Development of beryllide pebbles with low-hydrogen generation as advanced neutron multipliers

Highlights: • Prototypic pebbles of beryllides, Be₁₂Ti and Be₁₂V, were successfully fabricated. • It was possible to fabricate prototypic Be₁₂V pebbles without homogenization. • Beryllides pebbles was much more resistant to water vapor than pure Be pebbles. • The surface BeO layer was shown to act as a protective barrier against H₂ generation. - Abstract: Hydrogen generation via an oxidation reaction of Be with water vapor at high temperatures should reduce the safety associated with fusion reactors. Advanced neutron multipliers with higher stability at high temperatures are desired as replacements for the existing Be neutron multipliers for the pebble bed blanket design using a water coolant. Beryllium intermetallic compounds (beryllides) are the most promising material for advanced neutron multipliers. In this study, prototypic beryllide pebbles, Be₁₂Ti and Be₁₂V, were successfully fabricated using the rotating electrode granulation method with a plasma-sintered beryllide electrode. The beryllides pebbles were much more resistant to water vapor than pure Be pebbles. The surface BeO layer on the beryllide pebbles was shown to act as a protective barrier against hydrogen generation reaction.