Ken-ichi MATSUMOTO
Department of Physics, Toyama University Gofuku 3190, Toyama 930, JAPAN
(Received January 14, 1983)

Abstract
First, a brief review is given about the theory on nuclear β-decay. Next, an introduction is given about the recent attempts to estimate the neutrino mass from the β-spectrum in tritium decay and some related studies are added.

Toyosaburo TAKEUCHI, Atsuo MORI
Faculty of Science, Toyama University, Gofuku 3190, Toyama 930, JAPAN
(Received January 14, 1983)

Abstract
The enrichment of tritium in water by means of the isotopic effect in the reaction of the Raney alloys in the presence of sodium hydroxide was studied. 50% Ni-Al, 50% Co-Al, 50% Cu-Al were used as the Raney-alloy. The evolution of hydrogen gas occurred readlily below room temperature, and more than 80% of hydrogen gas was generated at this temperature. The concentration of tritium in the gas was 1/14 that of the original water. A great portion (more than 90%) of tritium remained in the reaction products. However, it was generated at high temperature (more than 300℃). It was concluded that the efficiency of enrichment of tritium was 14.0. This value is 2 times greater than that obtained from the electrolytical method.

Masao MATSUYAMA, Hitoshi MIYAKE, Kan ASHIDA, Kenji ICHIMURA, Kuniaki WATANABE,Toyosaburo TAKEUCHI, Shinji KON, Teruaki INOUE
Hydrogen Isotope Research Center, University of Toyama, Gofuku 3190, Toyama 930-8555, Japan

Abstract
An emergency tritium removing system, using a precious metal/alumina catalyst, was designed and constructed in order to decontaminate tritium leaked accidentally into laboratory rooms. The performance of thee system was examined using a balloon for helium recovery or an aluminum vessel as a substitute of a laboratory room. Tritium gas containing about 10% tritiated methane (CH₃T) as an impurity was introduced into the experimental room and then removed with an air flow rate of 72 m³/h. Tritium gas (T₂) was removed satisfactorily, i.e. the reaction probability was unity, due to a Pd/Al₂O₃ catalyst (Nippon Jun Suiso Co. Ltd) at 200℃, while the tritiated methane could not be removed with a sufficient amount of efficiency: its reaction probability was below unity. It was found that the reaction probability of the tritiated methane became unity above 300℃ for this catalyst. On the basis of these results, it is estimated that the accidental leakage of tritium of 5Ci (which is the maximum permissible amount used in a day in this laboratory) into a laboratory room can be removed within an 18h period..

Isao KANESAKA, Masaaki TSUCHIDA, Kiyoyasu KAWAI, Toyosaburo TAKEUCH
Faculty of Science, Toyama University,Gofuku 3190, Toyama 930, JAPAN
(Received January 14, 1983)

Abstract
The rotation-vibration spectrum of υ₂ of T₂¹⁸O is reported in the region of 1100～900cm-1 and analyzed on the basis of a rigid rotor. The band constants (in cm^-1) obtained are as follows: υ₀=986.35; A''=10.935; B''=4.857, and C''=3.314 in the ground state and A'=11.558, B'=4.903 and C'=3.276 in the excited state. The r₀ structures derived from the rotational constants of A and B are: r''=0.9574(A゜) and α''=104.80゜ in the ground state and r'=0.9449 (A゜) and α'=106.07゜in the excited state.

Osamu TAKAYASU, Yoshiki NAKANO, Toyosaburo TAKEUCHI
Faculty of Science, Toyama University
Gofuku 3190, Toyama 930, JAPAN
(Received January 14, 1983)

Abstract
　This study is concerned with the autoradiographical study on cohesive sites of tritium on the surface layer of neutron-irradiation LiF. Many linear lines were found in the autoradiographs, but some of these lines were not in the microphotographs. These results were discussed with reference to the studies on the temperature programmed desorption of tritium and those on the absorption u.v. spectra of the irradiated LiF. These results indicate that tritium accumulates preferentially on the lattice imperfections of step-edges of LiF.

Hitoshi MIYAKE, Masao MATSUYAMA, Kuniaki WATANABE

Tritium Research Center, Toyama University,Gofuku 3190, Toyama 930, JAPAN
(Received January 14, 1983)

Abstract
Diffusivity, solubility and permeability of three hydrogen isotopes and some inert gases were measured at room temperature by means of time-lag method for a polycarbonate (PC) film and PC film on which SS-304 film (100A) was coated by means of r-f sputtering. The diffusivity of hydrogen isotopes in the PC films and PC/SS-304 film decreased with an increase in the isotopes mass, however, their ratio deviated from the square root of the inverse mass ratio: the diffusivity of tritium was significantly smaller than those of hydrogen and deuterium. In addition, the solubility of the isotopes also decreased with an increases in their mass. Consequently, the permeability of tritium was 1/30-1/40 of those of hydrogen and deuterium. A drastic change in the permeability of the gases took place due to the SS-304 coating: hydrogen isotopes permeated through PC/SS304 film, while inert gases did not. The results indicate that the PC/SS304 film will separate completely the hydrogen isotopes and helium from the exhaust gas of thermonuclear fusion devices, and furthermore, it will efficiently tritium from the exhaust gases.

