Thermal Conductivity of Beryllium under Low Temperature High Dose Neutron Irradiation

摘要

Thermal conductivity of compact beryllium of several Russian grades such as TE-400, TE-56, TE-30, TIP and DIP differing in the production technology, grain size and impurity content has been investigated. The thermal diffusivity of beryllium was measured on the disks in the initial and irradiated conditions using the pulse method in the range from room temperature to 200℃. The thermal conductivity was calculated using the table values for the beryllium thermal capacity. The specimens and beryllium neutron source fragments were irradiated in the SM reactor at 70℃ and 200℃ to a neutron fluence of (0.5-11.4)-10~(22) cm~(-2) (E>0.1MeV) and in the BOR-60 reactor at 400℃ to 16·10~(22) cm~(-2) (E > 0.1MeV), respectively. The low-temperature irradiation leads to the drop decrease of the beryllium thermal conductivity and the effect depends on the irradiation parameters. The paper analyses the effect of irradiation parameters (temperature, neutron fluence), measurement temperature and structural factors on beryllium conductivity. The experiments have revealed that the short time post-irradiation annealing at high temperatures results in partial reduction.of the thermal conductivity of irradiated beryllium.