800.多目的高温ガス実験炉炉心のクロス流れ,(I)

In course of the design development of the VHTR (very high-temperature gas-cooled reactor) core, special attention has been given to the crossflow through the interface gaps between fuel blocks because of its adverse effect on thermal hydraulic performance of the core.Experiments were carried out to determine crossflow rate on full-scale two-block models based on a proposed design of fuel element. Air at atmospheric pressure and ambient temperature was used as a fluid. Crossflow rate and pressure difference were measured for various gap configurations and widths. Measurements of the crossflow rate that entered into individual coolant channel were also made.The experimental results were expressed by the relation between crossflow loss coefficient factor and Reynolds number with interface gap as a parameter, allowing the prediction of crossflow in the core thermal hydraulic analysis.