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© Francis Vigouroux

Nuclear

The Chernobyl nuclear power plant shelter structure in Ukraine

Three decades after the Chernobyl disaster, a containment structure now guarantees the safety of the site for the next century and enables work to begin on dismantling reactor 4, which exploded in April 1986.

On 29 November 2016, ceremony was held to mark the end of the positioning and the installation of the containment structure above the damaged reactor and the original containment structure built as an emergency measure following the explosion of nuclear reactor 4 in April 1986.

Designed and built by VINCI Construction, it is the largest mobile metal arch ever built. The figures are staggering: the dome measures 105 metres high and 150 metres long, and its steel structure weighs 36,000 tonnes (fully fitted), including 25,000 tonnes of steel.  Funded by 27 countries, the European Union and the EBRD (European Bank for Reconstruction and Development), this project will have involved more than 2,000 employees within the Novarka consortium led by VINCI Construction Grands Projets.

The Chernobyl shelter structure must withstand extreme climate conditions for a century

This project of rare technical complexity is totally unlike any other, was begun in 2010 and has involved more than 17 million hours of construction work. In terms of safety, it has been designed to withstand not only tornadoes and earthquakes for 100 years, but also extreme temperatures (from -43°C to +45°C).

The site now has equipment and systems in place to enable the future dismantling of reactor 4. This work will now be possible under conditions that ensure maximum flexibility and safety and minimum human involvement.

Enceinte de confinement du sarcophage de Tchernobyl - © Francis Vigouroux

The priority: protecting the teams against radiation

Radiation protection was the non-negotiable starting point for developing the construction methods used. Since exposure to radiation is lower at ground level, this is where the majority of work took place. The first half of the arch was initially assembled on the ground west of the damaged reactor before being assembled in three successive lifts. The same method was used to raise the second half of the arch.

Since the entire worksite is located in a high-risk area, the central challenge was to guarantee quality standards, at the same time as maintaining maximum safety. For this reason, the design and construction methods used have complied fully with the ALARA (As Low As Reasonably Achievable) principle. This principle is an extension of the precautionary principle of radiation protection: individuals exposed to toxic risks must be exposed at the lowest level reasonably achievable. For example, for some tasks - particularly those close to the shelter structure - personnel had to work behind concrete or lead screens. The work areas for the assembly and lifting of the arch were decontaminated, with personnel protected by appropriate clothing. A team of 60 people was dedicated to employee radiation protection.


Delivering such an unusual prototype project demanded the recruitment of skills from all over the world, with the result that people of more than 25 different nationalities were permanently present on-site, requiring multicultural management skills.

View the Chernobyl shelter structure on video:

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