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Journal Articles

Orientation dependence of yield strength in a new single crystal-like FeCrAl oxide dispersion strengthened alloy

Aghamiri, S. M. S.*; Sugawara, Naoya*; Ukai, Shigeharu; Ono, Naoko*; Sakamoto, Kan*; Yamashita, Shinichiro

Materials Characterization, 176, p.111043_1 - 111043_6, 2021/06

Advanced oxidation-resistant FeCrAl ODS alloys were developed via the control of composition-processing conditions for the accident tolerant fuel (ATF) cladding. For the first time, a single-crystal like recrystallized FeCrAl ODS alloy was achieved with a unique crystallographic texture of 110-plane and 211-direction and a high number density of fine nanoscale oxide particles. Evaluation of yield strengths at different temperatures showed higher values in transverse (T) direction than longitudinal (L) direction. The crystal orientation dependence of the yield strength up to 800$$^{circ}$$C was attributed to lower value of Schmid factor in transverse direction. Accordingly, the critical resolved shear stress of this practical class of advanced materials was calculated in various temperatures.

Journal Articles

Oxide dispersion strengthened steels

Ukai, Shigeharu*; Ono, Naoko*; Otsuka, Satoshi

Comprehensive Nuclear Materials, 2nd Edition, Vol.3, p.255 - 292, 2020/08

Fe-Cr-based oxide dispersion strengthened (ODS) steels have a strong potential for high burnup (long-life) and high-temperature applications typical for SFR fuel cladding. Current progress in the development of Fe-Cr-based ODS steel claddings is reviewed, including their relevant mechanical properties, e.g. tensile and creep rupture strengths in the hoop directions. In addition, this paper reviewed the current research status on corrosion resistant Fe-Cr-Al-based ODS steel claddings, which are greatly paid attention recently as the accident tolerant fuel claddings for the light water reactor (LWR) and also as the claddings of the lead fast reactors (LFR) utilizing Pb-Bi eutectic (LBE) coolant.

Journal Articles

Anomalous small-angle X-ray scattering (ASAXS) study of irradiation-induced nanostructure change in Fe-ion beam irradiated oxide dispersion-strengthened (ODS) steel

Kumada, Takayuki; Oba, Yojiro; Motokawa, Ryuhei; Morooka, Satoshi; Tominaga, Aki; Tanida, Hajime; Shobu, Takahisa; Konno, Azusa; Owada, Kenji*; Ono, Naoko*; et al.

Journal of Nuclear Materials, 528, p.151890_1 - 151890_7, 2020/01

 Times Cited Count:0 Percentile:0.01(Materials Science, Multidisciplinary)

We have developed an anomalous small-angle X-ray scattering (ASAXS) diffractometer in SPring-8 to investigate irradiation-induced nanostructural change in ion-beam irradiated stainless steel. A thermally-aged MA956 stainless steel sample displays power-law scattering that follows the Porod law at the magnitude of scattering vector, Q, below 0.5 nm$$^-1$$ and an overlapped shoulder around 0.7 nm$$^-1$$. After the ion-beam irradiation, the intensity of the shoulder remained unchanged, whereas that of the power-law scattering nearly doubled. This result indicates that none of the structural parameters of the Cr-rich nanoprecipitates, such as the number density, size, and interface roughness, were changed by the irradiation.

Journal Articles

Stability of $$gamma$$' precipitates in nickel based oxide dispersion-strengthened superalloys under high-temperature and heavy irradiation conditions

Konno, Azusa; Ono, Naoko*; Ukai, Shigeharu*; Kondo, Sosuke*; Hashitomi, Okinobu*; Kimura, Akihiko*

Materials Transactions, 60(11), p.2260 - 2266, 2019/11

 Times Cited Count:1 Percentile:13.55(Materials Science, Multidisciplinary)

A stability of cuboidal $$gamma$$' phase under heavy irradiation was studied for newly developed Ni-based Oxide Dispersion Strengthened (ODS) superalloy as a candidate for the core structural materials in VHTR or GFR. The ion irradiation was applied at 873K, 1073K, 1273K and the dose was 100 dpa. The $$gamma$$' phase remained the cuboidal shape at 873K but got out of the shape at 1073K after irradiation. Those growths can be explained by the Nelson-Hudson-Mazey (NHM) model. For the result of 1273K irradiation, however, huge $$gamma$$' phase appeared in the whole irradiated area at the post irradiation-observation. This behavior is interpreted in terms of disordering of the ordered $$gamma$$' phase due to cascade collision, and thus increasing Gibbs free energy of the disordered phase induces a change of the element distribution inside the irradiated area. The ordered $$gamma$$' phase was reproduced from the disordered state at the cooling after ion irradiation.

Journal Articles

Ultra-high temperature tensile properties of ODS steel claddings under severe accident conditions

Yano, Yasuhide; Tanno, Takashi; Oka, Hiroshi; Otsuka, Satoshi; Inoue, Toshihiko; Kato, Shoichi; Furukawa, Tomohiro; Uwaba, Tomoyuki; Kaito, Takeji; Ukai, Shigeharu*; et al.

