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中道 勝; 金 宰煥; 宮本 光貴*
Nuclear Materials and Energy (Internet), 9, p.55 - 58, 2016/12
Hydrogen generated via an oxidation reaction of beryllium (Be) with water vapor is explosive, and BeO produced by this reaction is harmful to human bodies. Advanced neutron multipliers with high stability at high temperatures are desirable for a fusion reactor. Development of beryllides as the advanced neutron multipliers has been started in the Broader Approach activities. The authors have developed the fabrication methods of beryllide pebbles: a combination of a plasma sintering method and a rotating electrode method (REM). The beryllide demonstrated a lower reactivity than Be. However, in the case of Be
Ti, it is a serious problem that an annealing treatment is necessary to homogenize the pebbles to a single BeTi phase. On the other hand, the homogenized BeTi pebbles thus produced by the above methods showed larger reactivity than that with no treatment, since the homogenization caused an increase in the specific surface area of the treated pebbles. To prevent increased surface area and reactivity, prototypic pebbles with Be
Ti
and BeV compositions that have no peritectic reaction during cooling process were successfully fabricated without homogenization. Then, the BeTi and BeV prototypic pebbles indicated to have a good oxidation resistance. In the present study, hydrogen retention property that will influence the used materials handling and the system safety as well as reactivity with water vapor are reported.
中道 勝; 金 宰煥; 落合 謙太郎
Fusion Engineering and Design, 109-111(Part B), p.1719 - 1723, 2016/11
Advanced neutron multipliers with high stability at high temperatures are desirable for the DEMO blankets. Development of the advanced neutron multipliers has been started in the Broader Approach activities. Beryllides are the most promising material for this purpose. To fabricate BeTi beryllide pebbles, a new granulation process has been established that combines a plasma sintering method for beryllide synthesis with a rotating electrode method (REM) using the plasma-sintered electrode for granulation. However, in the case of BeTi pebble fabrication, an annealing treatment is necessary to homogenize the pebbles to a single BeTi phase. From the viewpoint of mass production of beryllide pebbles, other potential structural compositions of beryllides that are able to fabricate without the annealing treatment for homogenization were surveyed. Based on this survey, the structural composition of Be
Zr was selected because this composition not only has no peritectic reaction during the cooling process from the liquid phase, but also has low neutron absorption property. From the result of fabrication examination, prototypic beryllide pebbles 1 mm in diameter composed of single phase BeZr were successfully fabricated directly by granulation using the rotating electrode method without homogenization treatment. The present study reports on not only the granulation of BeZr beryllide, but also on basic characterization of prototypic BeZr pebbles.
金 宰煥; 中道 勝
Fusion Engineering and Design, 109-111(Part B), p.1764 - 1768, 2016/11
被引用回数：16 パーセンタイル：77.87(Nuclear Science & Technology)Beryllium intermetallic compounds (beryllides) are the most promising advanced neutron multipliers in demonstration fusion power reactors. Advanced neutron multipliers are being developed by Japan and the EU as part of their BA activities. Beryllides are too brittle to fabricate into pebble- or rod-like shapes using conventional methods such as arc melting and hot isostatic pressing. To overcome this issue, we developed a new combined plasma sintering and rotating electrode method for the fabrication of beryllide rods and pebbles. By using these methods, preliminary synthesis of the ternary beryllide pebbles with different chemical compositions, BeTi
V
(x=0.0-1.0) was successful. Scanning electron microscopic observation revealed that grain size on the surface decreased while area fraction of Be phase on cross-section decreased as V amount increased. These decreases may be contributed by the fact that the chemical composition of the pebble was closely varied to single-phase BeV with no peritectic reaction as V amount increased while Be, BeTi and BeTi phases were formed with large grain due to peritecic reaction in the BeTi. This feature influenced to variation of reactivity with 1% water vapor at high temperature. It was concluded that weight gain as well as H generation decreased due to decreases of grain size as well as Be phase on the surface as V amount increased in BeTiV.
