Chernobyl, Ukraine CNN  — 

The sudden ear-piercing beep of a radiation meter fills the room as a Ukrainian soldier walks in. This is where Russian soldiers were living at the Chernobyl nuclear power plant, and radiation levels are now higher than normal.

There’s no visible presence of the source of the radioactive material in the room, but Ukrainian officials say it’s coming from small particles and dust that the soldiers brought into the building.

“They went to the Red Forest and brought radioactive material back with them on their shoes,” soldier Ihor Ugolkov explains. “Other places are fine, but radiation increased here, because they were living here.”

CNN was given exclusive access to the power plant for the first time since it came back into Ukrainian control.

Officials at the plant explain the levels inside the room used by Russian soldiers are only slightly above what the World Nuclear Association describes as naturally occurring radiation. One-time contact would not be dangerous but continuous exposure would pose a health hazard.

“They went everywhere, and they also took some radioactive dust on them [when they left],” Ugolkov adds.

It’s an example of what Ukrainian officials say was the lax and careless behavior of Russian soldiers while they were in control of the site of the 1986 nuclear disaster. The area around Chernobyl, namely the Red Forest, is still the most nuclear contaminated area on the planet, with most of the radioactive particles present on the soil.

Ukrainian officials have released drone footage of what they say were trenches dug by Russian soldiers in that area, which is particularly radioactive. At a safe location, on the edges of that area, CNN saw a Russian military ration box that exhibited radiation levels 50 times above naturally occurring values.

A Ukrainian soldier holds a radiation meter against a Russian military ration pack.

Russian soldiers held Chernobyl for a month and are thought to have been operating in contaminated areas most of the time.

“It’s crazy, really,” Ukrainian Energy Minister German Galushchenko tells CNN at the plant. “I really have no idea why they did it (go into the Red Forest).

“But we can see they went in there, the soldiers who went there, came back here and the level of radiation increased.”

Although Chernobyl is not an active power plant, the sarcophagus above the reactor that exploded nearly 36 years ago needs to be maintained to avoid further radiation leaks. There is also a considerable amount of spent nuclear fuel that needs to be looked after.

“That confinement is supposed to have electricity, it’s supposed to have the ventilation system and so on,” Galushchenko explains. “When the country cannot control this, and we are responsible, Ukraine is responsible for the security, of course, that is a threat.”

Ukrainian Energy Minister German Galushchenko says Russian soldiers have behaved irresponsibly in and around Ukrainian nuclear power plants.

Part of that threat also came from how Russian soldiers managed those responsible for maintaining the nuclear facilities.

[Our staff] were here from the first day of occupation, and they only had the possibility of being replaced a month later,” he says. “When people are physically and morally exhausted, when you are under threat of guns, and you have this everyday pressure from the soldiers, it’s really a very difficult job.”

Volodymyr Falshovnyk, 64, is a shift manager at Chernobyl. He returned to the power plant on March 20 when the Russian military allowed the fatigued personnel to rotate with their colleagues from the nearby city of Slavutych, where many of the plant’s workers live.

Volodymyr Falshovnyk, 64, shift manager at Chernobyl.

He says the staff were working under tremendous pressure, not just because of what was happening at Chernobyl, but also because of the news they were receiving from the outside world.

“Our relatives began to call and say that the city was being stormed, that there were wounded and dead,” he says. “We asked the Russians what was going on and they said there were no regular Russian troops there but we continued to hear that there was shelling.”

Falshovnyk also accused the Russian soldiers of looting the power plant.

“They gave us personnel from Rosatom (Russian Nuclear Agency) to escort us, and in their escort we toured the uncovered warehouses. They robbed these warehouses all the time,” he adds.

Russian soldiers ransacked the room where the plant staff were sleeping, looting some of their belongings, Falshovnyk says.

Operating under those conditions was intense, but nothing compared to what the security staff endured.

The 169 Ukraine National Guard soldiers, who guarded the facility, were locked in the plant’s Cold War era underground nuclear bunker, crammed up in tight quarters without access to natural light, fresh air or communication with the outside world, according to the Ukrainian Interior Minister.

“They were kept here for 30 days without sufficient lighting and food. They were not allowed outside. On the last day they were taken away from here to an unknown direction,” Denys Monastyrskyy says while standing inside the bunker.

The minister says he believes the men have been taken to Russia, via Belarus, as prisoners of war, but doesn’t know for certain.

“Today we know nothing about their fate unfortunately,” he says.

Ukrainian National Guardsmen were detained by Russian soldiers in Chernobyl's own underground nuclear bunker.

CNN was shown inside the bunker and other places usually occupied by the plant’s staff by Ukrainian officials who claimed Russian soldiers had ransacked the place. Clothes, hygiene supplies and other personal belongings were scattered all over the floor.

“The Russian military went through all Ukrainian clothes, personal belongings, like dogs, in search of, probably, money, valuables, laptops,” Monastyrskyy continues. “There was looting here. The Russian military stole computers and equipment.”

Moscow has said very little about what its soldiers did at Chernobyl. The last time the Russian Ministry of Defense mentioned the nuclear site was on February 26, confirming its capture and claiming it had made arrangements to ensure the safety of power units, the sarcophagus and a storage facility for spent nuclear fuel.

Chernobyl is not an isolated case

Ukrainian officials say the behavior of the Russian military and the treatment of Ukrainian staff at the Chernobyl power plant highlights the danger posed by Moscow’s invasion as it gains control of plants in other areas.

In addition to the decommissioned reactors at Chernobyl, Ukraine has four active nuclear power plants, including the largest in Europe in Zaporizhzhia. The Russian military occupied that facility in early March, when it took control of the area, shelling some of site’s buildings in the process.

“The situation there is also horrible, especially taking into account how they capture Zaporizhzhia because they fired at the station, with heavy weapons,” Energy Minister Galushchenko says.

“It is really an act of nuclear terrorism,” he adds. “I’m not even talking that they are shelling the stations well as a situation in Zaporizhzhia NPP, but when we do not have the possibility of being responsible for nuclear security, there’s a threat.”

And despite Ukraine having regained control of Chernobyl, Ukrainian officials fear that Russian soldiers could try to come back.

“We understand that today we must be ready for a new attack on a nuclear power plant at any moment. We will use the best world experience to ensure that the station is protected as the border is only a few dozen kilometers away,” Interior Minister Monastyrskyy says.

“What we see [in Chernobyl] is a vivid example of outrage at a nuclear facility. It is the responsibility not only of Ukraine, but of the whole world, to keep the stations safe,” he says. “The whole world watched live as tanks fired at nuclear power units [in Zaporizhzhia]. This history must never repeat itself.”

Monastyrskyy says in order to do that his country needs continued international support.

“We are ready to invest in the future of Ukraine and in the future security of the world,” he continues, repeating his government’s call for additional weapons to be sent to Ukraine.

“Today the border between totalitarianism and democracy passes behind our backs, the border between freedom and oppression,” he says. “We are ready to fight for it.”