Drop behaviors of a plate-type fuel assembly used in research reactor for a drop accident

The drop behaviors of a plate-type fuel assembly for a research reactor are investigated through a dropping test in water. In the test, a full-scale dummy fuel assembly and a water tank of 5 m high are utilized. Special devices are designed to minimize collisions between the equipment and test specimen and to induce a vertical drop of the fuel assembly. Falling velocities with respect to the drop heights are measured using a high-speed camera, and are determined through the image processing of the photographs. Using the analytical equation and experimental data, the drag coefficient and added mass of the plate-type fuel assembly which highly influence the falling behavior are estimated. The empirical formula with suitable drag coefficient and added mass is presented to predict the impact velocity of fuel assembly during a drop accident. The impact velocity can be utilized as an input variable in the finite element analysis of an impact. •The drop behaviors of a plate-type fuel assembly for research reactor are investigated.•The dropping test with full-scale fuel assembly in water is performed.•Falling velocities with respect to drop height in water are determined through the image processing of the photographs.•Appropriate drag coefficient and added mass of a plate-type fuel assembly are presented.•Empirical equation of fuel assembly drop behaviors is presented.