Written by Steven Pike, Argon Electronics

Chernobyl’s new sarcophagus took two decades to make. Bigger than Wembley Stadium and taller than the Statue of Liberty, it is intended to seal in the entire disaster site for 100 years. It’s an extraordinary engineering effort.

Chernobyl

On 26 April 1986, the fourth reactor at the Chernobyl nuclear power plant exploded during a routine stress test. A fire raged for nine days. The steel and concrete containment shell collapsed, and the super-heated fuel melted through the floors into the basement beneath. The exposed, burning reactor spewed radioactive isotopes into the atmosphere. The fallout reached across Europe as far as Scandinavia, but the worst-hit regions were in Ukraine, Belarus, and Russia.

The Chernobyl disaster still casts a pall over nuclear power. Even major disasters such as Fukushima are measured against it. Yet Chernobyl also set in motion a series of measures to ensure nuclear safety around the world.

The First Sarcophagus

In total, around a million men and women, known as liquidators, were drawn from across the Soviet Union to help with the initial clean-up and containment. Helicopters flew over the reactor, dropping sand, lead, and other substances to extinguish the fire and prevent radiation from escaping. Coal miners dug underneath the reactor’s core so that liquid nitrogen could be pumped in to cool the nuclear fuel.

Others removed contaminated materials and evacuated civilians. Reports differ, but some suggest that thousands of these liquidators died during their work. The consensus is that most of them suffered horrific long-term illnesses from acute radiation exposure.

With the clean-up complete, it took a further nightmarish 206 days to build the first sarcophagus, using 400,000 cubic meters of concrete and 7,300 tonnes of metal framework. Workers operated in 24-hour shifts but only for very limited times, throwing their clothes away after finishing work.

Despite the heroic efforts of liquidators and construction personnel, the first sarcophagus was never meant to last, and a long-term solution was still needed. Yet until the Soviet Union collapsed in 1991, the true situation at the site remained unclear. In the chaos that ensued, the International Atomic Energy Agency (IAEA) took charge, quickly commissioning a project to understand how Soviet-designed reactors operated and could be contained.

Seeking a Permanent Solution

A few months after the Soviet flag was lowered over the Kremlin for the last time, Ukraine launched an international competition for ideas about how to make Chernobyl safe again. But when the idea of building a vast structure at Chernobyl’s ground zero—where radiation levels remain hazardous to this day—was first put forward in the 90s, many thought it was impossible.

The call was won by a French consortium with a plan called ‘Resolution’. It was justifiably ambitious, involving encasing the entire Soviet-built sarcophagus, with the damaged reactor inside it, within a whole new structure. But the checklist for such an edifice was daunting.

It would have to be enormous. It would have to last for at least 100 years. And it would have to be built on the doorstep of a highly radioactive site without risking the safety of the workers—and then moved to its final position, further than anything that big had ever been moved before.

Unsurprisingly, it took a decade to get events moving. With the first sarcophagus beginning to deteriorate, in 1997, the leaders of the G7 agreed to put $300 million into the project.

The project became known as the Shelter Implementation Plan, and its first task was to shore up the existing sarcophagus to stop it from collapsing. This was hazardous as the concrete structure, hastily erected in awful conditions in the months immediately after the accident, was stopping further fallout from being spewed into the atmosphere.

Radiation levels inside were estimated to be as high as 10,000 röntgens per hour, 20 times more than a lethal dose. A straightforward repair project was out of the question; the whole structure teetered on the verge of collapse. It would take another 10 years to ready the site for the new structure.

A Lasting Solution. The Second Sarcophagus. 

The vast structure of the new containment unit was erected 300 meters away from the accident site to minimise radiation exposure for the workers. Once complete, it would be moved into position.

The segments of the sarcophagus were built and pre-assembled in Italy. From there, they were shipped by sea to Ukraine, then taken by road to the Chernobyl site. It was a gargantuan logistical effort, taking 18 ships and 2,500 truck movements to complete the task. With the components on site, the basic framework was erected in late 2014. By then, it was 28 years since the Chernobyl accident. In that time, Ukraine had gone through two revolutions and now found itself in the midst of a full-scale war in Crimea.

Over the next two years, the interior of the sarcophagus was assembled, including advanced ventilation systems and remote-controlled robotic cranes that would dismantle the existing Soviet-built structure and reactor once the new one was sealed.

The entire building was moved into its final resting place on 29 November 2016, 30 years and seven months since the explosion that set all of this in motion. More than 10,000 people were involved in this project.

Conclusion

The New Safe Confinement (NSC) has now been in place for some years and is already undergoing upgrade and maintenance work while the original structure inside is carefully and robotically dismantled.

It is hoped the second sarcophagus will draw a line under this catastrophic chapter in the history of nuclear energy. Its ambition is a symbol of what mankind’s engineering genius can achieve when the stakes are at their highest.


About the Author

Steven Pike is the founder and Managing Director of Argon Electronics (UK) Ltd. A graduate of the University of Hertfordshire, Steven has been awarded a number of international patents relating to the field of hazardous material training systems and technology.