研究報告

第17巻(1997)

研究報告17 - 1 解説 - Review

LHDから核融合炉へ
From LHD to Fusion Reactor

相良 昭男
核融合科学研究所
〒509-52 土岐市下石町字西山322-6

Akio SAGARA
National Institute for Fusion Science 322-6 Orishicho, Toki 509-52
(Received January 5, 1998; accepted March 9, 1998)


Abstract
 Research and development of helical systems have been persistently continued. New large devices using superconducting magnets, LHD in Japan and W-7X in Germany, are under construction. These aggressive programs accelerate several design studies of helical-type reactors, because of the main advantage of current-less steady operation, as promising alternatives for Demo reactors.
  A reference design of Force Free Helical Reactor (FTHR) is presented to discuss Demo relevant engineering issues in the concept definition phase. The main feature of FTHR is force-free-like configuration of helical coils, which makes it possible to simplify the coil supporting structure and to use high magnetic field instead of high plasma beta. The other feature is the selection of molten-salt Flibe as a self-cooling tritium breeder from the main reason of safety. Collaboration works based on the LHD project have made great progress in the reactor studies by focusing on engineering aspects of the high magnetic field and Flibe system design.

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研究報告17 - 2   解説 - Review

トリチウムの生物効果と今後の研究展望
Tritium Biological Effects and Perspective of the Biological Study

小松 賢志
広島大学原爆放射能医学研究所
広島市南区霞1-2-3

Kenshi KOMATSU
Research Institute for Radiation Biology and Medicine
Kasumi 1-2-3, Minami-ku, Hiroshima 734
(Received Sept., 4, 1997; accepted March 9, 1998)


Abstract
 Since tritium is an emitter of weak β-ray (5.7keV) and is able to bind to DNA, i.e., the most important genome component, the biological effects should be expected to be more profound than that of X-rays and γ-rays. When carcinogenesis, genetic effects and the detriments for fetus and embryo were used as a biological endpoint, most of tritium RBE (relative biological effectiveness) ranged from 1 to 2. The tritium risk is man could be calculated from these RBEs andγ-ray risk from human exposure, which are obtained mainly from the data on Atomic Bomb survivors. However, the exposure modality from environmental tritium should be a chronic irradiation with ultra low dose rate or a fractionated irradiation. We must estimate the tritium effect in man based on biological experiments alone, due to lack of such epidemiological data. Low dose rate experiment should be always accompanied by the statistical problem of data, since their biological effects are fairy low, and they should involve a possible repair system, such as adaptive response (or hormesis effect) and “Kada effect” observed in bacteria. Here we discuss future works for the tritium assessment in man, such as (1) developing a high radiation sensitive assay system with rodent hybrid cells containing a single human chromosome and also (2) study on mammal DNA repair at molecular levels using a radiosensitive disease, Nijmegen Breakage Syndrome.

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研究報告17 - 3  論文 - Original

100Ciトリチウム実験装置の開発
Development of 100Ci Tritium Handling System

渡辺 国昭、松山 政夫、芦田 完、舒 衛民、原 正憲、田中 るみ
富山大学水素同位体機能研究センター
〒930-8555 富山市五福3190
鈴木 達志、森 雄一郎、佐藤 康士、山口 昇、林 茂男
川崎重工業株式会社
〒136東京都江東区南砂2丁目6番5号

K. Watanabe, M. Matsuyama, K. Ashida, W. M. Shu, M. Hara, R. Tanaka
Hydrogen Isotope Research Center, Toyama University, Gofuku 3190, JAPAN
T. Suzuki, Y. Mori, K. Sato, N. Yamaguchi, S. Hayashi
Kawasaki Heavy Industry,Nansa 2-Chome 6-5, Koutou-Ku, Tokyo, JAPAN
(Received November 19, 1997; accepted March 9, 1998)


Abstract
 A new experimental system has been developed for use of pure tritium amounting to 100 Ci at a time. The system consists of two experimental chambers and other components such as tritium storage-supply, gas purification, isotope separation, and exhaust gas handling devices. These components provide a complete tritium circulation in the system, and hence tritium waste can be minimized for a variety of experimental works. One of the chambers is designed for experiments using molecular tritium, and the other for tritium plasma generated with ECR discharge. A Zr-Ni alloy is applied for impurity removal from the exhaust gas from both of the experimental chambers and gas chromatography is used for the isotope separation of purified hydrogen isotope mixtures. Other kinds of gettering materials are used for tritium storage-supply. The exhaust gas handling system has two different devices; one is a conventional wet device, consisting of a Pt-catalyst bed and a molecular sieve bed, the other a dry device using two getter beds.
  This paper describes the details of the system as well as its components and the results of system performance test using non-radioactive hydrogen isotopes.

