研究報告5 - 1 総説 - Review
トリチウムによる二次電子増倍管および質量分析計の機能障害とその回復
Impairment of Secondary Electron Multiplier and Mass Spectrometer by Tritium and Recovery from Tritium Contamination
渡辺 国昭、市村 憲司、松山 政夫
富山大学トリチウム科学センター
〒930 富山市五福3190
Kuniaki WATANABE, Kenji ICHIMURA, Masao MATSUYAMA
Tritium Research Center, Toyama University,Gofuku 3190, Toyama 930, JAPAN
(Received December 25, 1985)
Abstract
In D-T fusion experiments, secondary multipliers
will be widely used as detectors for plasma diagnostics and mass spectrometers
for fuel analysis and vacuum measurement. However, as significant impairment
of the multiplier performance is predicted owing to the β-rays from tritium
adsorbed on the detector surface (contamination), in-situ decontamination
technique are, therefore, required. On reviewing the contamination effect
on the performance of the secondary electron multipliers and decontamination
techniques, it is indicated that the adsorption of tritiated water vapor
is more serious than tritium gas. In principle, the tritium contamination
could be removed by vacuum heating but it is a time consuming technique.
Since photon irradiation is more effective in the decontamination than
vacuum heating, it is proposed as an in-situ decontamination method. It
is pointed out, however, that more extensive studies are required to understand
the decontamination and/or signal discrimination techniques.
研究報告5 - 2 論文 - Original
Pt/TiO2によるトリチウム水の光分解
Photoassisted Decomposition of Tritiated Water over Pt/T2O Catalysis
市村 憲司、井上 直哉、渡辺 国昭、松浦 郁也
富山大学トリチウム科学センター
〒930 富山市五福3190
*現在 アロカ株式会社
〒181 東京都三鷹市牟礼6-22-11
Kenji ICHIMURA, Naoya INOUE*, Kuniaki WATANABE, Ikuya MATSUURA
Tritium Research Center, Toyama University,Faculty of Science, Toyama UniversityGofuku 3190, Toyama 930, JAPAN
*Present Address: Aloka Co. Ltd.,Mure 6-22-11, Mitaka, Tokyo 181
(Received December 25, 1985)
Abstract
The recovery of tritium from tritiated water
is important for the safe handling of a large amount of tritium required
in thermonuclear fusion devices and heavy water moderated fission reactors.
Among a variety of techniques, photocatalytic decomposition of water is
attractive because tritium in tritiated water is enriched here by use of
the solar energy. From this viewpoint, the kinetics and separation factors
for hydrogen evolution from H2O-HTO and H2O-D2O
systems over Pt/TiO2 catalyst were investigated.
The separation factors defined with the initial
reaction rate were αRo (H2O-D2O)=5.1±0.05
and βRo (H2O-HTO)=15.4±0.2. They were independent
of the mixing ratio of the isotope waters but gradually decreased to steady
values when a closed experimental system was used. The separation factors
defined with the steady state were αe(H2O-HDO)=3.6±0.05, αe(D2O-HDO)=3.0±0.05,
and βe(H2O-HTO)=6.2±0.05. In addition, hydrogen evolution
was found to be considerably enhanced by the synergistic effect of β-rays
and photons.
The separation factors, αRo and
βRo, agreed with those predicted by theoretical calculation
for catalytic model in electrolysis indicating that the rate determining
step is the association reaction of hydrogen atoms absorbed on Pt surface.
The separation factors, αe and βe, agreed with those for the gas-liquid
equilibration reaction indicating that the equilibration reaction plays
a role.
研究報告5 - 3 論文 - Original
熱分解黒鉛に捕獲された水素同位体の昇温脱離スペクトルの解析
Analysis of Thermal Desorption Spectra of Hydrogen Isotopes Trapped in Pyrolytic Graphite
芦田 完、渡辺 国昭*
富山大学放射性同位元素総合実験室
*富山大学トリチウム科学センター
〒930 富山市五福3190
Kan ASHIDA, Kuniaki WATANABE*
Radio-isotope Lab., Toyama University
*Tritium Research Center, Toyama University
Gofuku 3190, Toyama 930, JAPAN
(Received December 25, 1985)
Abstract
To evaluate the recycling and inventory of
tritium in the first wall for thermonuclear fusion devices, detailed investigation
is required regarding the trapping and release of tritium in first wall
materials. Among a variety of materials, graphite is the primary candidate
for the first wall. In this respect, the thermal desorption spectra of
hydrogen isotopes trapped in graphite was measurement and analyzed. The
thermal desorption spectra consisting of three peaks (Ⅰ,Ⅱ, and Ⅲ) were
deconvoluted into individual components with stepwise detrapping method.
