An adaptive three-dimensional model for thermal hydraulics analysis of a PWR steam generator

Pressurized Water Reactor (PWR) steam generators (SGs) feature complex internal structures, including numerous heat exchanger tubes and support components. Accurate modeling of these internal structures is essential for reliable thermal–hydraulic analysis. However, conventional modeling approaches for SG thermal hydraulic analysis often require significant effort and time, limiting efficiency and flexibility. In this paper, we propose an adaptive three-dimensional (3D) modeling approach for the internal structures of PWR SGs, enabling comprehensive and efficient thermal–hydraulic analysis applicable to various designs. The 3D mesh encompasses all critical regions of the SG, including the U-tube heat exchanger, riser, downcomer, and steam dome. A dedicated mesh model accurately representing the shape of the U-tube bundle was developed, with the total tube length calculated from the model differing by less than 1% compared to design specifications. The CUPID-SG code (CUPID for SG application), based on the two-fluid model, is employed to perform the thermal–hydraulic analysis using the proposed 3D mesh. CUPID-SG incorporates primary coolant, U-tube heat conduction, and secondary coolant two-phase flow models, providing a comprehensive framework for simulation. The effectiveness of the proposed approach is demonstrated through the thermal–hydraulic analysis of the APR1400 SG, validating its capability for accurate and adaptable modeling of PWR SGs.