REDOX state analysis of platinoid elements in simulated high-level radioactive waste glass by synchrotron radiation based EXAFS

放射光EXAFSによる模擬ガラス中の白金族元素の酸化還元状態分析

岡本 芳浩  ; 塩飽 秀啓   ; 中田 正美  ; 駒嶺 哲*; 越智 英治*; 赤堀 光雄

Okamoto, Yoshihiro; Shiwaku, Hideaki; Nakada, Masami; Komamine, Satoshi*; Ochi, Eiji*; Akabori, Mitsuo

複数種類の温度と雰囲気の組み合わせ熱処理によって調製された模擬ガラス試料中の白金族元素の酸化還元状態を調べるために、放射光EXAFS分析を実施した。まず、EXAFS関数をRuOのような標準物質のスペクトルと比較し、カーブフィッティング解析から構造パラメーターを取得した。加えて、2種類の標準物質のデータの線形結合解析から、金属と酸化物の割合の導出を試み、熱処理温度の上昇に伴い、金属成分の割合が増加することを明らかにした。確認されたロジウムの化学形は、RhOではなくRhOであり、酸化物の形態ではルテニウムと同伴した挙動を示すことも明らかになった。

Extended X-ray Absorption Fine Structure (EXAFS) analyses were performed to evaluate REDOX (REDuction and OXidation) state of platinoid elements in simulated high-level nuclear waste glass samples prepared under different conditions of temperature and atmosphere. At first, EXAFS functions were compared with those of standard materials such as RuO. Then structural parameters were obtained from a curve fitting analysis. In addition, a fitting analysis used a linear combination of the two standard EXAFS functions of a given elements metal and oxide was applied to determine ratio of metal/oxide in the simulated glass. The redox state of Ru was successfully evaluated from the linear combination fitting results of EXAFS functions. The ratio of metal increased at more reducing atmosphere and at higher temperatures. Chemical form of rhodium oxide in the simulated glass samples was RhO unlike expected RhO. It can be estimated rhodium behaves according with ruthenium when the chemical form is oxide.