STUDY OF DESIGN PARAMETERS FOR MINIMIZING THE COST OF ELECTRICITY OF TOKAMAK FUSION POWER-REACTORS

The impact of the design parameters on the cost of electricity (COE) i s studied through a parameter survey in order to minimize the COE. Thr ee kinds of operating modes are considered; first stability (FS), seco nd stability (SS) and reversed shear (RS). The COE is calculated by a coupled physics-engineering-cost computer system code. Deuterium-triti um type, 1000 MW(e) at electric bus bar, steady state tokamak reactors with aspect ratios A from 3 to 4.5 are assumed. Several criteria are used for the parameter survey; for example, (a) the thermal to electri cal conversion efficiency is assumed to be 34.5% using water as a cool ant; (b) the average neutron wall load must not exceed 5 MW/m(2) for p lasma major radius R-p > 5 m; (c) a 2 MeV neutral beam injector (NBI) is applied. It is found that the RS operating mode most minimizes the COE among the three operating modes by reducing the cost of the curren t drive and the coils and structures. The cost-minimized RS reactor ca n attain high f(bs), high beta(N) and low q(95) at the same time, whic h results in a short R-p of 5.1 m, a low B-max of the maximum magnetic toroidal field (TF) of the TF coils of 13 T and a low A of 3.0. It ca n be concluded that this cost-minimized RS reactor is the most cost-mi nimized within the frameworks of this study. This cost-minimized RS re actor has two advantages: one is that a B-max = 13 T TF coil can be ma de by use of ITER coil technology and the other is that the same cooli ng technology as that of ITER (water cooking) can be used.