Open Access

ARTICLE

Numerical Simulation of Graphite Properties Using X-ray Tomography and Fast Multipole Boundary Element Method

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Computer Modeling in Engineering & Sciences 2008, 37(2), 153-174. https://doi.org/10.3970/cmes.2008.037.153

Abstract

Graphite materials are widely used in gas-cooled nuclear reactors as both moderators and reflectors. The graphite properties change when the microstructure damage occurs due to the in-core radiation and oxidation, thereby having a strong impact on the service life of graphite. In this paper, the X-ray tomography and the boundary element method (BEM) are introduced to the microstructure modeling and numerical simulations of both the mechanical and thermal property changes of nuclear graphite due to radiolytic oxidation. The model is established by the three-dimensional X-ray scan on the isotropic nuclear graphite Gilsocarbon, which is used in the UK commercial reactors. The BEM is accelerated by the fast multipole method (FMM) in allowing large scale simulations of the model to be performed on one desktop computer. The efficiency of the fast multipole BEM is evaluated numerically in comparison with other algorithms. The effects of the volume fractional porosity on both the bulk Young's modulus and thermal conductivity of graphite are evaluated. The numerical results are compared with the experimental data due to radiolytic oxidation and good agreement is observed. It is demonstrated that the presented model and the associated simulation method are beneficial to the understanding of graphite property changes from micro-structural views.

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