研究報告

第8巻(1988)

研究報告8 - 1 総説 - Review

トリチウム用ゲッター材の開発指針
A Guiding Rule to Design Tritium Getters

渡辺 国昭、松山 政夫、芦田 完、三宅 均
富山大学トリチウム科学センター
〒930 富山市五福3190

Kuniaki WATANABE, Masao MATSUYAMA, Kan ASHIDA, Hitoshi MIYAKE
Tritium Research Center, Toyama University , Gofuku 3190, Toyama 930, JAPAN
(Received December 24, 1988)


Abstract
Hydrogen getter materials, most of which are metals and alloys forming hydrides, are attractive for the establishment of safe handling techniques of a large amount of tritium for the research and development of thermonuclear fusion reactors. To develop materials suitable for tritium handling, it is indispensable to find some guiding rules to predict thermodynamic parameters determining the equilibrium pressure of tritium.
  From this viewpoint, we searched for the relations between the observed heat of hydride formation and physicochemical properties of metals and alloys for over 300 different data in about 100 systems. We found an empirical equation consisting of the electronegativeities of hydride formers. This equation could evaluate the heat of the hydride formation for not only metals but also alloys consisting of even three or more components with the standard deviation of about 4 kcal/mol (hydride). Although this equation is not quite accurate, especially for those having relatively small heat of hydride formation, it can be applied as a powerful guiding rule to design tritium getters with adequate thermodynamic parameters for tritium handling.

全文を読む (PDF File 1105KB)

研究報告8 - 2  論文 - Original

Zr系合金ゲッターによる水素同位体の分離・濃縮
Separation/Enrichment of Hydrogen Isotopes by Zr-alloy Getters

渡辺 国昭、芦田 完、市村 憲司*、竹内 豊三郎
富山大学トリチウム科学センター
〒930 富山市五福3190
*熊本大学理学部化学科
〒860 熊本市黒髪2丁目39番1号

Kuniaki WATANABE, Kan ASHIDA, Kenji ICHIMURA*, Toyosaburo TAKEUCHI
Tritium Research Center, Toyama University, Gofuku 3190, Toyama 930, JAPAN
*Faculty of Science, Kumamoto University,Kurokami 2-39-1, Kumamoto 860, JAPAN
(Received December 24, 1988)


Abstract
Safe handling and/or processing techniques, consisting of storage, supply, recovery, isotope separation and so on, are indispensable for research and development of thermonuclear fusion reactors. Nonevaporable getters have wide applicability for those kinds of processing. From this viewpoint, we have studied activation processes, absorption and desorption of hydrogen isotopes including isotope effect by using Zr-alloys as a model system. It was found that the kinetic isotope effect on the absorption processes was considerably large for the Zr67Ni33 getter. On the basis of this observation, we studied the enrichment/separation of hydrogen isotopes. It was observed experimentally that a mixture of hydrogen and deuterium (H:D=57:43) changed its composition to H:D=53:47 by passing the mixture gas through Zr67Ni33 column held at liquid nitrogen temperature. Namely, deuterium was enriched in the gas outflow from the column. Similar results were observed with computational simulation using the experimentally observed rate constants for hydrogen and deuterium, indicating that the present simulation is reliable. Further simulation revealed that hydrogen isotope mixtures such as H:D=1:1 and D:T=1:1 change their composition to H:D=1:9 and D:T=1:4, respectively, in the outflow gas with passing those gases repeatedly in the column at liquid nitrogen temperature. This indicates that hydrogen isotope separation is possible by application of the kinetic isotope effect. The present method has high potentially because of it is safe, economical and simple to operate as well as having high separation efficiency.

全文を読む (PDF File 848KB)

研究報告8 - 3  論文 - Original

Al-1wt%Mg合金表面層における水素同位体の挙動
Trapped States of Hydrogen Isotopes in the Subsurface Region of Al-1wt%Mg Alloy

園部 勝、渡辺 浩章、多々 静夫、渡辺 国昭*、松山 政夫*、芦田 完*、池野 進**
富山大学工学部
〒930-8555 富山市五福3190
*富山大学トリチウム科学センター
**富山大学地域共同研究センター
〒930 富山市五福3190

Masaru SONOBE, Hiroaki WARANABE, Shizuo TADA, Kuniaki WATANABE*, Masao MATSUYAMA*, Kan ASHIDA*, Susumu IKENO**
Faculty of Engineering, Toyama University
*Tritium Research Center, Toyama University
**Research and Development Center, Toyama University
Gofuku 3190, Toyama 930,JAPAN
(Received December 24, 1988)


