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 dayand 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.

Monitoring levels at Chornobyl

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.

Russian troops refused to let Chornobyl workers leave

Chornobyl was among the first areas to be captured when the Russian invasion began on Feb. 24. It lies only 16 kilometres from the border with Belarus, through which Russian tanks poured into Ukraine.

On arrival, the Russian soldiers refused to allow station workers to leave as scheduled, prompting international warnings that employee exhaustion could lead to an accident at the sensitive site.

When they retreated from the site, Russian forces took 169 members of Ukraine's National Guard as prisoners, according to Ukraine's Ministry of Internal Affairs.

WATCH | When Russia took control of Chornobyl, plant workers' families raised concerns:

Chornobyl worker's daughter fears for his safety after plant loses power

3 years ago

Duration 2:30

The Chornobyl nuclear power plant in Ukraine has lost power, and the daughter of one plant worker says she's worried for her father's life and the safety of the plant itself.

Some Russian soldiers are said to have become sick after digging trenches in the contaminated no-man's land surrounding Chornobyl, according to Ukrainian officials within government and connected to Energoatom, the country's utility.

Signs in the area warn against disrupting dust and soil.

"There have been some moments when the [radiation] levels have gone up because of the movement of the heavy equipment that Russian forces were bringing here and when they left," Grossi said.

The International Atomic Energy Agency notes that exposure to low levels of radiation over a period of time is much less dangerous than a one-time exposure to a significant amount of it.

The Kremlin, meanwhile, has denied that its forces have put nuclear facilities inside Ukraine at risk.

Other reactors in areas of conflict

Ukraine has four other nuclear power stations, some of which have multiple reactors.

The Zaporizhzhia power station in the southeastern city of Enerhodar has six reactors, and the site came under fire from Russian forces early in the war. At the time, Grossi said a Russian projectile hit a training centre but not any of the reactors.

There is one other power stationnear the battered city of Mykolaivin the country's south,where Russian military activity has spiked after an operational reset that saw forces leave the north and concentrate their firepower in the south and east of the country.

A grim anniversary

Chornobyl is surrounded by a 20-kilometre exclusion zone. The once thriving towns that surround the plant have been largely abandoned, with thick brush obscuring many buildings from what was once a busy road.

In the aftermath of the 1986 explosion, a base was established for the hundreds of firefighters brought in from across the country in an attempt to manage the fire and radioactive scene.

In the same location, Chornobyl's fire station still stands.

On Tuesday's anniversary, dozens of firefighters paid tribute to their predecessors; many firefighters died in the days and years following the accident.

More recently, the fire station faced a new menace: the appearance of Russian soldiers at its gates.

"We were not ready for war," Col. Sergii Strelchenko said. "But we did our duty and our Ukrainian flag was always flying."