Abstract. Uranium dioxide (UO₂ ) is the uranium compound that has been used for water cooled reactors since the early days of nuclear reactor technology. Although UO₂ pellets are fabricated today on a large scale, research and development studies are still going on. In this study, UO₂ powder which was produced at Nuclear Fuel Technology Department of Çl;NRTC was pressed up to %50 TD and sintered under %90 Ar and %10 H ₂ atmosphere at 1400℃, 1500℃, 1600℃, and 1700℃ for duration of 1, 2, 3, 4, and 5 hours. Pellet densities, longitudinal and shear wave ultrasonic velocities at each pellet were measured. After ceramografic preparation, average grain diameter for each pellet was found. Elastic properties of pellets were determined from these measurements. The change of the Young?s modulus, shear modulus and bulk modulus with respect to density and mean grain diameter of pellets were studied.

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