金 宰煥; 中道 勝
JAEA-Review 2015-044, 260 Pages, 2016/03
JAEA-Review-2015-044.pdf:121.42MB
第12回ベリリウム技術に関する国際会議(The 12th International Workshop on Beryllium Technology (BeWS-12))は、平成27年9月10日(木)及び11日(金)の2日間に渡り、韓国済州島の済州国際コンベンションセンター(ICCJEJU)にて開催された。本国際会議は、1993年から2年毎に開催されており、今回で12回目となる。本国際会議では、世界におけるベリリウム関連材料(ベリリウム金属及びその合金、金属間化合物など)と核融合炉工学研究開発に携わる研究者及び技術者が一同に会し、最新研究成果報告、討論及び情報交換を行うものであり、本テーマにおける研究活動の一層の活性化を図ることを目的としている。本報告書は、当該会議における論文及び発表資料を取りまとめたものである。
Ti intermetallic compounds金 宰煥; 岩切 宏友*; 古堅 辰明*; 中道 勝
Fusion Engineering and Design, 102, p.44 - 49, 2016/01
To investigate feasibility for application of BeTi as a neutron multiplier as well as a refractory material, single-phase BeTi intermetallic compounds were synthesized using an annealing heat treatment of the starting powder and a plasma sintering method. Scanning electron microscopic observations and X-ray diffraction measurements reveal that the single-phase BeTi compounds were successfully synthesized. We examined the reactivity of BeTi with 1% HO and discovered that a larger stoichiometric amount of Ti resulted in the formation of TiO on the surface at high temperatures. This oxidation may also contribute to an increase in both weight gain and generation of H. This suggests that the formation of the Ti-depleted BeTi
layer as a result of oxidation facilitates an increased reactivity with HO. To evaluate the safety aspects of BeTi, we also investigated the hydrogen positions and solution energies based on the first principle. The calculations reveal that there are 10 theoretical sites, where 9 of these sites have hydrogen solution energies with a positive value (endothermic) and 1 site located at the center of a tetrahedron comprising two Be and two Ti atoms gives a negative value (exothermic).
金 宰煥; 中道 勝
Fusion Engineering and Design, 100, p.614 - 618, 2015/11
被引用回数：0 パーセンタイル：0.00(Nuclear Science & Technology)Beryllium metal is a candidate material of not only neutron-multiplier for fusion reactors but also a water-cooled target material for an accelerator-based boron neutron capture therapy. To investigate its reactivity in dry air and 1% HO/Ar at 873, 1073, and 1273 K, Be samples were fabricated by a novel plasma-sintering method proposed herein. Because of its reactivity in dry atmosphere, parabolic oxidation of Be along grain boundaries was predominant up to 1173 K at an activation energy of 52 kJ/mol, while catastrophic oxidation occurred at 1273 K. The introduction of HO facilitated breakaway in Be oxidation. Hence, the weight and H concentration of Be tested in 1% HO/Ar dramatically increased from 973 K, while samples tested for 24 h were completely oxidized in appearance.
金 宰煥; 中道 勝
Fusion Engineering and Design, 98-99, p.1812 - 1816, 2015/10
被引用回数：9 パーセンタイル：55.20(Nuclear Science & Technology)Titanium beryllium intermetallic compounds, beryllides, have been investigated as a candidate of advanced neutron multipliers in a fusion demonstration reactor. To investigate effect of Be contents in titanium beryllide pebbles on the crush strength and oxidation resistance, the beryllide pebbles with 3 to 10.5 at.% Ti were fabricated. As a result of SEM observation, it was clear that Be phase on the surface identified in Be-3 and 5 at.% Ti while no Be phase found in Be-7 to 10.5 at.% Ti. According to cross-sectional images, moreover, area fraction of Be phase decreased with decrease of Be content in 3 to 9 at.% Ti beryllide pebbles whereas the pebble with 10.5 at.% Ti was mainly consisted of BeTi phase. It was confirmed from crushed tests of the pebbles that ductility increases as increased of Be contents in the pebbles since the existence of Be phase leads to ductile fracture. On the other hand, Be phase on the surface of the pebbles with Be-3 and 5 at.% Ti resulted in increase of the weight gain due to oxidation while other pebbles indicated similar values because the surface of pebbles with 7 to 10.5 at.% Ti consisted of either BeTi or BeTi. Accordingly, this existence of Be phase in the pebble leads to increase of ductility while it results in decrease of oxidation resistance on the surface at 1273 K.