It is shown that the desorption of hydrogen isotopes forming the Ⅱ obeyed
the second order kinetics with respect to the amount of trapped isotope
atoms, indicating that the rate determining step for desorption is the
recombination reaction of the trapped isotope atoms. The kinetic parameters
were determined as
- kⅡ(H2)=(7.5x10-4)exp (-59x103/RT)
- kⅡ(D2)=(2.4x10-4)exp (-59x103/RT)
where the frequency factor and activation energy are in [molec・sec] and [cal/mol] unit, respectively. The activation energy for desorption of T2 was the same as that for the other two isotopes. The frequency factor for T2, however, considerably deviated from those for the other two. This is considered due to the present of impurity gases in the tritium gas used in the present study.
研究報告5 - 4 論文 - Original
黒鉛に打ち込まれた水素同位体の脱離機構と再結合係数
Desorption Mechanisms of Hydrogen Isotopes Implanted into Graphite and Recombination Factors
渡辺 国昭、芦田 完*
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
Kuniaki WATANABE, Kan ASHIDA*
Tritium Research Center, Toyama University
*Radio-isotope Labs., Toyama University
Gofuku 3190, Toyama 930, JAPAN
(Received December 25, 1985)
Abstract
Kinetics and mechanisms were studied for the
thermal release of hydrogen isotopes implanted into pyrolytic graphite.
The kinetic measurements were carried out with mass analyzed thermal desorption
spectroscopy. The desorption spectra consisted of three peaks, Ⅰ, Ⅱ,
and Ⅲ. The peak Ⅰ obeyed the second order kinetics regarding the amount
of trapped hydrogen isotope atoms. The recombination factors averaged over
the sub-surface layer were determined as
- kr(H2)=(13.0x10-19)exp(-44.0x103/RT) [cm4/sec・molec]
- kr(D2)=(7.18x10-19)exp(-44.0x103/RT)
- kr(T2)=(5.26x10-19)exp(-44.0x103/RT)
- kr(D2)=(7.18x10-19)exp(-44.0x103/RT)
- ks K2 (H2)=(4.68x10-19)exp(-44.0x103/RT) [cm2/sec・molec]
- ks K2 (D2)=(2.58x10-19)exp(-44.0x103/RT)
- ks K2 (T2)=(1.89x10-19)exp(-44.0x103/RT)
- ks K2 (D2)=(2.58x10-19)exp(-44.0x103/RT)
It was concluded that the rate determining step for desorption forming the peak Ⅰ was the surface recombination reaction of hydrogen isotope atoms trapped on the normal graphite lattice of the basal plane.
研究報告5 - 5 論文 - Original
ポリカーボネート膜における水素同位体の透過と拡散Ⅱ
Diffusion and Permeation of hydrogen Isotopes in/through polycarbonate Ⅱ
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 25, 1985)
Abstract
Permeation and solution of tritium through/in
organic polymers are important problems for applying these materials to
tritium handling systems. In this connection, the solution and diffusion
of tritium in several polymers were studied by means of time-lag method
and considerable abnormal behavior for tritium permeation though polycarbonate
film was observed. The causes of this abnormality were investigated by
measuring diffusivity and solubility of tritium under various experimental
conditions. It was observed that the solubility and diffusivity and hence
permeability of tritium was significantly affected by the presence of residual
solvent originating from the manufacturing processes. In addition, the
residual solvent enhanced the solution of isobutene contained in counting
gas when the permeation was measured by β-ray counting method using G-M
counter. Both the residual solvent and dissolved isobutene disturbed the
diffusion of tritium. The latter, however, significantly impaired the diffusion
of tritium. When the residual solvent was removed from the film in vacuum
and the permeation was measured by quadrupole mass spectrometer, the abnormality
disappeared and normal isotope effect was observed. The extent of isotope
effect, however, differed from that of the classical rate law prediction.
