Synthesis and characteristics of ternary Be-Ti-V beryllide pebbles as advanced neutron multipliers

先進中性子増倍材としてのBe-Ti-V3元系ベリライド微小球の合成及びその反応性評価

金 宰煥; 中道 勝

Kim, Jae-Hwan; Nakamichi, Masaru

Beryllium intermetallic compounds (beryllides) are the most promising advanced neutron multipliers in demonstration fusion power reactors. Advanced neutron multipliers are being developed by Japan and the EU as part of their BA activities. Beryllides are too brittle to fabricate into pebble- or rod-like shapes using conventional methods such as arc melting and hot isostatic pressing. To overcome this issue, we developed a new combined plasma sintering and rotating electrode method for the fabrication of beryllide rods and pebbles. By using these methods, preliminary synthesis of the ternary beryllide pebbles with different chemical compositions, BeTiV (x=0.0-1.0) was successful. Scanning electron microscopic observation revealed that grain size on the surface decreased while area fraction of Be phase on cross-section decreased as V amount increased. These decreases may be contributed by the fact that the chemical composition of the pebble was closely varied to single-phase BeV with no peritectic reaction as V amount increased while Be, BeTi and BeTi phases were formed with large grain due to peritecic reaction in the BeTi. This feature influenced to variation of reactivity with 1% water vapor at high temperature. It was concluded that weight gain as well as H generation decreased due to decreases of grain size as well as Be phase on the surface as V amount increased in BeTiV.