Flow-induced Vibration Tests for Large Diameter and High Velocity Piping (1) Test Planning and Fabrication of Test Facility

Fujii, Tadashi; Nishiguchi, Yohei; Konomura, Mamoru

The conceptual design study of the large-scale sodium-cooled reactor is in progress in the "Feasibility Study on Commercialized Fast Reactor Cycle Systems (F/S)".The cooling system of a large-scale sodium-cooled reactor is composed of two loops in order to reduce construction cost. According to reduction of the loop number, the large diameter pipings are adopted in the primary cooling system (for example, inner diameter of a hot leg piping is 1.27m). And the average velocity in the piping increases to 9 m/s level, which is well over to a conventional plant design, therefore, Reynolds number reaches 10order levels. The hydraulic behaviors of the piping elbow, such as pressure fluctuation characteristics and formation range of flow separated layer near an elbow, under high velocity and high Reynolds number conditions are expected to be different to those under lower Reynolds number which is the highest existing number. Further, there would be the possibility of vibration of the piping by flow instability under high velocity condition. However, information of flow-induced vibration behaviors for large diameter piping is limited.Then, flow visualization and flow-induced vibration tests using 1/3 scale water test facility, which simulates hot leg piping, have been planned in order to confirm the realization of the piping design for primary cooling system. Flow pattern in the piping and pressure fluctuation near the elbow, which is a main cause of flow-induced vibration, will be measured in the flow visualization tests using the acrylic elbow model. Moreover, vibration modes and vibration response characteristics of the piping system will be measured in the flow-induced vibration tests using the stainless steel elbow model.The design of the test facility and production of the elbow models and the loop pipings were finished by 2002. In 2003, fabrication and installation of the test facility will be finished and a part of flow visualization tests will be started.