Thermal Shock Resistances and the Irradiation Effects ot Graphites and C/C-Composites for Fusion Reactor Devices

Graphites and/or C/C-composites as plasma-facing first wall components for fusion reactor devices are subjected occasionally to plasma disruption. Therefore the thermal shock resistances and fracture toughnesses of these materials must be evaluated to assure appropriate performances. In this study, the thermal shock resistance and fracture toughness of several kinds of graphites and C/C-composites for candidate first wall component tiles are evaluated. The mechanical and fracture mechanics properties for these specimens are also measured. Then, two graphites and three C/C-composites are irradiated with 1.1-1.9×10^n/cm^2 (Energy>29fJ) at 650-1000℃ 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 irradiation are quantitatively studied

Effect of Neutron Irradiation on the Microstructures and Tensile Properties of Different Carbon Fibers

Since carbon fiber reinforced carbon composite (C/C composite) materials have high thermal conductivity and good mechanical properties, they have been used as the plasma facing components in fusion facilities. As the plasma facing components are subjected to neutron irradiation in the fusion reactors, it is necessary to use irradiation damage resistant C/C composite materials as plasma facing components. Properties of C/C composite materials after neutron irradiation are generally influenced by irradiation behavior of carbon fiber and carbon matrix. In particular, the effect of irradiation on carbon fiber is important, because it is less crystalline than carbon matrix. The purpose of this study is to evaluate neutron irradiation effects on the microstructures and tensile properties of nine kinds of carbon fibers and to find out the necessary knowledge to identify the radiation resistant carbon fiber

Neutron Irradiation Effects on Thermal Shock Resistances and Fracture Mechanical Properties of Fuel Compacts for the HTTR

To simulate the nuclear fuel for the High Temperature Engineering Test Reactor (HTTR), a fuel compact model using SiC-kernel coated particles instead of UO_2-kernel coated particles was prepared under the same conditions as those for the real fuel compact. The mechanical and fracture mechanics properties were studied at room temperature. The thermal shock resistance and fracture toughness for thermal stresses of the fuel compact model were experimentally assessed by means of arc discharge heating applied at a central area of the disk specimens. These model specimens were then neutron irradiated in the Japan Material Testing Reactor (JMTR) for fluences up to 1.7×10^n/cm^2 (E>29fJ) at 900℃±50℃. The effects of irradiation on a series of fracture mechanical properties were evaluated and compared with the cases of graphite IG-110 used as the core materials in the HTTR