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Oyaizu, Makoto; Isobe, Kanetsugu; Hayashi, Takumi
Nuclear Materials and Energy (Internet), 9, p.508 - 511, 2016/12
Stainless steels of SS304, SS316L and such will be widely used in fusion reactor. Corrosion of such metals is an important issue for the establishment of safety and soundness of fusion reactors. It has recently been reported that the passivation of SS304 stainless steel was inhibited in tritiated solution, resulting in significant corrosion enhancement. Therefore in the present study, the effects of tritium on the passivation behavior of SS316L stainless steel in tritiated water circumstance is electrochemically studied by comparing to those of SS304 stainless steel previously studied. As the results, it was found that no significant effects of tritium on the passivation behavior of SS316L stainless steel could be observed, which is contrary to that of SS304 stainless steel.
Iwai, Yasunori; Edao, Yuki; Asahara, Hiroo*; Hayashi, Takumi
Nuclear Materials and Energy (Internet), 9, p.267 - 272, 2016/12
Tritium oxidation over noble catalyst is a fundamental reaction in the fusion fields since the system of catalytic reactor for the oxidation of tritium in combination with following tritiated vapor absorber has been applied in tritium handling facilities to control the tritium release into the environment as low as achievable. To enhance tritium safety as much as possible with taking severe accidents such as complete loss of power supply into account, technology of hydrophobic catalyst has been drawing intense interest recently because of its potential application in passive recombiner for tritium oxidation at room temperature. To design a passive recombiner packed with hydrophobic catalyst for tritium oxidation, the development of manufacturing technology for hydrophobic platinum catalyst and the following data on reaction rate are essential. This presentation deals with the reaction rate for tritium oxidation over hydrophobic platinum catalyst at temperatures from room temperature to 343 K. Two kinds of hydrophobic platinum catalysts; supported with styrene-divinylbenzene and with silica were used for this test. The results indicate that (1) the reaction rate is effected by the particle size of platinum, (2) the order of reaction is 0.5 of hydrogen concentration at room temperature. The rate-determining step approximation method is applied for the discussion on the reaction mechanism of tritium oxidation over platinum catalyst.
Takeuchi, Tomoaki; Nakano, Hiroko; Uehara, Toshiaki; Tsuchiya, Kunihiko
Nuclear Materials and Energy (Internet), 9, p.451 - 454, 2016/12
Times Cited Count：1 Percentile：9.29(Nuclear Science & Technology)no abstracts in English
Tanno, Takashi; Yano, Yasuhide; Oka, Hiroshi; Otsuka, Satoshi; Uwaba, Tomoyuki; Kaito, Takeji
Nuclear Materials and Energy (Internet), 9, p.353 - 359, 2016/12
Times Cited Count：13 Percentile：71.89(Nuclear Science & Technology)Materials for core components of fusion reactors and fast reactors, such as blankets and fuel cladding tubes, must be excellent in high temperature strength and irradiation resistance because they will be exposed to high heat flux and heavy neutron irradiation. Oxide dispersion strengthened (ODS) steels have been developing as the candidate material. Japan Atomic Energy Agency (JAEA) have been developing 9 and 11 Chromium (Cr) ODS steels for advanced fast reactor cladding tubes. The JAEA 11Cr-ODS steels were rolled in order to evaluate their anisotropy. Tensile tests and creep tests of them were carried out at 700 
C in longitudinal and transverse orientation. The anisotropy of tensile strength was negligible, though that of creep strength was distinct. The observation results and chemical composition analysis suggested that the cause of the anisotropy in creep strength was prior powder boundary including Ti-rich precipitates.
Furukawa, Tomohiro; Hirakawa, Yasushi; Kondo, Hiroo; Kanemura, Takuji
Nuclear Materials and Energy (Internet), 9, p.286 - 291, 2016/12
Times Cited Count：10 Percentile：62.76(Nuclear Science & Technology)In order to exchange the components which received irradiation damage during the operation at the International Fusion Materials Irradiation Facility, the adhered lithium, which is partially converted to lithium compounds such as lithium oxide and lithium hydroxide, should be removed from the components. In this study, the dissolution experiments of lithium compounds (lithium nitride, lithium hydroxide, and lithium oxide) were performed in a candidate solvent, allowing the clarification of time and temperature dependence. Based on the results, a cleaning procedure for adhered lithium on the inner surface of the components was proposed.
