Elemental characterisation of beryllium and electrical behaviour of their pebbles beds

The temperature dependence of the electrical resistivity of a 1 mm single-size pebble bed is presented as a function of different applied pressures. The pebble bed was maintained in a He+0.1 vol.% H2 flowing atmosphere. In agreement with previous studies, the resistivity displays two distinct regimes under the applied load. The first one is characterised by a strong reduction in the resistivity and is likely correlated with the mechanical rearrangement of the pebbles during the first compression phase. The load range of this regime is strongly reduced when the temperature is increased. The second regime is characterised (in a semilogarithmic plot) by a linear decrease of the resistivity with the applied load. The ultimate reached resistivity was 3.0×10−4 Ωm under a pressure of 53 MPa at all temperatures from 20 to 800 °C. The slope of the resistivity curve decreases with temperature, which can be likely correlated with an increase in the plasticity of the pebbles.