中道 勝; 金 宰煥
Fusion Engineering and Design, 98-99, p.1838 - 1842, 2015/10
被引用回数：17 パーセンタイル：76.81(Nuclear Science & Technology)原型炉ブランケットにおいては、高温下でより安定な先進中性子増倍材が必要である。ベリリウム金属間化合物(ベリライド)は、その候補の一つである。原料電極棒の製造のためのプラズマ焼結法と、造粒法として回転電極法を組み合わせることによって、ベリライド微小球製造に成功した。本研究では、Ti系ベリライド微小球のみならず、V系ベリライド微小球の製造技術開発の現状について報告するとともに、これらベリライド微小球の水素生成反応について報告する。
金 宰煥; 中道 勝
Journal of Alloys and Compounds, 640, p.285 - 289, 2015/08
被引用回数：4 パーセンタイル：20.28(Chemistry, Physical)Beryllium intermetallic compounds (beryllides) such as BeTi and BeV are the most promising advanced neutron multipliers in demonstration power reactors. We developed a new combined plasma sintering and rotating electrode method for the fabrication of beryllide rods and pebbles. Previously, we prepared a beryllide pebble with a Be-7.7 at.% Ti composition as the stoichiometric value of the BeTi phase; however, BeTi and Be phases were present along with the BeTi phase that formed as the result of a peritectic reaction due to re-melting during granulation using the rotating electrode method. This Be phase was found to be highly reactive with oxygen and water vapor. Accordingly, to investigate the Be phase reduction and applicability for fabrication of electrodes prior to granulation using the rotating electrode method, Be-Ti-V ternary beryllides were synthesized using the plasma sintering method. Surface observation results indicated that increasing plasma sintering time and V addition led to an increase in the intermetallic compound phases compared with plasma-sintered beryllide with a Be-7.7 at.% Ti composition. Additionally, evaluation of the reactivity of samples with water vapor at high temperature revealed that specimens with larger fractions of Be phases experienced larger weight gains and H generation rates because of oxidation, as BeTi and BeV phases have a similar oxidation tendency.
金 宰煥; 中道 勝
Journal of Alloys and Compounds, 638, p.277 - 281, 2015/07
被引用回数：7 パーセンタイル：32.20(Chemistry, Physical)Niobium and vanadium-beryllium intermetallic compounds (beryllides) were synthesized by plasma sintering under different sintering times at 1273 K. The beryllide with 7.7 at.% Nb mainly consisted of various phases of Be, BeNb, BeNb, and BeNb, whereas that with 7.7 at.% V consisted of BeV, BeV, and V. As the sintering time increased, area fractions of the target compositions BeNb and BeV increased while that of Be decreased. A comparative analysis demonstrated that the beryllide with 7.7 at.% Nb a showed higher density as well as a greater hardness than that with 7.7 at.% V, due to there being less difference between the sintering temperature and the melting point. In terms of thermal phase stability, the beryllide with 7.7 at.% Nb showed good thermal phase stability with fewer pores and a smaller unhomogenized area, because the beryllide contained a smaller area fraction of the Be phase, which may cause evaporation resulting in pore formation.
