Abstract
The oxidation damage is one of the crucial factors to degrade mechanical properties of graphite components in the HTGRs. It is important to estimate the inner porous conditions of the graphite which strongly affect the mechanical properties. A new non-destructive evaluation method was developed to estimate the conditions by an ultrasonic wave propagation analysis. An evaluation model was proposed in order to determine the value of the Young modulus for an ideal graphite polycrystals without pore which is an important factor in the analysis to evaluate the apparent Young modulus for porous graphite. It was shown that the apparent moduli for isotropic porous graphites are evaluated appropriately by using the analyzed values of the ideal polycrystals. The evaluation model is available to evaluate the modulus for anisotropic graphite by considering anisotropy and pore shape precisely. It suggests that it is possible to estimate the porous conditions of the graphite components by the developed method, provided that their apparent Young moduli are experimentally measured. This new method is promising to evaluate the oxidation damage of the graphite components and it has a potential to estimate other material properties which highly depend on the porous conditions, by non-destructive way.