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研究報告15 - 4  論文 - Original

TFTR黒鉛プローブ表面のXPS-SIMSによる分析
Surface Characterization of TFTR Graphite Probe by XPS-SIMS

芦田 完、広岡 慶彦*、渡辺 国昭
富山大学水素同位体機能研究センター
〒930-8555 富山市五福3190番地
*カリフォルニア大学サンディエゴ校、工学部、応用力学、工業科学科
カリフォルニア州ラホヤ市、92093-0417

Kan ASHIDA, Yoshihiko HIROOKA* and Kuniaki WATANABE
Hydrogen Isotope Research Center, Toyama University,Gofuku 3190, Toyama 930-5888, JAPAN
*Fusion Energy Research Program
Department of Applied Mechanics & Engineering Science
University of California, San Diego, La Jolla, California 92093-0417, USA (Received December 15, 1997; accepted March 9, 1998)


Abstract
 Deposition probe measurements using a cylindrical 4D C-C composite was conducted to investigate the deposition layers on the graphite first wall of TFTR (Tokamak Fusion Test Reactor), Princeton University. XPS measurements revealed that the surface atomic compositions of probe areas differed from each other. This indicates that the probe surface was covered with deposits. SIMS measurements detected lithium, carbon, oxygen and deuterium. Lithium was found even at the depth ranging up to 7-8 μm far beyond the expected depth and/or thickness of the deposits. This suggests that Li atoms diffused to the bulk along grain boundaries of the probe. Another characteristic feature of SIMS spectra is the appearance of Li-relating signals such as M/e=28(6Li2O), 29(6Li7LiO) and 30(7Li2O), whereas M/e=22 and 44 (6LiO and 6Li2O2) were not observed. It is concluded that the surface of the TFTR graphite probe was covered with carbon deposits containing Li, H, D and O with a trace amount of Cr and Fe from stainless steel.

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研究報告17 - 5  論文 - Original

TFTR炭素材プローブ中のトリチウム測定
Analysis of Tritium Implanted in an Edge Probe in TFTR

原 正憲*1、芦田 完*1、松山 政夫*1、渡辺 国昭*1、広岡 慶彦*2
*1富山大学水素同位体機能研究センター
〒930-8555 富山市五福3190番地
*2カリフォルニア大学サンディエゴ校
92093-0417 カリフォルニア州ラホヤ市

Masanori HARA*1, Kan ASHIDA*1, Masao MATSUYAMA*1, Kuniaki WATANABE*1, Yoshi HIROOKA*2
*1Hydrogen Isotope Research Center, Toyama University,Gofuku 3190, Toyama 930-8555, JAPAN
*2Fusion Energy Research Program and Department of Applied Mechanics and Engineering Sciences,
University of California, San Diego
La Jolla, California 92093-0417
(Received January 5, 1998; accepted March 9, 1998)


Abstract
 Tritium analysis has carried out for the 4D C-C composite deposition probe exposed to the edge of D-D plasma several times in Tokamak Fusion Test Reactor (TFTR) at Princeton University. It is expected that a non-negligible amount of tritium would be captured in it. The samples of tritium measurement were small thin slices taken from different parts of the probe and powder yielded. The amount of tritium was measured in two different ways. One was the conventional combustion and scintillation counting of trapped water for the sliced samples, and the other a direct counting method of the powder suspended in the scintillator. The burning method gave 87 to 398 kBq/g, depending on the part of probe areas. The data indicate that the ion drift side contains more tritium than the electron drift side, which is consistent with earlier surface measurements for deuterium and lithium. On the other hand, the direct counting method resulted in 61 kBq/g. The smaller activity by the direct method indicates that tritium was distributed beyond the escape depth of the beta rays from the surface. Nevertheless, the direct counting appears to be applicable to for the estimation of tritium inventory in the carbon first wall as a rapid technique and should be convenient for carbon debris of considerably small particle sizes.

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研究報告17 - 6  論文 - Original

燒結型Mg2Niの充放電特性
Charge/Discharge Characteristics of Sintered Mg2Ni

舒 衛民、水上 憲三、渡辺 国昭、諸住 正太郎

富山大学水素同位体機能研究センター
〒930-8555 富山市五福3190

W. M. SHU, K. MIZUKAMI, K. WATANABE and S. MOROZUMI
Hydrogen Isotope Research Center, Toyama University,Gofuku 3190, Toyama 930-8555, JAPAN
(Received November 19, 1997; accepted March 9, 1998)


Abstract
  The charge/discharge characteristics of sintered Mg2Ni as an anode of nickel/metal hydride battery were studied with an electrochemical cell. The discharge capacity of sintered Mg2Ni increases initially with the charge/discharge cycles. Cycle life (CL) for sintered samples is much greater than that of the un-sintered sample, and the largest CL appears at the sintering temperature of 550℃. The effects of sintered sample, and the largest CL degradation were examined through the changes in the specific surface area and the chemical composition. The sample sintered at 550℃ holds the largest surface area, and the segregation of Mg over the outside layer of samples was confirmed for those sintered at temperatures higher than 550℃. The degradation after charge/discharge cycling was investigated with X-rays diffraction and scanning electron microscopy. The XRD pattern shows a new phase of Mg(OH)2 besides the phase of Mg2Ni after charge/discharge cycling. It indicated that the formation of Mg(OH)2 at the outside layer of samples contributes to the degradation of the anode performance.

