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The influence of alloying additives Al(OH)3 and TiO2 on the structure and properties of uranium dioxide fuel pellets is investigated. It is established that their introduction improves the characteristics of the macrostructure and microstructure of fuel pellets and positively affects their properties. For example, the grain size in the fuel pellet increases to 39 mm (instead of 10–15 mm in the case of usual technology), the number of large (>10 mm) pores decreases, and the strength and thermal conductivity increase slightly.

Features of the macrostructure and microstructure of uranium dioxide powders are considered. Assumptions are made on the mechanisms of the behavior of powders of various natures during pelletizing. Experimental data that reflect the effect of these powders on the quality of fuel pellets, which is evaluated by modern procedures, are presented. To investigate the structure of the powders, modern methods of electron microscopy, helium pycnometry, etc., are used. The presented results indicate the disadvantages of wet methods for obtaining the starting UO2 powders by the ammonium diuranate (ADU) flow sheet because strong agglomerates and conglomerates, which complicate the process of pelletizing, are formed. The main directions of investigation that can lead to understanding the regularities of formation of the structure of starting UO2 powders, which will allow one to control the process of their fabrication and stabilize the properties of powders and pellets, are emphasized.

A mathematical model allowing one to analyze consolidation and compaction processes of uranium dioxide powders of ceramic grade and mixtures based on it is suggested and confirmed experimentally. The model makes it possible to predict the final parameters of powder products that are simple in form starting from the results obtained during testing of the powders on the basis of the deformation function of a powdered body at two pressing pressures without subsequent sintering. This decreases the time and expense compared to the technological testing used in industry.