研究報告5 - 6 論文 - Original
光照射による吸着トリチウム水の除去
Removal of Tritiated Water Adsorbed on Gold by Photon Irradiation
松山 政夫、市村 憲司、渡辺 国昭、加藤 一真*、前川 寛*、佐藤 博夫*
富山大学トリチウム科学センター
〒930 富山市五福3190
*アロカ株式会社
東京都三鷹市牟礼6-22-1
Masao MATSUYAMA, Kenji ICHIMURA, Kuniaki WATANABE, Kazuma KATO*,Hiroshi MAEKAWA*, Hiroo SATO*
Tritium Research Center, Toyama University,Gofuku 3190, Toyama 930, JAPAN
*Research and Development Laboratory, Aloka Co. Ltd.,Mure 6-22-1, Mitaka, Tokyo 181, JAPAN
(Received December 25, 1985)
Abstract
The adsorption of tritium on material surface
causes significant contamination of tritium handling systems, β-ray counting
devices and parts contained in them. Therefore, it is necessary to establish
effective decontamination techniques or develop materials free from contamination.
From this viewpoint, the decontamination of a gold-plated ionization chamber
was studied in which tritiated water was adsorbed by photon irradiation
in order to establish an in-situ decontamination technique.
It was observed that photon irradiation enhanced
the desorption of tritiated water. The extent of the enhancement was larger
in deuterium lamp illumination than halogen lamp illumination. The photon
irradiation in various atmospheres such as room air, argon and moistened
argon gave no appreciable differentce in the decontamination effect, indicating
that the enhanced desorption of tritiated water was not due to the interaction
between adsorbed tritiated water and ions produced in the phase but caused
by photodesorption of tritiated water. It was concluded that the irradiation
of photons in the ultraviolet region was applicable as the in-situ decontamination
technique to devices such as ionization chamber where materials with low
thermal stability are used.
研究報告5 - 7 ノート - Research Note
赤外によるトリチウムを含む水の定量
Determination of Tritiated Waters by means of Infrared Spectroscopy
金坂 績、川井 清保、市村 憲司*、渡辺 国昭*
富山大学理学部
*富山大学トリチウム科学センター
〒930 富山市五福3190
Isao KANESAKA, Kiyoyasu KAWAI, Kenji ICHIMURA*, Kuniaki WATANABE*
Faculty of Science, Toyama University
*Tritium Research Center, Toyama University
Gofuku 3190, Toyama 930, JAPAN
(Received December 25, 1985)
Abstract
The absorption coefficient, ε, of HDO was
reported for two bands and compared with those of T2O and D2O
(Ichimura et al., Nuclear Instr. Methods Phys. Res., A241, (1985), 614).
It is noted that ε of some bands is important for determination from view
point that ε depends on temperature. The additional values of ε are tabulated
for T2O. The useful bands for determination of T2O,
D2O and HDO are discussed on the basis of assignments.
研究報告5 - 8 ノート - Research Note
二重標識3Hおよび14C化合物の放射能測定
Measurement of Radioactivity of Doubly Labeled 3H- and 14C-Compound
朝野 武美、桐谷 玲子、川西 徹朗*
大阪府立放射線中央研究所
大阪府堺市新家町
*近畿大学農学部
大阪府東大阪市小若江
Takeyoshi ASANO, Reiko KIRITANI, Tetsuro KAWANISHI*
Radiation Center of Osaka Prefecture,Shinke-cho, Sakai, Osaka, JAPAN
*Kinki University, Department of Agriculture,Kowakae, Higashiosaka, Osaka, JAPAN
Gofuku 3190, Toyama 930, JAPAN
(Received December 25, 1985)
Abstract
The radioactivity of spot doubly labeled 3H-
and 14C- compound on a thin layer chromatograph plate was measured
with a radiochromatogram spark chamber. The results were compared with
those obtained from a radio thin layer chromatograph and an autoradiograph.
For the radiochromatogram spark chamber, the lower limits on detectable
intensity of
3H- and 14C-radioactivities were 1000
dpm and 100 dpm, respectively. Accordingly, it was found that more than
105 dpm of radioactivity was required for the detection of the
doubly labeled compound,which has a 14C/3H radioactivity
ratio of 1/490 on this instrument. Further, it was revealed that the amount
of radioactiveity of tritium and carbon-14 could be estimated from the
brightness of spark images.