More than 100 employees then found themselves trapped at the site of the Ukrainian power plant, the scene of the worst civilian nuclear accident in history in 1986, as Moscow forces advanced from the Belarusian border towards kyiv.

The capture of Chernobyl led to difficult weeks which saw electricity briefly cut off and personnel closely watched by the new masters of the place.

“We weren’t mentally ready for that, but we had no other possible way out,” Oleksiï Chelesty told AFP.

As head of the night shift, he supervises a dozen people responsible for monitoring the electricity supply to the site, where the radioactive remains of the damaged reactor have been covered with a giant sarcophagus.

As a result of the 1986 disaster, thousands of Ukrainian employees supported by international experts are tasked with daily monitoring of radioactivity levels. They have been following a specific program for years.

When Russian troops took over the plant holding the workers captive, they also cut the site off from the world.

“I understood that an accident was possible, but the emotional and psychological pressure did not allow me to think about it. We were just trying to do our job and control all the parameters so that nothing happened,” says Mr Chelesty .

– Radioactive trenches –

The most harrowing period of the occupation began on March 9, when electricity was cut off at the site due to nearby fighting. According to the experts, an accident of the magnitude of 1986 was however excluded, in the absence of a working reactor.

For days, the workers relied first on their diesel reserves, then on fuel provided by the Russians, until they were able to bring in electricity from neighboring Belarus.

All the while, Ukrainians trapped at the site could only get snippets of what was going on outside Chernobyl by listening to radio broadcasts and occasionally calling home via one of the landlines of the power plant.

“It was mentally and emotionally difficult,” says Oleksiï Chelesty, revealing that the employees were closely watched and forced to navigate through a complex network of Russian checkpoints, which made it difficult to move around the site.

Ukrainian authorities have accused Russia of showing a complete disregard for security during its occupation of Chernobyl, saying Russian soldiers dug trenches and set up camps in the contaminated area, receiving heavy doses of radioactivity.

“They dug up the bare soil contaminated by radiation, collected radioactive sand in bags for their fortifications, they breathed in this dust,” Energy Minister German Galushchenko said in April.

The head of the International Atomic Energy Agency (IAEA), Rafael Grossi, had told him of an “increase in levels” of radioactivity at Chernobyl, but insisted that the situation was under control and did not present no danger.

Oleksiï Chelesty is not in a position to confirm the violations attributed to the Russians, because he is most often forced to stay at his job.

– “Worried and nervous” –

The neighboring town of the plant, Slavutych, where most of the employees’ families reside, was surrounded by Russian forces.

Mayor Yuri Fomichev had to manage perilous relations with troops in Moscow while trying to reassure workers’ families.

“I had to calm them down and explain that you have to be patient,” he explains.

For many residents of Slavutytch, a city built after the 1986 accident to accommodate the evacuees of the power plant, the new adventures of Chernobyl have a deja-vu effect.

“We were worried, nervous,” sums up Tamara Chyrobokova, 75, a former Chernobyl employee who settled in Slavutych after the disaster, saying she was like many Ukrainians “shocked” that Russia attacked her country.

The whole episode puzzled Oleksiï Chelesty, released after negotiations a few days before the Russians withdrew from the region to concentrate their forces on the eastern and southern fronts.

The Russian soldiers “said that they were trying to free me, but I did not understand from what”, ironically Oleksiï, referring to the assertions of Moscow, which claims to want to “denazify” the country.