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Journal Articles

Electrochemistry of actinide

Kitatsuji, Yoshihiro

Radioisotopes, 67(10), p.483 - 493, 2018/10

https://doi.org/10.3769/radioisotopes.67.483

Electrochemical reactions and redox properties of actinides such as uranium and neptunium are outlined. The flow electrolysis enables rapid and high-efficient treatment. It was demonstrated to measure slow processes of actinide redox. Experimental results of electrolysis of actinide ions and the preparation method of oxidation state of the ions based on the fundamental data are described. Mediator reaction and catalysis observed in the process of electrolysis of actinide ions are also explained.

Journal Articles

Rapid and quantitative electrolytic preparation and speciation of neptunium ions of various oxidation states using multi-step column electrodes

Aoyagi, Hisao*; Kitatsuji, Yoshihiro; Yoshida, Zenko; Kihara, Sorin*

Analytica Chimica Acta, 538(1-2), p.283 - 289, 2005/05

https://doi.org/10.1016/j.aca.2005.02.035

Times Cited Count：15 Percentile：41.55(Chemistry, Analytical)

Redox behavior of Np(III), (IV), (V) and (VI) ions in aqueous perchloric, nitric and sulphuric acid solutions was elucidated by using column electrodes connected in series in a flow system. Using a glassy carbon fiber working electrode as the column electrode was found to be very useful for the investigation of current-potential relations of not only reversible redox processes such as Np(VI)/(V) or Np(IV)/(III) but also irreversible processes such as Np(V)/(IV) or Np(V)/(III), the latter not observed by conventional voltammetry which uses a glassy carbon or platinum electrode. Quantitative electrolysis could be executed even if the redox process was completely irreversible by the use of the column electrodes. By taking advantage of column electrode electrolysis, a novel method was developed for the rapid preparation of a neptunium species of a desired oxidation state, including unstable species. The multi-step column electrode system was demonstrated to be useful for the coulometric determination and speciation of Np(IV), (V) and (VI) in aqueous HNO $_{3}$ solution as an example.

JAEA Reports

Determination of neptunium in neptunium-uranium-plutonium mixed oxide fuel by spectrophotometry.

; ; ; ; ; *; *

JNC TN8400 2001-026, 29 Pages, 2001/12

JNC-TN8400-2001-026.pdf:0.99MB

The measurement condition by spectrophotometry was evaluated to measure Np content in MOX fuel containing Np. The Np concentration was obtained by measuring the 727nm absorption peak, after the valence of Np in the sample solution was adjusted to the Np(Ⅳ). The calibration curve showed the linearity up to Np concentration 0.8mg/ml. Though Pu and U quantity were respectively added to the Np solution to 30 times and 60 times of Np concentration, there was no effect to the Np analysis. By using this method, relative standard deviation (RSD) of the analyzed values of Np content for 2%Np - MOX fuel was about 4%. In addition, It was confirmed that the Np content could be measured without separating Np from Pu and U. This method can be sufficiently applied as a quick simple method to analyze Np content in MOX fuel containing Np.

Journal Articles

Electronic structures and chemical bonding of actinyl nitrates dihydrates

Hirata, Masaru; Tachimori, Shoichi; Sekine, Rika*; Onoe, Jun*; Nakamatsu, Hirohide*

Advances in Quantum Chemistry, Volume 37, p.335 - 351, 2001/00

https://doi.org/10.1016/S0065-3276(00)37024-1

no abstracts in English

Journal Articles

Structural and magnetic studies of the lanthanide deficient perovskite Ce $_{2/3}$ TiO $_{3}$

Yoshii, Kenji

Journal of Alloys and Compounds, 305(1-2), p.72 - 75, 2000/06

https://doi.org/10.1016/S0925-8388(00)00699-X

Times Cited Count：13 Percentile：61.56(Chemistry, Physical)

no abstracts in English

JAEA Reports

Apparent diffusion coefficients of uranium, neptunium and technetium in compacted bentonite under reducing conditions

*; Nakazawa, Toshiyuki*; Ueta, Shinzo*; Shibata, Masahiro

JNC TN8400 99-069, 41 Pages, 1999/11

JNC-TN8400-99-069.pdf:1.62MB

As a part of the evaluation for the sorption phenomena of nuclides in compacted bentonite, apparent diffusivities for uranium, neptunium and technetium that are redox-sensitive elements, were measured under reducing conditions. Bentonite used was a sodium bentonite, Kunigel V1. Apparent diffusivities were measured by using in-diffusion method (concentration profile method), under the conditions with varying dry densities of compacted bentonite and sorts of the solution used for water saturation of bentonite in diffusion experiments. As a result of the measurements, following ranges of values for apparent diffusivities were acquired. ...

JAEA Reports