Narita, Hirokazu*; Nicolson, R. M.*; Motokawa, Ryuhei; Ito, Fumiyuki*; Morisaku, Kazuko*; Goto, Midori*; Tanaka, Mikiya*; Heller, W. T.*; Shiwaku, Hideaki; Yaita, Tsuyoshi; et al.
Inorganic Chemistry, 58(13), p.8720 - 8734, 2019/07
Suzuki, Chikashi; Yaita, Tsuyoshi; Suzuki, Shinichi; Pacold, J.*; Altman, A. B.*; Minasian, S. G.*; Tyliszczak, T.*; Shuk, D. K.*; Yoshida, Hiroyuki; Osaka, Masahiko
Journal of Physics and Chemistry of Solids, 127, p.169 - 177, 2019/04
A combined method of NEXAFS measurement and DFT-calculation was employed for Cs evaluation in clay minerals. The Cs M NEXAFS spectra of Cs halides were analyzed using the DFT-calculations, and were well reproduced by incorporating the core-hole strength. The Cs M NEXAFS spectrum of clay minerals was well-reproduced by the DFT-calculations including the major transitions and tail structures with the established method. The further evaluation of this spectrum by charge density suggests that these major transitions and the tail structures likely reflect bonding states and local environments around the Cs atoms. Comparison of electronic states of Cs in the clay mineral with those in the Cs halides by DFT-calculations has shown that the interaction between Cs and the nearest-neighbor atom is largest in the clay mineral, because the energy level of Cs-5s and 5p is closer to that of O-2s and 2p than the s and p orbitals of other alkali metal and alkali earth metal elements.
Ambai, Hiromu; Nishizuka, Yusuke*; Sano, Yuichi; Uchida, Naoki; Iijima, Shizuka; Shiwaku, Hideaki; Yaita, Tsuyoshi
Journal of Nuclear Science and Technology, 56(2), p.193 - 200, 2019/02
During the accident that occurred at the Fukushima Daiichi Nuclear Power Plant, a large volume of seawater was introduced as coolant into the storage pools for spent nuclear fuel. If this fuel is reprocessed, some components of seawater will be mixed with the nitric acid solution containing metal ions in the reprocessing process where stainless steels are used as structural material. In this study, we investigated the effect of seawater components in high active liquid waste (HAW) containing nitric acid and metal ions as fission products on the corrosion behavior of SUS316L stainless steel. Corrosion tests were conducted in surrogate HAW containing artificial seawater (ASW). Intergranular corrosion was observed in the HAW with ASW, where Ru increased the corrosion potential to the transpassive region. An increase in the amount of ASW led to a decrease in the corrosion rate and suppression of intergranular corrosion. Interactions between Ru ions and seawater components, such as chloride ions, were indicated by the results of extended Xray absorption fine structure spectroscopy and cyclic voltammetry analyses of the solution containing ASW and HAW.
Simonnet, M.; Miyazaki, Yuji; Suzuki, Shinichi; Yaita, Tsuyoshi
Progress in Nuclear Science and Technology (Internet), 5, p.66 - 69, 2018/11
Sekiguchi, Tetsuhiro; Yokoyama, Keiichi; Uozumi, Yuki*; Yano, Masahiro; Asaoka, Hidehito; Suzuki, Shinichi; Yaita, Tsuyoshi
Progress in Nuclear Science and Technology (Internet), 5, p.161 - 164, 2018/11
For nuclear transmutation of cesium-135 (Cs), which is long-lived fission product, we are developing selective absorbent which takes only Cs atom in, but does not CsI. In this study, absorbing property of Cs atom onto the surface of fullerene (C) film has been investigated using synchrotron-based angle-dependent X-ray photoelectron spectroscopy (XPS). The results were compared with those of CsI. It was found that Cs penetrates into C deep bulk. In contrast, CsI deposits on shallow surface. Furthermore, XPS spectra were measured as a function of Ar-sputtering time in order to know Cs concentration profiles in deep region. Results showed that Cs penetrates into deep region of several hundreds .
