Annealing of radiation damage in graphite

The effect of thermal annealing (up to 2000 °C) on the structure : nd physical properties of irradiated graphite has been investigated. The irradiation was carried out in the reactor at 100-900 °C up to : dose rate of about 15·10 20 n/cm 2 (E n > 0.18 MeV). Two types of the material were tested: pyrolytic and reactor graphites with different grade of structure perfection. Variations of the crystal lattice parameters, linear dimensions, elastic modulus and electrical conductivity of graphite were investigated during the irradiation and subsequent annealing. The effect of the thermal annealing on the radiation defect behaviour was also investigated using the electron microscopy method. The analysis of the results of investigation of irradiated graphite tnnealing made it possible to refine the model of radiation damage in graphite materials. The investigation of defect production showed that the following three types of radiation defects form in graphite under the given conditions: