Simulation-Based Heat Transfer Optimization for Mass Concrete in Nuclear Power Station Construction: A Case Study

The construction of mass concrete foundations for nuclear power plants faces significant challenges in controlling hydration heat and preventing early-age thermal cracking. This study develops an integrated framework combining high-fidelity thermal-mechanical simulation, real-time temperature monitoring, and construction process optimization to address these issues. Focusing on the VVER-1200 reactor raft foundation in the Xudapu NPP Phase II Project, an innovative center-to-periphery synchronous pouring method is proposed. Numerical simulations demonstrate that this method strategically utilizes construction stage time lags to moderate temperature distribution and reduce thermal stress. Field monitoring data show good agreement with simulated results, which provide conservative and safe estimates for curing guidance. Post-construction verification confirmed the absence of thermal cracks. The proposed methodology offers a reliable, science-based approach for thermal crack mitigation and can serve as a valuable reference for similar large-scale mass concrete structures in nuclear and other critical infrastructure projects.