Rheology, which deals with the flow and deformation of substances, is a discipline that unravels the complexity of complex fluids. In addition, when we prepare slurries as functional materials, rheology can be used both for evaluation of their properties and quality control. In this paper, the basics of rheological evaluation of fluids containing particles (mainly slurries) will be explained along with actual examples.

A collision plate type jet mill is assumed to be a promising pulverizer that can control the particle size for nuclear fuel fabrication. The collision plate type jet mill consists of two modules, a classifier and a pulverizer. Coarse component of powder is cycled in the equipment and finally pulverized into objective particle size. In this report, simulated crushed powders were classified and pulverized step by step, and particle size distribution were compared. The collision plate type jet mil can produce objective size particles with less overgrinding.

In the spent fuel reprocessing process, a mixed solution of uranyl nitrate and plutonium nitrate is converted into mixed oxide powder by the microwave heating. To evaluate the applicability to the industrial-scale and acquire the characteristics data of the microwave heating denitration of various metal nitrate aqueous solutions based on the knowledge studied in the development of laboratory-scale basic experiments, the microwave heating characteristics and metal oxide powder properties were investigated using cerium nitrate, cobalt nitrate and copper nitrate aqueous solutions. The progress rate of the denitration reaction was depended on the position, and the denitration reaction proceeded faster at the periphery than at the center. The morphologies of the synthesized products were porous and hard dry solid for cerium nitrate aqueous solution, foamed dry solid for cobalt nitrate aqueous solution, and powdery particles for copper nitrate aqueous solution. The denitration ratio and average particle size of the synthesized products increased in the order of the cerium nitrate aqueous solution, the cobalt nitrate aqueous solution, and the copper nitrate aqueous solution. The numerical simulations revealed that the periphery of the bottom surface of the metal nitrate aqueous solution was heated by microwaves. These simulation results were consistent with the experimental results in which the denitration reaction started from the periphery of the metal nitrate aqueous solution.

HKUST-1 nanocomposites incorporating Fe₃O₄ nanoparticles (Fe₃O₄/HKUST-1) are fabricated by a spray-assisted synthetic process. By adding Fe₃O₄ nanoparticles without surface modification to a HKUST-1 mother solution, Fe₃O₄/HKUST-1 can be obtained after spray-drying of the mother solution. The amount of nanoparticles incorporated can be controlled by simply changing the concentration in the mother solution. The nanocomposites have a high surface area (1,492 m²/g), giving very high adsorption capacities for methylene blue (779 mg/g). Furthermore, Fe₃O₄/HKUST-1 with superparamagnetic properties due to the incorporated magnetic Fe₃O₄ nanoparticles can be recovered from solvent by applying an external magnetic field.