研究報告　-　9巻　(1989年)

総説・解説 - Review

9-1

富山大学におけるトリチウム取扱い技術の研究開発と今後の課題
Research and Development in Tritium Handling Techniques at Toyama University and Problems in Future

渡辺　国昭、松山　政夫

Kuniaki WATANABE, Masao MATSUYAMA

9-2

環境水の地球化学的研究における水素同位体の役割
The Role of Hydrogen Isotopes in Environmental Geochemistry of Natural Waters

水谷　義彦

Yoshihiko MIZUTANI

論文 - Original

9-3

金属間化合物超伝導体V₂Zr水素吸収における超伝導臨界温度の同位体(H,D,T)効果
Isotope Effects of Superconducting Transition Temperature in V₂ZrHx(Dx,Tx)

森　克徳、後藤　真宏、大塚　一弘、石川　義和、佐藤　清雄、芦田　完、渡辺　国昭

Katsunori MORI, Masahiro GOTO, Kazuhiro OHTSUKA, Yosikazu ISHIKAWA, Kiyoo SATO, Kan ASHIDA, Kuniaki WATANABE

9-4

Zr-Ni系合金の水素化物生成熱
Heat of Hydride Formation of Zr-Ni Alloy

田中　公利、宇佐美　四郎、長谷川　淳、松山　政夫、渡辺　国昭

Kouri TANAKA, Shiro USAMI, Kiyoshi HASEGAWA, Masao MATSUYAMA, Kuniaki WATANABE

9-5

各種黒鉛材料中のトリチウムインベントリーの評価
Tritium Inventory in Graphite

芦田　完、渡辺　国昭

Kan ASHIDA, Kuniaki WATANABE

9-6

アルミニウム表面近傍における重水素の捕獲と拡散
Trapped State and Diffusion of Deuterium in Subsurface Region of Aluminum

園部　勝、多々　静夫、芦田　完、渡辺　国昭、池野　進

Masaru SONOBE, Shizuo TADA, Kan ASHIDA, Kuniaki WATANABE, Susumu IKENO

9-7

小容積電離箱による高濃度トリチウムのin situ 測定
In situ Measurement of High Level Tritium by Small Ionization Chamber

松山　政夫、中谷　秀夫、山崎　登志成、渡辺　国昭

Masao MATSUYAMA, Hideo NAKATANI, Toshinari YAMAZAKI, Kuniaki WATANABE

9-8

トリチウムをトレーサーとする熱分析装置の開発（�T）　−性能試験と問題点−
Development of Thermal Analysis System Coupled with Tritium Tracer Technique (�T) −Performance Test and Improvement Required−

三宅　均、松山　政夫、渡辺　国昭

Hitoshi MIYAKE, Masao MATSUYAMA, Kuniaki WATANABE

9-9

北アルプス内蔵助雪渓のトリチウム濃度、安定同位体比と化学組成
Tritium and Stable Isotope Geochemistry of The Kuranosuke Snow Patch, Central Japan.

佐竹　洋、神田　義之

Hiroshi SATAKE, Yoshiyuki KANDA

9-10

トリチウムガスの酸化に及ぼす紫外線の影響　−トリチウムガスの酸化過程−
Effect of UV Irradiation on the Oxidation of Elemental Tritium −Oxidation Process of Tritium−

宇佐美　四郎、伏間江　弘、長谷川　淳、松山　政夫、渡辺　国昭、竹内　豊三郎

Shiro USAMI, Hiroshi FUSUMAE, Kiyoshi HASEGAWA, Masao MATSUYAMA, Kuniaki WATANABE, Toyosaburo TAKEUCHI

ノート - Notes

9-11

77KでのT₂O氷の赤外線吸収スペクトル
Infrared Spectrum of T₂O Ice at 77K

金坂　績、林　秀治、喜多　勇人、川井　清保

Isao KANESAKA, Hideharu HAYASHI, Hayato KITA, Kiyoyasu KAWAI

研究報告9-1
総説

　The Tritium Research Center at Toyama University was established in 1980. Basic researches have been conducted in collaboration with TRC staffs and investigators of Toyama University and others to contribute the R&D for the safe handling of tritium in D-T fusion reactors.

1. Research on this topic can be roughly classified as follows:Essentials in tritium handling techniques such as storage-supply-recovery, high/low level tritium measurements, and the separation/enrichment of tritium gas.
2. Material interactions with tritium such as contamination/decontamination, permeation and waste processing.

　The results of these investigations are briefly described and problems for future study are indicated.

