The damaged spent fuel rods must be stabilized by encapsulation or dry re-fabrication technologies before geological disposal. For applying the dry re-fabrication technology, we manufactured a vertical type furnace to perform both fuel material recovery from damaged fuel rods by oxidative decladding and sinterability improvement of fuel powder by repetition of oxidative and reaction treatment. A horizontal type furnace provides only a diffusion-controlled reaction resulting in longer reaction time and decreasing amount of powder for oxidation and reduction, whereas a vertical type furnace with a submerged gas distributor gives rapid reaction due to flowing gas-solid contact by fluidization. For observation of fluidization behaviors of uranium oxides at room temperature, fluidized column was prepared with transparent cylindrical tube, pressure transmitter and gas flow meter. Number of size of orifice holes was determined by equations in Fluidization Engineering [D.Kunii, O. Levenspiel]. Before uranium oxide test, as surrogates, WO2 (10.8 g/cm3) and Ta2O5 (8.2 g/cm3) powder similar to density of UO2 (10.96 g/cm3) and U3O8 (8.3 g/cm3), respectively were used to achieve fluidization operation conditions in the region from minimum to expanded fluidization. Fluidization behaviors and pressure drop of powder bed was observed according to operation parameters such as gas velocity, number and size of orifice holes, and powder amount.

One append way of liquid state inhibitor was investigated, which putting V, Cr into W-Co composite solutions in the form of ionization. After spray drying and being calcined, W-Co composite oxides could come into being. Then taking fluidization techniques, well-proportioned W-Co composite powder compounded with inhibitor could be produced in the end.

Hybridization system, Spraying chamber coating system and aerothermal fluidization spraying (ATFS) system, were tested to find an economic and practical method for vitamin coating. Ae coating by hybridization was done by commercial hybridizer. But both spraying chamber and aerothermal fluidization spraying system were developed by authors for this test. Two vitamins, Vit. E and Vit. C, were employed for coating with four different coating materials, such as eudragit, corn zein, ethylcellulose and gelatin. Coating by hybridization was unsuccessful due to high intake velocity, temperature increase, and bridge formation between vitamin particles. Spraying chamber system was marginally successful to coat vitamins. But the quality of coated vitamin was poor possibly because of the failure of uniform mixing between vitamin and coating materials inside the chamber. Vitamin coating was successfully achieved by ATFS system. The system enables to give not only uniform mixing between coating material and vitamin, but also drying of coated vitamin and uniform diffusion of vitamin particles by thermal aeration. This result was also confirmed through surface micrograph by scanning electron microscope. Therfore, the ATFS system can be considered as a practical system for coating sensitive materials such as vitamins as well as other feed additives.