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Asai, Shiho; Ohata, Masaki*; Yomogida, Takumi; Saeki, Morihisa*; Oba, Hironori*; Hanzawa, Yukiko; Horita, Takuma; Kitatsuji, Yoshihiro
no journal, ,
Safe and cost-effective disposal of radioactive wastes requires reliable evaluation of the amount of the radionuclides found in such wastes. Measurement of 
Pd, one of the radionuclides that are necessary to be evaluated, is associated with highly radioactive sample (e.g., spent nuclear fuel sample), resulting in only a few data in published forms. We separated Pd as a precipitate from a spent nuclear fuel sample and then determined the precise amount of Pd. However, the method needed dissolution of the Pd precipitate to carry it to the sample introduction system of ICP-MS. In this study, we tried direct measurement of the Pd precipitate with laser-ablation (LA)-ICP-MS that enables solid sample measurement. The diameters of the recovered Pd precipitates were less than 500 nm, which is much smaller than the ablation spot. This allowed Pd to be uniformly vaporized, leading to sufficiently stable signals with high precisions equivalent to those of conventional ICP-MS.
Yomogida, Takumi; Esaka, Fumitaka; Miyamoto, Yutaka
no journal, ,
Identification of the chemical forms of individual uranium particles in environmental samples is important tool for deducing the nuclear activity at nuclear facilities. However, there are few reports on the chemical state analysis of sub-micron sized uranium particles. In this study, micro-sampling and micro-Raman spectroscopy were applied in combination to analyze uranium particles with sub-micrometer size. As a result, the chemical form of individual uranium particles with sub-micrometer size can be analyzed non-destructively thanks to the optimization of the laser power at a micro-Raman measurement.
Okamura, Hiroyuki; Nagano, Tetsushi; Naganawa, Hirochika
no journal, ,
The separation process based on solvent extraction in the nuclear fuel reprocessing has the problem of being affected by sludge components such as undissolved residues. Because the emulsion flow method can actualize highly efficient and rapid solvent extraction by only solution sending with pump, this method has attracted much attention as an innovative technique. Recently, a new emulsion flow apparatus capable of continuously recovering and removing sludge has been developed. In this study, the development of a system integrating highly efficient solvent extraction of uranium with recovery and removal of sludge components from a nitric acid aqueous solution simulating reprocessing process by the emulsion flow method was investigated. In the case of using the emulsion flow apparatus, it was revealed that almost all of uranium can be extracted after circulation and approximately 83% of uranium can be extracted in continuous processing into the organic phase without being affected by sludge components. Furthermore, the sludge components were trapped at the liquid-liquid interface and stripping section of the apparatus, indicating the possibility that part of sludge can be recovered and removed by the emulsion flow apparatus.