Helium cooling circuits for a fusion reactor

A thermal and hydraulic analysis of the complete cooling circuit of a conceptual helium-cooled fusion reactor is presented. A manifolding analysis is first applied to rows of blanket cells. It is shown that duct diameters must be of the order of 0.15 m or greater; if they are too small not only is the pressure drop too great but some blanket cells are overcooled at the expense of others which overheat. The complete system consisting of many rows of cells and the interconnecting ductwork, together with pumps and heat exchangers, is then analysed. Design option regions are drawn for a variety of operating parameters. These regions are determined by maximum pumping power fraction, minimum economic wall loading, minimum thermodynamic efficiency and maximum temperature. Because the maximum operating temperature depends on the material of construction, different regions can be drawn for different materials. The size of the region, and with it the maximum wall loading, decreases as the pressure and the coolant ducting diameter decrease. (orig.)