POWER-PLANT DESIGN STUDY OF A HIGH-ASPECT-RATIO TOKAMAK USING A SIC COMPOSITE STRUCTURE

The DREAM (DRastically EAsy Maintenance) Tokamak is a fusion power pla nt which is designed from the viewpoint of maintenance feasibility. Fo r this purpose, the DREAM reactor uses a plasma with a very high aspec t ratio (A) and adopts SiC as a structural material. The choice of SiC affects the design of the core plasma, i.e. large inboard shield thic kness, low synchrotron radiation reflectivity, and small plasma elonga tion for positional stability. The objectives of this study are to exp lore the feasibility of a high-A device, such as a power plant, and to clarify the technological impact of SiC material on the plasma design . Plasma size is optimized by the physics guidelines similar to ITER. The plasma major and minor radii of DREAM are 16 m and 2 m, respective ly, and the average neutron wall load is 2.5 . MW m(-2), the maximum t oroidal field is 20 T, and the fusion power is 5.5 GW. Steady-state op eration is obtained with 50 MW of external current-drive power and 90% bootstrap current. The divertor heat load is estimated to be about 10 MW m(-2). A radiative divertor concept is adopted to achieve a low di vertor plasma temperature. The DREAM Tokamak concept is found to be a possible candidate for a future power plant with more than 5 GW of fus ion power and an acceptable divertor condition. (C) 1998 Elsevier Scie nce S.A. All rights reserved.