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Journal Articles

Fundamental experiments on phase stabilities of Fe-B-C ternary systems

Sudo, Ayako; Nishi, Tsuyoshi; Shirasu, Noriko; Takano, Masahide; Kurata, Masaki

Journal of Nuclear Science and Technology, 52(10), p.1308 - 1312, 2015/10

 Times Cited Count:4 Percentile:52.77(Nuclear Science & Technology)

For understanding the control blade degradation mechanism of BWR, the thermodynamic database for the fuel assembly materials is a useful tool. Although iron, boron, and carbon ternary system is a dominant phase diagram, phase relation data is not sufficient for the region in which the boron and carbon compositions are richer than the eutectic composition. The phase relations of three samples were analyzed by X-ray diffraction, scanning electron microscope and energy dispersed X-ray spectrometry. The results indicate that Fe$$_{3}$$(B,C) phase only exists in the intermediate region at 1273 K and that the solidus temperature widely maintains at about 1400 K for all three samples, which are different from the calculated data using previous thermodynamic database. The difference might be originated from the over-estimations of the interaction parameter between boron and carbon in Fe$$_{3}$$(B,C).

Journal Articles

Thermal conductivity of U-20 wt.%Pu-2 wt.%Am-10 wt.%Zr alloy

Nishi, Tsuyoshi; Nakajima, Kunihisa; Takano, Masahide; Kurata, Masaki; Arita, Yuji*

Journal of Nuclear Materials, 464, p.270 - 274, 2015/09

 Times Cited Count:2 Percentile:73.33(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Behavior of Nb$$_{3}$$Sn cable assembled with conduit for ITER central solenoid

Nabara, Yoshihiro; Suwa, Tomone; Takahashi, Yoshikazu; Hemmi, Tsutomu; Kajitani, Hideki; Ozeki, Hidemasa; Sakurai, Takeru; Iguchi, Masahide; Nunoya, Yoshihiko; Isono, Takaaki; et al.

IEEE Transactions on Applied Superconductivity, 25(3), p.4200305_1 - 4200305_5, 2015/06

 Times Cited Count:0 Percentile:100(Engineering, Electrical & Electronic)

Journal Articles

Recent progress and future R&D plan of nitride fuel cycle technology for transmutation of minor actinides

Hayashi, Hirokazu; Nishi, Tsuyoshi; Takano, Masahide; Sato, Takumi; Shibata, Hiroki; Kurata, Masaki

NEA/NSC/R(2015)2 (Internet), p.360 - 367, 2015/06

Uranium-free nitride fuel was chosen as the first candidate for transmutation of long-lived minor actinides (MA) using accelerator-driven system (ADS) under the double strata fuel cycle concept by Japan Atomic Energy Agency (JAEA). The advantages of nitride fuel are good thermal properties and large mutual solubility among actinide elements. A pyrochemical process is proposed as the first candidate for the reprocessing of the spent nitride fuel, because this technique has some advantages over aqueous process, such as the resistance to radiation damage, which is an important issue for the fuels containing large amounts of highly radioactive MA. This paper overviews the recent progress and future R&D plan of the study on the nitride fuel cycle technology in JAEA.

Journal Articles

Characterization of solidified melt among materials of UO$$_{2}$$ fuel and B$$_{4}$$C control blade

Takano, Masahide; Nishi, Tsuyoshi; Shirasu, Noriko

Journal of Nuclear Science and Technology, 51(7-8), p.859 - 875, 2014/07

 Times Cited Count:13 Percentile:17.64(Nuclear Science & Technology)

To predict phase relationships in the solidified core melt of Fukushima Daiichi Nuclear Power Plants, the solidified melt samples among core materials were prepared by arc melting. Phases and compositions in the samples were determined by X-ray diffraction, microscopy and elemental analysis. The only oxide phase formed is (U,Zr)O$$_{2}$$. The stable metallic phases are Fe-Cr-Ni alloy and Fe$$_{2}$$Zr-type (Fe,Cr,Ni)$$_{2}$$(Zr,U) intermetallic. The borides, ZrB$$_{2}$$ and (Fe,Cr,Ni)$$_{2}$$B, are solidified in the metallic part. Annealing at 1773 K under an oxidizing atmosphere resulted in the oxidation of uranium and zirconium in the alloy and ZrB$$_{2}$$, instead the (Fe,Cr,Ni)$$_{2}$$B and Fe-Cr-Ni alloy became dominant. The metallic zirconium content in the melt is found to be a key factor that determines the phase relationships. As a basic mechanical property, the microhardness of each phase was measured. The borides showed notably higher hardness than any other oxide and metallic phases.

