Novel granulation process of beryllide as advanced neutron multipliers

Nakamichi, Masaru; Kim, Jae-Hwan; Yonehara, Kazuo

Advanced neutron multipliers with lower swelling and higher stability at high temperature are desired in pebble-bed blankets, which would have a big impact on the design of a DEMO reactor, especially on the blanket operating temperature. Development of advanced neutron multipliers has been started by Japan and EU in the DEMO R&D as a part of the Broader Approach (BA) activities. Beryllium intermetallic compounds (beryllides) such as BeTi are one of the most promising advanced neutron multipliers. In order to fabricate the beryllide pebbles, beryllide with shapes of block and/or rod is necessary when a melting granulation process is applied such as a rotating electrode method. However, beryllide is too brittle for the fabrication of blocks or rods by these methods. A plasma sintering method has been proposed as new technique which uses a non conventional consolidation process, because this method is simple, and is easy to control. It was clarified that the beryllide could be simultaneously synthesized and jointed by the plasma sintering method in the insert material region between two beryllide blocks, with no variation of the phase and hardness. Beryllide rod of BeTi with 10 mm in diameter and 60 mm in length has been successfully fabricated by the plasma sintering method. Using this plasma-sintered beryllide rod, prototype pebble of beryllide was performed by a rotating electrode method. The prototype pebbles of BeTi with 1 mm in average diameter were successfully fabricated. The present paper describes novel granulation process of beryllide using these methods including fabrication and granulation techniques.