For more than three decades, very little has disturbed the Chernobyl exclusion zone: 2,600 square kilometres of contaminated land and the most visible legacy of the worst nuclear accident in human history.
The Ukrainian territory — an area larger than the Australian Capital Territory and bordering Belarus — has been deemed uninhabitable due to high levels of radiation. In the absence of a human population, wildlife has reclaimed the space, silently creeping through the dilapidated remains of a once-thriving community.
At the centre, sits the defunct Chernobyl nuclear power plant; the imposing dome of the New Safe Confinement structure, built in 2016 to contain the epicentre of the disaster, looming large over the landscape.
Inside is more than 200,000 kilograms of radioactive material, according to the World Nuclear Association, with some estimates suggesting it will remain that way for thousands of years.
Just three kilometres away from the plant is Pripyat, a ghost town once home to about 50,000 thousand residents, mostly made up of Chernobyl workers and their families. In 1986, 36 hours after reactor number four exploded spewing radiation into the atmosphere, all were evacuated. Many would never return.
Aside from a growing stream of "dark" tourists, eager to see the destruction for themselves, and workers tasked with protecting the security of the site, measuring radiation levels, and overseeing the process of decommissioning the reactors, the exclusion zone has, as intended, remained relatively deserted.
That is until February 24, the first day of Russia's invasion of Ukraine, when troops rolled in, kicking up dust in their wake. (A spike in radiation levels was put down to the increased activity causing radioactive dust to rise into the air.)
Within hours, the International Atomic Energy Agency (IAEA), a body within the United Nations tasked with promoting the safe use of nuclear technology, announced armed forces had taken control of the Chernobyl facility. Inside, they said, 211 plant workers were being held hostage.
In the three weeks since, the workers have dutifully reported for their shifts, only now there is no one to replace them at knock-off. Instead of returning to their homes in the nearby town of Slavutych — built in the wake of the disaster as housing for Pripyat's former residents — they're sleeping on makeshift beds inside the facility.
There are now grave fears for the Ukrainian staff, who IAEA Director General Rafael Grossi says are working "under enormous stress without the necessary rest".
There are also concerns their mental and physical state could impact the safety of the site. Last week, Ukraine's nuclear regulator reportedly told the IAEA staff were "no longer carrying out repair and maintenance of safety-related equipment, in part due to their physical and psychological fatigue after working non-stop for nearly three weeks."
In an article on Tuesday, the Wall Street Journal detailed tense conditions within the facility. Workers were being shadowed by Russian soldiers, they reported, and arguments were starting to erupt.
There's so far been no indication when, or if, they will be relieved from their duties.
A worsening crisis
Over in Slavutych, the mayor and family members of the trapped workers have been desperately calling for a safe corridor to allow them to leave freely.
This week, they held an emotional rally calling for more to be done to help their loved ones. In a show of defiance, the local council announced on Facebook that 14 children have been born in the city since the start of the war. "Most girl's parents plan to name them Victoria," the post reads. "Victory is upon us."
But people in town are facing their own challenges. Getting food to the city, by now surrounded by Russian forces, has become difficult. There is no safe way for residents to access Kyiv. Air sirens come in the form of church bells and honks from police vehicles.
On March 9, two weeks after Russia seized the exclusion zone, attacks damaged both power lines supplying the plant. The same outage affected Slavutych, with residents unable to heat their homes and forced to resort to cooking on outdoor campfires. Tents were set up to allow residents to charge their mobile phones and batteries.
While Chernobyl no longer generates nuclear power — the last reactor was decommissioned in 2000 — access to the electricity grid is required to maintain cooling systems in the site's spent fuel storage facility. Following the outage, a back-up diesel generator was quickly kicked into gear while work to fix the damaged lines commenced.
At the time, Grossi expressed "deep concern" about the development but added that the outage would "would not have a critical impact on essential safety functions" because the "volume of cooling water in the pool is sufficient to maintain effective heat removal of spent fuel without a supply of electricity".
Nevertheless, he said, "the lack of power is likely to lead to a further deterioration of operational radiation safety at the site and create additional stress" for the workers living at the facility around the clock.
But Ukraine's Deputy Prime Minister Iryna Vereshchuk offered a grimmer outlook when she spoke to ABC's Four Corners, warning of a potential nuclear catastrophe if the site was cut off from the grid.
"This is a threat not only to Ukraine but to Russia and the whole world," she said. As of Friday, external power has been restored for now.
Could a disaster like 1986 happen again?
