Abstract
This work consists of three main parts. The first part describes IG-110, IG-430, and NBG-18 grade nuclear graphite based on the size and shape of the filler particles and how the forming method affects the pore distribution. The second part presents an experimental investigation of nuclear graphite oxidation in air at temperatures ranging from 700°C to 1100°C and correlates the results to the theory of graphite active sites. Mercury porosimetry is used to quantify the phenomenon of pore structure developments at various temperatures. X-ray diffraction analysis of selected graphite is conducted to determine the crystallographic parameters. The results of mercury porosimetry and scanning electron microscopy images are correlated to the theory of graphite active sites, demonstrating the relationship between pore distribution and active sites. The third part of the study presents two experiments. The first experiment investigates the size effect of samples with the same aspect ratio and the second examines the size of fuel pellets and graphite sleeves to evaluate the degradation of graphite components in an air-ingress scenario.