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Journal Articles

Status of efforts for safeguards challenges by Ningyo-toge Uranium Enrichment Facility

Ishida, Tsuyoshi; Nakashima, Shinichi; Kondo, Shinji; Hayashibara, Kenichi; Yamada, Shigeki*; Okamoto, Ryo*; Nakamura, Hironobu

Dai-44-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 4 Pages, 2023/11

no abstracts in English

Journal Articles

PANDORA Project for the study of photonuclear reactions below $$A=60$$

Tamii, Atsushi*; Pellegri, L.*; S$"o$derstr$"o$m, P.-A.*; Allard, D.*; Goriely, S.*; Inakura, Tsunenori*; Khan, E.*; Kido, Eiji*; Kimura, Masaaki*; Litvinova, E.*; et al.

European Physical Journal A, 59(9), p.208_1 - 208_21, 2023/09

no abstracts in English

Journal Articles

Study on the relation between the crystal structure and thermal stability of FeUO$$_{4}$$ and CrUO$$_{4}$$

Akiyama, Daisuke*; Kusaka, Ryoji; Kumagai, Yuta; Nakada, Masami; Watanabe, Masayuki; Okamoto, Yoshihiro; Nagai, Takayuki; Sato, Nobuaki*; Kirishima, Akira*

Journal of Nuclear Materials, 568, p.153847_1 - 153847_10, 2022/09

 Times Cited Count:2 Percentile:71.05(Materials Science, Multidisciplinary)

FeUO$$_{4}$$, CrUO$$_{4}$$, and Fe$$_{x}$$Cr$$_{1-x}$$UO$$_{4}$$ are monouranates containing pentavalent U. Even though these compounds have similar crystal structures, their formation conditions and thermal stability are significantly different. To determine the factors causing the difference in thermal stability between FeUO$$_{4}$$ and CrUO$$_{4}$$, their crystal structures were evaluated in detail. A Raman band was observed at 700 cm$$^{-1}$$ in all the samples. This Raman band was derived from the stretching vibration of the O-U-O axis band, indicating that Fe$$_{x}$$Cr$$_{1-x}$$UO$$_{4}$$ was composed of a uranyl-like structure in its lattice regardless of its "x"' value. M$"o$ssbauer measurements indicated that the Fe in FeUO$$_{4}$$ and Fe$$_{x}$$Cr$$_{1-x}$$UO$$_{4}$$ were trivalent. Furthermore, Fe$$_{x}$$Cr$$_{1-x}$$UO$$_{4}$$ lost its symmetry around Fe$$^{mathrm{III}}$$ with increasing electron densities around Fe$$^{mathrm{III}}$$, as the abundance of Cr increased. These results suggested no significant structural differences between FeUO$$_{4}$$ and CrUO$$_{4}$$. Thermogravimetric measurements for UO$$_{2}$$, FeUO$$_{4}$$, and CrUO$$_{4}$$ showed that the temperature at which FeUO$$_{4}$$ decomposed under an oxidizing condition (approximately 800 $$^{circ}$$C) was significantly lower than the temperature at which the decomposition of CrUO$$_{4}$$ started (approximately 1250 $$^{circ}$$C). Based on these results, we concluded that the decomposition of FeUO$$_{4}$$ was triggered by an "in-crystal" redox reaction, i.e., Fe$$^{mathrm{III}}$$ $${+}$$ U$$^{mathrm{V}}$$ $$rightarrow$$ Fe$$^{mathrm{II}}$$ $${+}$$ U$$^{mathrm{VI}}$$, which would not occur in the CrUO$$_{4}$$ lattice because Cr$$^{mathrm{III}}$$ could never be reduced under the investigated condition. Finally, the existence of Cr$$^{mathrm{III}}$$ in FexCr$$_{1-x}$$UO$$_{4}$$ effectively suppressed the decomposition of the Fe$$_{x}$$Cr$$_{1-x}$$UO$$_{4}$$ crystal, even at a very low Cr content.

