Initial integration concept of the DEMO lower horizontal port

The realisation of a Demonstration Fusion Power Reactor (DEMO) is the remaining and crucial step towards the exploitation of fusion power. This is the shared view of Europe and the nations engaged in the construction of ITER. DEMO will follow ITER and must be capable to produce several hundred MW of net electricity as well as operating with a closed fuel-cycle. The DEMO machine has three main entrance levels to the plasma chamber. According to the current DEMO reference configuration the vacuum vessel has 16 vertical upper, horizontal equatorial, and horizontal lower ports, respectively. This article introduces the initial integration concept of the lower port. The concept considers the external space constraints e.g. due to the supports of the vacuum vessel, the neutron shielding requirements of the superconducting coils, and the main lower port functions. These include hosting a number of tokamak systems, in particular the torus vacuum pump and feeding pipes of in-vessel components, and to allow for divertor remote maintenance. The size and position of the lower port are constrained by the adjacent toroidal and poloidal field coils. At the same time the lower port drives the layout of the cryostat and the tokamak building.