Initial DEMO tokamak design configuration studies

Abstract

To prepare the DEMO conceptual design phase a number of physics and engineering assessments werecarried out in recent years in the frame of EFDA concluding in an initial design configuration of a DEMOtokamak. This paper gives an insight into the identified engineering requirements and constraints anddescribes their impact on the selection of the technologies and design principles of the main tokamakcomponents. The EU DEMO program aims at making best use of the technologies developed for ITER (e.g.,magnets, vessel, cryostat, and to some degree also the divertor). However, other systems in particular thebreeding blanket require design solutions and advanced technologies that will only partially be tested inITER. The main differences from ITER include the requirement to breed, to extract, to process and to recyclethe tritium needed for plasma operation, the two orders of magnitude larger lifetime neutron fluence, theconsequent radiation dose levels, which limit remote maintenance options, and the requirement to uselow-activation steel for in-vessel components that also must operate at high temperature for efficientenergy conversion.