Abstract
Aluminum alloys are of great interest in their application for D-T burning fusion experimental devices because of their low induced activity and low-out-gassing nature. From the viewpoint of tritium inventory for this application, we studied the capturing and motion hydrogen isotopes by/in an Al-1wt%Mg alloy by means of X-ray photoelectron spectroscopy and secondary ion mass spectrometry. Deuterium was implanted into the alloy samples with ion bombardment (5 keV) or electrochemical charge. It was observed that the sample surfaces were covered with aluminum oxides of 6-8x10-5 cm thickness and deuterium implanted was captured in two different states in the subsurface region of the samples: one is the deuterium trapped by metals (Al and Mg) and the other by oxygen. Their mobility differed from each other in the order of Al-H>Mg-H>O-H. This is considered to be due to the difference in stability of those bonds. In the case of the electrochemical charge, the penetration depth of deuterium (1.4x10-4 cm) was about one order of magnitude greater than that for ion implantations (6x10-6cm). This indicates that deuterium is in the ionic state in the surface oxide layer and enhanced diffusion takes place with the presence of electric field gradient. The present results suggest that tritium inventory in aluminum alloys will be greatly influenced as a result of the presence of an oxide layer as well as the alloy composition.

全文を読む (PDF File 1139KB)

研究報告8 - 4  論文 - Original

金属、セラミックス及び有機材料に対するトリチウムの吸着(Ⅱ) -ステンレスに対するトリチウムの吸着防止-
Adsorption of Tritium on Metals, Ceramics and Organic Materials(Ⅱ)
-Adsorption Inhibition of Tritium for Stainless Steel-

松山 政夫、新木 裕一*、芦田 完、三宅 均、渡辺 国昭
富山大学トリチウム科学センター
*富山大学放射性同位元素総合実験室
〒930 富山市五福3190

Masao MATSUYAMA, Yuichi ARAKI*, Kan ASHIDA, Hitoshi MIYAKE, Kuniaki WATANABE
Tritium Research Center, Toyama University
*Radio Isotope Laboratory, Toyama University
Gofuku 3190, Toyama 930, JAPAN
(Received December 24, 1988)


Abstract
Tritium contamination of materials used for tritium handling systems becomes a serious problem because an increasing amount of tritium is used for the research and development of thermonuclear fusion reactors. As a first step to develop materials free from tritium contamination, we studied the adsorption and desorption of tritium on Ni, Fe, and various stainless steels.
  The stainless steels used were SS-304 and SS-304/BN doped with Ce. The measurements were also carried out for passivated ones: namely, SS-304 passivated with electrochemical method (SS-304/P) and SS-304/BN annealed in vacuum at 800℃ for 3 hr (SS-304/BN(H)). In addition, BN discs prepared by chemical vapor deposition were also used for comparison with SS-304/BN(H).
  The amount of tritium adsorption and that of subsequent tritium desorption with heating considerably varied with samples. The order of the amount was
    Ni>>(Fe, SS-304, SS-304/BN>>(SS-304/P, SS-304/BN(H), BN).
  The amount of adsorption on Ni was about 100 times greater than that on Fe, SS-304 and SS-304/BN. The amount of adsorption on SS-304 was about 100 times greater than that on SS-304/P, SS-304/BN(H) and BN. Those results indicate that the adsorption of tritium is dependent to a considerable on Ni content in the subsurface layers of samples. This is supported by the surface analysis with X-ray photoelectron spectroscopy. It is noticeable that little tritium was adsorbed on SS-304/P and SS-304/BN(H). It was concluded that the stainless steels with surface passivation layers such as SS-304/P and SS-304/BN(H) are excellent as construction materials to minimize the tritium inventory and tritium contamination in the handling systems as well as thermonuclear fusion devices.

