SiC coatings in tri-structural isotropic-coated (TRISO) particles were thermally treated at 2000 degrees C for 1h in argon atmosphere. The fracture strength of the SiC decreased while change in the Weibull modulus of the failure strength is more complex after the thermal treatment. The variation in both fracture strength and Weibull modulus can be explained by the formation of the pores in SiC due to thermal treatments, as annihilation of the stacking faults and diffusion of intrinsic defects lead to the pore formation.