Papers by Keyword: Fuel Pellets

Abstract: Plastic waste will potentially cause serious environmental problems. In this study aluminum-plasticspackaging waste is recycled into pellets for alternative fuel. Plastic waste is pelletized using an extruder with temperature variations of 140°C, 160°C and 180°C. Then, the calorific value, moisture content, density and compressive strength of the pellet were measured. The calorific value of the pellet is 38.79 mJ/ Kg. The density value shows good results because it exceeds the standard density for pellet solid fuel of more than 600 kg/m³. Meanwhile, the compressive strength exceeding the specified standard and experiencing an increase from each temperature variant. The economic feasibility analysis shows an NPV of Rp. 3.249.934.093. IRR 28.16%, B/CR 1.617 and PP 5.84 years. From these data, it indicates that the aluminum foil plastic pellet business is possible to be implemented.

Abstract: UO₂ fuel pellets may be swelling and recrystallization during irradiation. Density, dimension and distribution of pores are main factors to induce irradiation swelling, especially the size distribution of pellet pores plays an important role. 4×4-4 fuel assembly was a high performance fuel assembly which was self-designed and manufactured, the average burn-up of the fuel assembly was 42GWd/tU.For studying the effect of irradiation on pore modality, the specimens of irradiated UO₂ fuel pellets were taken from 4×4-4 fuel assembly after dismantling, microscopic structure and distribution of pores for UO₂ fuel assembly by scanning electron microscopy were studied in this paper. The results showed that there were many cracks in fuel pellets, most micro-cracks were transgranular crack. The release rate of fission gas with burn up were augmentation, which was consistent with the porosity of diversity burp up fuel rod. Pores were distributed non-uniformly in irradiated fuel pellets, gathered at local area and more obvious connectivity of pores. The size of pores after the irradiation was between 0.2~1.2 μm, and mostly distributed at 0.3μm ~0.6 μm; The pores at grain boundary of two adjacent grains was less, the pores at grain boundary were distributed by the way of triangle or quadrilateral. The size of pores was increased than pre-irradiation, but ratio of pores and density of pores were decreased obviously, the phenomenon of irradiation densification was occurred in fuel pellets after irradiated. Recrystallization and Rim structure effect were not found.

Abstract: The results of development and investigation of computer-vision systems for inspection of the external view of fuel pellets for nuclear fuel elements are presented. The systems developed utilize CCD-cameras to record the images of a fuel pellet’s external view in reflected beams that ensures high contrast of the defects in the picture area. One has developed a database containing images of simulators, as well as real pellets. Tests of an experimental set for fuel pellet inspection have demonstrated its inspection productivity to be 1 pellet per second and its detection probability higher than 95%. The research team has also developed an experimental set with higher inspection productivity (at least 7 pellets per second).

Abstract: The direct incorporation of Gd2O3 powder into UO2 powder by dry mechanical blending is the most attractive process for producing UO2-Gd2O3 nuclear fuel. However, previous experimental results by our group indicated that pore formation due to the Kirkendall effect delays densification and, consequently, diminishes the final density of this type of nuclear fuel. Considering this mechanism as responsible for the poor sintering behavior of UO2-Gd2O3 fuel prepared by the mechanical blending method, it was possible to propose, discuss and, in certain cases, preliminarily test feasible adjustments in fabrication procedures that would minimize, or even totally compensate, the negative effects of pore formation due to the Kirkendall effect. This work presents these considerations.