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研究報告9-2
解説

　Isotope techniques have found increasingly wide scope of application to the environmental geochemistry of natural waters since 1960. The stable isotope ratio of hydrogen (D/H) varies in natural waters, as dose that of oxygen (¹⁸O/¹⁶O), due to isotopic separation during evaporation and condensation processes in the hydrologic cycle. The concentration of radioactive hydrogen isotope (tritium) in natural waters increased sharply following the atmospheric testing of nuclear bombs during the 1950s and 1960s. Thermonuclear tritium remaining in natural waters is a good indicator of the presence or absence of recent recharge and water age (residence time). Since deuterium, tritium and oxygen-18 are constituents of water molecules (HDO, HTO and H₂¹⁸O) they serve as unique tracers in environmental geochemistry of natural waters.
  This paper presents measurement scales and units, techniques, behavior of isotopes within the hydrologic and the application of isotope techniques to the environment in Japan.

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研究報告9-3
論文

　Isotope effects on superconducting transition temperature, Tc, are of interest from fundamental and/or theoretical standpoints. New data are presented on variation in the superconducting transition temperature, Tc, and structural phase transition temperature, T_M, for cubic Laves phase compounds, V₂ZrHx, V₂ZrDx and V₂ZrTx with 0≦x≦0.11, where H, D, and T are protium, deuterium and tritium, respectively. It should be pointed out that, the superconductivity of V₂Zr tritide is reported here for the first time.

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研究報告9-4
論文

　Hydrogen absorption alloys are widely used for tritium handling, such as its storage, supply and recovery. For such application, it is of paramount importance that the equilibrium dissociation pressure (P_eq) of metal tritide be very low at room temperature and the temperature reaching P_eq of 1 atm, (T_1atm), not be too high.
  Thus, the thermodynamical properties related to the heat of formation of Zr-Ni deuteride instead of tritide were studied so as to find the best material. The composition of the Zr-Ni alloy used in this study was Zr₉Ni₁₁, which was characterized by X-ray diffractometry. The Zr₉Ni₁₁, activated in advance, was exposed to a given amount of deuterium at room temperature, and then the deuteride was heated stepwise to 300℃. Each temperature was kept constant for adequate time till P_eq become constant. The data for both P_eq and temperature were arranged by the van’t Hoff equation:
           lnP_eq=(ΔHﾟ/RT)-(ΔSﾟ/R).
  Values of -ΔHﾟ=24〜25kcal/mol[D₂] and -ΔSﾟ=33〜34kcal/mol[D₂]・deg were obtained when atomic composition of deuteride was in the range from Zr₉Ni₁₁D₁ to Zr₉Ni₁₁D₃. From these values, Peq at 20℃ and T_1atm were obtained as 10^-6〜10^-7 Pa and ca. 450℃, respectively. The deuteride did not ignite even when exposed to the atmosphere at room temperature nor did it take on the form of a fine powder.
  These results thus show Zr₉Ni₁₁ to be a preferable material for storage-supply-recovery of tritium gas.

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研究報告9-5
論文

　Graphite is widely used as a plasma facing component in many magnetically confined fusion devices. Before using it in D-T burning experimental devices, tritium inventory and recycling in graphite should be understood with respect to fuel balance control, safety control and tritium economy. Tritium inventory in a high temperature region (700-1000℃) was measured for graphite of various grades. The results indicate that the tritium inventory was determined by diffusion limited process.
  The diffusion constants of tritium for samples of graphite differed by one order of magnitude from each other. Nevertheless, tritium inventory was mainly determined from crystallite size. In addition, a first interpretation was given for the scattering of diffusion constants of tritium in graphite reported so far through the compensation effect.

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研究報告9-6
論文

　Aluminum/aluminum alloy is a promising material for vacuum components in D-T burning experimental devices owing to its low activation toward 14 MeV neutrons, low outgassing and other features. Prior to its application, however, fundamental interactions between aluminum and fuel (deuterium and tritium) must be understood in regard to tritium inventory, fuel recycling, and environmental safety. For this purpose, a study was made of trapped states and diffusion of deuterium implanted into aluminum using computer-aided x-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS). Following deuterium ion implantation (5 keV), a new secondary ion peak, AID⁺, was detected in the SIMS spectra, indicating deuterium atoms to be directly trapped on aluminum atoms. Changes in the profiles of implanted D atoms in sample at a given temperature were examined by shape analysis using diffusion control model. The diffraction coefficients of deuterium were determined from changes in depth profiles as about 10^-16 (at R.T.) and 10^-14[cm²/sec](at 70℃). These value are 4 to 8 orders of magnitude lower than those for Fe or Ni; thus aluminum alloys should be superior to tritium in thermonuclear devices than Fe-based materials such as stainless steel.

