Flow Pattern and Pressure Fluctuation Characteristics on the 1/3 Scale Hot-Leg Piping Experiments of a Primary Circuit Hot-Leg Piping in a Sodium-Cooled Fast Reactor

A conceptual design study of the Japan Sodium-cooled Fast Reactor (JSFR) is in progress in “the Fast Reactor Cycle Technology Development (FaCT) project”. In this project, a two-loop primary system is adopted in order to economize the plant construction cost. The reduction of the number of loops for the primary cooling system increases the primary coolant flow rate per loop. The mean sodium velocity in the pipes increases to over 9 m/s and Reynolds number in the hot-leg pipes is about 4x107. In the JSFR the pipe thickness is designed to be considerably thinner than that of a light water reactor, because the fast reactor is operated at low pressure and high temperature. One of the issues for the piping design is to understand the behavior of flow-induced vibration that is derived from the hydraulic characteristics under high Reynolds number conditions. We made a flow-induced vibration test facility that simulates the hot-leg piping with a 1/3-scale model .Flow-induced vibration experiments were performed using this facility to evaluate and confirm the integrity of piping against the flow-induced vibration. In these tests, we investigate flow patterns and fluctuating pressures on the pipe wall. This paper describes a summary of the 1/3-scale experimental results under the rectified-flow, swirl -flow and deflected-flow conditions at the inlet of the hot-leg piping.