Thermal and mechanical properties of beryllium pebbles

A low impurity and low cost pebble production method has been developed using an improved rotating electrode, and basic characteristics of the beryllium pebbles have been measured. Thermal expansion coefficient and specific heat of the unirradiated pebble samples were measured by laser interferometry and differential scanning calorimetry respectively. These thermal properties are almost identical to those of hot-pressed beryllium. Compression tests were also conducted for the evaluation of mechanical properties. The pebbles with total fast neutrons fluence of 1.3 × 1021 n cm−2 were tested at room temperature. The embrittlement of irradiated beryllium pebbles was observed from the compression test.