Direct-Drive Gas-Cooled Reactor Power System: Concept and Preliminary Testing

This paper describes the concept and preliminary component testing of a gas‐cooled. UN‐fueled, pin‐type reactor which uses He/Xe gas that goes directly into a recuperated Brayton system to produce electricity for nuclear electric propulsion. This Direct‐Drive Gas‐Cooled Reactor (DDG) is designed to be subcritical under water or wet‐sand immersion in case of a launch accident. Because the gas‐cooled reactor can directly drive the Brayton turbomachinery, it is possible to configure the system such that there are no external surfaces or pressure boundaries that are refractory metal, even though the gas delivered to the turbine is 1144 K. The He/Xe gas mixture is a good heat transport medium when flowing, and a good insulator when stagnant. Judicious use of stagnant cavities as insulating regions allows transport of the 1144‐K gas while keeping all external surfaces below 900 K. At this temperature super‐alloys (Hastelloy or Inconel) can be used instead of refractory metals. Super‐alloys reduce the technology...