金 宰煥; 中道 勝
Journal of Nuclear Materials, 455(1-3), p.26 - 30, 2014/12
被引用回数：14 パーセンタイル：68.20(Materials Science, Multidisciplinary)The establishment of the synthesis technique for beryllides is a key issue of the advanced neutron multiplier development. In the previous study, trial fabrication examinations were carried out. Plasma sintering is a non-conventional consolidation process for beryllides synthesis. The synthesis results clarified that the beryllide has been successfully fabricated by this method. In this study, the effect of phase compositions on high temperature reactivity of the plasma-sintered beryllides was evaluated. The beryllides sintered for various times, which they have different phase compositions, were examined by thermal-gravimetry and hydrogen gas generation rate was simultaneously measured at 873 K, 1073 K and 1273 K for 24 hr under Ar gas containing water vapor to investigate the effect of phase compositions on the reactivity with water vapor. The result of weight gains clarified that with increase of the area fraction of Be, oxidation resistance decreases under dry air. H gas generation rates of the beryllides at high temperature demonstrate that the larger fraction of Be the beryllide has, the higher H generation rate it indicates. It is clear that the Be phase in the plasma-sintered beryllide attributes to increase of the H gas generation. In this study, we report on the effect of phase compositions on reactivity with water vapor of the plasma-sintered beryllides which were fabricated with different sintering conditions.
金 宰煥; 中道 勝
Fusion Engineering and Design, 89(7-8), p.1440 - 1443, 2014/10
被引用回数：8 パーセンタイル：49.11(Nuclear Science & Technology)Beryllide is a promising candidate as advanced neutron multiplier owing to higher stability and lower reactivity at high temperature. It was clarified in the previous studies on synthesis of beryllide that plasma sintering as non-conventional consolidation process could easily and rapidly synthesize the beryllide. In this study, to evaluate the effect of the plasma sintering consolidation of the material on fundamental property, the reactivity with oxygen at high temperature was examined using beryllium metals. The plasma-sintered beryllium was prepared for comparison of commercial grades of berylliums, that is, S65C and S65E, because it is well-known that the plasma sintering can facilitate to not only eliminate impurities but activate the powder surface due to applying a pulse current. The weight gain and optical surface observation result obviously clarified that the Be-PS and S65E exhibited the higher oxidation resistance than S65C which has larger grain size. Accordingly, it was obvious that the smaller grain size the beryllium has, the better oxidation resistance it has. In addition, the electron probe micro-analysis clearly proved that impurity was apt to be intensively located near grain boundary as an oxide type and the Be-PS contained less impurity than others. Therefore not only grain size but also impurity seems to have a close correlation on reactivity at the high temperature.
榎枝 幹男; 谷川 尚; 廣瀬 貴規; 中島 基樹; 佐藤 聡; 落合 謙太郎; 今野 力; 河村 繕範; 林 巧; 山西 敏彦; et al.
Fusion Engineering and Design, 89(7-8), p.1131 - 1136, 2014/10
被引用回数：22 パーセンタイル：81.84(Nuclear Science & Technology)我が国の原型炉ブランケット開発の最重要ステップとして、水冷却固体増殖テストブランケット・モジュール(TBM)の開発が進められている。TBM試験と原型炉ブランケット開発のために、モジュール製作技術開発、増殖増倍材ペブル製作技術、トリチウム生成率評価試験と構造設計が行われている。実機構造材F82Hを用いた製作技術開発は、F82Hの工学物性値の評価結果に基づいて実施され、実規模のモジュールの第一壁,側壁,増殖材充填容器、の製作に成功するとともに、第一壁と側壁の接合、厚さ90mmの後壁の実規模モックアップの製作に成功した。モジュール筐体モックアップの製作を検討している。また、トリチウム生産のために必要な技術として、高温での耐久性に優れた先進増殖・増倍材ペブル製作技術の開発を進めた。また、核融合中性子研究施設(FNS)を用いたトリチウム生成回収試験による、トリチウム生産技術開発についても進展した。本報告ではこれらのTBM開発の最新の成果を報告する。
中道 勝; 金 宰煥
Fusion Engineering and Design, 89(7-8), p.1304 - 1308, 2014/10
被引用回数：17 パーセンタイル：74.43(Nuclear Science & Technology)Beryllides are one of the most promising candidates as advanced materials. We suggested a new beryllide granulation process, which was combinational process with a plasma sintering method and a rotating electrode method (REM). The prototype pebbles were successfully fabricated by the REM using the plasma-sintered beryllide electrode. The beryllide electrode fabrication process was investigated in light of the mass production. From the optimization results, it was revealed that beryllide pebbles with the identical phase composition could be fabricated regardless of the difference of the phase compositions in the beryllide electrodes sintered for different temperature and time. Furthermore, the optimization result could lead to expectation of the time reduction because this result can reduce the time of electrode fabrication by 40%.
