Post-irradiation Experiment on IG-110 and A3-3 Graphites for HTGR - 18494

The first irradiation test of A3-3 graphite matrix and IG-110 graphite were performed in Hanaro during the period of August 2013 through March 2014. The dimensional and weight changes, microstructure, and thermal diffusivity were investigated in different directions of the specimen after the irradiation. Interestingly, the density of the A3-3 matrix was increased by 9.4% due to the weight increase after the irradiation. Moreover, the thermal diffusivity in the radial direction of the A3-3 matrix is almost 3-times higher than that of the axial direction owing to the radially oriented graphite texture shown in the microstructure. Meanwhile, 10-20 #mu#m sized irradiation induced pores are observed in the microstructure of IG-110. The thermal diffusivity measurement of pre- and post-irradiated IG-110 results in a 68% irradiation-dominant decrease of thermal conductivity. (authors)