A nuclear thermionic converter has a vertical stack of annular or ring-shaped nuclear fuel members. Within the ring-shaped members is reflector material. Thermionic diodes are mounted on the periphery of the fuel rings, with the emitters being in contact with the fuel. The collectors are filled with moderating material and the reactor is cooled by heat radiation.
A thermionic energy conversion system assembly is described which comprises a fissionable nuclear fuel which surrounds a cylindrical arrangement of thermionic emitter electrodes which surround corresponding collector electrodes, which in turn surround a cylindrical container of a heat sink material, such as lithium hydride, which can absorb large amounts of waste heat energy through a phase change. The heat sink material may also act as a nuclear moderator to reduce the amount of required nuclear fuel. A heat pipe is enclosed within the container of heat sink material to remove waste heat stored in the material. A thermionic energy conversion module is described which comprises 100 stacked-in-series thermionic converter assemblies. A complete space-based thermionic nuclear reactor is described which comprises an array of 91 thermionic converter modules wherein the heat pipes connect to a lithium hydride radiation shield which acts as a further heat sink. The radiation shield connects to radiators to remove the waste heat to space.
