Beryllide pebble fabrication of Be-Zr compositions as advanced neutron multipliers

先進中性子増倍材としてのBe-Zr系ベリライド微小球製造

中道 勝; 金 宰煥; 落合 謙太郎

Nakamichi, Masaru; Kim, Jae-Hwan; Ochiai, Kentaro

Advanced neutron multipliers with high stability at high temperatures are desirable for the DEMO blankets. Development of the advanced neutron multipliers has been started in the Broader Approach activities. Beryllides are the most promising material for this purpose. To fabricate BeTi beryllide pebbles, a new granulation process has been established that combines a plasma sintering method for beryllide synthesis with a rotating electrode method (REM) using the plasma-sintered electrode for granulation. However, in the case of BeTi pebble fabrication, an annealing treatment is necessary to homogenize the pebbles to a single BeTi phase. From the viewpoint of mass production of beryllide pebbles, other potential structural compositions of beryllides that are able to fabricate without the annealing treatment for homogenization were surveyed. Based on this survey, the structural composition of BeZr was selected because this composition not only has no peritectic reaction during the cooling process from the liquid phase, but also has low neutron absorption property. From the result of fabrication examination, prototypic beryllide pebbles 1 mm in diameter composed of single phase BeZr were successfully fabricated directly by granulation using the rotating electrode method without homogenization treatment. The present study reports on not only the granulation of BeZr beryllide, but also on basic characterization of prototypic BeZr pebbles.