Daily Load-Follow Operation in LEU+-Loaded APR1400 Using Mode-K+ Control Logic

This study evaluates the efficacy of the mode-K+ control logic for daily load-follow operation (DLFO) in a two-batch LEU+ fuel-loaded APR1400 reactor with an accident tolerant fuel (ATF) cladding. The objective is to assess the performance of the control strategy under various operational conditions including high burnup. The simulation results showcase a robust control for both reactor power and the ASI of the equilibrium core by utilizing a manganese absorber for the partial strength control element assembly (PSCEA) instead of the weak Inconel absorber in the standard design, particularly under high burnup conditions. The simulation employs a two-step method, where cross sections are generated using the SERPENT2 Monte Carlo code, and the whole core 3D simulation is conducted using the KANT in-house diffusion code. The results demonstrate successful power and ASI control within the desired limits throughout the whole operational period.