Reduced-order method for nuclear reactor primary circuit calculation

Accurate real-time simulations of nuclear reactor circuit systems are particularly important for system safety analysis and design. To effectively improve computational efficiency without reducing accuracy, this study establishes a thermal-hydraulics reduced-order model (ROM) for nuclear reactor circuit systems. The full-order circuit system calculation model is first established and verified and then used to calculate the thermal-hydraulic properties of the circuit system under different states as snapshots. The proper orthogonal decomposition method is used to extract the basis functions from snapshots, and the ROM is constructed using the least-squares method, effectively reducing the difficulty in constructing the ROM. A comparison between the full-order simulation and ROM prediction results of the AP1000 circuit system shows that the proposed ROM can improve computational efficiency by 1500 times while achieving a maximum relative error of 0.223%. This research develops a new direction and perspective for the digital twin modeling of nuclear reactor system circuits.