Journal Articles

Fabrication of enzyme-degradable and size-controlled protein nanowires using single particle nano-fabrication technique

Omichi, Masaaki*; Asano, Atsushi*; Tsukuda, Satoshi*; Takano, Katsuyoshi*; Sugimoto, Masaki; Saeki, Akinori*; Sakamaki, Daisuke*; Onoda, Akira*; Hayashi, Takashi*; Seki, Shu*

Nature Communications (Internet), 5, p.3718_1 - 3718_8, 2014/04

 Times Cited Count:31 Percentile:15.31(Multidisciplinary Sciences)

Protein nanowires exhibiting specific biological activities hold promise for interacting with living cells and controlling and predicting biological responses such as apoptosis, endocytosis and cell adhesion. Here we report the result of the interaction of a single high-energy charged particle with protein molecules. Degradation of the human serum albumin nanowires was examined using trypsin. The biotinylated human serum albumin nanowires bound avidin, demonstrating the high affinity of the nanowires. Human serum albumin-avidin hybrid nanowires were also fabricated from a solid state mixture and exhibited good mechanical strength. The biotinylated human serum albumin nanowires can be transformed into nanowires exhibiting a biological function such as avidin-biotinyl interactions and peroxidase activity. The present technique is a versatile platform for functionalizing the surface of any protein molecule with an extremely large surface area.

JAEA Reports

Property database of TRU nitride fuel

Nishi, Tsuyoshi; Arai, Yasuo; Takano, Masahide; Kurata, Masaki

JAEA-Data/Code 2014-001, 45 Pages, 2014/03


The purpose of this study is to prepare a property database of nitride fuel needed for the fuel design of accelerator-driven system (ADS) for transmutation of minor actinide (MA). Nitride fuel of ADS is characterized by high content of Pu and MA as principal components, and addition of a diluent material such as ZrN. Experimental data or evaluated values from the raw data on properties Pu and MA nitrides, and nitride solid solutions containing ZrN are collected and summarized, which cover the properties needed for the fuel design of ADS. They are expressed as an equation as much as possible for corresponding to a variety conditions. Error evaluation is also made as much as possible. Since property data on transuranium (TRU) nitrides are often lacking, those on UN and (U,Pu)N are substitutionally shown in such cases in order to facilitate the fuel design with a tolerable accuracy by complementing the database.

Journal Articles

Sintering and characterization of (Pu,Zr)N

Pukari, M.*; Takano, Masahide; Nishi, Tsuyoshi

Journal of Nuclear Materials, 444(1-3), p.421 - 427, 2014/01

 Times Cited Count:10 Percentile:29.24(Materials Science, Multidisciplinary)

Nitride fuel with the composition (Pu$$_{0.4}$$Zr$$_{0.6}$$)N is fabricated for studying the sinterability of nitride fuel as a function of oxygen concentration in the material. Oxygen concentration of up to 0.6 wt% evidently enhances the densification of the material. Increasing the sintering temperature from 1923 to 1973 K improves the sintered pellet densities by up to 3.8%TD. In addition, the measured thermophysical and electrical properties of (Pu$$_{0.4}$$Zr$$_{0.6}$$)N reveal that the values are close to those of PuN. Oxygen concentration of 0.34 wt% in (Pu,Zr)N is a consequence of the fabrication process, considering the relatively pure ZrN (0.03 wt% O) and PuN (0.08 wt% O) powders initially fabricated.

