Some considerations on selection criteria for graphites as fusion materials

Some considerations are made on the selection criteria for graphite materials when they are used for the fusion reactor components. The selection criteria are examined considering that the graphite might fracture due to internal stresses. The internal stresses consist of a thermal stress based on temperature gradient in the components and irradiation-induced stress associated with dimensional changes due to neutron irradiation. It is stressed that the irradiation-induced stress is particularly important. There it may be impossible for the graphite to fracture if a stress generated is smaller than the fracture stress and a stress intensity factor or a J-integral value which controls initiation and extension of cracks is smaller than the respective fracture toughness value. From such viewpoints the selection criteria for graphite materials are examined and the present status of the data base on properties which are considered to be significant is reviewed. As a result, the data group which should be intensively obtained are defined