Kofuji, Hirohide; Watanabe, So; Takeuchi, Masayuki; Suzuki, Hideya; Matsumura, Tatsuro; Shiwaku, Hideaki; Yaita, Tsuyoshi
Progress in Nuclear Science and Technology (Internet), 5, p.61 - 65, 2018/11
Kobayashi, Toru; Suzuki, Shinichi; Shiwaku, Hideaki; Yaita, Tsuyoshi
Progress in Nuclear Science and Technology (Internet), 5, p.74 - 77, 2018/11
Development of extractant, which can efficiently separate actinides, is of increasing importance because it concerns establishment and simplification of separation techniques in nuclear fuel cycle and decontamination of radioactive wastes. In this study, the complexation properties of N-alkyl-N-phenyl-1,10-phenanthroline-2-carboxamide (PTA) with trivalent lanthanides (Ln) were investigated based on structural analysis by using X-ray crystallography and extended X-ray absorption fine structure (EXAFS) methods. As a result, it is revealed that two PTA molecules coordinate with Ln as tridentate ligand via two nitrogen in phenanthroline moiety and one oxygen in amide moiety in both crystal and solution states. The slight difference in coordination bond distances are observed between Eu and Nd complexes, this difference corresponds to the difference in ionic radius between Nd and Eu. This result indicates slight difference in ionic radii of Ln hardly affects coordination properties of PTA.
Nakase, Masahiko*; Kobayashi, Toru; Shiwaku, Hideaki; Kawamura, Takuya*; Takeshita, Kenji*; Yamamura, Tomoo*; Yaita, Tsuyoshi
Progress in Nuclear Science and Technology (Internet), 5, p.56 - 60, 2018/11
Gel/liquid extraction was investigated to achieve selective separation of trivalent actinides over lanthanides. In this study, thermosensitive hydrogel including N,N,N',N'-tetraallylpyridine-2,6-dicarboxamine (PDA) was synthesized, and its complexation with lanthanide was investigated by extended X-ray absorption fine structure experiments at SPring-8. The radial structure functions (RSF) of solution with gels with and without ligands at different temperatures showed slight differences. As the temperature increased, the RSF decreased owing to the increase in thermal vibration, but PDA-gel showed a shift in the first peak toward the shorter direction. This shift was attributed to the change in stoichiometry of PDA-Ln(III) complexes or coordination number of water molecules affected by the change of conformation of polymer chains and the hydrophilic/hydrophobic properties in the hydrogel.
Suzuki, Tomoya*; Ogata, Takeshi*; Tanaka, Mikiya*; Kobayashi, Toru; Shiwaku, Hideaki; Yaita, Tsuyoshi; Narita, Hirokazu*
Metals, 8(7), p.558_1 - 558_10, 2018/07
The refining of platinum group metals is based mainly on solvent extraction methods, whereas Ru is selectively recovered by distillation as RuO. Replacement of distillation byextraction is expected to simplify the purification process. To develop an effective extraction system for Ru, we analyzed the Ru species in HCl with UV-Vis and EXAFS spectroscopies, and we examined the properties of Ru extracted with N-2-ethylhexyl-bis(N-di-2-ethylhexyl-ethylamide) amine (EHBAA). EXAFS and UV-Vis spectra of Ru in HCl solutions revealed that the predominant Ru species in 0.5-10 M HCl solutions changed from [RuCl(HO)] to [RuCl] with the HCl concentration. The extraction percentages of Ru in the EHBAA system increased with increasing HCl concentration, reached 80% at [HCl] = 5 M, and decreased athigher HCl concentrations. EXAFS analysis of the extracted complex indicated that the Ru had 5 Cl and 1 HO in its inner coordination sphere. The similarity of the dependence on HCl concentrations of the extraction in the EHBAA system and the distribution profile of [RuCl(HO)] on [RuCl(HO)] suggested that the EHBAA extracted the pentachlorido species.
Yoshigoe, Akitaka; Shiwaku, Hideaki; Kobayashi, Toru; Shimoyama, Iwao; Matsumura, Daiju; Tsuji, Takuya; Nishihata, Yasuo; Kogure, Toshihiro*; Okochi, Takuo*; Yasui, Akira*; et al.
Applied Physics Letters, 112(2), p.021603_1 - 021603_5, 2018/01
A synchrotron radiation photoemission electron microscope (SR-PEEM) was applied to demonstrate pinpoint analysis of micrometer-sized weathered biotite clay particles with artificially adsorbed cesium (Cs) atoms. Despite the insulating properties of the clay, we observed the spatial distributions of constituent elements (Si, Al, Cs, Mg, Fe) without charging issues. We found that Cs atoms were likely to be adsorbed evenly over the entire particle. Spatially-resolved X-ray absorption spectra (XAS) of the Cs M-edge region showed Cs to be present in a monocation state (Cs). Further pinpoint XAS measurements were also performed at the Fe L-edge to determine the chemical valence of the Fe atoms. Our results demonstrate the utility of SR-PEEM as a tool for spatially-resolved chemical analyses of various environmental substances, which is not limited by the poor conductivity of samples.
