Effect of the pore radius on the effective conductivity of UO2 in 2D and 3D: A computational approach

We performed 2D and 3D steady-state heat conduction simulations with a Crank–Nicolson implicit scheme implementation. The parameter ϕ is introduced, with a value of 1 within the matrix and 0 inside a pore. At the interface between a matrix and a pore, this parameter continuously changes from 0 to 1 or vice versa. We investigated the effect of not only the porosity but also the pore radius on the effective thermal conductivity of UO2. To perform large-scale 2D and 3D (10.242μm2, 10.243μm3) simulations, we utilized CUDA-accelerated parallel computing, which consumed only approximately 10% of the time required by serial computation to obtain the same results in 3D. We found that the pore radius, which has not previously been considered a notable microstructural parameter of porous UO2 nuclear fuel, significantly affects the effective thermal conductivity of UO2. •Investigate role of not only porosity but also pore radius on effective conductivity of UO2.•Evaluate β of the Schulz equation is evaluated for circular (2D) and spherical (3D) pore radii.•The pore radius effect on the exponent β in Schulz equation was evaluated.