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Vast project to consolidate CERN’s technical galleries gets under way

13 kilometres of underground technical galleries, vital for the functioning of the accelerator complex and the CERN site, will be renovated over the next ten years


Technical galleries
The technical galleries run below the Meyrin and Prévessin sites (Image: CERN)

CERN’s vast underground maze spans several hectares in France and Switzerland. In addition to the tunnels of the main accelerators, some 80 less well-known technical galleries are located underneath the Meyrin and Prévessin sites. They contain the infrastructure required to keep the sites and the accelerators running, other than the equipment directly related to the operation of the accelerators. This includes the cables and pipes connecting the various buildings and facilities, as well as heating systems and optical fibres. Following approval by the Finance Committee in 2020, a vast project to renovate this underground maze is now taking shape. The aim is to make the technical infrastructure more reliable and environmentally-friendly while improving on-site safety.

The technical galleries, some of which are as old as the Organization itself, are sorely in need of renovation: the network has not been given a general overhaul since it was first built, so incidents could arise that compromise the systems’ functioning, such as water leaks. The consolidation project will prevent such problems and get the Organization in good shape for its future scientific endeavours.

Once it had been decided which galleries required work, an inventory and 3D modelling campaign began in May 2021. From the access doors to the electrical circuits, the entire underground structure will be modelled by teams from the Site and Civil Engineering department (SCE) and the Engineering department (EN). In the words of the project leader, Sébastien Evrard: “When the project is completed, our knowledge and understanding of these galleries should be comparable to those of the accelerator caverns.”

Preparing for the future means stripping away the past: once the galleries have been fully modelled, a lot of obsolete infrastructure will be removed and space will be optimised to make room for the equipment required to operate new facilities, such as the data processing centre whose construction on the Prévessin site will start in 2022. “These galleries are vital to all the current projects on the Meyrin and Prévessin sites,” explains Sébastien. No effort will be spared to guarantee the reliability of the galleries and the facilities that depend on them. While some of the infrastructure, such as the stainless steel pipes, will be reused, other components that are based on obsolete technologies or are in very poor condition will be completely replaced.

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Maps of the Meyrin and Prévessin sites showing the technical galleries in red (Image: CERN)

The project, which has financing for an initial ten-year period, will inevitably cause some minor disruption in the vicinity of the buildings concerned (see map). But the teams involved, who come from almost all the CERN departments, are ahead of the game in taking steps to guarantee that essential services continue. To do so, they are carrying out two pilot schemes to assess their technical processes and their ability to keep the disruption to a minimum. The lessons learned will be applied across the project.

The smooth running of the pilot projects around Buildings 376 and 860 bodes well for an effective and coordinated consolidation campaign. “I’m particularly pleased with the commitment shown by all the teams involved,” says Sébastien. “They’re working together to achieve an objective that’s important to all of us: preventing rather than coping with crises by guaranteeing the reliability of our facilities.”