全文を読む (PDF File 849KB)

研究報告8 - 5  論文 - Original

制動X線計測によるトリチウムガスの非破壊測定(Ⅱ)
-制動X線の発生及び透過過程-
Non-Destructive Determination of Tritium by Bremsstrahlung Counting(Ⅱ)
-Generation and Depletion Processes of Bremsstrahlung X-rays-

松山 政夫、中谷 秀夫*、渡辺 国昭

富山大学トリチウム科学センター
*富山大学工学部
〒930 富山市五福3190

Masao MATSUYAMA, Hideo NAKATANI*, Kuniaki WATANABE
Tritium Research Center, Toyama University
*Faculty of Engineering, Toyama University
Gofuku 3190, Toyama 930, JAPAN
(Received December 24, 1988)


Abstract
To apply the bremsstrahlung counting method to in-situ and real-time measurements of tritium pressure in the fuel processes of thermonuclear fusion devices as well as conventional tritium handling system of tritium research laboratories, we studied theoretically the processes of generation of bremsstrahlung X-rays and its depletion in materials.
  The spectra of bremsstrahlung X-rays generated by tritium β-rays at the inner surface of measuring tube were calculated with the β-spectrum and Wyard formula. The bremsstrahlung spectra at the outer surface of the measuring tube made of Pyrex glass were calculated using the mass absorption coefficient for the glass and calculated bremsstrahlung intensity at the inner surface. The calculated bremsstrahlung spectra agreed quite well with the observed ones. In addition, the present analysis showed that the ratio of bremsstrahlung intensity for glass to that for aluminum alloy was 7.5. This value was in good agreement with the observed ratio (8.2).
  The changes in the bremsstrahlung intensity with thickness of glass were also evaluated. It was found that the bremsstrahlung intensity decreases with thickness in a convex manner. This convex curve could be approximated to -2.38 power of the thickness in the range from 0.5~2.0mm. This thickness dependence agreed well with the experimental results.
  It was concluded that the present method is quite valuable to predict the bremsstrahlung spectra owing to the deceleration ofβ-rays in material. It was also revealed that the measuring tube of double-layers structure constructed with different atomic number materials is useful because a large increase in sensitivity can be expected with this device.

全文を読む (PDF File 777KB)

研究報告8 - 6  論文 - Original

XPSによるホットプレスベリリウムの表面分析
Surface Characterization of Hot-Pressed Beryllium with X-rays Photoelectron Spectroscopy

石塚 悦男、河村 弘、芦田 完*、松山 政夫*、渡辺 国昭*、瀬崎 勝二、斎藤 実

日本原子力研究所 大洗研究所 茨城県東茨城郡大洗町成田町3607
*富山大学トリチウム科学センター 富山市五福3190

Etsuo ISHITSUKA, Hiroshi KAWAMURA, Kan ASHIDA*, Masao MATSUYAMA*, Kuniaki WATANABE*, Katsuji SEZAKI, Minoru SAITO

Japan Atomic Energy Research Institute, Oarai Research Establishment Narita-Cho 3607, Oarai-Machi, Higashi Ibaraki-Gun, Ibaraki-Ken, JAPAN
*Tritium Research Center, Toyama University, Gofuku 3190, Toyama 930, Japan
(Received December 24, 1988)


Abstract
In the case of using hot-pressed beryllium in a fusion reactor, the surface state of hot-pressed beryllium is one of the items most necessary to investigate the behavior of hydrogen in beryllium. Therefore, the surface characterization of the hot-pressed beryllium was examined by X-rays photoelectron spectroscopy (XPS) after vacuum heating and deuterium ion bombardment. On the surface of the as-received sample, carbon, fluorine, oxygen and beryllium were observed. However, carbon that is sure to be adsorbed and fluorine that was mixed as an impurity during fabrication process decreased to a great extent by heating, and both elements (carbon and fluorine) were barely observed after heating at 800℃for 20 min. From the element-abundance-ratio of Be to O and ratio of the two peaks of Be 1s, it was obvious that surface of hot-pressed beryllium was covered by two parts of Be and one of BeO due to heating at 800℃ for 20 min.   Additionally, it was observed that the oxidation of the surface of hot-pressed beryllium is induced by deuterium implantation using an ion gun.

全文を読む (PDF File 857KB)

研究報告8 - 7  論文 - Original

トリチウムガスの酸化に及ぼす紫外線の影響 -酸素圧及び水素圧依存性-
Effect of UV Irradiation on the Oxidation of Elemental Tritium
-Pressure Dependence of Oxygen and Hydrogen-

宇佐美 四郎、浅井 祐二、長谷川 淳、松山 政夫*、渡辺 国昭*、竹内 豊三郎*

富山大学工学部
*富山大学トリチウム科学センター
〒930 富山市五福3190

Shiro USAMI, Yuji ASAI, Kiyoshi HASEGAWA, Masao MATSUYAMA*, Kuniaki WATANABE*,Toyosaburo TAKEUCHI*