Honda, Mitsunori; Shimoyama, Iwao; Kogure, Toshihiro*; Baba, Yuji; Suzuki, Shinichi; Yaita, Tsuyoshi
ACS Omega (Internet), 2(12), p.8678 - 8681, 2017/12
Narita, Hirokazu*; Maeda, Motoki*; Tokoro, Chiharu*; Suzuki, Tomoya*; Tanaka, Mikiya*; Motokawa, Ryuhei; Shiwaku, Hideaki; Yaita, Tsuyoshi
Analytical Sciences, 33(11), p.1305 - 1309, 2017/11
Nippon Genshiryoku Gakkai-Shi, 59(8), p.441 - 443, 2017/08
no abstracts in English
Yaita, Tsuyoshi; Honda, Mitsunori; Shimoyama, Iwao; Ito, Kenichi*; Mampuku, Yuzo*; Tsuji, Takuya; Matsumura, Daiju
Nippon Genshiryoku Gakkai-Shi, 59(8), p.483 - 487, 2017/08
no abstracts in English
Watanabe, So; Sano, Yuichi; Shiwaku, Hideaki; Yaita, Tsuyoshi; Ono, Shimpei*; Arai, Tsuyoshi*; Matsuura, Haruaki*; Koka, Masashi*; Sato, Takahiro*
Nuclear Instruments and Methods in Physics Research B, 404, p.202 - 206, 2017/08
Hisamatsu, Shugo; Suzuki, Shinichi; Komoto, Shigeo*; Kishikawa, Keiki*; Yamamoto, Yusuke*; Motokawa, Ryuhei; Yaita, Tsuyoshi
Tetrahedron, 73(27-28), p.3993 - 3998, 2017/07
Shimoyama, Iwao; Honda, Mitsunori; Kogure, Toshihiro*; Baba, Yuji; Hirao, Norie*; Okamoto, Yoshihiro; Yaita, Tsuyoshi; Suzuki, Shinichi
Photon Factory News, 35(1), p.17 - 22, 2017/05
We introduce Cs-free mineralization (CFM) for Cs removal and reuse of radioactive-contaminated soil in Fukushima and report recent work conducted in the BL27A beamline in Photon Factory. In this work, we investigated compositional and structural changes of Cs-sorbed weathered biotite (WB) before and after heating treatment with addition of NaCl-CaCl salts under low-pressure condition, to study Cs desorption mechanism from clay minerals. X-ray fluorescence spectroscopy clarified that almost all Cs and K were removed with the salts at 700 C. On the other hand, Ca increased with heating temperature. X-ray diffraction and transmission electron microscopy analysis clarified that phase transitions from WB to some Ca-rich silicate minerals, e.g., augite, were caused by the heating treatment with the salt. Based on these results, CFM is proposed for Cs removal utilizing the mechanism in which large monovalent cations are discharged with accompanying the phase transition. We also discuss the role of Cl in this reaction showing chemical bonding change of Cl observed using X-ray absorption spectroscopy in the early stage of the chemical reaction.
Maeda, Motoki*; Narita, Hirokazu*; Tokoro, Chiharu*; Tanaka, Mikiya*; Motokawa, Ryuhei; Shiwaku, Hideaki; Yaita, Tsuyoshi
Separation and Purification Technology, 177, p.176 - 181, 2017/04
Honda, Mitsunori; Okamoto, Yoshihiro; Shimoyama, Iwao; Shiwaku, Hideaki; Suzuki, Shinichi; Yaita, Tsuyoshi
ACS Omega (Internet), 2(2), p.721 - 727, 2017/02
Motai, Satoko*; Mukai, Hiroki*; Watanuki, Tetsu; Owada, Kenji; Fukuda, Tatsuo; Machida, Akihiko; Kuramata, Chisaki*; Kikuchi, Ryosuke*; Yaita, Tsuyoshi; Kogure, Toshihiro*
Journal of Mineralogical and Petrological Sciences, 111(5), p.305 - 312, 2016/10
no abstracts in English