抄録
The crushing strength of thorium oxide and thorium-uranium mixed oxide fuel kernels for high-temperature gas-cooled reactors (HTGR) was estimated by application of the Hertz theory of contact to the failure load obtained in a simple crushing test. The strength data were interpreted assuming the Weibull distribution. The crushing strength of the Th02 kernels ranged from 1.7 to 1.9 GPa. The strength was found to be closely related to the microstructure of the kernel and to be increased by the kernel properties : small grain size and smooth surface. Fracture would occur in a transgranular manner for the fine-grained kernels and in an intergranular manner for the coarse-grained. Flaws, which are located at or near surface of the boundary of the contact area, act as fracture origins.