Journal of Nuclear Materials, 487, p.229 - 237, 2017/04

 Times Cited Count:27 Percentile:97.79(Materials Science, Multidisciplinary)

Ultra-high temperature ring tensile tests were carried out to investigate the tensile behavior of oxide dispersion strengthened (ODS) steel claddings and wrapper materials under severe accident conditions; temperatures ranged from room temperature to 1400$$^{circ}$$C which is near the melting point of core materials. The experimental results showed that tensile strength of 9Cr-ODS steel claddings was highest in the core materials at the ultra-high temperatures between 900 and 1200$$^{circ}$$C, but that there was significant degradation in tensile strength of 9Cr-ODS steel claddings above 1200$$^{circ}$$C. This degradation was attributed to grain boundary sliding deformation with $$gamma$$/$$delta$$ transformation, which was associated with reduced ductility. On the other hand, tensile strength of recrystallized 12Cr-ODS and FeCrAl-ODS steel claddings retained its high value above 1200 $$^{circ}$$C unlike the other tested materials. Present study includes the result of "R&D of ODS ferritic steel fuel cladding for maintaining fuel integrity at the high temperature accident condition" entrusted to Hokkaido University by the Ministry of Education, Culture, Sports, Science and Technology of Japan (MEXT).

Journal Articles

Consideration of the oxide particle-dislocation interaction in 9Cr-ODS steel

Ijiri, Yuta*; Ono, Naoko*; Ukai, Shigeharu*; Yu, H.*; Otsuka, Satoshi; Abe, Yosuke; Matsukawa, Yoshitaka*

Philosophical Magazine, 97(13), p.1047 - 1056, 2017/02

 Times Cited Count:2 Percentile:17.39(Materials Science, Multidisciplinary)

The interaction between oxide particles and dislocations in a 9Cr-ODS ferritic steel is investigated by both static and in-situ TEM observation under dynamic straining conditions and room temperature. The measured obstacle strength ($$alpha$$) of the oxide particles was no greater than 0.80 and the average was 0.63. The dislocation loops around some coarsened particles were also observed. The calculated obstacle strength by a stress formula of the Orowan interaction is nearly equaled to the average experimental value. Not only cross-slip system but also the Orowan interaction should be considered as the main interaction mechanism between oxide particles and dislocation in 9Cr-ODS ferritic steel.

Journal Articles

Effect of the dilation caused by helium bubbles on edge dislocation motion in $$alpha$$-iron; Molecular dynamics simulation

Abe, Yosuke; Tsuru, Tomohito; Shi, S.*; Ono, Naoko*; Ukai, Shigeharu*

Journal of Nuclear Science and Technology, 53(10), p.1528 - 1534, 2016/10

 Times Cited Count:5 Percentile:54.39(Nuclear Science & Technology)

Various types of nanometric defects such as voids and helium (He) bubbles produced by high energy neutron irradiations are known to degrade the mechanical properties of irradiated materials. In this study, we have evaluated the obstacle strength of He bubbles to the mobility of an edge dislocation in $$alpha$$-iron for 2 and 4 nm bubbles with He-to-vacancy (He/V) ratios ranging from 0 to 1 at 300 and 500 K, by molecular dynamics simulation. Results showed that as the He/V ratio increases, the obstacle strength needed for the release of a dislocation from the bubble becomes stronger up to a moderate He/V ratio, and a further increase in the He/V ratio leads to weakening of the obstacle strength. For He/V = 1, the obstacle strengths are $$10-30%$$ weaker than those at moderate He/V ratios depending on the bubble size and temperature. The extent of obstacle strength was found to be correlated with the dilation caused by He bubbles depending on the bubble size, He/V ratio, and temperature.

Journal Articles

Dipole tracer migration and diffusion tests in fractured sedimentary rock at Horonobe URL

Tanaka, Shingo*; Yokota, Hideharu; Ono, Hirokazu; Nakayama, Masashi; Fujita, Tomo; Takiya, Hiroaki*; Watanabe, Naoko*; Kozaki, Tamotsu*

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 6 Pages, 2015/05

Journal Articles

Genome analysis of the high temperature tolerant mutant of ${it Bradyrhizobium japonicum}$ USDA110 generated by ion-beam irradiation

Takeda, Kiyoko*; Sato, Katsuya; Narumi, Issey*; Ono, Yutaka; Otsu, Naoko*; Yokoyama, Tadashi*

JAEA-Review 2014-050, JAEA Takasaki Annual Report 2013, P. 120, 2015/03

Journal Articles

Synthesis of bubble dispersion strengthened copper by using pyrolysis gases of Poly (methyl methacrylate)

Shi, S.*; Ono, Naoko*; Ukai, Shigeharu*; Abe, Yosuke

Materials Science & Engineering A, 617, p.61 - 65, 2014/11

 Times Cited Count:1 Percentile:8.19(Nanoscience & Nanotechnology)

Bubble dispersion strengthened copper (BDS-Cu) was synthesized by using the pyrolysis gaseous products of Poly (methyl methacrylate) (PMMA) during spark plasma sintering (SPS) process. Bubbles with an average diameter of 14 nm are densely dispersed in copper matrix with a dispersion distance 119 nm. Vickers' hardness of BDS-Cu is 400 MPa higher than that of pure copper. The strengthening effect is due to the dislocation pinning effect of bubbles.

