Shielding design options and impact on reactor size and cost for the advanced fuel reactor Apollo

Apollo is a D-³He-fueled tokamak reactor which directly converts synchrotron radiation to electricity using rectenna circuits. The low level of neutron production allows for significant reduction in the shield size, particularly on the inboard side. The design of the inboard shield, has been especially emphasized since it directly affects the size of the machine and thus the cost of electricity (COE). Several shield-design options were analyzed and the effect of the shield type and thickness on the overall machine size and cost was assessed. Besides shielding performance, the choice between the different materials was governed by some safety-related issues, such as tritium production, decay heat generation, and waste management. The most attractive shield-design option is the water-cooled SS shield. The economic analysis show that although the SS shield results in a thicker inboard shield, the COE is slightly lower than that of a machine using an inboard W shield. This is because the lower shield cost has offset the slightly larger machine cost