Thermal shock resistances and fracture toughnesses of graphites and C/C-composites as plasma-facing first wall components for fusion reactor devices

AbstractOn the basis of our analysis of a transient thermal stress problem of a thin circular disk, which is locally heated at an arbitrary eccentric position, influences on thermal stresses and stress intensity factors in the thermal shock testings of the disk specimens are discussed. The thermal shock resistances and fracture toughnesses of five kinds of graphite and six kinds of C/C-composite as the first wall materials in fusion reactor devices are evaluated by means of arc discharge heating method. These results are compared with preliminary observations of the plasma-facing first wall tiles for a fusion reactor device (JT-60). Other mechanical and fracture mechanics properties are also measured. Two graphites and three C/C-composites are irradiated up to about 1.1–1.9×1021 n/cm2 (E > 29 fJ) at about 650–1000°C in a fission reactor (Japan Material Testing Reactor, JMTR) and the degradations in the thermal shock resistances and fracture toughnesses and the changes of mechanical and fracture mechanics properties due to the neutron irradiations are quantitatively given.