西谷 健夫; 山西 敏彦; 谷川 博康; 中道 勝; 野澤 貴史; 星野 毅; 落合 謙太郎
Fusion Engineering and Design, 89(7-8), p.1699 - 1703, 2014/10
幅広いアプローチ(BA)活動では、ブランケットに関連する材料及び工学のR&D活動が日欧で実施されている。日本において、六ヶ所のBAサイトを中心として実施されている。先進ブランケット用材料であるSiC/SiC複合材料に関するR&Dでは、1000
C、真空環境下でCVI-SiC/SiC複合材料の機械的特性を取得した。トリチウム工学では、微細粒再結晶化タングステンのトリチウム保持量を測定した。低放射化フェライト鋼の開発では、20トンの大規模溶解を電気炉を使用して初めて実施した。先進中性子増倍材の開発では、新しい回転電極装置を導入し、ベリライドの微小球の製造に成功した。また先進トリチウム増殖材では、粒界径が5
m以下のチタン酸リチウムの微小球の製造に成功した。
金 宰煥; 中道 勝
Journal of Nuclear Materials, 453(1-3), p.22 - 26, 2014/10
被引用回数：19 パーセンタイル：77.84(Materials Science, Multidisciplinary)Beryllium and its intermetallic compounds have attracted great attention as promising neutron multipliers in fusion reactors. In this study, mechanical and chemical properties of fabricated plasma-sintered beryllium (PS-Be) with different grain-sizes are investigated. Density and hardness analysis results of the fabricated PS-Be samples infer that a smaller grain size in the sintered Be indicates higher porosity and hardness. Sintered Be with a large grain size exhibits better resistance toward oxidation at 1273 Kin dry air and at 1073 K in Ar/1% HO, since oxidation at the grain boundaries of the determines the rate. In contrast, at 1273 K in Ar/1% HO, a catastrophic oxidation is indicated by the increase of weight of the samples and the generation of H from the bulk Be.
中道 勝; 金 宰煥
Fusion Science and Technology, 66, p.157 - 162, 2014/08
被引用回数：1 パーセンタイル：7.80(Nuclear Science & Technology)Advanced neutron multipliers and tritium breeders with higher stability at high temperature are desired. Beryllide is one of candidates for the advanced neutron multipliers. To fabricate the beryllide pebbles, a rotating electrode method (REM) was selected. Beryllide electrode fro the REM is necessary. Beryllide electrode has been successfully fabricated by the plasma sintering method. The prototypic beryllide pebbles were successfully fabricated by the REM using this plasma-sintered beryllide electrode. As a advanced tritium breeder, LiTiO
with excess Li (Li
TiO
) is one of the candidates. For raw material fabarication, synthesis process of LiTiO powder has been developed by the solid phase reaction. From the granulation result by the emulsion method using this raw material, the prototypic pebbles of the LiTiO with less than 5m in grain size and high sphericity, were successfully fabricated.
