Large-scale numerical simulation of mechanical and thermal properties of nuclear graphite using a microstructure-based model

The mechanical and thermal properties of nuclear graphite depend strongly on the microstructures. In this paper, a large-scale three-dimensional boundary element model is presented to study the relationships between the bulk effective properties and microstructure changes in nuclear graphite. Acceleration of the associated boundary element method (BEM) is achieved by use of a fast multipole method (FMM) in allowing large-scale numerical simulations of the model containing up to several hundred micro-structural pores to be performed on one desktop computer. The effects of several key micro-structural parameters such as the pore aspect ratio and the fractional porosity on the bulk mechanical and thermal properties of nuclear graphite are evaluated. The numerical results are compared with some experimental data due to oxidation and good agreement is observed. It is demonstrated that the presented method is potential for fundamental understanding of the bulk properties of nuclear graphite from micro-structural views.