A study on flow-induced vibration in the primary cooling system of Japan Sodium cooled Fast Reactor (JSFR) has been conducted 111 Japan Atomic Energy Agency (JAEA). The flow-induced vibration in the elbow is an important issue in design study of JSFR consisting of large diameter pipe and elbow with short curvature radius, because it may affect to structural integrity of the pipe. In this study, Unsteady Reynolds Averaged Navier-Stokes equations (U-RANS) approach with the Reynolds Stress Model (RSM) using a commercial CFD code has been applied to the flow through single and double short-elbows under a high Reynolds number condition. This numerical simulation has utilized a 1/7 scaled water experiment of the JSFR cold-leg piping in order to investigate the flow structure in a three-dimensionally connected double elbow. As a result, applicability of the numerical simulation method was confirmed by comparison between the numerical and experimental results. The simulation has also shown that flow fields m the 1st elbow was different from that in the 2nd elbow and pressure fluctuation in the 2nd elbow was larger than that in the 1st elbow because their larger vortex flow structure.
