Study on Power Regulation Methods of Microreactor Coupled With Closed Helium Gas Turbine Direct Cycle

Abstract Microreactor is a class of rapidly developing small advanced reactor. It has many advantages: mobility and transport ability, resilience, and independence from the grid, as well as its capacity for long refueling intervals. The microreactor utilizing high-temperature gas-cooled reactor technology has inherent safety. By coupling microreactor with the helium turbine direct cycle power generation system, it can operate at high temperature. Therefore, the microreactor coupled with closed helium gas turbine direct cycle (MR-GT) has broad prospects for development. In this paper, the mathematical model of the MR-GT system is established to study the dynamic characteristics. Based on the conservation equations of mass, momentum and energy, the thermo-hydraulic model of power conversion system including heat transfer components and turbomachinery is established. The transient reactor power is calculated by the point reactor neutron kinetics equations. Finally, the lumped parameter nonlinear system model of the MR-GT is established by coupling the above models. The Modelica simulation language is used to solve these nonlinear ordinary differential and algebraic equations. The dynamic characteristics of the MR-GT system under the conditions of reactivity insertion and helium inventory regulation are studied. The results show that the system power can be independently adjusted within a certain range by changing the reactivity or helium inventory. By synergistically regulating the reactor reactivity and helium inventory, the temperature and efficiency of the MR-GT system can be kept basically unchanged, which is an ideal power regulation method.