Osamu TAKAYASU, Masatoshi TAKAGI, Toyosaburo TAKEUCHI

Faculty of Science, Toyama University, Gofuku 3190, Toyama 930, JAPAN
(Received January 14, 1983)

Abstract
 It has already been shown using the H₂-TH，D₂-TD，and He-T₂ systems that the modified Waldmann equation (M.W.E.) is available for calculating the equilibrium separation factor (q_e) in the enrichment of tritium by a hot-wire type column or by a cylindrical column. The M.W.E. additional includes two parameters, a and b, in the Waldmann equation which can be applied to the flat-type column.
  This study is concerned with the same applicability of the equation for the H₂-T₂ and He-TH systems. As a result, it was shown that the M.W.E. is available also for the enrichment of tritium in these systems. Furthermore, thermal diffusion coefficient (α) was determined by substituting theoretical q_e calculated by the equation into the Furry-Jones equation. The results showed the following relationship: b=1.26α. It became evident that the parameters of the M.W.E. are a=1.07±0.05, and b=1.26α.

Hiroshi SATAKE, Hirohito KAMEGAI, Yoshihiko MIZUTANI

Department of Earth Sciences, Faculty of Science, Toyama University,Gofuku 3190, Toyama 930, JAPAN
(Received January 14, 1983)

Abstract
 Tritium content in precipitation and river water samples from the Toyama district were measured. To test the reproducibility of the measurement, the tritium content in tap water was repeatedly measured. Excluding one set of data which was probably lower because of the accidental condensation of atmospheric moisture on the water sample during electrolysis, the results obtained ranged from 25.6 to 27.4 T.U..
  In the Toyama district, the tritium content in precipitation shows its maximum value in spring, and a rather constant value (～12T.U.) during summer to winter. In some other districts in Japan, however, it was observed that winter precipitation from the air mass generated within the Asia continent has a maximum tritium content.
  Tritium content of the seven large rivers in the Toyama district ranged from 19.6 to 27.0 T.U. in April and June, 1980. The tritium content of the river water samples were about two times higher than the annual tritium content average in precipitation, and did not reveal any seasonal variations. These facts suggest that the rivers are recharged from aquifers in which past precipitation is well mixed.

Masao MATSUYAMA, Hitoshi MIYAKE, Kan ASHIDA, Kenji ICHIMURA, Kuniaki WATANABE

Tritium Research Center, Toyama University,Gofuku 3190, Toyama 930, JAPAN
(Received January 14, 1983)

Abstract
 Variation of the background levels of tritium monitors due to natural radioactivity in air was measured by measured by means of tritium monitors, each of which was equipped with an ionization chamber as a detector. The background levels of the monitors varied significantly depending on the ventilator-on and -off mode. The decay curve of the result of ²²²Rn. The concentration of ²²²Rn in the laboratory room amounted about 1x10^-8 μCi/cm³ when the ventilator was not used for a day.
  The variation of the background level of a low-background liquid scintillation counter also fluctuated due to the variation of the concentration of ²²²Rn in air. Although the fluctuation could be partially prevented by weather-stripping the counter, other counterplans such as gas-purging might be necessary in order to measure tritium in a low concentration.

Osamu TAKAYASU, Masatoshi TAKAGI, Toyosaburo TAKEUCHI

Tritium Research Center, Toyama University,Gofuku 3190, Toyama 930, JAPAN
(Received January 14, 1983)

Abstract
Development of tritium handling techniques is of great importance for thermonuclear fusion experiments. In such experimental devices, tritium will be stored in some suitable getter materials, released to gas phase due to heating and recovered again by the getter after use. From this viewpoint, we examined absorption and desorption of tritium by a getter material (Zr-V-Fe) delivered from SAES Getters using a mass spectrometer. Tritium amounted to 5Ci was stored in the getter of 300mg (Zr-V-Fe) at room temperature after activation at 780℃in vacuo (7x10^-5 Torr). The tritium began to appear in a gas phase in a measurable level at around 200℃, however, most of the tritium appeared in the gas phase as HT. Raising the temperature resulted in an increase in the T2/HT ratio due to the increase in the tritium pressure. The tritium released in the gas phase could be efficiently recovered by the getter at room temperature. The tritium pressure decreased below 1x10^-9 Torr. The pumping speed was estimated to be as large as 8cc/sec・mg. It was revealed that hydrogen in HT was due to an exchange reaction between the released tritium and residual hydrogen.