Hydraulic experiment investigation on the plate-throttle entry tube flow characteristics of fast reactor fuel assembly

The entry tube of fast reactor fuel assembly plays an important role in controlling flow rate, adjusting pressure drop and limiting flow velocity, which has a significant effect on safety and economy of fast reactor. Due to some shortcomings of traditional straight-through entry tube, an optimized plate-throttle entry tube is designed and manufactured in the current investigation. Reynolds number from 8.99 x 10(4) to 1.65 x 10(6) is considered and experiment data are generated from hydraulic experiment conducted at constant water temperature (84 degrees C). The experiment results indicate that the flow characteristics of plate-throttle entry tube is excellent, i.e. it can significantly increase pressure drop with the large-diameter entry-tube holes to avoid excessive vibration. It is verified that the pressure drop of plate-throttle entry tube is more sensitive to the width of plate throttle rather than the diameter of entry-tube holes. In the experiments or practical engineering applications, the pressure drop should be adjusted by changing the width of plate throttle as much as possible to reduce cost. A dimensionless number called the throttling-area ratio is introduced to represent the geometrical parameters effect on flow characteristics of plate-throttle entry tube. The resistance-coefficient empirical correlations and an empirical criterion equation are obtained by regression analysis of experiment data, which can be used for structure design of sodium-cooled fast reactor and preliminary estimation of entry-tube flow characteristics.