研究報告

第3巻(1983)

研究報告3 - 1 論文 - Original

担持白金触媒によるトリチウム化メタンの燃焼
Oxidation of Tritiated Methane by Supported Platinum Catalyst.

松山 政夫、宮田 洋子、渡辺 国昭、竹内 豊三郎
富山大学トリチウム科学センター
富山市五福3190

Masao MATSUYAMA, Yoko MIYATA, Kuniaki WATANABE, Toyosaburo TAKEUCHI
Tritium Research Center, Toyama University,Gofuku 3190, Toyama 930, JAPAN
(Received December 24, 1983)


Abstract
The oxidation reaction of CH4 and CH3T by silica- and alumina-supported catalysts was studied. The oxidation rate of methane was pseudo-first order with respect to the methane pressure and the catalytic activity of Pt/Al2O3 catalyst was higher than that of the Pt/SiO2 catalyst. A kinetic isotope effect was observed for the oxidation reaction on the Pt/Al2O3 catalyst; the activation energies for CH4 and CH3T were 19.2 and 17.3 Kcal/mol, respectively.
  A large part of the tritium in CH3T was removed as the tritiated water, but some of it was trapped on the supported catalyst. Tritium was also found to be trapped on the surface of alumina, the amount being comparable to that observed for the Pt/Al2O3 catalyst. Thus, the exchange reaction between CH3T and hydroxyl group on the Pt/Al2O3 catalyst is considered to a predominant role in the trapping of tritium on the catalyst.
  In regard to waste handling, the above findings demonstrate contamination of the oxidation catalyst due to the captured tritium.

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研究報告3 - 2  論文 - Original

[2-14C, 5-3H] シトシンの合成
Synthesis of [2-14C, 5-3H] Cytosine with Use of Bromine and Tritium Gas

朝野 武美、桐谷 玲子、藤田 慎一
大阪府立放射線中央研究所
大阪府堺市新家町

Takeyoshi ASANO, Reiko KIRITANI, Shinichi Fujita
Radiation Center of Osaka Prefecture, Shinke-cho, Sakai, Osaka, JAPAN


Abstract
A small scale synthesis of [2-14C, 5-3H] cytosine was attemped by the bromination of [2-14C] cytosine followed by the catalytic exchange reaction with tritium gas. The radioactive materials were always in the presence of those nonradioactive as carriers. Bromination were compared for the solutions of CCl4 and CCl4/H2O. In the former, bromocytosine was formed without any byproduct, but the reaction rate was very slow. In the latter, the reaction occurred quite rapidly and bromocytosine was obtained in a relatively high yield (41~70%), though undesirable bromouracil was also found. The double labeled cytosine was easily formed by a Br-3H exchange between [2-14C, 5-Br] cytosine and 3H2 gas using a catalyst of 10% Pd/CaCO3.
  This paper also presents the experimental results for the adsorption of unreacted 3H2 gas by active charcoal at 77K. The amount of 3H2 gas remaining in the reaction vessel was determined with a tritium monitor. The radioactiveity was 13 μCi, which was 1/4000 that of the 3H2 gas initially used.

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研究報告3 - 3  論文 - Original

セラミックス二次電子増倍管へのトリチウムの吸着とその影響
Tritium Adsorption and its Effect on Ceramic Secondary Electron Multiplier

市村 憲司、松山 政夫、渡辺 国昭、西沢 嘉寿成*、藤田 順治**
富山大学トリチウム科学センター
930-8555 富山市五福3190 *大阪大学工学部原子力工学科
**名古屋大学プラズマ研究所

Kenji ICHIMURA, Masao MATSUYAMA, Kuniaki WATANABE, Kazunari NISHIZAWA*,Junji FUJITA**
Tritium Research Center, Toyama University
*Faculty of Engineering, Osaka University
**Institute of Plasma Physics, Nagoya University
(Received December 24, 1983)


Abstract
To find a means to avoid tritium contamination which affects secondary electron multipliers (SEM), the material used in a marked ceramic multiplier and the SEM itself were studied with respect to adsorption-desorption behavior and tritium removal.
  The tritium adsorbed on the material was desorbed to a large degree as tritiated water and to small extent as tritiated hydrocarbons. The desorption took place at to distinct adsorption/desorption sites. Effective removal from the material was achieved by heating in an inert gas flow at 500℃for 6 hours. However, heating in vacuo and/or in the presence of reactive gases (below 5x10-6 Torr) showed insufficient decontamination when Ceratron was used in the ultrahigh vacuum system. This is ascribed to re-adsorption of tritium accumulating on the cold parts of the vacuum system. On the other hand, the photon irradiation showed a substantial decrease in the noise level to its own background. The decontamination was not due to thermal effects, possibly arising from photodesorption and/or photocatalysis. The partial pressure of tritium could be measured with the Ceratron, while reducing the noise level by photon irradiation, with good reproducibility.

