Transient Response of Asymmetric Operation in SFR Based on Multi-scale Coupled Model

In multi-loop nuclear systems, asymmetric operation serves as a critical strategy to enhance operational flexibility and reliability. This study leverages the domestic vPower simulation platform to model a typical three-loop loop-type sodium-cooled fast reactor (SFR), establishing an integrated thermal-hydraulic-neutronic multiscale coupling model for the primary system. The model encompasses the core, primary, secondary, and tertiary circuits, with verification under full-power conditions (100% FP) confirming its accuracy and suitability for control strategy analysis. Building on this model and its associated power regulation and flow control systems, a partial loop operation control strategy is proposed. Dynamic response simulations during single-loop cut-off scenarios demonstrate that the sodium outlet temperature at the Intermediate Heat Exchanger (AHX) stabilizes within safety margins, with transient behaviors aligning with design predictions. Key parameters in the two operational loops (e.g., flow rate, temperature gradient, and pressure differential) are maintained within stable margins, demonstrating robust operational stability under asymmetric conditions.