The results of an investigation into the effects of neutron irradiation on the mechanical properties and structure of beryllium are presented. Irradiation was performed in the BOR-60 reactor up to doses of 0.7–1.1 × 10²² n/cm² (E > 0.1 MeV) at irradiation temperatures of 350°C, 400°C, 520°C, 780°C. Two modifications of RF beryllium, i.e. DShG-200 and TShG-56, were chosen for investigation.

For irradiation at temperatures of 350 – 400°C Be hardening due to the accumulation of radiation defect complexes. Hardening is accompanied with a sharp drop in plasticity at T^test ≤ 300°C. The fracture of samples is of brittle, mainly transcrystallite, type. High-temperature irradiation (T^irr = 780°C) gives rise to large helium pores over the grain boundaries and smaller pores in the grain body. Fracture is brittle and intercrystalline at T^test ≥ 600°C. Helium embrittlement is also accompanied with a drop in the Be mechanical properties. The conclusion is made that the irradiation temperature range, where irradiated beryllium has a satisfactory level of properties, is rather narrow: 300°C ≤ T ≤500°C.