Model studies on conical fluidized beds for coating of nuclear fuel particles

The pyrolytic coating of nuclear fuel particles takes place in conical fluidized beds at temperatures exceeding 2000°C, making direct observation of the movement processes impossible. The fundamentals for conducting model experiments at room temperature to simulate the movement processes are presented, and measurements with the solid/gas system of petunia seeds/hydrogen using a 2-channel nozzle system are reported. The different gas distribution between the central and annular nozzles allows for the adjustment of various movement forms. Coating experiments showed that for undisturbed bubble movement, the relatively best results regarding the uniformity of depositions were achieved.