The operation to slide the two arches together required 24 precise connections on the 28,000 tonne structure to be aligned within millimetres of each other across the full 260-metre arch span. Operation “skid back” was successfully completed within a day and work has subsequently focussed on adjusting and tightening nearly 1,000 bolts to seal the two halves together.

In a statement, Vince Novak, EBRD (European Bank for Reconstruction and Development) director, Nuclear Safety said: “The construction of the New Safe Confinement steel structure is nearing completion and good progress is also being made on fitting the steel frame with the auxiliary systems and equipment essential for operation of the facility and deconstruction of reactor 4. We are confident that all work will be concluded by end-2017 as planned.”

The New Safe Confinement is being constructed to seal off reactor 4, which was destroyed in the 1986 nuclear accident at Chernobyl. The 110m high steel structure – which is 165m long and has an arch span of 260m – has been designed to protect the environment from radiation releases and provide the infrastructure to support the deconstruction of the shelter and nuclear waste management operations.

According to EBRD, remaining tasks include the installation of a sophisticated ventilation system which will keep the structure corrosion-free during its lifespan of 100 years, the construction of a technological building as the future control centre and fitting the arch with fully-automated cranes, tools for deconstruction and other auxiliary systems.

The New Safe Confinement is being constructed by the international consortium Novarka, led by Vinci Construction and Bouygues Travaux Publics. The New Safe Confinement is being financed by the Chernobyl Shelter Fund and the EBRD.