In the Japan Atomic Energy Research Institute, R&D and design activities on a MW-class spallation neutron source have been carried out under the High Intensity Accelerator Project. Through these activities, a cross-flow type (CFT) mercury target working as the spallation neutron source was devised to realize excellent thermo-mechanical performance. Flow patterns such as velocity and turbulent energy distributions in a mockup model of the CFT target were measured with a PIV technique under water flow conditions. Analytical results attained with the Reynolds stress model (RSM) showed good agreements with the experimental results, especially on a flow separation and recirculation flow patterns, which affect temperature distributions in the target.
