FIG. 11 is a top-down schematic view of a molten nuclear fuel salt fast reactor core with fuel region 1102 surrounded by a neutron reflector assembly 1100 with a neutron reflector material 1104 flowing through channels 1110, and flowing through tubes 1108 in channels 1112, tubes 1108 being in thermal communication with a molten nuclear fuel salt flowing through fuel region 1102 and through channels 1112 in a tube and shell style heat exchanger. From the viewpoint of FIG. 11, the molten fuel salt flows upward through fuel region 1102 and downward through channels 1112. The flowing reflecting liquid flows downward through channels 1110 and upward through tubes 1108. In this implementation, the flowing reflecting liquid 1104 is also a secondary coolant for the fuel in fuel region 1102. Tubes 1108 may take a variety of configurations, including without limitation any number of tubes in each channel 1112 or tubes of any geometric shape. Selection of the number of tubes 1108 per channel 1112 and the shape of tubes 1108 will determine the surface area in contact with molten fuel salt flowing upward in channel 1112, and alter the amount of heat exchanged between flowing reflecting liquid 1104 and molten fuel salt 1102. Although pairs of tubes 1108 per channel 1112 are shown in FIG. 11, a variety of configurations are possible. For example, tubes 1108 may take a meandering path through channels 1112 to increase surface area thermally exposed to the molten fuel salt. In another implementation, channels 1112 may contain a series of baffles around which the molten fuel salt must flow in an indirect pattern between the inlet and outlet ports. The indirect flow pattern increases the thermal contact between the molten fuel salt and the tubes, and increases the angle between the tubes and the molten fuel salt flow to increase thermal communication.
