LAUSR

Abstract Reactor parameters and an optimal radial build of a tokamak DEMO reactor with an aspect ratio, A ranging from 2.5 to 4.0 were determined and analyzed using a coupled tokamak systems analysis, along with constraints extrapolated from those applied in the design of the International Thermonuclear Experimental Reactor (ITER). The minimum major radius, R0 and the reactor size were mainly determined by desired plasma performance and tokamak engineering constraints, while the neutronic constraints determined the thicknesses of the blanket and the shield. The impact of the neutronic constraints on the tritium breeding and the shielding depends on the aspect, A. As the aspect ratio, A increased, the inboard shield thickness slightly decreased although the inboard neutron wall loading increased due to increased shielding contribution from the inboard blanket and the TF coil case; the outboard shield thickness also slightly decreased due to decreased outboard neutron wall loading; the inboard blanket thickness increased and relative contribution of the inboard blanket to the tritium breeding increased due to decreased outboard neutron wall loading.