Flow-induced Vibration Tests of Large Diameter and High Velocity Piping

Fujii, Tadashi; Chikazawa, Yoshitaka  ; Konomura, Mamoru; Yamaguchi, Akira

The conceptual design study of sodium cooled reactor is in progress in the Feasibility Study on Commercialized Fast Reactor Cycle Systems. The cooling system is composed of two loops in order to reduce plant construction cost. With loop number reduction, large diameter pipings are adopted and mean velocity in the piping also increases in comparison with former design. As for these piping systems, knowledge concerning hydraulic behaviors around the elbow and vibration phenomenon which is caused by the turbulence of fluid was insufficient. Therefore, flow-induced vibration tests have been started using water test facility, which simulates a hot leg piping of primary cooling system of large-scale reactor at the 1/3 reduced scale. Until now, flow visualization was conducted using acryl model and hydraulic behaviors such as velocity distributions in the piping were clarified. Further, as for the pressure fluctuations of the fluid which become vibration sources to the piping, it confirmed that the pressure fluctuations in the piping could be divided into four sections according to the degree of the turbulence caused at flow separation in the elbow.