Transient Dynamic Study of Swing Check Valves in High-Temperature and High-Pressure Systems of Nuclear Power Plants

As a core safety barrier in the piping systems of nuclear power plants, swing check valves are analyzed in this study through the establishment of a three-dimensional model and high-precision transient fluid dynamics calculations. The internal flow field characteristics at different stages of valve flap opening are investigated, including velocity and pressure distributions, to reveal the dynamic behavior of swing check valves. The results indicate that during the initial stage of small valve flap opening, a significant pressure difference exists between the front and rear sides of the valve flap, with high-velocity regions concentrated around the valve flap gaps. At the intermediate stage, high-velocity zones shift to the bottom of the outlet pipeline. When the valve flap reaches maximum opening, pressure concentrates on the upper part of the valve flap, and a distinct high-velocity region forms near the valve outlet. The angular velocity of the valve flap increases continuously during opening, but its rate of acceleration gradually decreases. These findings provide theoretical guidance for optimizing the operation and maintenance of swing check valves under real-world conditions.