Simulation of a Simplified Loop Model for the Gas-Cooled Microreactor

To investigate the coupling characteristics between the core and the loop components of an indirect Brayton-cycle gas-cooled microreactor, as well as to analyze the system behavior under off-design conditions, a coupled model combining a point reactor and a one-dimensional loop was developed. Dynamic simulations of the primary and secondary loops were implemented using both the Modelica-based MWorks platform and a pure Python code. Typical transient scenarios, including reactor startup, control rod withdrawal and insertion, and variations in secondary loop flow rate, were analyzed. The results show that the Python-based loop model achieves faster computation speed than the MWorks model while maintaining sufficient accuracy. Under variable operating conditions, the dynamic responses of key parameters such as reactor power, coolant temperature, and pressure are consistent with physical expectations. Furthermore, variations in the secondary loop flow rate have a significant influence on the efficiency of the open Brayton cycle, thereby affecting the overall thermo-electric conversion performance of the system.