The world's worst nuclear accident began as a routine test. At 1:23 am on April 26, 1986, plant operators wanted to see if they would be able to cool the reactor's core in the event of an emergency.
Chernobyl used Soviet-designed RBMK-type reactors, now understood to have inherent safety flaws. When power to the reactor began to fall, the poor design coupled with inadequately trained personnel led to a catastrophic meltdown.
A series of explosions blew the 1,000-tonne roof off reactor four. The radiation released in the aftermath was 100 times higher than that unleashed by the atom bombs dropped on Nagasaki and Hiroshima during World War II.
The death toll from the disaster remains disputed. The official number of deaths recorded as a direct result of the accident stands at 31, but a United Nations report investigating "the true scale of the accident" has estimated up 4,000 people could eventually perish due to radiation exposure.
Tony Irwin has spent his career operating big nuclear plants in the United Kingdom and was part of a team sent to the then-Soviet Union in the wake of the Chernobyl accident to improve nuclear safety standards.
Now a consultant and Honorary Associate Professor at the Australian National University, he says the risk of a disaster at Chernobyl, like what happened in 1986, is virtually non-existent.
"Because the fuel is so old, there's not a lot of heat being produced by it," he says. "There's the potential for bushfires in the area and more airborne radiation, but it's still relatively low levels. I don't think there's a situation at Chernobyl that can get really, really bad."
Prior to the invasion, he says, the plant was in the process of transferring approximately 20,000 spent fuel assemblies from cooling ponds to a new dry storage facility.
"The bottom line in Chernobyl is there are no major hazards," he says. "The main thing is we're not progressing with the decommissioning of that pump."
Ukraine's nuclear landscape
While Chernobyl looms large in the public's collective consciousness — even more so after the 2019 release of a chilling HBO mini-series about the disaster — it's not Ukraine's only nuclear power plant.
Across the country, there are 15 nuclear reactors, eight of which remained active as of Friday. Before the invasion, they produced about half of the country's power.
In the south-east of the country, in Enerhodar, lies the six-reactor Zaporizhzhia plant — the largest in Europe — which, unlike Chernobyl, is still in operation.
It, too, has been seized by Russian military, effectively giving President Vladimir Putin control of 25 per cent of the country's electricity supply.
"The big thing about Zaporizhzhia is it's not a Chernobyl-type reactor," Irwin says. Known in Russia as a VVER, this type of reactor runs on pressurised water and is surrounded by a thick, steel-lined concrete containment vessel that has been designed to withstand impact from planes. It's the same style of reactor built in the West and seen most commonly across the globe.
"It's not as vulnerable to accidents as a Chernobyl type reactor," Irwin adds, "but, having said that, a war around any operating reactor is not a good thing."
Russian forces gained control of the facility on March 4, but the Ukrainian workforce has been permitted to go home between shifts, according to the IAEA. Earlier this month, the regional military administration announced Russian attacks at the site had caused a fire that damaged the plant's number one reactor, but ultimately did not impact its safety.
In an emotional middle-of-the-night address immediately following the attack, Ukrainian President Volodymyr Zelenskyy said he feared an explosion at Zaporizhzhia could mean "the end of Europe".
"Do not allow the death of Europe from a catastrophe at a nuclear power station," he urged. Ukraine's Foreign Minister Dmytro Kuleba was similarly concerned. "If it blows up, it will be 10 times larger than Chernobyl," he warned as he called for a ceasefire.
The site has also been plagued by power outages after three of five external power lines were damaged. As a result, only two of the six reactors are still operating. As of Friday, the IAEA reported that Zaporizhzhia had decreased its power generation to about half of its maximum capacity, but added again that there were no safety concerns.
If external power was completely cut, the site would need to be shutdown. To do this safely, there are two key steps: control rods need to be inserted to stop the fission reaction and the decay heat needs to be removed. The first, Irwin says, is relatively easy, but the latter would require the emergency core cooling systems to function effectively.
"The very worst case would be if they can't remove the heat and the core melts," he says. But even in that scenario, he predicts, much of the damage would likely be contained within the reactor's mammoth containment shell.
"The Russians don't want any major release activity because it obviously affects their army, and you could get radioactive clouds all over Russia as well," he says. "These are Russian-designed reactors, so the Russians know very well what they have to do to operate these reactors and what's required to keep them safe."
But that's likely of little consolation to the Chernobyl workers, who are now in their fourth week trapped inside one of the most radioactive places on earth.