Journal Articles

Thermal conductivity of minor actinide nitride fuels

Nishi, Tsuyoshi; Takano, Masahide; Arai, Yasuo; Kurata, Masaki

Dai-34-Kai Nippon Netsu Bussei Shimpojiumu Koen Rombunshu, p.199 - 201, 2013/11

By installing the laser flash apparatus and the drop calorimeter in the glove box, the thermal diffusivity and the heat capacity measurements of nitride containing MA elements of long-lived radioactive nuclides were enabled. The sample holder and the platinum container were designed to measure the thermal diffusivity and the heat capacity of very small quantity of MA nitride samples. The thermal conductivities of MA nitride increased with temperature, unlike that of conventional oxide-type nuclear fuels. In addition, the thermal conductivities of MA nitride decreased with increasing Am contents. The thermal conductivity of ZrN-based MA nitride, which is proposed as a candidate material for the ADS fuel, was fitted to equations as functions of the temperature and ZrN concentration. The predicted values agreed well with the experimental ones, indicating that the thermal conductivity of nitride fuel for ADS can be predicted for a practical design.

Journal Articles

Thermal conductivity of (Np$$_{0.20}$$Pu$$_{0.50}$$Am$$_{0.25}$$Cm$$_{0.05}$$)O$$_{2-x}$$ solid solutions

Nishi, Tsuyoshi; Takano, Masahide; Akabori, Mitsuo; Arai, Yasuo

Journal of Nuclear Materials, 440(1-3), p.534 - 538, 2013/09

 Times Cited Count:2 Percentile:76.77(Materials Science, Multidisciplinary)

To clarify the dependence of thermal conductivity on storage time of curium containing oxide, the authors prepared the sintered sample of (Np$$_{0.20}$$Pu$$_{0.50}$$Am$$_{0.25}$$Cm$$_{0.05}$$)O$$_{2-x}$$ (x = 0.02, 0.04) solid solutions and evaluated the thermal conductivity. The thermal conductivities of (Np$$_{0.20}$$Pu$$_{0.50}$$Am$$_{0.25}$$Cm$$_{0.05}$$)O$$_{2-x}$$ exponentially decreased with increasing storage duration. This result suggested that the degradation of the thermal conductivities was attributed to the accumulation of lattice defects by self-irradiation.

Journal Articles

High temperature reaction between sea salt deposit and (U,Zr)O$$_{2}$$ simulated corium debris

Takano, Masahide; Nishi, Tsuyoshi

Journal of Nuclear Materials, 443(1-3), p.32 - 39, 2013/09

 Times Cited Count:9 Percentile:31.58(Materials Science, Multidisciplinary)

In order to clarify the possible impacts of sea salt deposit on the chemical and physical state of the fuel debris formed in the severe accident at Fukushima Daiichi Nuclear Power Plant, the high temperature reaction between sea salt deposit and (U,Zr)O$$_{2}$$ simulated fuel debris (sim-debris) was examined in the temperature range from 1088 to 1668 K. The dense layer of calcium and/or sodium uranate formed on the surface of sim-debris pellet at 1275 K under airflow, with the thickness of over 50 $$mu$$m. When the oxygen partial pressure is low, calcium likely dissolve into the sim-debris to form solid solution. The diffusion depth was 5-6 $$mu$$m from the surface at 1275 K for 12 h. The crystalline MgO remains as the main residue stuck on the surface. A part of it can dissolve into the sim-debris depending on the temperature.

Journal Articles

Micromachining of commodity plastics by proton beam writing and fabrication of spatial resolution test-chart for neutron radiography

Sakai, Takuro; Yasuda, Ryo; Iikura, Hiroshi; Nojima, Takehiro; Matsubayashi, Masahito; Kada, Wataru; Koka, Masashi; Sato, Takahiro; Okubo, Takeru; Ishii, Yasuyuki; et al.

Nuclear Instruments and Methods in Physics Research B, 306, p.299 - 301, 2013/07

 Times Cited Count:7 Percentile:40.75(Instruments & Instrumentation)

Journal Articles

Self-irradiation effect on thermal conductivity of (Pu$$_{0.91}$$Cm$$_{0.09}$$)O$$_{2}$$

Nishi, Tsuyoshi; Takano, Masahide; Akabori, Mitsuo; Arai, Yasuo

Journal of Nuclear Materials, 433(1-3), p.531 - 533, 2013/02

 Times Cited Count:5 Percentile:52.28(Materials Science, Multidisciplinary)

To clarify the storage duration dependence of the thermal conductivity of MA containing oxide fuel, the thermal diffusivity of (Pu$$_{0.91}$$Cm$$_{0.09}$$)O$$_{2}$$ was measured at 473, 523 and 573 K by a laser flash method using the sample stored for 48, 264, 504, and 960 h. The heat capacity was measured by a drop calorimetry to derive the thermal conductivity. It was confirmed that the degradation of the thermal conductivity was attributed to the accumulation of lattice defects caused by self-irradiation, because the storage duration dependence of the thermal conductivity could be approximated by the equation used for self-irradiation lattice expansion model.