Yano, Yasuhide; Tanno, Takashi; Sekio, Yoshihiro; Oka, Hiroshi; Otsuka, Satoshi; Uwaba, Tomoyuki; Kaito, Takeji
Nuclear Materials and Energy (Internet), 9, p.324 - 330, 2016/12
Times Cited Count：18 Percentile：81.39(Nuclear Science & Technology)Wakai, Eiichi; Kanemura, Takuji; Kondo, Hiroo; Hirakawa, Yasushi; Ito, Yuzuru*; Higashi, Takuma*; Suzuki, Akihiro*; Fukada, Satoshi*; Yagi, Juro*; Tsuji, Yoshiyuki*; et al.
Nuclear Materials and Energy (Internet), 9, p.278 - 285, 2016/12
The EVEDA (Engineering Validation and Engineering Design Activity) lithium test loop with the world's highest flow rate was constructed and has been operated mainly at 250C. It succeeded in generating a 100 mm wide and 25 mm thick free-surface lithium flow along a concave back plate steadily at a high-speed of 15 m/s at 250C for 1,300 h under the Broader Approach Activities. A new wave height measuring method (laser-probe method) was developed for measurements of the 3D geometry of the liquid Li target surface. Using the device, the stability of the Li flow (the thickness variation of 
1 mm or less) required for the actual liquid Li target of the IFMIF was satisfied and the feasibility of the long-term stable liquid Li flow was verified. The results of the other engineering validation tests such as lithium purification tests and the engineering design of lithium facility have also been evaluated and summarized.
Oka, Hiroshi; Tanno, Takashi; Otsuka, Satoshi; Yano, Yasuhide; Uwaba, Tomoyuki; Kaito, Takeji; Onuma, Masato*
Nuclear Materials and Energy (Internet), 9, p.346 - 352, 2016/12
Times Cited Count：22 Percentile：86.36(Nuclear Science & Technology)Edao, Yuki; Iwai, Yasunori; Hayashi, Takumi
Nuclear Materials and Energy (Internet), 9, p.273 - 277, 2016/12
Nakamichi, Masaru; Kim, Jae-Hwan; Miyamoto, Mitsutaka*
Nuclear Materials and Energy (Internet), 9, p.55 - 58, 2016/12
Ozawa, Kazumi; Koyanagi, Takaaki*; Nozawa, Takashi; Kato, Yutai*; Kondo, Sosuke*; Tanigawa, Hiroyasu; Snead, L. L.*
no journal, ,
A silicon carbide fiber-reinforced silicon carbide matrix (SiC/SiC) composite is a promising candidate material for an advanced fusion DEMO blanket. High-dose irradiation experiments were performed with our special focuses on understanding; (1) integrity of the Hi-Nicalon Type-S (HNLS) composites, (2) functionality of thin pyrocarbon (PyC) /SiC multilayer, and (3) clarifying the mechanism underlying degradation, as feedback to R&D on SiC/SiC composites. The materials used in this study were plain-weave HNLS composites produced via the chemical vapor infiltration process. Neutron irradiation was conducted in the HFIR at ORNL. The peak neutron fluence was ~1.0
10
n/m
(E 
0.1 MeV, equivalent to ~100 dpa) at nominal irradiation temperatures of 300, 500, and 800C. Results of post irradiation experiments including 1/4-four-point flexural tests, SEM, and TEM observation were reported.
Suzudo, Tomoaki
no journal, ,
Tungsten is expected to be a promising plasma-facing material for future fusion devices, but radiation-induced precipitation (RIP), which leads the material to hardening, is a concern at their practical use. One of the keys to accurate prediction of the emergence of RIP is migration of solute atoms, rhenium and osmium, that are produced by nuclear transmutation through irradiation. We conduct numerical simulations using an ab initio informed atomic kinetic Monte Carlo method and investigate the migration of these solute atoms in the form of tungsten-rhenium and tungsten-osmium mixed dumbbells, considered to be the most efficient "carriers" of the solute atoms. We find that the low rotation energy barrier of these mixed dumbbells leading to three-dimensional migration. The result also suggests that, although these dumbbells have three-dimensional motion, one cannot simply reduce their migration behavior to that of vacancy-like spherical objects.
