Carbon-carbon-composite salt-cooled electric space reactors

The primary requirements for a deep space or planetary nuclear reactor for production of electricity are reliability, long life, and a high power-to-mass ratio. Advanced reactors (core, structure, power-conversion systems, radiator, etc.) are proposed that are built entirely from carbon-based materials that use salts (liquid or gas) as the heat transfer medium between the reactor and power-generation equipment and/or heat rejection systems to create reactor systems with very high power-to-mass ratios. While currently proposed space nuclear reactors have peak temperatures between 900 and 1400K with potential efficiencies as high as 30% for advanced Stirling engines, the new reactors would have peak operating temperatures between 1800 and 2300K with potential efficiencies twice that of other concepts. Because there are no other classes of materials that can potentially operate at such temperatures and have very low masses, most of the components of such a space electric nuclear reactor must be built of carbon-based materials. Based on theoretical considerations and the developments in carbon-carbon technologies over the last 20 years, such machines appear to be potentially viable. However, significant research is required to demonstrate feasibility and a major long-term development program would be required to build such machines.