Weight control in design of space nuclear reactor system

Space nuclear power system is the key technology for deep space exploration missions in the future, especially for space base building-up. This paper evaluates several typical latest space nuclear reactor system (SNRS) designs, and finds that most of their weights are heavier than necessary. From the point of weight-control, the S^4 design is the best but its design is more complex than others. A newly designed SNRS, based on the SAFE400 model, uses annular fuel and has better performance, with a fuel mass lower than that of the SAFE400 prototype by 18.75%. Meanwhile, different from former opinions, the delay neutron fractions of SNRS are not constant and change with the different SNRS designs. Therefore, designs of SNRS not to count the delayed neutron fracture or directly to consider it as 0.00677 are not appropriate.