颗粒＜500μm的硼及其合金(含量≥97%,不论球形,椭球体,雾化,片状,研碎金属燃料)

Boron and its alloys, granularity＜500μm（containing more than 97% by weight of boron whether in the form of spheroid, ellipsoid, flakes, atomized or pulverized metallic fuel）