Thirty years since the world’s worst nuclear accident, engineers are sliding a giant shield over the Chernobyl reactor to finally enable its deconstruction and decontamination. By Katie Silver.
New Safe Confinement in Chernobyl
It’s being hailed as one of the most ambitious projects in the history of engineering. Against the backdrop of a deserted industrial wasteland, a giant arched hangar is being slid atop the wreckage of the world’s worst nuclear accident.
Three decades have passed since reactor 4 at the Chernobyl nuclear power plant exploded, but it’s only now that real progress is being made towards dismantling the ruined equipment and decontaminating the site and its surroundings.
A combination of errors caused one of Chernobyl’s four 1000-megawatt reactors to go into meltdown on Saturday, April 26, 1986, near the city of Pripyat in the far north of Ukraine. Just after 1am engineers were stress-testing the steam turbines. They wanted to make sure the turbines would keep the coolant pumps running in the case of a power outage. Deliberately switching off the safety systems, they began lowering the power. It dropped quicker and further than they expected, so they slowly increased the power again. Thirty seconds later there was an unexpected power surge, but a flaw in the Soviet-designed reactor made the emergency shutdown mechanism fail. The first explosion occurred at 1.23am, shooting a fireball into the sky. It was followed by a second more powerful explosion. Fires would continue to burn for about two weeks.
Chernobyl had been the only nuclear accident to receive the maximum classification from the International Atomic Energy Agency until the disaster at the Fukushima plant after Japan’s devastating earthquake and tsunami in 2011.
The Chernobyl plant became part of newly independent Ukraine after Mikhail Gorbachev’s reforms ended in the United Soviet Socialist Republic’s dissolution. Its remaining three reactors continued operating until the last was switched off in 2000.
In the immediate aftermath of the disaster, the difficult political climate stalled efforts to clean up the site. The Kremlin reportedly withheld information about its former facility from the Ukraine government. A massive concrete shield was built on top of the ruins of reactor 4 – nicknamed the “sarcophagus” – but it was done hastily, with reports since of leaks, blowouts and emissions of radioactive dust. An exclusion zone initially of 30 square kilometres was declared, much of which has since returned to forest. Much radioactive material has remained in situ since the accident, and the sarcophagus has long been considered unsound and at risk of collapsing, resulting in further radiation of the atmosphere.
There have been many delays in plans to complete the dismantling of the nuclear plant and decontamination of the site.
“Everybody was struggling to figure out what the solution should be. There were literally hundreds of ideas of what to do,” says Vince Novak, head of nuclear safety at the European Bank for Reconstruction and Development (EBRD).
The bank funded about half of the €1.5 billion ($2.16 billion) project to put in place the new arched shield over the reactor’s sarcophagus. The New Safe Confinement (NSC) is the largest moveable land-based structure ever built. Its purpose is to allow for the safe demolition of the sarcophagus and the removal of radioactive material, in order to rehabilitate the site.
“It provides a shield which will finally protect the environment and people,” says Novak, “and importantly, it has been designed in such a way that even if the shelter collapses, its function will be maintained.”
Resembling the stage of a music festival, the NSC’s size is astonishing. Tall enough to house London’s St Paul’s Cathedral, or Notre Dame in Paris, it is twice the length of a 747 commercial jet. It weighs about 36,000 tonnes. Engineers began the process of sliding the NSC into place last week, and at the time of writing the complex operation was continuing.
The NSC’s outer shield looks like nothing more than metallic sheeting, but Novak describes it as a very complicated sandwich of different materials that makes it resistant to fire, humidity and radiation. The most remarkable part of the equipment is a crane inside, which will allow engineers to dismantle reactor 4.
While the Ukrainian government agreed to the design in 2004, much work was needed to bring the plan into operation. “It was a difficult regulatory and technical task that no one has done before. You could not make a wrong decision,” says Novak.
A massive space 300 metres away from the reactor site had to be cleared – requiring the removal of millions of tonnes of soil – so that workers could assemble the shield at a site with less radiation. The engineers then needed to develop a special skidding system using hundreds of hydraulic jacks to push the arch into place.
