Russia may have left Chornobyl, but top nuclear monitor warns of ongoing threat amid violence

The world's top nuclear monitor warned Tuesday that while Ukraine has regained control over the Chornobyl power plant, there's a need for ongoing vigilance at the infamous facility amid the war.

"The situation is not stable; we have to be on alert," International Atomic Energy Agency director general Rafael Grossi said on a visit to the facility prompted by concerns over Russia's earlier seizure of the power plant.

Grossi arrived just weeks after Russian forces retreated from northern Ukraine.

His visit was also 36 years to the day after a reactor at the plant suffered a meltdown in 1986. It was the worst nuclear disaster to date and left a vast area around the plant largely uninhabitable to this day and released nuclear material that contaminated areas beyond the country's borders.

Chornobyl's three other nuclear reactors continued to operate for 14 years after the accident; in 2000, the plant began the process of being decommissioned. That work is ongoing and involves decontamination of the plant and the area surrounding it, including any soil and water that may be radioactive, according to the International Atomic Energy Agency.  

Though the plant no longer provides power to Ukrainians, it will likely require monitoring for generations to come, the agency said.

On Tuesday's visit, agency inspectors moved new monitoring equipment into Chornobyl to re-establish a communication link that provides data from the facility to the agency's headquarters in Vienna.

During the initial attack on Ukraine, Chornobyl was disconnected from the country's central electrical grid by Russian forces. The station had backup generators, but if those failed, a sustained loss of electricity could have prevented the cooling of used fuel rods and led to a massive radiation containment failure at the facility.

"We were worried," a senior commander with Ukraine's National Guard told a CBC News crew at the site.

Oleksii, who did not want his surname or rank used, worried the Russians could return. 

"There is spent nuclear fuel, and when there wasn't electricity, it could have led to catastrophic consequences. A second Chornobyl," he explained.

Grossi underscored that danger.

 "What we had was a nuclear safety situation that could have developed into an accident," the international agency's director general said.

More work now needs to be done to ensure safety is guaranteed, he said.