Composition of insoluble materials in highly active liquid waste at Tokai Reprocessing Plant

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久野 剛彦 ; 中村 芳信; 岡野 正紀 ; 佐藤 宗一 ; 綿引 優

Kuno, Takehiko; Nakamura, Yoshinobu; Okano, Masanori; Sato, Soichi; Watahiki, Masaru

再処理施設の高放射性廃液(HALW)中の不溶解性物質の組成については、長期間貯蔵されたHALWの実測データがほとんど得られていないことから、東海再処理工場のHALW貯蔵工程中の不溶解性物質の組成調査を行った。調査では、比較検討のため、貯蔵期間の異なるHALW2貯槽とHALW蒸発缶の3種類の試料を採取し、ろ過により不溶解性物質とろ液に分離後、不溶解性物質の重量測定及び不溶解性物質とろ液中のFP元素、U、Pu分析を実施した。得られた結果から、HALWの不溶解性物質及びろ液中の元素組成を把握するとともに、既報等からの知見を参照に不溶解性物質の化学形態を推定した。

The elemental composition and amount of insoluble materials in highly active liquid waste (HALW) were measured at the Tokai Reprocessing Plant. To evaluate the composition of the insoluble material between the treatment and storage processes, samples from the evaporator and two vessels which differ in the storage period, were taken. The concentration of insoluble material evaluated by both its weight on filter paper after filtration as well as by filtration volume showed no difference for three different samples. Inductively coupled plasma atomic emission spectrometry and isotope dilution mass spectrometry were used to determine the elements in samples dissolved by sulfate fusion. Analytical data revealed that Zr and Mo were the main components of the insoluble material in three samples, but low levels of Rh, Ru and Pd were also present. These results suggest that most of insoluble material had re-precipitated from the HALW solution during the concentration process.