Irradiation-induced volumetric deformations in dispersion nuclear fuels arouse a critical concern in nuclear fuel design. Utilizing the concepts from mesomechanics and homogenization, a multi-level-variable correlated mechanistic model system called the Dispersion Fuel Swelling Analysis Model System (DFSAMS) is developed for the irradiation-induced multi-scale volume growths of U-10Mo/Zr dispersion nuclear fuels. These models could directly correlate the macroscopic irradiation-induced volume growth strain with the dynamically varying multi-level information, including the obtained particle volume fractions, the current porosities of recrystallized zones of fuel grains, the macroscale porosities of fuel particles, the average numbers of fission gas atoms within fuel bubbles, the average bubble pressures and the macroscale pressures of fuel particles related to the macroscale hydrostatic pressures of dispersion fuels. The obtained theoretical results align favorably with finite element predictions and a diverse range of experimental data, demonstrating the effectiveness of the newly developed model system. It is indicated that: (1) the irradiation creep performance of the Zr matrix becomes the predominant factor influencing the macroscale volume growth deformations of U-10Mo/Zr dispersion fuels, due to the differed resistance to volumetric deformations of U-10Mo particles; (2) the as-fabricated bubbles of fuel particles will gradually decrease in size under the macroscale hydrostatic pressures due to the irradiation creep deformations occurring in the surrounding solid skeleton, contributing negatively to the macroscale volumetric expansion of U-10Mo/Zr dispersion fuels, especially in cases with higher initial porosity. The important theoretical models are supplied here for efficient numerical simulation of the irradiation-induced thermal-mechanical coupling behaviors in U-10Mo/Zr dispersion fuel elements.
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