Design and integration of the ground level platform for W7-X

Wendelstein 7-X (W7-X) is a fusion device of the stellarator type with optimized magnetic field geometry and superconducting coils. The scientific goals of W7-X are to confirm the predicted improvement of the plasma confinement and to demonstrate the technical suitability of such a device as a fusion reactor. It is presently under construction at the Max Planck Institute for Plasma Physics (IPP) in Greifswald, Germany. The equatorial plane of the W7-X machine is 5,75m above the level of the floor of the Torus Hall. Several diagnostics and peripheral components operate at or above the equatorial level. Instead of designing multiple dedicated support structures, it has been decided to design and install a main platform at the ground level of the Torus Hall, 4,25m above the floor. This platform serves as a support structure for the components placed on it, a working stage to ease access and maintenance, a dedicated space for cable trays and piping for the vacuum and cooling systems. The design of such a platform, considering the space-constrained environment of the Torus Hall, represents an engineering and integration challenge. In this paper the design process, from concept to detail, will be explained. The requirements and boundary conditions considered such as access, flexibility, maintenance below the platform and stability will be presented. The selected technical solutions will be detailed and the integration issues will be discussed.