The oxidation effects of nuclear graphite during air-ingress accidents in HTGR

This study consists of two main parts. The first part presents an experimental investigation of two types of nuclear graphite (IG-110, IG-430) at temperatures ranging from 700 to 1000 °C. Mercury porosimetry results and the quantification of pores in SEM/OM image show that the pores (pore diameter >4 μm) tended to grow into larger pores at temperatures >700 °C. The second part of this study presents a simulation of air-ingress accident. This experiment was conducted at temperatures ranging from 800 to 1000 °C with a flow rate of 0.35 L/min to simulate an air-ingress accident. Results indicate that IG-430 showed a tremendous improvement over IG-110 at medium temperature (<800 °C). However, the advantages of IG-430 began to diminish when the temperature increased.