Design studies of thermionic lithium-niobium nuclear power generating systems with electric output of 5-10 MW

In the context of the combined power and propulsion unit of the Martian Expeditionary Vehicle, design studies reviewed five options for modular lithium-niobium thermionic Nuclear Power Generating System (NPGS) with 5-10 MW electric output. The first option was designed to meet specifications of the planned NPGS for the orbital transfer vehicle Hercules, while the other options had higher specific output performances, which, to a significant degree, were validated in experiments, including reactor tests. The paper provides design parameters for thermionic power-generating channels, packages and a thermionic fast neutron converter/reactor, five-layered biological protection against radiation, lithium cooling system, as well as specifications of the NPGS as a whole. The paper points out the need to develop a new, as compared to the Hercules NPGS, reactor control and protection system. It provides NPGS layouts for the transportation configuration (when launched in a cargo transportation container of an Energia-type launch vehicle) and the operational configuration. It discusses the issues involved in further improvement of power and mass properties.