High-Fidelity Drum Controller Design of Thermionic Space Nuclear Reactor

Space nuclear reactors have the advantages of not relying on solar energy and being able to adapt to complex external conditions. Different from ground reactors, space nuclear reactors work in space and are unattended during the entire operating cycle. Thus, a reliable automatic control system is very important. In this paper, a control drum system is designed based on the high-fidelity thermionic space reactor system code TASTIN. A model predictive controller (MPC) is installed in the control drum system, which can satisfy the optimal control problem under constraints. The model predictive controller adopts point kinetics model with six groups of delayed neutrons, and seven different parts of reactivity feedback models as an internal model, which have relatively high fidelity. By selecting the appropriate prediction horizon, control horizon and input and output weights, the MPC controller with superior performance is finally obtained. Finally, in order to evaluate the control performance of the model predictive controller, the simulations are carried out for the control variable step condition and the nuclear power following condition, and compared with a PID controller with good performance. The results show that, in various transient conditions, the MPC controller has better control performance than the traditional PID controller. In the nuclear power step condition, the MPC controller has better performance, its setting time is 0.12 s, and overshoot is 0.45% (in the PID controller, the setting time is 15.30 s, and the overshoot is 9.08%). In the electric power step condition, the setting time of the MPC controller is 11.95 s, and the overshoot is 0.22% (in the PID controller, the setting time is 71.28 s, and the overshoot is 13.27%). In the outlet temperature step condition, the MPC controller reduces the steady-state error to 0.02 K (0.22 K in the PID controller). In the nuclear power following condition, the MPC controller can better track the target value.