Optical properties of trinuclear citrate complexes containing 4f and 5f block metals

Aoyagi, Noboru; Palladino, G.*; Nagasaki, Shinya*; Kimura, Takaumi

Bulletin of the Chemical Society of Japan, 91(6), p.882 - 890, 2018/06

https://doi.org/10.1246/bcsj.20170419

The speciation and coordination geometries of M(III)-citrate complexes in aqueous solutions, where M denotes Eu, Tb, Lu, or Cm, are studied using potentiometric titration, nuclear magnetic resonance spectroscopies. Their photophysical properties are also characterized by time-resolved fluorescence spectra. The formation constants of mononuclear, dinuclear, and trinuclear Lu-citrate species were determined by potentiometric titration in 3.00 M NaClO aqueous media. Terminal carboxylic conformation in trinuclear complexes comprised both the five- and six-membered rings at different exchanging rates. Hydration states evaluated for Eu ions are the chemical formula of [Eu(Cit) (H O) ] and [Eu(OH)(Cit)(HO)]. These complexes in aqueous solution have geometrical similarity to the crystal structures in the literature. Furthermore, the entity of the hetero-trinuclear complex induces the intramolecular energy transfer from Tb to Eu. The incorporation of Cm into these homo/hetero-trinuclear citrate complexes proved to be a successful trial to probe the formation of actinide polymer at a trace level.

Sorption behavior of Np(V) on illite, shale and MX-80 in high ionic strength solutions

Nagasaki, Shinya*; Saito, Takumi; Yang, T.*

Journal of Radioanalytical and Nuclear Chemistry, 308(1), p.143 - 153, 2016/04

https://doi.org/10.1007/s10967-015-4332-x

Sorption of Np(V) on illite, shale and MX-80 under oxidizing conditions were first studied in two types of high ionic strength solutions: (1) a reference brine solution (SR-270-PW) with an ionic strength (I) of 6.0 M, and (2) Na-Ca-Cl solutions (with different Na/Ca molar ratios and different ionic strengths, up to a maximum of 4.6 M). The effects of pHc, Na/Ca ratio, and ionic strength on sorption in Na-Ca-Cl solutions were investigated. The Kd values increased with increasing pHc and Na/Ca ratio for all sorbents studied. The Kd values on illite and shale were independent of the ionic strength over the range 0.10-4.6 M, and the Kd value on MX-80 was independent of ionic strength greater than 1.0 M. The Kd values and the sorption isotherms in both SR-270-PW and Na-Ca-Cl solutions were also studied.

Speciation of Eu bound to humic substances by time-resolved laser fluorescence spectroscopy (TRLFS) and parallel factor analysis (PARAFAC)

Lukman, S.*; Saito, Takumi*; Aoyagi, Noboru; Kimura, Takaumi; Nagasaki, Shinya*

Geochimica et Cosmochimica Acta, 88, p.199 - 215, 2012/07

https://doi.org/10.1016/j.gca.2012.04.023

Burning of MOX fuels in LWRs; Fuel history effects on thermal properties of hull and end piece wastes and the repository performance

Hirano, Fumio; Sato, Seichi*; Kozaki, Tamotsu*; Inagaki, Yaohiro*; Iwasaki, Tomohiko*; Oe, Toshiaki*; Kato, Kazuyuki*; Kitayama, Kazumi*; Nagasaki, Shinya*; Niibori, Yuichi*

Journal of Nuclear Science and Technology, 49(3), p.310 - 319, 2012/03

AA2011-0278.pdf:0.56MB

https://doi.org/10.1080/00223131.2012.660021

The thermal impacts of hull and end piece wastes from the reprocessing of MOX spent fuels burned in LWRs on repository performance were investigated. The heat generation rates in MOX spent fuels and the resulting heat generation rates in hull and end piece wastes change depending on the fuel histories including the burn-up of UO spent fuels, the cooling period before reprocessing, the storage period of fresh MOX fuels. The heat generation rates of hull and end piece wastes from the reprocessing of MOX spent fuels with any of those histories are significantly larger than those from UO spent fuels with burn-ups of 45 GWd/THM. If a temperature below 80C is specified for cement-based materials used in waste packages after disposal, the allowable number of canisters containing compacted hull and end pieces in a package for 45 GWd-MOX needs to be limited to a value of 0.7 to 1.6, which is significantly lower than the value of 4.0 for 45 GWd-UO.

Radioactive waste engineering and management

Nakayama, Shinichi; Okoshi, Minoru; Shimada, Taro; Tachibana, Mitsuo; Momma, Toshiyuki; Niibori, Yuichi*; Nagasaki, Shinya*; Ahn, J.*

Genshiryoku Kyokasho "Hoshasei Haikibutsu No Kogaku", 235 Pages, 2011/01

This book is designed to provide everyone with an interest in radioactive waste issues, including students and individuals involved in engineering and public administration, with a graduate-level understanding of radioactive wastes from the scientific foundations that support radioactive waste management covering radioactive waste generation including decommissioning of nuclear facilities, treatment, disposal, clearance and their safety assessment. This book is the one volume of the English translation of the text series "An Advanced Course in Nuclear Engineering" lectured in the University of Tokyo.

