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.

Evaluation of particle release from montmorillonite gel by flowing groundwater based on the DLVO theory

Kurosawa, Susumu; Nagasaki, Shinya*; Tanaka, Satoru*

Nihon Genshiryoku Gakkai Wabun Rombunshi, 6(2), p.205 - 213, 2007/06

https://doi.org/10.3327/taesj.J06.024

no abstracts in English

Sorption of Nuclides on Organic Colloids and their Migration through Porous Media (III)

Nagasaki, Shinya*

JNC TJ8400 2003-064, 106 Pages, 2004/03

JNC-TJ8400-2003-064.pdf:0.86MB

We explained how the metal binding to heterogeneous surfaces can be modeled and showed the modeling results of the copper binding to humic acid by the NICA-Donnan model. This report concentrates on two topic: (i) the modeling of the copper binding to goethite, one of representative metal (hydr)oxides, by the CD-MUSIC model and (ii) the influence of the adsorption of humic acid on goethite upon the proton binding to their mixture. The recent progress in the modeling of the ternary system (metal ions/ NOMs/ OXs) is also introduced at the end of the report.

Sorption nuclides on organic colloids and their migration through porous media (II)

Nagasaki, Shinya*

JNC TJ8400 2002-058, 186 Pages, 2003/03

JNC-TJ8400-2002-058.pdf:2.1MB

Model V and NICA-Donnan model, which can describe the interaction of humic acids with metals, were reviewed and CD-MUSIC model, which is a typical surface complexation model of metals with solid surfaces, was also introduced. In Model V, the equilibrium of chemicals among water in environment, sediments and solids is considered. In NICA-Donnan model, the electrostatic interactions due to the difference in the activities between humic acids and bulk is included and the heterogeneity of binding sites in humic acids is also taken into account. In this report, the problems of these models was summarized and the future development was discussed. In experimental part, the proton dissociation reaction and the interaction with Cu were investigated, by titration experiments using Aldrich humic acids. Considering NICA-Donnan model, the interaction parameters of the proton dissociation reaction and the interaction with Cu were evaluated. In calculation part, the mixing characteristics of water flow in fracture junctions was discussed by Real-coded Lattice Gas model. The mixing ratio at the outlet of fracture junctions was analyzed qualitatively and quantitatively as a function of Peclet number. Furthermore, the trajectory of colloid transport in the laminar flow at bending tube was calculated, and the effect of the mass of colloid was qualitatively studied. The random walk and diffusion phenomena of colloids were found to be successfully calculated by Real-coded Lattice Gas model developed in this work.

Sorption of nuclides on organic colloids and their migration through porous media

Nagasaki, Shinya*

JNC TJ8400 2001-051, 136 Pages, 2002/03

JNC-TJ8400-2001-051.pdf:2.18MB

Humic acid (HA) is popular organic colloid ubiquitous in the environment and forms stable complexes with actinides, such as U(VI), resulted from nuclear wastes. However, such complexation is complicated because HA has heterogeneous distribution of its functional groups and polyelectrolyte properties. In this work, complexation between HA and UO was examined by means of fluorescence quenching, ultracentrifuge and Foulier transform infrared(FTIR) spectroscopy, especially from the points of above features of HA.. From the results of fluorescence quenching method, it was elucidated that the presence of complexing sites which resulted in the quenching of the fluorescence of HA, and such sites were mostly contained in the lower molecular weight fraction. The comparison of these results with those of ultracentrifuge also leaded to the presence of complexing sites in all fractions which did not contribute to the fluorescence of HA. Furthermore, from FTIR measurement of the complexes after washing with different medium, the possibility of the two complexing modes was indicated: the direct binding between the functional groups of HA and UO (innersphere complex) and the electrostatic binding of UO with HA, accompanied with hydrated water of UO (outersphere complex). For the further understanding of the colloid mediated transport in a natural barrier of nuclear waste disposal, the analysis for the relation between the flow of fluid and the mixing ratio of transported materials in cross-intersected flow-paths (Fracture Junctions) with Real-coded Lattice Gas method (RLG), which based on new micro and mesoscopic simulation, revealed the characteristic of underground water flow and the material transport phenomena. The investigation of the distance dependency of he pressure between entrance-exits leads to that its dependency is linear. These results suggested that the analysis of pressure-driven fluid with RLG was effective ...