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研究報告3 - 4  論文 - Original

Zr-V-Feゲッターの活性化過程及び水素同位体の吸蔵-脱離機構と同位体効果
Absorption-Desorption Mechanism and Isotopic Effects of Hydrogen Isotopes on Zr-V-Fe

井上 直哉、市村 憲司、渡辺 国昭、竹内 豊三郎
富山大学トリチウム科学センター
富山市五福3190

Naoya INOUE, Kenji ICHIMURA, Kuniaki WATANABE, Toyosaburo TAKEUCHI
Tritium Research Center, Toyama University, Gofuku 3190, Toyama 930, JAPAN
(Received December 24, 1983)


Abstract
The absorption-desorption behavior of hydrogen isotopes in a non-evaporable getter (Zr-V-Fe) was examined, with respect to tritium storage and recovery, by mass analyzed thermal desorption spectroscopy, X-ray photoelectron and secondary ion mass spectroscopy. The activation (in vacuo at 700℃) formed pure Zr and V from the oxides of these metals initially present on the as-received surface. Fe existing as an oxide migrated into bulk during the activation.
  The absorption rate of hydrogen isotopes was in proportion to their pressure, indicating the rate determining step to be the dissociative adsorption process. The activation energy was very small, being from 10 to 20 calories per mole. The desorption rate was proportional to the square of the amount of absorption, so that the associative desorption process was the rate determining step. The activation energies were 28.0, 28.6 and 29.3 kcal/mol for H2, D2 and T2, respectively. This is agreement with the heat of absorption observed by Boffito et al., 27.8 and 28.8 Kcal/mol for H2 and D2, respectively.

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研究報告3 - 5  論文 - Original

D, T, 18Oから見た北陸地方の降水と河川水の水文学的特徴
Environmental isotope hydrology of precipitaions and river waters in the Hokuriku district, Japan

佐竹 洋、向井 利明、水谷 義彦

富山大学理学部地球科学教室
富山市五福3190

Hitoshi SATAKE, Toshiaki MUKAI, Yoshihiko MIZUTANI
Department of Earth Sciences, Toyama University,Gofuku 3190, Toyama 930, JAPAN
(Received December 24, 1983)


Abstract
To study the hydrology of the Hokuriku district, measurement was made of the D, T and 18O contents of precipitation samples collected at Toyama and Wajima during May, 1981 to October, 1983and river water samples from the Kurobe River during April, 1980 to March,1983 were measured.
  The δD and δ18O values of the precipitation samples were minimum in the summer and a maximum in winter. Precipitation during the spring to autumn, was δD=8δ18O+10 and for the winter, δD=8δ18O+30. The source of the water vapor of precipitation differed for the summer and winter seasons. The summer air mass generated on the southern Pacific Ocean or the East China Sea precipitated rain depleted in the heavy isotopes. A large value for the intercept with the δD axis, such as 30 in the case of winter precipitation, may imply the rapid evaporation of water vapor from the sea surface. The tritium content in the precipitation samples wa s rather constant (10-15 TU) except for the spring peak.
  The Kurobe River samples showed no seasonalisotopic variation having values close to, δD=8δ18O+20, suggesting the water from this river to be recharged by aquifers in which equal amounts of summer and winter precipitation are well mixed. The tritium content of the Kurobe River ranged from 25 to 30 TU, this being larger than that of the precipitation samples. This fact suggests that precipitation polluted by past thermonuclear tests is still present in aquifers and is being discharged to some extent in the river.

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研究報告3 - 6  論文 - Original

ラドンに由来するバックグラウンド計数の低減と安定化
-液体シンチレーションカウンタにおける-
Reduction and Stabilization of the Radon-induced Background Count Rate of a Liquid Scintillation Counter

佐竹 洋、松山 政夫*

富山大学理学部地球科学教
富山大学トリチウム科学センター
〒930 富山市五福3190

Hiroshi SATAKE, Masao MATSUYAMA*

Department of Earth Sciences, Toyama University
*Tritium Research Center, Toyama University
3National Institute for Fusion Science Oroshi-Cho 322-6, Toki 509-5292
Gofuku 3190, Toyama 930, JAPAN
(Received December 24, 1983)


Abstract
The 3H channel background count rate of a liquid scintillation counter in Tritium Research Center, Toyama Univ. showed a daily fluctuation due to adsorption of radon and/or its daughter elements on a vial surface. To reduce and stabilize the background count rate, the following experiment was performed.
  Three background samples which were emulsion scintillators in 20ml Teflon Vials, two being covered with polystyene cups, were measured for the 3H channel count rate. The count rate of the non-insulated sample increased from 2 to 5 cpm and those of the two insulated samples were each about 1.5 cpm less. This suggests that the vial coverage considerably reduce the background count rate.
  Background samples (D, E, F) having the same count rate were measured under different conditions (D: non-insulated, E: insulated by polystyrene cup, F: insulated by polystyrene cup and sponge rubber). The averaged count rate and standard deviation (±2s) of samples D, E, and F were 2.71±0.88, 1.98±0.49, 1.96±0.33, respectively. Thus, the insulation of a vial from Rn and its daughter elements in room air caused the background count rate to reduced and stabilized.