Faculty of Engineering, Toyama University
*Tritium Research Center, Toyama University
Gofuku 3190, Toyama 930, JAPAN
(Received December 24, 1988)


Abstract
It has been reported in the previous paper that UV-Photon irradiation significantly enhances the oxidation of tritium gas (HT) in an oxygen atmosphere. To understand the mechanisms of this effect, we studied the pressure dependence of this reaction. The oxidation rate was determined by measuring the amount of tritiated water formed as a function of irradiation time by use of a conventional liquid scintillation counter.
  It was found that the oxidation rate increased linearly with oxygen pressure in the range 0~160 Torr under a constant hydrogen pressure of 0.7 Torr: namely, the reaction obeys the first order kinetics with respect to oxygen. This indicates that excited oxygen atoms, O(3P), formed with UV-photon irradiation play an important role for the enhancement of the oxidation.
  Hydrogen pressure dependence was examined with varying hydrogen pressure in the range from 0~5.5 Torr under a constant pressure of 160 Torr. In this case, the amount of tritium used was kept constant. It was observed that the formation rate of tritiated water decreased with the increase in hydrogen pressure: the rate was approximately proportional to {[HT]/[H2]}1/2. Based on those observations, plausible mechanisms of the photon-induced oxidation of tritium gas in an oxygen atmosphere are discussed along with need for further systematic studied.

全文を読む (PDF File 857KB)

研究報告8 - 8  リサーチノート -Research Note

赤外スペクトルによる[Co(en-d4)3]Cl3・3T2Oのβ放射線分解の研究(en:エチレンジアミン)
[β-Radiolysis of [Co(en-d4)3]Cl3・3T2O]
Infrared Study on β-Radiolysis of [Co(en-d4)3]Cl3・3T2O(en:ethylenediamine)

金坂 績、西村 裕幸、金森 寛、川井 清保

富山大学理学部
〒930 富山市五福3190

Isao KANESAKA, Hiroyuki NISHIMURA, Kan KANAMORI, Kiyoyasu KAWAI

Faculty of Science, Toyama University,Gofuku 3190, Toyama 930, JAPAN
(Received December 24, 1988)


Abstract
β-Radiolysis of [Co(en-d4)3]Cl3・3T2O was studied under a mild condition by means of infrared spectroscopy over a period of 8 months. The spectra became complex due to the appearance of many new bands in the initial process. This is explained in terms of the exchange reaction in hydrogen isotopes between water and ethylenediamine. It was found that ethylenediamine decomposed by ~50% in 100 days, forming ammonia coordinated to a Co2+ ion and an ammonium ion. On the other hand, a Co (Ⅲ) ammine complex, acetylene and so on were not found. A scheme for the β-radiolysis is proposed.

全文を読む (PDF File 367KB)

研究報告8 - 9  リサーチノート -Research Note

Ready CapTMを用いたトリチウム水中のトリチウムの濃度測定
Tritium Measurement by Use of Ready CapTM

三宅 均、松山 政夫、渡辺 国昭

富山大学トリチウム科学センター
〒930 富山市五福3190

Hitoshi MIYAKE, Masao MATSUYAMA, Kuniaki WATANABE

Tritium Research Center, Toyama University
Gofuku 3190, Toyama 930, JAPAN
(Received December 24, 1988)


Abstract
Liquid scintillators have been widely used in the research and development of safe handling techniques of a large amount of tritium for thermonuclear fusion reactors. This gives rise to bothersome problems such as waste handling, several solid scintillators have been developed. Among those, Ready CapTM developed by Beckman Instruments appears to have great potential for tritium measurement. Its applicability for tritium, however, has not been investigated so far. We examined, therefore, its reliability for tritium measurements by using tritiated water as a model system. The count rates were kept constant irrespective to the amount of tritiated water above 0.03cm3. This is due to the fact that the maximum range of the tritium β-rays is only 6 μm in water. This observation indicates that the apparent counting efficiency is inversely proportional to the amount of the sample water. It was revealed that it is possible to determine the tritium activity of tritiated water with Ready CapTM by taking the inverse proportionality of the efficiency into account. In addition, the present examination showed that accuracy and reproducibility are quite good. They are comparable to the measurements using liquid scintillators, although its detection limit of tritium is estimated as about 1x10-9 Ci/cm3. On the basis of those results, it was concluded that Ready CapTM is quite helpful for the tritium measurements in the research and development of tritium handling techniques.

全文を読む (PDF File 564KB)