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研究報告9-7
論文

　For the research and development of D-T thermonuclear fusion devices, in situ methods to measure high levels of tritium should be established. Thus, a small ionization chamber was made and examined for its applicability to in situ and real time measurements of high levels of tritium.
  The ionization chamber was easily constructed, did not leak owing to VCR fitting and a considerably small effective volume of 1.9cm³. Excellent saturation-current characteristics were observed at an applied voltage above +20V to the center electrode when the chamber was filled with tritium gas mixed with hydrogen isotopes at a pressure below 1 atm. No special power source or electric circuit was required. The present system showed excellent linearity in a wide concentration range from 1x10^-6 to 3x10^-1 Ci/cm³, when the total pressure was kept constant at 1 atm.
  Consequently, it was concluded that the small ionization chamber developed in the present study was quite useful for in situ and real time measurements of high levels of tritium in tritium processing in magnetic fusion devices.

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研究報告9-8
論文

　Heat of reaction data are needed for examining interactions between hydrogen isotopes and materials used in thermonuclear fusion reactors. To measure the heat itself produced from hydrogen (tritium) -material interactions, a thermal analysis system provided with a tritium measuring device was established. It consisted of a differential scanning calorimeter (DSC) and ionization chamber. The DSC was modified to assure that there would be no leakage of tritium and removal of tritium contamination. Its performance was assessed with respect to stability of the base line in DSC measurement, and desorption of D₂ (DT) from Zr-V-Fe getter (dry gas desorption) and H₂O(HTO) from CuSO₄・5H₂O(HTO) (wet gas system). The heat of desorption of D₂(DT) could be determined directly. For wet gas desorption, however, heat determination differed considerably from that by other methods. The reason for this was the adsorption of HTO on the inner surface of the pipe line and ionization chamber.

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研究報告9-9
論文

　Tritium concentrations and oxygen isotope ratios of ice samples from Kuranosuke snow patch were measured to determine the ages of ice bodies and climatic conditions for their formation. An ice body of the snow patch may be divided into upper and lower parts by the clear surface of unconformity observed at a height of 13.4m. In the upper part, at 19.5 (the surface of snow patch) -17.5m height, the tritium concentration was 10-20 TU and increased rapidly to 143 TU at 13.9m. It then decreased to 67.3 TU at a 13.4m height. From this vertical profile, the ice at the 13.9m was considered to have been deposited in 1963. The tritium concentration of 0 TU was observed in the lower part (at a 3.2-10.3m height). This is consistent with the age of the lower part of ice body (BP 580-1760 years) determined by carbon-14 dating. Tritium concentrations of 2.8-14.5 TU (at the 11.3-12.9m height) and 2.0-3.3 TU (below 0.9m), however, were noted in the lower part, indicating contamination by water from the melted ice of the upper part having high tritium concentration or ground water which entered from the bottom of the ice body. The oxygen isotope ratios of the ice body at a 11.2-18.4m height ranged from -12.1‰ to -11.1‰. While at less than 10.3m, they were -13.5 to -11.8‰. The ice body below 10.3m showed a lower oxygen isotope ratio than that of the upper part by about 1‰.
  From the relationship between the annual average of oxygen isotope ratio of precipitation and annual mean temperature, the ice body below 10.3m was concluded to have been deposited in a cold climate period in which atmospheric temperature was lower than that at present by about 1.5℃.

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研究報告9-10
論文

　For the UV-photon induced oxidation of tritium gas, an experimental kinetic equation in the previous paper did not agree with a theoretical equation derived from possible elemental reactions. In the present study, we examined in detail the dependence of the reaction rate on the total pressure of the hydrogen isotope, [H₂]+[HT], and HT fraction, [HT]/([H₂]+[HT]).
  The initial reaction rate was proportional to the fraction of [HT]/([H₂]+[HT]) and one-half order with respect to [H₂]+[HT]. Based on these results in addition to oxygen pressure dependence, the rate equation is given as

OH and/or H radicals appeared essential to the enhancement of the oxidation rate, although the observed rate equation could not be explicitly derived from theoretical considerations. The increase in OH radical in troposphere owing to that in air pollution materials such as NOx is considered capable of accelerating the rate of formation of tritiated water in the presence of UV-photons.

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研究報告9-11
ノート

　The infrared spectrum of T₂O ice at 77K was observed in the region of 4000-330 cm^-1. No remarkable changes in spectral features could be found in 7 hours. A slight change in bandwidth and frequency for the impurity band ν(O-H) was noted in 〜10 minutes, due possible to the phase transition from vitreous to cubic ice, Ic, based on similar change in cold runs. T₂O Ice-Ic was considerably stable, whereas the bandwidth was 〜4 times larger than that in H₂O ice, indicating increased ion mobility.