Journal Articles

From laboratory to field; ${it OsNRAMP5}$-knockdown rice is a promising candidate for Cd phytoremediation in paddy fields

Takahashi, Ryuichi*; Ishimaru, Yasuhiro*; Shimo, H.*; Bashir, K.*; Senoura, Takeshi*; Sugimoto, Kazuhiko*; Ono, Kazuko*; Suzui, Nobuo; Kawachi, Naoki; Ishii, Satomi; et al.

PLOS ONE (Internet), 9(6), p.e98816_1 - e98816_7, 2014/06

 Times Cited Count:34 Percentile:82.91(Multidisciplinary Sciences)

Journal Articles

In-vessel tritium

Ueda, Yoshio*; Oya, Kaoru*; Ashikawa, Naoko*; Ito, Atsushi*; Ono, Tadayoshi*; Kato, Daiji*; Kawashima, Hisato; Kawamura, Gakushi*; Kenmotsu, Takahiro*; Saito, Seiki*; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 88(9), p.484 - 502, 2012/09

no abstracts in English

Journal Articles

Report on ITPA meeting, 33

Asakura, Nobuyuki; Ashikawa, Naoko*; Ueda, Yoshio*; Ono, Noriyasu*; Tanabe, Tetsuo*; Nakano, Tomohide; Masuzaki, Suguru*; Itami, Kiyoshi; Kawano, Yasunori; Kawahata, Kazuo*; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 87(7), p.485 - 486, 2011/07

no abstracts in English

Journal Articles

28th report on the ITPA (International Tokamak Physics Activity) meeting

Asakura, Nobuyuki; Nakano, Tomohide; Masuzaki, Takashi*; Ashikawa, Naoko*; Ueda, Yoshio*; Tanabe, Tetsuo*; Ono, Noriyasu*

Purazuma, Kaku Yugo Gakkai-Shi, 86(2), P. 124, 2010/02

no abstracts in English

Journal Articles

Tritium science and technology for fusion reactor, 3; Theory and code development for evaluation of tritium retention and exhaust in fusion reactor

Oya, Kaoru*; Inai, Kensuke*; Shimizu, Katsuhiro; Takizuka, Tomonori; Kawashima, Hisato; Hoshino, Kazuo; Hatayama, Akiyoshi*; Toma, Mitsunori*; Tomita, Yukihiro*; Kawamura, Gakushi*; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 85(10), p.695 - 703, 2009/10

no abstracts in English

Journal Articles

Report on ITPA meetings, 24

Idomura, Yasuhiro; Yoshida, Maiko; Yagi, Masatoshi*; Tanaka, Kenji*; Hayashi, Nobuhiko; Sakamoto, Yoshiteru; Tamura, Naoki*; Oyama, Naoyuki; Urano, Hajime; Aiba, Nobuyuki; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 84(12), p.952 - 955, 2008/12

no abstracts in English

Journal Articles

Rice plants take up iron as an Fe$$^{3+}$$-phytosiderophore and as Fe$$^{2+}$$

Ishimaru, Yasuhiro*; Suzuki, Motofumi*; Tsukamoto, Takashi*; Suzuki, Kazumasa*; Nakazono, Mikio*; Kobayashi, Takanori*; Wada, Yasuaki*; Watanabe, Satoshi; Matsuhashi, Shimpei; Takahashi, Michiko*; et al.

Plant Journal, 45(3), p.335 - 346, 2006/02

 Times Cited Count:442 Percentile:99.63(Plant Sciences)

Oral presentation

Free energy landscape of nucleosome

Kono, Hidetoshi; Kanaeda, Naoko

no journal, , 

no abstracts in English

Oral presentation

The Free energy profile of a nucleosome core particle through the molecular dynamics simulation

Kanaeda, Naoko; Ishida, Hisashi; Kono, Hidetoshi

no journal, , 

The nucleosomes are the basic unit of eucaryotic chromosome structure. It has recently been discovered that chromatine remodeling complexes peel the nucleosomal DNA away from the histone octomer(the remodeling). The change in the translational and rotational positioning permits access to the binding site of the nucleosomal DNA by proteins involved in gene expression, DNA replication and repair. The free energy profile in the process of the remodeling should provide important clues to clarify the mechanism of the protein binding to the nucleosomal DNA. We perform the molecular dynamics simulation starting from the high-resolution structure of a nucleosome core particle including explicit water and ions. After the equilibration of the nucleosome core particle, we pull the ends of nucleosomal DNA to peel it away from the histone core and obtain the free energy profile.

Oral presentation

Free energy profile calculation of nucleosome core particles

Kanaeda, Naoko; Kono, Hidetoshi

no journal, , 

no abstracts in English

50 (Records 1-20 displayed on this page)