The shield is designed to last at least 100 years, which Novak describes as “ample time for the dismantling to take place”. The plan is to have deconstructed the most unstable parts of the old sarcophagus by 2023.
Igor Gramotkin, director-general of the Chernobyl nuclear power plant, said: “For us the arch is not just 36,000 tonnes of prefabricated metal. It is 36,000 tonnes of our belief in success, of trust in our site, our people and in Ukraine.”
The effects of the Chernobyl disaster have been far-reaching and worsened by changing wind direction in the first few days after the explosions. Initially the wind was blowing north-west, spreading radioactive plumes over what is now Belarus, as well as Scandinavia and Britain.
“But then on the 30th of April, four days after, the wind direction changed and Kiev was hit,” says the BBC’s Olexiy Solohubenko, who was working as a radio reporter in nearby Kiev at the time and had to evacuate his young daughter. “Trains and planes were full, everyone was trying to leave. It was quite a dramatic escape.”
Solohubenko says the government clamped down on information and manipulated readings of radioactivity. “There was a great degree of secrecy at the time. We knew something was happening, but it was in the level of rumour. The chief sanitary doctor of the USSR was saying that the water was safe to drink. Then he saw the document [of radiation levels] and changed the parameters for drinking water. So it was safe according to the new limits.”
Ukrainians were also receiving conflicting advice, Solohubenko says, at different times being told to stay indoors or go outside, or to drink milk and then not to drink milk. “It was a very conflicting situation.”
Things were worse for the estimated 830,000 people who performed the rescue and clean-up immediately after the accident. They are known as liquidators.
“They were the real heroes. They came rushing into the nuclear stations thinking it was just a fire. No one knew it was radiation,” says Californian doctor Peter Gale, who treated about 200 liquidators in Moscow in the days following the accident.
“You needed to try and identify who is going to survive, and the group at the other extreme who is going to die, regardless of what we do. And then you had to focus your attention on the ones in the middle.”
Today’s engineers continue to face lethal conditions in the construction and ongoing operation of the NSC. Radioactive dust can reportedly deliver the permissible annual radiation dose in 12 minutes spent immediately above the sarcophagus. Large crews are required to work strict rotational shifts.
Aside from the long-term health effects of the disaster – which are contested, with Gale maintaining there is no long-term discernible change in cancer incidence, while a report commissioned by a German Green member of the European Parliament predicted 40,000 fatal cancers among other diseases – some attribute the fall of the USSR in part to the legacy of Chernobyl.
Solohubenko says the disaster “gave birth to the green environment movement, which caused lots of unrest for the government”. He witnessed rallies of tens of thousands of demonstrators with anti-nuclear, anti-government posters. “It was a very dramatic moment.”
In an essay included in Gerd Ludwig’s photo-documentary book The Long Shadow of Chernobyl, Gorbachev labelled the Chernobyl explosion a “turning point” that “opened the possibility of much greater freedom of expression, to the point that the system as we knew it could no longer continue”.
For the younger generation of Ukrainians, the New Safe Confinement represents a fresh start. Now 35, Oleg Karpyak was five years old when his grandmother told him about reactor 4 exploding.
Chernobyl has become a mysterious relic in pop culture, he says. “It has always been something of another time. It’s something you can read about and play computer games about.”
Karpyak says for many older Ukrainians, the word Chernobyl is fear-inducing. “People try to avoid it. For some saying its name is like saying the name of the devil.”
Virtually untouched by humans for the past 30 years, the exclusion zone is a thriving place for local wildlife. The Ukrainian national government is working to set up a UNESCO environment program on the site.
The presence of wildlife adds to the zone’s attraction as a fascinating destination for Karpyak’s friends, some of whom go hiking illegally there.
“There’s a sense of danger, history and beautiful scenery in those abandoned villages. We’re attracted to it for some mystical reasons. It’s one of the most interesting places on Earth I’ve ever seen.”
This article was first published in the print edition of The Saturday Paper on November 26, 2016 as "Nuclear shelter".
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