Journal of Nuclear Fuel Cycle and Waste Technology

A voloxidizer for a hot cell demonstration, that handles spent fuels of a high radiation level in a limited space should be small and spent fuel powders should not be dispersed out of the equipment involved. In this study a density rate equation as well as the Stokes'; equation has been proposed in order to obtain the theoretical terminal velocity of powders. The terminal velocity of U3O8 has been predicted by using the terminal velocity of SiO2, and then etermination has been the optimum air flow rate which is able to prevent powders from scattering. An equation which has shown a relationship between theoretical terminal velocities of U3O8 and SiO2 has been derived with the help of the Stokes'; equation, and then an experimental verification made for the theoretical Stokes'; equation of SiO2 by means of an experimental device made of acryl. The theoretical terminal velocity based on the proposed density rate equation has been verified by detecting U3O8 powders in a filter installed in the mock-up voloxidizer. As the results, the optimum air flow rates seem to be 20 LPM by the Stokes'; equation while they are 14.5 L/min by the density rate equation. At the experiments with the mock-up voloxidizer, a trace amount of U3O8 seems to be detectable at the air flow rate of 14.5 L/min by the density rate equation, but U3O8 powders of 7 ㎛ diameter seem detectable at the air flow rate of 20 L/min by the Stokes'; equation. It is revealed that 14.5 L/min is the optimum air flowe rate which is capable of preventing U3O8 powders from scattering in the UO2 voloxidizer and the proposeed density rate equation is proper to calculate the terminal velocity of U3O8 powders.

Keywords

SiO2,UO2 pellet,Terminal velocity,U3O8,Demonstration,Voloxidizer