Chemical composition of insoluble residue generated at the Rokkasho Reprocessing Plant

六ヶ所再処理工場で発生した不溶解残渣の化学組成

山岸 功 ; 小田倉 誠美 ; 市毛 良明; 黒羽 光彦; 高野 公秀 ; 赤堀 光雄; 吉岡 正弘*

Yamagishi, Isao; Odakura, Makoto; Ichige, Yoshiaki; Kuroha, Mitsuhiko; Takano, Masahide; Akabori, Mitsuo; Yoshioka, Masahiro*

六ヶ所再処理工場で発生した不溶解残渣の化学組成を分析した。XRD分析では、Mo-Tc-Ru-Rh-Pdからなる白金族合金、モリブデン酸ジルコニウム等の複合Mo酸化物、ジルコニアの存在を確認した。定量した12元素(Ca, Cr, Fe, Ni, Zr, Mo, Tc, Ru, Rh, Pd, Te, U)重量の90%以上は、白金族合金が占めた。シュウ酸溶液で複合Mo酸化物を選択的に洗浄溶解する手法を開発し、白金族合金と複合Mo酸化物の形態で存在するMoの割合を明らかにした。

The characteristics of insoluble residues in fine suspension at the Rokkasho Reprocessing Plant were analyzed. The insoluble residues were washed with oxalic acid solution to dissolve zirconium molybdate residues. XRD profiles of unwashed residues showed the presence of a noble metal alloy, zirconium molybdate, and zirconia, but zirconium molybdate was not found after washing. More than 50% of the Sb-125 and Pu in thee residues was washed out as well. The noble metal alloy composed of Mo, Tc, Ru, Rh, and Pd occupied more than 90% of the total weight of 12 elements (Ca, Cr, Fe, Ni, Zr, Mo, Tc, Ru, Rh, Pd, Te, and U) found in the residues. In consideration of the chemical forms of 12 elements, the alloy-to-residue weight ratio was evaluated to be 64% and 78% with and without 18% of an unknown component, respectively.