Journal Articles

C-face interface defects in 4H-SiC MOSFETs studied by electrically detected magnetic resonance

Umeda, Takahide*; Okamoto, Mitsuo*; Arai, Ryo*; Sato, Yoshihiro*; Kosugi, Ryoji*; Harada, Shinsuke*; Okumura, Hajime*; Makino, Takahiro; Oshima, Takeshi

Materials Science Forum, 778-780, p.414 - 417, 2014/02

 Times Cited Count:2 Percentile:72.87

Interface defects of Metal-Oxide-Semiconductors (MOSFETs) fabricated on Carbone (C) face 4H-SiC were investigated by Electrically Detected Magnet Resistance (EDMR). Gate oxide of the MOSFETs was formed by either wet-oxidation and H$$_{2}$$ annealing or dry-oxidation. The values of channel mobility for MOSFETS with wet gate oxide and dry gate oxide are less than 1 and 90 cm$$^{2}$$/Vs, respectively. By EDMR measurement under low temperature (less than 20 K), EDMR signals related to C were detected. The peak height of the signals increased with increasing $$gamma$$-ray doses, and the channel mobility decreased. From this result, it is assumed that hydrogen atoms passivating C dangling bonds are released by $$gamma$$-rays and the channel mobility decreases with increasing the C related defects.

JAEA Reports

Fabrication of mercury target vessel

Wakui, Takashi; Kogawa, Hiroyuki; Haga, Katsuhiro; Futakawa, Masatoshi; Hayashi, Ryoichi*; Uchiyama, Naoyoshi*; Okamoto, Yoshinao*; Nakamura, Koji*

JAEA-Technology 2009-040, 96 Pages, 2010/03

JAEA-Technology-2009-040.pdf:35.52MB

The construction of materials and life science experimental facility in J-PARC project had been completed. The mercury target vessel consists of triple-walled structure in order to prevent the leak of mercury to outside at the failure of the mercury vessel and to remove the heat of the safety hull, which covers the mercury vessel, due to the injection of the pulsed proton beams. The high fabrication accuracy is required for the mercury target vessel assembled by the welding. In this report, the required specification and basic structure of parts in the mercury target vessel are described and the fabrication procedure of the mercury target vessel by the vender is reported. In the fabrication of the mercury target vessel, there were many troubles such as large deformation due to the welding and then the vender repaired and brought the mercury target vessel to completion. Furthermore, improvements for the design and fabrication of the mercury target are reported.

Journal Articles

Homodimeric cross-over structure of the human granulocyte colony-stimulating factor (GCSF) receptor signaling complex

Tamada, Taro; Honjo, Eijiro; Maeda, Yoshitake*; Okamoto, Tomoyuki*; Ishibashi, Matsujiro*; Tokunaga, Masao*; Kuroki, Ryota

Proceedings of the National Academy of Sciences of the United States of America, 103(9), p.3135 - 3140, 2006/02

 Times Cited Count:90 Percentile:84.38(Multidisciplinary Sciences)

A crystal structure of the signaling complex between human granulocyte colony-stimulating factor (GCSF), and a ligand binding region of GCSF receptor (GCSF-R), has been determined to 2.8${AA}$ resolution. The GCSF:GCSF-R complex formed a 2:2 stoichiometry via a cross-over interaction between the Ig-like domains of GCSF-R and GCSF. The conformation of the complex is quite different to that between human GCSF and the CRH domain of mouse GCSF-R, but similar to that of the interleukin-6 (IL-6)/gp130 signaling complex. The Ig-like domain cross-over structure necessary for GCSF-R activation is consistent with previously reported thermodynamic and mutational analyses.

Journal Articles

Crystallization of a 2:2 complex of Granulocyte-Colony Stimulating Factor (GCSF) with the ligand-binding region of the GCSF receptor

Honjo, Eijiro; Tamada, Taro; Maeda, Yoshitake*; Koshiba, Takumi*; Matsukura, Yasuko*; Okamoto, Tomoyuki*; Ishibashi, Matsujiro*; Tokunaga, Masao*; Kuroki, Ryota

Acta Crystallographica Section F, 61(8), p.788 - 790, 2005/08

 Times Cited Count:7 Percentile:55.29(Biochemical Research Methods)

