Cascaded HTGR Power-Level Control Only by Regulating Primary Helium Flow Rate

Reactor power-level control is a key technique of enhancing the safety, stability, and efficiency of nuclear plants. Currently, nearly all the power-level control methods are based on the scheme of inducing reactivity directly via control rods. However, the reactivity can also be injected indirectly via the negative temperature feedback effect, which results in the opportunity to develop indirect nuclear reactor power-level control methods. Motivated by this, a cascaded power-level control of high-temperature gas-cooled reactor, which is composed of a helium temperature controller and a neutron flux controller, is proposed based on only regulating the primary helium flow rate. The temperature controller, which is in the inner loop, regulates the primary helium flow rate according to the setpoint of helium temperature. The flux controller, which is in the outer loop, revises the setpoint of the inner-loop controller so as to eliminate the error of reactor neutron flux. It is proved that the closed-loop system can be guaranteed to be globally asymptotically stable. Finally, numerical simulation results corresponding to the application to the high-temperature gas-cooled reactor pebble-bed module (HTR-PM) plant verifies the theoretical result while showing the satisfactory performance as well as the influence of the controller parameters.