Features of Space Reactor Brayton Cycle Under Power Regulation by Control Drums

Abstract The development of space exploration technologies such as planetary bases and orbital propulsion has higher requirements for space power systems. The reactor coolant of the space reactor Brayton cycle (SRBC) is also the cycle working fluid, which has the advantages of high power conversion efficiency, compact configuration, small mass and volume. It is the one of the best options for future high-power space power systems. Reactivity insertion by control drums is an effective means of power regulation for the SRBC. In this paper, the dynamic model for the SRBC were established, the safety characteristics of the SRBC under power reduction conditions by control drum insertion were studied. The results indicated that the control drum insertion decreases the output power of the turbine and further leads to speed fluctuations. The bypass valve control can ensure stable shaft speed and balance between power generation and load of the generator, ensuring the safe operation of the SRBC under reactivity insertion conditions. Furthermore, the safety boundary for control drum insertion conditions of the SRBC was investigated. The results indicated that more control drum insertion decreased the output power of the turbine. The speed decreases far from the rated speed and exceeds the safety margin of the bypass valve control. The continuous decrease in speed leads to system shutdown, and there is a safety boundary. The analysis provides a reference for the operation and control of the SRBC in the future.