Speaker
Description
The urgent need for carbon-free energy production has established Small Modular Reactors (SMRs) as a vital component of the clean energy transition. Characterized by an electrical output of 10 to 300 MWe, SMRs offer significant versatility, operating in base-load mode for grid stability or in load-following mode to compensate for intermittent Renewable Energy Sources (RES). A key advantage over conventional reactors is their enhanced safety, relying on passive systems that operate without external power or human intervention. To ensure safe deployment, high-fidelity simulation tools are essential for educational purposes and for studying reactor behavior during normal and malfunction scenarios. This study investigates the operational behavior of an integral Pressurized Water Reactor (iPWR) using the IAEA-TECNATOM simulator. The tool models a generic 150 MWth (45 MWe) iPWR with a 4.95% enriched UO2 fuel core, integrating comprehensive primary, secondary, safety, and control systems. Specifically, we examine the dynamic response of the iPWR under a 10% load maneuvering scenario (100% to 90% power reduction and subsequent restoration), comparing two distinct plant operating modes: Turbine Leading and Reactor Leading. In the Turbine Leading mode, electrical output is regulated directly by the turbine control valve, with the control rods modulating core thermal power to match secondary side demand. Conversely, the Reactor Leading mode drives electrical output indirectly via core thermal power regulation using control rods and boron concentration modifications. The results demonstrate that the Turbine Leading mode provides superior precision and faster dynamics. The Turbine Leading mode completes the power decrease in 11 minutes and recovery in 19 minutes. In contrast, the Reactor Leading mode requires 25 minutes for power reduction and 33 minutes for recovery due to indirect neutronic and reactivity feedback. Consequently, the Turbine Leading strategy proves more effective for the high-RES penetration grids and flexible nuclear operations characterizing modern and future power systems.