A 32,000-tonne arch that will end up costing $1.5 billion is being built to eliminate the risk of further contamination at the site of the 1986 nuclear reactor explosion.
Against the decaying skyline here, a one-of-a-kind engineering project is rising near the remains of the world’s worst civilian nuclear disaster.
An army of workers, shielded from radiation by thick concrete slabs, is constructing a huge arch, sheathed in acres of gleaming stainless steel and vast enough to cover the Statue of Liberty. The structure is so otherworldly it looks as if it could have been dropped by aliens onto this Soviet-era industrial landscape. If all goes as planned, by 2017, the 32,000-tonne arch will be delicately pushed on Teflon pads to cover the ramshackle shelter that was built to entomb the radioactive remains of the reactor that exploded and burned here in April 1986. When its ends are closed, it will be able to contain any radioactive dust should the aging shelter collapse.
By all but eliminating the risk of additional atmospheric contamination, the arch will remove the lingering threat of even a limited reprise of those nightmarish days 28 years ago, when radioactive fallout poisoned the flatlands for miles around and turned villages into ghost towns.
The arch will also allow the final stage of the Chernobyl cleanup to begin — an arduous task to remove the heavily contaminated reactor debris for permanent safe storage. That this job will fall from international hands to those of Ukraine presents new worries, especially as Russia threatens the nation’s borders.
For now, the rising arch is a sign of progress.
“It’s an amazing structure. You can’t compare it to anything else” said Nicolas Caille, project director for Novarka, the consortium of French construction companies that is building it.
With nations debating the future of atomic power as one way to reduce greenhouse-gas emissions and fight climate change, the arch is also a stark reminder that nuclear energy, for all of its benefits, carries enormous risks. When things go wrong, huge challenges follow.
Containment and cleanup push engineering capabilities to their limits, as Japan is also finding out since the meltdowns at the Fukushima power plant three years ago.
The costs are enormous — the Chernobyl arch alone will end up costing about $1.5 billion, financed largely by the United States and about 30 other nations.
Engineers have designed the arch to stand for 100 years; they figure that is how long it may take to fully clean the area. But there have always been questions about Ukraine’s long-term commitment, and the political turmoil and tensions with Russia have raised new concerns.
The arch, though, is a formidable structure, said Vince Novak, the director of nuclear safety for the European Bank for Reconstruction and Development, which administers the project’s financing. If necessary, he said, “it might be able to last 300 years or more.”
Like a huge dirty bomb
The Chernobyl accident can be likened to a huge dirty bomb, an explosion that spewed radioactive material in all directions.
In this way, the disaster differs from nuclear power’s two other major accidents, at Three Mile Island in Pennsylvania in 1979 and Fukushima in 2011. At both of those plants, reactor cores melted down, but the core material — the nuclear fuel — remained within protective containment structures.
The four reactors at the Chernobyl plant had no such containment. The system for controlling the nuclear fission reaction was temperamental, and under certain conditions reactor power could quickly soar out of control.
That is what happened in the early hours of April 26, 1986, at Chernobyl’s Unit 4, during an ill-advised test of some of the reactor’s safety systems. In a matter of seconds, the reactor power rose exponentially and the core was blasted apart by steam.
A few workers died immediately, but most of the technicians in Unit 4, and the firefighters who initially responded, suffered agonising deaths over the ensuing weeks.
Officially, several dozen people were killed. The radiation also caused thousands of later cancers — though just how many is still the subject of much debate.
In the immediate aftermath, the Soviet authorities brought in the military to fight the reactor fire and evacuate nearby villages and the city of Pripyat, home to most of the plant workers and their families. Labourers were enlisted to hastily build the concrete-and-steel shelter, known as the sarcophagus. When their radiation exposure grew too high, the workers were replaced; in all, more than half a million people were involved in the initial cleanup.
That was nearly three decades ago. But in Chernobyl, it is as if the calendar froze.
The human toll
On the night of the accident, Andrei Glukhov was at home, off from his job as a nuclear safety specialist at Chernobyl. When he heard the explosion he was not overly concerned — loud sounds occasionally came from the plant.
The next morning, he telephoned the Unit 2 control room. A technician told him they were increasing power to make up for the loss of Unit 4. “What happened to Unit 4?” Glukhov asked. “Look out the window,” the man replied.
Glukhov, who lived with his wife and two young children in an apartment building, was less than two miles away, in Pripyat.
Telling his family to stay indoors, he left to offer help. Most of Pripyat’s residents received no such warning and went on with their day, oblivious to what was by then a severe radiation hazard. It was a Saturday.
On Sunday morning, the residents were told that in a few hours they would be evacuated by bus and were advised to bring a few possessions.
Glukhov, now 55, and his family headed toward Kiev. But halfway to Kiev, he said goodbye and hitched a ride back.
Glukhov, who now helps manage the arch project, said he cannot forget the sight that greeted him when he got back to Chernobyl.
“I realised the scale of the disaster when I saw the open core, glowing,” he said. “I don’t wish anyone would ever see it.”
Artur Korneyev has seen the core, again and again. Korneyev, 65, a radiation specialist and native of Kazakhstan, first came to Chernobyl shortly after the accident. He understands more than most people the extent of the radioactive mess that remains in what was Unit 4.
While the number of radioactive particles released during the explosion and subsequent fire was enormous, they came from only about five tonnes of reactor fuel. Close to 200 tonnes of fuel remain in the bowels of the destroyed building. Korneyev’s job was to locate the fuel.
These days Korneyev works in the project management unit, but because of his health — he has cataracts and other problems related to his heavy radiation exposure — he is no longer allowed inside the plant.
Korneyev was one of the first people to alert Western experts that the sarcophagus was in poor shape. Alarmed at the possibility of another large release of radioactivity, the group of seven nations agreed in 1995 to finance work to make Unit 4 safe. In return, Ukraine agreed to close the two Chernobyl reactors that were still operating; the last was shut in 2000.
Keeping a steel structure standing for a century is normally a straightforward task, Caille said. It’s all about controlling rust.
“Painting,” he said. “The Eiffel Tower, for example, is painted every 15 years.”
But when the arch is in place over the ruined Unit 4 reactor, radiation levels will be high. There would be no safe way for workers to scrape and repaint. So the design goes to great lengths to eliminate the risk. Both the exterior and interior are being sheathed in rustproof stainless steel. The arch trusses are made from conventional steel, as are the 580,000 bolts that will hold the pieces together. Dehumidifiers will treat the air that will be circulated around them.
Even before the current political upheaval, Novak said, there were concerns about having to ask donors to contribute more money. “But the risk of leaving this whole programme unfinished is a prospect which I don’t think anyone would want to contemplate,” he said.