Fusion DEMO reactor design based on nuclear analysis

The neutronics of a fusion reactor is crucial in the conceptual design of all in-vessel components and the overall reactor design. A successful DEMO reactor must demonstrate self-sufficient production of tritium to allow sufficient plant availability and electrical generation. The neutronics shows that the design constraint of the neutron wall load (NWL) is related to the tritium breeding ratio and nuclear heating, which determine the fusion power and plasma configuration and are essential for the blanket design in a fusion reactor. To align the outlet temperatures of the blanket modules, the coolant piping system must be arranged to match the distribution of the NWL. 3D neutronics analysis ensures that the blanket design allows a self-sufficient supply of tritium. The maintenance scheme for the remote handling equipment to operate Japan's DEMO reactor should consider the shutdown dose rate and residual heat in the vacuum vessel. Base on neutronics analysis, it is important to classify radwaste disposal and to develop radwaste management scenarios. The analyses in this paper show that the radiation exposure caused by nuclides is as low as 3.4 μSv/y when the radwaste is disposed in a shallow concrete pit. This radiation exposure level is below the shallow-land burial limit in Japan (<10 μSv/y).