Failure analysis of the effects of porosity in thermally oxidised nuclear graphite using finite element modelling

Finite element models of thermally oxidised nuclear graphite were generated using three-dimensional high-resolution tomography images. Bulk tensile strength was then evaluated using a smeared-crack model, which shows an exponential decay in the bulk strength with increasing pore volume. The finite element results were in good agreement with radiolytic oxidation experiments. A stochastic analysis using a modified Weibull theory was also performed to describe the evolution of the failure process with increasing load for different levels of porosities.