Research and development of radiation resistant beryllium grades for nuclear fusion applications

Research and development results on beryllium with high radiation resistance obtained recently are described in this report. Data are presented on nine different grades of isotropic beryllium manufactured by VNIINM which differ both by initial powder characteristics and properties of billets made from these powders. The average grain size of the investigated beryllium grades varied from 8 to 26 μm, the content of oxide in the beryllium varied from 0.9 to 3.9 wt%, the dispersity of the beryllium oxide particles was 0.04 to 0.5 μm, and the tensile strength varied from 250 to 650 MPa. All materials were irradiated in the SM-2 reactor over the temperature range 550-780 C. The results of the investigation showed, that HIP beryllium grades are less susceptible to swelling at higher temperatures in comparison with hot pressed and extruded grades. Beryllium samples having the smallest grain size demonstrated minimal swelling, which was less than 0.8% at 750 C and a fluence FS=3.7.1021 cm-2 (E>0.1 MeV). The mechanical properties, creep and microstructure parameters, measured before and after irradiation, are presented. (orig.)