Basic actinide chemistry and physics research in close cooperation with hot laboratories; ACTILAB

Minato, Kazuo; Konashi, Kenji*; Fujii, Toshiyuki*; Uehara, Akihiro*; Nagasaki, Shinya*; Otori, Norikazu*; Tokunaga, Yo; Kambe, Shinsaku

IOP Conference Series; Materials Science and Engineering, 9, p.012018_1 - 012018_7, 2010/05

https://doi.org/10.1088/1757-899X/9/1/012018

Basic research in actinide chemistry and physics is indispensable to maintain sustainable development of innovative nuclear technology. Actinides, especially minor actinides of americium and curium, need to be handled in special facilities with containment and radiation shields. To promote and facilitate the actinide research, close cooperation with the facilities and sharing of technical and scientific information must be very important and effective. A three-year-program "Basic actinide chemistry and physics research in close cooperation with hot laboratories", ACTILAB, was started to form the bases of sustainable development of innovative nuclear technology. In this program, researches on actinide solid-state physics, solution chemistry and solid-liquid interface chemistry are made using four main facilities in Japan in close cooperation with each other, where basic experiments with transuranium elements can be made. The O-NMR measurements were performed on (PuAm)O to study the electronic state and the chemical behaviour of Am and Cm ions in electrolyte solutions was studied by distribution experiments.

Location of deuterium atoms in BaZrInO by neutron powder diffraction

Nagasaki, Takanori*; Ito, Tsuyoshi*; Yoshino, Masahito*; Iwasaki, Kota*; Shiotani, Shinya*; Fukazawa, Hiroshi; Igawa, Naoki; Ishii, Yoshinobu*

Journal of Nuclear Science and Technology, 45(Suppl.6), p.122 - 127, 2008/09

https://doi.org/10.1080/00223131.2008.10875992

The neutron powder diffraction measurement was carried out at 10 K on the proton-conducting oxide BaZrInO with and without dissolved DO. Obtained diffraction data were analyzed by the Rietveld method and the maximum entropy method. It was found that deuterium atoms were located close the 12 site of the cubic perovskite structure with the space group -.

Metal sorption to ; Influence of pH, ionic strength and metal concentrations

Takenaka, Yoko*; Saito, Takumi*; Nagasaki, Shinya*; Tanaka, Satoru*; Kozai, Naofumi; Onuki, Toshihiko

Geomicrobiology Journal, 24(3-4), p.205 - 210, 2007/09

https://doi.org/10.1080/01490450701457337

no abstracts in English

Announced document collection of the 1st Information Exchange Meeting on Radioactive Waste Disposal Research Network (Joint research)

Nakayama, Shinichi; Nagasaki, Shinya*; Inagaki, Yaohiro*; Oe, Toshiaki*; Sasaki, Takayuki*; Sato, Seichi*; Sato, Tsutomu*; Tanaka, Satoru*; Tochiyama, Osamu*; Nagao, Seiya*; et al.

JAEA-Conf 2007-003, 120 Pages, 2007/03

JAEA-Conf-2007-003.pdf:53.18MB

The 1st information exchange meeting on Radioactive Waste Disposal Research Network was held in Nuclear Science Research Institute of Japan Atomic Energy Agency on August 4, 2006. Radioactive Waste Disposal Research Network was established by under Interorganization Atomic Energy Research Program of Japan Atomic Energy Agency, and the objective is to bring both research infrastructures and human expertise in Japan to an adequate performance level, thereby contributing to the development of the fundamental research area in the field of radioactive waste disposal. This lecture material is a collection of research presentations and discussions during the information exchange meeting.

Mechanism of Redox Reactions of Actinide Ions on Solid/Water Interface

Tanaka, Satoru*; Nagasaki, Shinya*; Nakata, Kotaro*; Oda, Takuji*; Kameda, Jun*; Kamei, Gento; Tachi, Yukio

JNC TY8400 2003-008, 88 Pages, 2003/05

JNC-TY8400-2003-008.pdf:1.29MB

Redox reactions between Cr(VI) and iron(II) chloride (FeCl2) and those between Cr(VI) and magnetite (Fe(II)1Fe(III)2O4) were observed as a preliminary study. According to the experimental results, it was suggested that the redox reactions were promoted more than the amount of Fe(II) on magnetite surface because of electron transfer from internal Fe(II) to magnetite surface. The results were quantitatively supported from quantum chemical calculations. Redox reactions between Np(V) and magnetite and the reduction of Np to tetravalent were observed, while those between Np(V) and FeCl2 were not observed obviously. It was observed that the reactions were promoted rapidly when the magnetite / solution ratio and the temperature were high, and the rate constant of the reactions was obtained. Furthermore, it was found that hydrogen gas and hydrogen ion were generated with crushing the quartz in an inert gas atmosphere.