Nuclear Reactor Closed Brayton Cycle Power Conversion System Optimization Trends for Extra-Terrestrial Applications

Extra-terrestrial exploration and development missions of the next century will require reliable, low-mass power generation modules of 100 kW and more. These modules will be required to support both fixed-base and manned rover/explorer power needs. Low insolation levels at and beyond Mars and long periods of darkness on the moon make solar conversion less desireable for surface missions. For these missions, a closed Brayton cycle energy conversion system coupled with a reactor heat source is a very attractive approach. The authors conducted detailed parametric studies to assess optimized system design trends for nuclear Brayton systems as a function of operating environment and user requirements. The inherent design flexibility of the closed Brayton cycle energy conversion system permits ready adaptation of the system to future design constraints. This paper describes a dramatic contrast between system designs requiring man-rated radiation shielding and systems requiring instrument-rated shielding. The paper also considers the ramifications of using indigenous materials to provide reactor shielding for a fixed-bass power source.