Thermal diffusivity of tungsten irradiated with protons up to 5.8 dpa

Thermal properties of pure tungsten, irradiated in the Swiss neutron spallation source at the Paul Scherrer Institut, have been studied in the temperature range 25-500 °C. Disk-shaped specimens were prepared from a tungsten sheet which was irradiated with high energy protons and spallation neutrons. The specimens tested in this work received total damages of maximum 3.9 and 5.8 dpa at average irradiation temperatures of 115 and 140 °C, respectively. The thermal diffusivity of the irradiated tungsten was measured using the conventional flash method. For both specimens, the results show a significant decrease in thermal diffusivity after irradiation. Relative to unirradiated tungsten, the irradiated samples show thermal diffusivity values which are 28-51% lower, depending on temperature. Annealing of the irradiated specimen of 3.9 dpa at 1000 °C for 1 h resulted in a slight recovery of thermal diffusivity. In addition, thermal conductivity values were calculated from the thermal diffusivity data.