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Abstract  

To understand the behaviour of Tl/II/ and the bridging group SO 4 2– in radiation induced electron exchange reactions we have investigated the rate constants and mechanisms of reaction of Tl/II/ with Tl/I/ and Tl/III/ in perchloric acid solutions. The results indicated that Tl/II/ is an intermediate in the -ray induced electron exchange process of T1/I/–T1/III/. Sulfate ions at [SO 4 2– ]>-0.02M serve as bridging groups and play an important role in accelerating the T1/II/–T1/I/ reaction. A cooperative effect was found between hydrogen peroxide and sulfate ion at low sulfate ion concentration, [SO 4 2– ]0.02M in perchloric acid solution.

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Abstract  

A combined -spectrometric and mass-spectrometric determination of237Np in spent nuclear fuels using239Np as an inherent spike has been developed. In spent fuel239Np is in radiochemical equilibrium with243Am. Neptunium in the tetravalent state is separated by TTA solvent extraction from the other actinides and most of the fission products and the -activity ratio of237Np to239Np is measured. The237Np activity is via239Np directly linked to the243Am mass in a sample, which is determined by mass-spectrometric isotope dilution analysis.

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Abstract  

Isotope dilution mass spectrometry using enriched isotope96Ru as a spike was applied to the determination of ruthenium as a fission product. Ruthenium in the solution was oxidized to RuO4 by Ce/IV/ and separated from coexisting metal elements by distillation. Silica-gel technique was employed to enhance ion current of ruthenium in the mass spectrometric measurement. The lower detection limit was 0.005 g ml–1 and the relative standard deviations /n=3/ for 1.2 and 0.05 g ml–1 of ruthenium were 0.2 and 0.5%, respectively.

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Abstract  

Separation method of a few ppb of uranium and thorium in tantalum metal by ion exchange for neutron activation analysis was established. After dissolving tantalum metal by hydrofluoric acid, uranium and thorium were separated from tantalum using cation exchange resin column in 0.5M hydrofluoric –0.65M boric acid media. Both of the yields for uranium and thorium during separation were above 95% and the remaining amount of tantalum be lowered below 400 ng.

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Abstract  

Alpha-emitters on the surfaces of Zircaloy-4 cladding of PWR spent nuclear fuel have been examined at fuel burnup of 6900, 29,400 and 38,100 MWd/t. The amount of -emitter on the inner and outer surfaces of cladding increased with fuel burnup, whereas the amount of plutonium on the outer surface remained roughly constant. The distribution of -activity in the cladding varied with fuel burnup. The ratio of -activity on the outer surface to total -activity of the cladding decreased from about 50% at fuel burnup of 6900 MWd/t to 3% at fuel burnup of 38,100 MWd/t. The inventory of the -activity in unit weight of cladding was found to be 4.75·102 and 4.35·104 Bq/g-cladding at fuel burnup of 6900 and 38,100 MWd/t, respectively. Adsorptive ability of the outersurface of irradiated cladding was about one order of magnitude greater than that of unirradiated Zircaloy-4 for -emitters and some of the fission products except ruthenium.

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Scientometrics
Authors:
K. Kaneiwa
,
J. Adachi
,
M. Aoki
,
T. Masuda
,
A. Midorikawa
,
A. Tanimura
, and
S. Yamazaki

Abstract  

In this paper,Nature andScience, the two distinguished multi-disciplinary scientific journals were compared placing emphasis on their internationality. The items investigated were as follows. A general comparison: 1. number of authors per article, 2. distribution of countries to which first authors' institutions belong, 3. distribution of main discplines studied by first authors, 4. time-lag between the date of receipt of an article by the editor and the date of its publication. B. the position with regard to Japanese author: 1. number of Japanese authors, 2. relationship between the ranking of a Japanese author in the list of authors' names and the country where his institution is located, 3. relationship between the time-lag stated in A-4 and the items stated in B-2. As a result, it can be said thatNature is a more highly international journal thanScience.

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