[en] Hydrolysis behavior of U(VI) has been examined at elevated temperatures (up to 100 deg. C) and pressures (0.1-40 MPa) using time-resolved laser-induced fluorescence spectroscopy. Emission spectra and lifetimes of 5 x 10^-5 M uranium(VI) in 0.5 M NaClO₄ at pH 3.8-6.0 were measured as a function of temperature and pressure. With increasing temperature, the emission intensities and lifetimes of uranium(VI) hydrolysis species decreased rapidly. On the other hand, the pressure effect on the luminescence properties was quite small as compared with the effect of temperature. The temperature dependence of the lifetimes followed well the Arrhenius law, enabling the activation energies to be estimated for the luminescent species. These experimental results were compared with the speciation calculations carried out at several temperatures by using the DQUANT equation together with the thermodynamic data in the literature. From this comparison, each component of luminescence could be assigned to the hydrolysis species such as UO₂(OH)⁺, (UO₂)₂(OH)₂²⁺, (UO₂)₃(OH)₅⁺ or uranyl(VI) ion indicating that the Arrhenius plot of luminescence lifetime is an effective method for in-situ speciation of uranyl hydrolysis product at elevated temperatures

[en] In this report, the problems in the research on cold nuclear fusion reaction as of December, 1990, particularly those in the measurement of neutron are described. Since the report of the success in normal temperature nuclear fusion reaction in March, 1989, many researchers and the large amount of money were poured into this research, but after one and a half years, the phenomena reported by Fleischmann and Pons at the beginning are almost denied. The method of detecting cold nuclear fusion reaction progressed steadily in the process of the research carried out so far, but the parameters which determine the reaction are unknown, and the reproducibility has not been able to be confirmed. As the method of verification, other methods than the detection of 2.45 MeV neutrons by highly reliable measurement of extremely minute amount cannot be considered. The evaluation of the influence of cosmic radiation and environmental radioactivity, the problems in the measurement of neutrons at extremely weak level and so on are described. It is desirable to standardize the reaction system and detection system and cross-check the affirmative results. (K.I.)

[en] Several topics on solution chemistry of actinides(An) and lanthanides(Ln) studied by time-resolved laser-induced fluorescence spectroscopy(TRLFS) will be mentioned in this presentation. Those are hydration studies of An(III) and Ln(III) and its applications, speciation study of U(VI), and luminescence of U(IV) in aqueous solution. (author)

[en] In order to promote the development of technologies related to spent fuel reprocessing and radioactive waste processing/disposal, it is essential to enhance basic research on the solution chemistry of actinides, and time-resolved laser-induced fluorescence spectroscopy (TRFLS) is one of the important research tools. Although as the most effective research target for determining the internal hydration number of trivalent ions, the direct comparison of the ion configuration environment in the separation of actinides and lanthanides using ion exchange or solvent extraction is named, TRFLS is an effective means for exploring the configuration state and separation mechanisms of trivalent ions with similar chemical behaviors. Since U(VI), which has a relaxation process different from actinide(III), has the emission lifetime and emission spectra unique to its dissolved state, TRFLS has been proven to be useful for the state analysis of chemical species. In addition, since hydration and solvation studies have been extended to lanthanide ion Nd (III) etc., comparative studies between actinides and lanthanides have become possible. One of the advantages of TLFLS is that it can be applied to all conditions of samples, such as solution, solid, solid-liquid or liquid-liquid interfaces, extremely low temperatures to high temperature, and high pressure, and it is particularly essential for studies on solid-liquid interface whose analytical methods are limited. (A.O.)

[en] Published in summary form only

[en] The R and D effort on partitioning of minor actinides (MA) at the Japan Atomic Energy Agency (JAEA) has been concentrated on development and improvement of innovative extractants and adsorbents as the fundamental studies and of MA recovery process as the advanced aqueous reprocessing system in fast reactor cycle technology development (FaCT) project. This paper reviews current status and prospects of the R and D activities on the partitioning of MA at JAEA. (authors)

[en] Published in summary form only

[en] The airborne dust samples were collected in March and May 2011 with an Andersen-type low pressure cascade impactor, and the radioactivities collected on each sampling stage were measured with a HP-Ge spectrometer. The radioactive nuclides discharged from the Fukushima 1st NPPs accident, "1"3"4Cs, "1"3"6Cs, "1"3"7Cs, "1"3"1I, and "1"2"9"mTe were detected. These nuclides gathered in the coarse grains. The activity median aerodynamic diameter (AMAD) of these nuclides was 1.5 μm, and Al- and Si-rich minerals such as clays and sea-salts were observed in the samples of this size. Iodine-131 gathered in the fine grains, and the AMAD was 0.58 μm. Carbon and sulfur-rich grains were observed in the samples. The airborne dust collected in the May had two different AMAD of "1"3"7Cs; the size of fine grain was < 1.0 μm and that of coarse grain was > 10 μm. This seasonal change of "1"3"7Cs AMAD suggests that the host phase of "1"3"7Cs and transport mechanism may be different from those in the March. (author)

[en] Laser-induced fluorescence(LIF) studies of Sm(III), Tb(III), Dy(III) and Cm(III) complexes in NaSCN/DHDECMP solvent extraction system have been carried out. Luminescence lifetime were measured to determine the number of water molecules coordinated to Sm(III), Tb(III), Dy(III) and Cm(III) in the sodium thiocyanate solution and in DHDECMP phase. The hydration number of Sm(III), Tb(III), Dy(III) and Cm(III) in the sodium thiocyanate solution decreased linearly with an increasing sodium thiocyanate concentration. The hydration numbers of Sm(III), Dy(III) and Cm(III) in DHDECMP phase decreased with an increase of sodium thiocyanate concentration. The water molecules in the inner coordination sphere of Sm(III) and Dy(III) extracted into the DHDECMP were not completely removed at the low sodium thiocyanate concentration and decreased with an increase of sodium thiocyanate concentration. But, Cm(III) extracted into the DHDECMP phase from sodium thiocyanate solution represented there was no water in the inner coordination sphere. (Author). 18 refs., 3 figs

[en] Laser-induced photoacoustic spectroscopy (LPAS) has been developed for the direct speciation of actinoids in solution with the minimal disturbance of species equilibria. The speciation of actinoids is defined as the elucidation of the individual physical and chemical forms of actinoids in a sample. In the present review, the characteristics of the optical absorption spectra of actinoids, the principle, theory, and construction of the LPAS system are described in detail with its application to the speciation of actinoids in aqueous solution. (author)