Intermediate heat exchanger in a pool-type fast breeder reactor transfers heat from the primary sodium to secondary sodium. A dual cell coupling porous media model is used to simulate flow field in both primary and secondary side at the same time. The velocity distribution in the inlet and outlet are also studied in order to find the velocity change of inlet and outlet. Flow-induced vibration is investigated. On the top of primary side outlet, it is easy to occur flow-induced vibration, support plates or baffles need to be installed here to reduce the radial velocity to avoid flow-induced vibration.