The goal of this work is to understand and obtain fundamental data on the thermal and mechanical behavior of a packed bed in the solid breeder blanket configuration. This is fulfilled through the following separate, but related efforts:; First, a 3D micro-mechanics model was developed to simulate the mechanical behavior of packed beds for different initial packing, particle size, normal stiffness, shear stiffness, friction coefficient, and coefficient of thermal expansion. The simulations indicate the following: (1) The stress-strain relationships of packed beds are non-linear. A portion of the deformation comes from the rearrangement of particles. (2) With a large friction coefficient, the packed bed behaves more like a solid. Conversely, for a small friction coefficient, the packed bed behaves more like a fluid. (3) An increase in the range of particle sizes leads to a decrease in stress and a lower effective deformation modulus. (4) The calculated deformation modulus is 2--3 orders of magnitude smaller than that of solid material and compares reasonably well with experimental data.; Second, a 3D micro-scale model was developed to predict the effective thermal conductivity of a packed bed based on the information of the bed microstructure, contact force, contact area, solid phase, gas phase, and radiation effects. The results indicate the following: (1) The effective thermal conductivity of metal beds could increase by a factor of 2--4 over a relatively small range of applied load (∼1MPa), which is mainly due to the increased interface contact conductance. (2) Under anisotropic load, a packed bed displays anisotropic behavior---different thermal conductivity along different directions, despite the initial packing being isotropic. (3) Good agreement was achieved between the model predictions and the experimental results that the author found in the literature.; Finally, a benchmark test article was constructed to measure the thermal stress induced by the thermal expansion mismatch between the packed bed and the cylindrical container. Measurements were performed for Al, Li2ZrO 3, Li4SiO4, and beryllium beds. An empirical correlation for the effective deformation modulus of particle beds was derived. The agreement between the experimental results and numerical predictions is very good.
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