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[1990_01]
Journal of Nuclear Materials, 173 (1990) 294-306
Kuniaki Watanabe, Kan Ashida and Masaru Sonobe
Tritium Research Center, Toyama University, Gofuku 3190, Toyama 930, Japan
Abstract
The diffusion constants of hydrogen in metals scatter
considerably in the Arrhenius plot diagram even for a given metal. We found
regularity in the scattering of the diffusion constants of hydrogen in
some metals: namely, there is a linear relationship between the pre-exponential
factors and activation energies for C, Al, a-Fe,
Cu and Pd. This is similar to the phenomenon known as the compensation
effect in heterogeneous catalysis.
Three different interpretation are proposed: they
are based on the assumption of energetically heterogeneous sites, energetically
homogeneous sites on which there exists a linear relationship between entropies
and heats of adsorption, or the presence of two distinct diffusion paths.
Three of them could give the relation, log(D0) = αEd
+ β. In contrast to the above, no clear correlation
was observed for V, Nb, Zr, and Ta which belong to the IVB or VB groups
in the periodic table.
[1990_02]
Physica B, 165&166 (1990) 1523-1524
Katsunori MORI, Yosikazu ISIKAWA, Kiyoo SATO*, Kan ASHIDA#, and Kuniaki WATANABE#
College of Liberal Arts, Toyama University, 3190 Gofuku, Toyama 930, Japan
*Facully of Science, Toyama University, 3190 Gofuku, Toyama 930, Japan
#Tritium Research Center, Toyama University, 3190 Gofuku, Toyama 930, Japan
Abstract
Superconducting transition temperatures, TCs, and structural phase transition temperatures, TMs, of V2ZrHx, V2ZrDx and V2ZrTx have been measured in the composition range from x = 0 to 0.11, respectively. Protium(H),deuterium(D) or tritium(T) absorption is found to increase TC up to x = 0.04 and it suggests the correlation with the structural phase transition. Above x = 0.04, TCs decrease with increasing composition, x, but inverse isotope effects have been observed apparently.
[1990_03]
Journal of Nuclear Materials, 175 (1990) 47-54
Masaru Sonobe and Sizuo Tada
Department of Metallurgical Engineering, Faculty of Engineering, Toyama University, Gofuku 3190, Toyama 930, Japan
Susumu Ikeno
Center for Cooperative Research, Toyama University, Gofuku 3190, Toyama 930, Japan
Kan Ashida and Kuniaki Watanabe
Tritium Research Center, Toyama University, Gofuku 3190, Toyama 930, Japan
Abstract
As a step to understand factors affecting tritium inventory in Al alloys at low temperatures, diffusion of deuterium in Al at a low temperature region was measured using the ion-implantation techniques and secondary ion mass spectroscopy. The diffusion constants were evaluated as 1×10-20 and 1×10-18 m2/s at 20 and 70 °C, respectively. Those values are considerably smaller than those by Ishikawa et al. in a similar temperature region. The compensation effect being taken into account, the difference in those diffusion constants as well as those reported so far were analyzed by assuming the presence of two parallel and/or series diffusion channels. The analysis could interpret the scattering of diffusion constants and compensation effect, suggesting that the observed diffusion constants of hydrogen are not necessarily unique to a given material, but depend on sample preparations and temperatures in which measurements are performed.
[1990_04]
Environ. Sci. Technol., 24(4) (1990) 581-583
S. Usami and Y. Asai
Department of Industrial Chemistry, Faculty of Engineering, Toyama University, Gofuku 3190, Toyama 930, Japan
M. Matsuyama and K. Watanabe
Tritium Research Center, Toyama University, Gofuku 3190, Toyama 930, Japan
Abstract
A part of tritium loaded in thermonuclear fusion reactors will be released to the environment. It is oxidized to form tritiated water, which is considerably more hazardous than elemental tritium (T2 and/or HT). Investigations on the oxidation carried so far are radiochemical (including effects of X- and ß-rays), catalytic, and biochemical oxidation processes. We examined the effect of UV irradiation and found that the UV irradiation remarkably enhanced the oxidation rate of elemental tritium, suggesting that this effect plays an important role for the formation of tritiated water from elemental tritium in the atmosphere.