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研究報告17 - 7  論文 - Original

トリチウム化メタンからのトリチウム回収に対するZr80Ni20合金の適用性
Availability of Zr80Ni20-Alloy for Tritium Extraction from Tritiated Methane

松山 政夫、本橋 英一、舒 衛民、渡辺 国昭
富山大学水素同位体機能研究センター
〒930-8555 富山市五福3190番地

Masao MATSUYAMA, Eiichi MOTOHASHI, W. M. SHU and Kuniaki WATANABE
Hydrogen Isotope Research Center, Toyama University,Gofuku 3190, Toyama 930-8555, JAPAN


(Received December 5, 1997; accepted March 9, 1998)


Abstract
 Decomposition of methane by getting materials is one of promising methods to extract tritium atoms from tritiated hydrocarbon species in the exhaust gases of thermonuclear fusion devices. Basic properties of the powered Zr80Ni20-alloy on the decomposition kinetics of methane and the absorption-desorption characteristics of hydrogen isotopes have been investigated. The Zr80Ni20-alloy mainly consisted of Zr and Zr2Ni crystals. The decomposition rate obeyed the first order kinetics with respect to the pressure of methane, and most of methane (>99.7%) was decomposed within a few minutes at 723K. The activation energies for the decomposition were determined as 37.2 and 58.3 kJ/mol for temperatures of RegionⅠ and RegionⅡ, respectively. Pressure changes of hydrogen in the temperature range from 373 to 673K indicated the existence of two hydrides. △H゜ and △S゜ evaluated from temperature dependence of the equilibrium dissociation pressure at a low hydrogen concentration were determined as -168 kJ/mol-H2 and ?124J/K・mol-H2, respectively. These values were close to those of Zr-hydride. On the other hand, the pressure changes at a high hydrogen concentration indicated the existence of Zr2Ni-hydride. It was revealed, therefore, that hydrogen atoms liberated by methane decomposition are absorbed by Zr and Zr2Ni crystals, depending on the hydrogen concentration in the Zr80Ni20-alloy.

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研究報告17 - 8  論文 - Original

Pd-Pt合金の水素同位体吸蔵-放出特性
Absorption and Desorption of Hydrogen Isotopes by Palladium-Platinum Alloys

安松 拓洋、原 正憲、松山 政夫、渡辺 国昭 富山大学水素同位体機能研究センター
〒930-8555 富山市五福3190

Takuyo YASUMATSU, Masanori HARA, Masao MATSUYAMA, Kuniaki WATANABE
Hydrogen Isotope Research Center, Toyama University,Gofuku 3190, Toyama 930, JAPAN
**Japan Atomic Energy Research Institute
(Received January 8, 1998; accepted March 9, 1998)


Abstract
 Absorption and desorption of hydrogen isotopes by Pd-Pt alloys are studied to find appropriate column materials for the self-developing gas chromatography around room temperature for hydrogen isotope separation. The equilibrium pressure of H2 and D2 increased with increasing Pt contents in the alloys in the range from 0 to 10 at%Pt, indicating that the free energy of hydrogen absorption and hydride formation decreased with Pt contents. It was found that the decrease in the free energy change is principally due to the decrease in the heat of absorption and hydride formation; the entropy change was kept almost constant irrespective of the alloy composition.
  On the other hand, the isotope effect evaluated from the ratio between the plateau pressures of H2 and D2 was not much dependent on the alloy composition, indicating that any alloy investigated will be applicable as a separation column, depending on operation conditions of the self-developing gas chromatography.

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研究報告17 - 9  論文 - Original

トリチウム増殖材データベース(3)Li2TiO3 固体増殖材
Breeding Material Data Base for Fusion Reactor (3) (Li2TiO3 Solid Breeder)

二村 嘉明
富山大学水素同位体機能研究センター
〒930-8555 富山市五福3190番地
河村 弘、土谷 邦彦
日本原子力研究所
〒311-1394 茨城県東茨城郡大洗町成田新堀3607

Yoshiaki FUTAMURA
Hydrogen Isotope Research Center, Toyama Universit
Gofuku 3190, Toyama 930-8555, JAPAN
Hiroshi KAWAMURA and Kunihiko TSUCHIYA
Japan Atomic Energy Research Institute
Shinbori 3607, Narita, Oarai-machi, Higashi-Ibaragi-Gun, Ibaragi 311-1394, JAPAN


Abstract
 This up-to-date compilation of data for lithium titanate, Li2TiO3, is part of a study to construct a database for breeding blanket of a fusion reactor, where existing data for breeding materials and neutron multipliers have been collected from as many literature as possible.
  This compilation includes physical properties, thermal and mechanical properties, chemical stability and compatibility, tritium solubility and transport, irradiation effects, afterheat characteristics, thermal cycling effects, waste disposal and other miscellaneous properties of lithium titanate.

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