power line supplying electricity to the plant went offline Thursday, requiring the diesel generators to be used. The power on the last remaining line has since been restored as of Thursday evening. 

“The world must understand what a threat this is: If the diesel generators hadn’t turned on, if the automation and our staff of the plant had not reacted after the blackout, then we would already be forced to overcome the consequences of the radiation accident,” Zelensky said. 

The generators are installed to supply power to cooling pumps to stop the fuel from overheating in the event of a blackout, but are not fully reliable, the CEO of Energoatom, Ukraine’s state energy operator, Petro Kotin, told CNN on Monday. 

“Russia has put Ukraine and all Europeans in a situation one step away from a radiation disaster,” Zelensky alleged. 

The International Atomic Energy Agency and other international bodies “must work much faster than they’re acting now” he said, “because every minute the Russian troops stay at the nuclear power plant is a risk of a global radiation disaster.”

More background: The Zaporizhzhia nuclear power plant is currently not supplying electricity to Ukraine — it is off the grid — however, the reactors need to continue to receive electricity so they can safely operate and avoid a nuclear accident. 

The reactors must have backup power supplies so the systems that provide cooling for spent fuel elements and cooling of residual heat produced in shut down reactors continue to work safely. The electricity to the plant is also needed for maintaining services such as lighting, and ventilation to the reactor.