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研究報告3 - 7  論文 - Original

液体シンチレーションカウンターに対する自然放射能の影響
Variation of the Background Count Rate of a Liquid Scintillation Counter due to Natural Radioactivities

松山 政夫、佐竹 洋*、渡辺 国昭

富山大学トリチウム科学センター *富山大学理学部地球科学教室
富山市五福3190

Masao MATSUYAMA, Hiroshi SATAKE*, Kuniaki WATANABE

Tritium Research Center, Toyama University
*Department of Earth Science, Faculty of Science, Toyama University,Gofuku 3190, Toyama 930, JAPAN
(Received December 24, 1983)


Abstract
Variation in the background count rate of a liquid scintillation counter due to natural radioactiveity was measured by repeat and cycle modes. The samples used for measuring the background count rate were polyethylene, Teflon, quartz glass and low-potassium glass vials contained the liquid scintillator only. The background count rate of the polyethylene vial was found to be lowest among the four vials.
  Variation in background count rate was correlated with the concentration of 222Rn which was strongly affected by ventilation in the laboratory. 222Rn and its daughter nuclides giving rise to the variation in background count rate were apparently carried into the detector section not only by adsorption on the vial but also by the solution in the vial material. To reduce the effects of 222Rn and its daughter nuclides, each vial kept in the changer section of the liquid scintillation counter was covered with a “cap”. As a result, variation in the background count rate was found to be considerably reduced for all the vials.

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研究報告3 - 8  ノート - Note

黒鉛中に打ち込まれた重水素およびトリチウムの昇温脱離
Thermal Desorption of Deuterium and Tritium Implanted into Pyrolytic Graphite

松山 政夫、芦田 完、渡辺 国昭

富山大学トリチウム科学センター
富山市五福3190

Masao MATSUYAMA, Kan ASHIDA, Kuniaki WATANABE

Tritium Research Center, Toyama University, Gofuku 3190, Toyama 930, JAPAN
(Received December 24, 1983)


Abstract
The desorption of deuterium and tritium implanted in pyrolytic graphite was studied, from a view point of tritium inventory in the first wall of nuclear fusion devices, by means of the thermal desorption spectroscopy. Damage to the graphite resulting from such an implantation was also studied by Laser Raman spectroscopy. Deuterium ions and triton were generated by a conventional ion gun and a 3He(n,p) 3H nuclear reaction respectively. The average recoil energy of the latter is 190 keV.
  A desorption peak and shoulders were observed for both the deuterium and tritium spectra. The spectral shape and peak temperature of deuterium were quite close to those of tritium below a total dose of 7x1017 ions/cm2, where the Raman spectra showed that the damage incurred by graphite was to small extent for both the deuterium ions (5 keV) and triton (190 keV) bombardment. These findings indicate that the desorption behavior of hydrogen isotopes is not significantly dependent on the implantation energy. Above this dose, the desorption spectra showed three distinct peaks and the Raman spectra indicated accumulation of the damage in the graphite. Thus, the desorption behavior of hydrogen isotopes depends on the amount of the damage incurred by the graphite rather than on the energy of the implanted ions.

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研究報告3 - 9  ノート - Note

Analysis of Rotation-Vibration Spectrum of ν3 of T218O

土田 雅昭、金坂 績、川井 清保

富山大学理学部
富山市五福3190

Masaaki TSUCHIDA, Isao Kanesaka, Kiyoyasu Kawai

Faculty of Science, Toyama University, Gofuku 3190, Toyama 930, JAPAN
(Received December 24, 1983)


Abstract
The rotation-vibration spectrum ofν3 of T218O was analyzed on the basis of a rigid rotor approximation. The band constants used for the ground state (Ⅰ. Kanesaka et al., J. Mol. Spectrosc., in press) were in cm-1: A’ ’=10.952, B’’=4.863 and C’’=3.315. Those obtained were: ν0=2346.68(11), A’=10.497(6), B’=4.628(10) and C’=3.197(9). The ν0 structures derived from the rotational constants of A’ and B’ are: r’=0.9794 (A) and α’=105.00(゜). The inertia defect, 0.041x10-40 g・cm2, was found to be consistent with that from a vibrational analysis.

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