金 宰煥; 中道 勝
Journal of Alloys and Compounds, 585, p.63 - 68, 2014/02
被引用回数：16 パーセンタイル：55.73(Chemistry, Physical)Beryllide is well-known as the most promising candidate for advanced multipliers in demonstration fusion reactors. However, due to its brittleness, it is difficult to fabricate a pebble-type beryllide. Here, we report the synthesis and analysis of beryllide pebbles with different chemical compositions. In order to clarify the effect of the content of Ti on the fabrication of beryllide pebbles, a rotating electrode method was applied using a plasma-sintered beryllide rod jointed by two beryllide blocks and powder. The beryllide pebbles were successfully fabricated accompanied by phase changes induced by re-melting during the rotating electrode method. The SEM images of the rods and the cross-section of the pebbles demonstrated that the phases of the plasma-sintered beryllide rods with 6 at.%, 7 at.%, and 7.7 at.% Ti were transformed to the peritectic BeTi phase with a BeTi phase due to re-melting whereas pebbles with 3 at.% and 5 at.% Ti showed similar phases as the plasma-sintered beryllide rods. Additionally, the dependence of the Ti amount on crush load depicted that the pebbles with the larger area fraction of Be indicated the higher crush load as well as longer displacement because the Be contributed to increase of ductility in the pebbles.
金 宰煥; 中道 勝
Journal of Alloys and Compounds, 577, p.90 - 96, 2013/11
被引用回数：11 パーセンタイル：47.54(Chemistry, Physical)Plasma sintering method has been newly suggested as a synthesis method for beryllium titanium intermetallic compounds (beryllides) as an advanced neutron multiplier in a system of water cooled solid breeder demonstration fusion reactors. Not only synthesis of the beryllide but joining the beryllide could be successfully fabricated. We report on the optimization of the main sintering conditions, on the sinterabilityof the plasma-sintered beryllides in the light of sinterability, as well as consolidation to the BeTi phase. The optimum sintering temperature for consolidation to the BeTi phase was 1273 K and the area fraction of the BeTi phase obtained when sintering at 1273 K, was approximately 83%. To increase the fraction of the BeTi phase, increasing the sintering time was inevitable and this led to an increase in the BeTi phase corresponding to 97.5%. However, as the sintering time increased, variation in grain size of the beryllides was observed. With regard to the sintering pressure, the higher the sintering pressure applied, the higher the sinterability, even though lower pressure may lead to better consolidation with respect to the absence of the BeTi phase.
中道 勝; 金 宰煥; 宗像 健三*; 柴山 環樹*; 宮本 光貴*
Journal of Nuclear Materials, 442(1-3), p.S465 - S471, 2013/11
被引用回数：12 パーセンタイル：63.43(Materials Science, Multidisciplinary)Advanced neutron multipliers with low swelling and high stability at high temperature are desired for pebble bed blankets. Beryllium intermetallic compounds (beryllides) are the most promising advanced neutron multipliers. Development of advanced neutron multiplier has been started between Japan and the EU in the DEMO R&D of the International Fusion Energy Research Centre (IFERC) project as a part of the Broader Approach activities. The plasma sintering method has been selected as a new beryllides synthesis method. The plasma sintering results in starting powder particle surface activation that enhances sinterability and reduces high temperature exposure. The plasma sintering shows that the intermetallic compound beryllide such as BeTi, BeTi and BeTi can be directly synthesized from mixed elemental powders of Be and Ti at a temperature lower than the melting point. In this report, the preliminary characterization of plasma sintered Be-Ti beryllide was carried out such as reactivity with water vapor, microstructure analysis by ion irradiation effect and deuterium retention property compared with beryllium (Be) metal. From the result of the preliminary characterization, it revealed that plasma sintered Be-Ti beryllide sample has a good performance as a neutron multiplier. This beryllide sample has enough oxidation resistance, high radiation resistance and low deuterium retention property more than Be metal.
