A new cover for Chernobyl

The nuclear disaster of Chernobyl happened more than 30 years ago. During the meltdown of the reactor core in April 1986 and the subsequent hydrogen explosion, the original protective cover of the reactor was completely destroyed. The nuclear core of the reactor was wide open. Radioactive isotopes escaped into the environment, contaminating large parts of Ukraine, Belarus and other regions in Europe.

To contain the danger, engineers began constructing a steel enforced concrete structure, called a sarcophagus, around the reactor. It was supposed to enclose the reactor core and prevent the release of further radioactive substances. The sarcophagus looks somewhat like an air-raid shelter, several storeys tall.

But that bunker was not enough: wet weather the hastily constructed behemoth to decay. Parts of the steel reinforcements have corroded and, reportedly, there are even holes in the roof. Construction engineers can't even rule out the possibility that the construction may one day collapse.

A huge mobile hangar

Just years after the first sarcophagus was finished, in late 1986, it was clear that a new building would have to be built to cover the original protective shell. In 1997, the G-7 countries agreed to implement the plan. More than 40 countries participated in the financing, and construction started in 2010.

But the new shell was supposed to do much more than just protect the environment from radiation and to keep radioactive substances inside. The new construction was meant to offer a lasting solution for the future.

The dimension of the hangar was deliberately designed to facilitate the demolition and safe removal of radioactive debris from the destroyed reactor. For the clean-up, the building is equipped with two huge hanging bridge-cranes, which run on parallel rails on the ground and ceiling of the building.

The hall is supposed to stand for 100 years. This timeframe also sets the stage for the removal and clean-up of the destroyed reactor building. The removal will be a huge task, however, since the reactor still contains an estimated 150 tons of nuclear fuel.

When exactly the work can begin remains unclear. Only one thing is certain: at this point, Ukraine cannot afford to pay for the huge task.

A building of superlatives

The new protective shell is one of the largest dome constructions in the world. At 108 meters tall, it is exactly one meter taller than the current record-holder, the former CargoLifter  zeppelin hangar in Brand, Germany, south of Berlin.

Its span is considerably bigger - at 257 meters it exceeds the decommissioned Brand hangar by 47 meters. Only in length does the Chernobyl shell play second fiddle - it is 162 meters long, while the hangar in Brand is more than twice that size.

The new building offers some other impressive records: it can withstand an earthquake of magnitude 6 as well as a level-3 tornado. Its foundations alone consumed as much steel-enforced concrete as a fifth of the old sarcophagus. With 36,000 tons of steel, it is the world's heaviest mobile building.

The whole structure was not built on the spot but at a safe distance. It was moved to its final destination on special rails - at an impressive speed of ten kilometers per hour - with the assistance of a mighty hydraulic system. Today, the construction companies will hand the building over to Ukraine during an inauguration ceremony.