Journal Articles

Operation of the AVF cyclotron

Okumura, Susumu; Ishibori, Ikuo; Kurashima, Satoshi; Yoshida, Kenichi; Yuyama, Takahiro; Ishizaka, Tomohisa; Miyawaki, Nobumasa; Kashiwagi, Hirotsugu; Yuri, Yosuke; Nara, Takayuki; et al.

JAEA-Review 2012-046, JAEA Takasaki Annual Report 2011, P. 172, 2013/01

The AVF cyclotron was operated from May 9th in fiscal 2011 and all the planned experiments on April were cancelled due to scheduled blackouts originated from the Great East Japan Earthquake. The total operation time amounted to 3,038.4 hours. The extended operation from Friday evening to Saturday evening was carried out eight times in order to supply the cancellation on April. The regular yearly overhaul and maintenance were carried out.

Journal Articles

Mach-Zehnder polymer waveguides fabricated using proton beam writing

Miura, Kenta*; Sato, Takahiro; Ishii, Yasuyuki; Koka, Masashi; Kiryu, Hiromu*; Ozawa, Yusuke*; Takano, Katsuyoshi*; Okubo, Takeru; Yamazaki, Akiyoshi; Kada, Wataru; et al.

JAEA-Review 2012-046, JAEA Takasaki Annual Report 2011, P. 126, 2013/01

Journal Articles

MFM observation of micrometer-sized magnetic patterns produced by heavy ion microbeam irradiation in FeRh films

Aiko, Kazuma*; Toki, Atsushi*; Matsui, Toshiyuki*; Iwase, Akihiro*; Sato, Takahiro; Takano, Katsuyoshi*; Koka, Masashi; Saito, Yuichi; Kamiya, Tomihiro

JAEA-Review 2012-046, JAEA Takasaki Annual Report 2011, P. 133, 2013/01

Journal Articles

Visualization of a single cluster particle track in polystyrene films

Asano, Atsushi*; Takano, Katsuyoshi*; Chiba, Atsuya; Saito, Yuichi; Marui, Hiromi*; Omichi, Masaaki*; Maeyoshi, Yuta*; Honsho, Yoshito*; Saeki, Akinori*; Yamada, Keisuke; et al.

JAEA-Review 2012-046, JAEA Takasaki Annual Report 2011, P. 163, 2013/01

Journal Articles

Fabrication of Mach-Zehnder polimer waveguides by a direct-drawing technique using a focused proton beam

Miura, Kenta*; Sato, Takahiro; Ishii, Yasuyuki; Kiryu, Hiromu*; Ozawa, Yusuke*; Koka, Masashi; Takano, Katsuyoshi*; Okubo, Takeru; Yamazaki, Akiyoshi; Kada, Wataru; et al.

Key Engineering Materials, 534, p.158 - 161, 2013/00

 Times Cited Count:5 Percentile:5.84

Journal Articles

A Line pair indicator made of Gd film for evaluating spatial resolution

Yasuda, Ryo; Matsubayashi, Masahito; Sakai, Takuro; Nojima, Takehiro; Iikura, Hiroshi; Katagiri, Masaki*; Takano, Katsuyoshi*; Pikuz, T.; Faenov, A.*

Physics Procedia, 43, p.196 - 204, 2013/00

 Times Cited Count:1 Percentile:40.47

Journal Articles

Visualization of focused proton beam dose distribution by atomic force microscopy using blended polymer films based on polyacrylic acid

Omichi, Masaaki*; Takano, Katsuyoshi*; Sato, Takahiro; Kamiya, Tomihiro; Ishii, Yasuyuki; Okubo, Takeru; Koka, Masashi; Kada, Wataru; Sugimoto, Masaki; Nishikawa, Hiroyuki*; et al.

Journal of Nanoscience and Nanotechnology, 12, p.7401 - 7404, 2012/09

 Times Cited Count:2 Percentile:86.19(Chemistry, Multidisciplinary)

161 (Records 1-20 displayed on this page)