Heat Pipe Thermionic Reactor Concept

The report describes a preliminary design study of a Heat Pipe Thermionic Reactor Concept and indicates a possible arrangement of a compact 1 MW(e) thermionic reactor. In the Heat Pipe Thermionic Reactor Concept thermal power generated in the reactor core is transported by heat pipes to thermionic diodes located outside the reactor core. The thermionic emitters are in direct contact with the outside envelope of the heat pipes and the collectors are in contact with a liquid metal cooling system that transfers the waste heat to a radiator. The heat pipe uses the heat of vaporization and capillary action of a fluid to transport thermal energy at a high efficiency and a constant temperature along the entire heat pipe. It is therefore possible to obtain inpile temperatures outside the core and thereby avoiding most of the problems associated with the in-pile thermionic designs, such as: Change of emitter dimensions due to fuel swelling upon irradiation; interaction between emitter and fuel; fission product contamination of the interelectrode space charge material; and the effect of nonuniform reactor power generation on the performance of the thermionic diodes.