Granulocyte colony-stimulating factor (GCSF) receptor receives signals for regulating the proliferation and differentiation of the precursor cells of granulocytes. The complex composed of two GCSFs and two GCSF receptors was crystallized. The crystal of the complex was grown in 1.0 M sodium formate and 0.1 M sodium acetate (pH4.6). It belongs to the space group ${it P}$4$$_{1}$$2$$_{1}$$2 (or its enantiomorph ${it P}$4$$_{3}$$2$$_{1}$$2) with unit cell dimensions of ${it a}$ = ${it b}$ = 110.1 ${AA}$, ${it c}$ = 331.8 ${AA}$. However, the diffraction data from the crystal beyond 5 ${AA}$ resolution could not be collected. Since the heterogeneity of GCSF receptor seems to interrupt growth of good quality crystals, the GCSF receptor was fractionated by achromatography. Crystals of GCSF/fractionated GCSF receptor complex were grown as a new crystal form in 0.2 M ammonium phosphate. The new crystal diffracts beyond 3.0 ${AA}$ resolution and belongs to space group ${it P}$3$$_{1}$$21 (or its enantiomorph ${it P}$3$$_{2}$$21) with unit-cell parameters ${it a}$ = ${it b}$ = 134.8, ${it c}$ = 105.7 ${AA}$.

JAEA Reports

Design of uninstrumented irradiation subassembly type-D (UNIS-D)

Okamoto, Kaoru; Miyakawa, Shunichi; Mitsugi, Takeshi; Kitamura, Ryoichi

JNC TN9410 99-010, 350 Pages, 1999/06

JNC-TN9410-99-010.pdf:11.62MB

In the needs of the fuel irradiation test in "Joyo" MK-III core, there have been required that the irradiation of high performance fuel at high liner heat rate to high burn-up range, or the irradiation of advanced fuel such as MA fuel and Vipac fuel. In order to carry out these irradiation tests, newly designed irradiation subassembly is required with special features of; (1)Capability of the re-assembling after post-irradiation examination, even if the number of fuel in the identical irradiation condition decreases because of intermediate inspection. (2)Enhanced flexibility of the irradiation temperature setting ( in the present, UNIS-B's has 6 cases on the maximum). (3)Sufficient flexibility for the coolant flow distribution in the subassembly by extending variety of the flow rate setting. UNIS-D is a fuel irradiation subassembly which has been developed from above viewpoints. It is a compartment loading type irradiation subassembly that is able to load maximum of 18 compartments. Two types of compartments $$gamma$$ -type and $$delta$$ -typc arc prepared for UNIS-D. Thc sufficient consideration has also been made on the rc-assembling. A $$gamma$$ -type is the same compartment as the existing UNIS-B's and a $$delta$$ -type is the newly designed one for UNIS-D. Three to five fuel pins are loaded into a $$gamma$$ -type compartment and only one pin is loadcd into a $$delta$$ -type compartment. It is possible to carry out the irradiation test in a maximum of 18 test temperature conditions within a subassembly, since it has the sufficient flexibility for the coolant flow distribution. As for the development of UNIS-D, we have finished the detailed structure design and the design verification by the water flow examination, which confirmed that the UNIS-D exceeded its required performances in use and that its structure design was satisfactory.

Oral presentation

X-ray crystallographic analysis of the Fab derived from antigenase ($$alpha$$HA1-2mAb Fab) with antigen peptide

Arai, Shigeki; Tamada, Taro; Okamoto, Yoshiko*; Hifumi, Megumi*; Uda, Taizo*; Kuroki, Ryota

no journal, , 

no abstracts in English

Oral presentation

Homodimeric crossover structure of the human GCSF-receptor signaling complex

Tamada, Taro; Honjo, Eijiro; Maeda, Yoshitake*; Okamoto, Tomoyuki*; Ishibashi, Matsujiro*; Tokunaga, Masao*; Kuroki, Ryota

no journal, , 

We have succeeded in crystallization of 2:2 complex between human granulocyte colony-stimulating factor (hGCSF) and the Ig-like and CRH domains of human GCSF-R (hGCSF-R) and determined its tertiary structure by X-ray crystallography at 2.8 ${AA}$ resolution. The signaling 2:2 complex is formed via cross-over interactions between the Ig-like domain of hGCSF-R and the neighboring hGCSF, forming a two-fold axis of crystallographic symmetry. This conformation is quite different from that of the heterogeneous mGCSF-R complex, and more closely resembles the 2:2:2 active assembly of human interleukin-6 (IL-6), human IL-6 $$alpha$$-receptor and human gp130 (which is a shared signal transducing receptor for several cytokines), and the 2:2 assembly of viral IL-6 and human gp130. The Ig-like domain cross-over structure necessary for GCSF-R activation is consistent with previously reported thermodynamic and mutational analyses.

Oral presentation

Electrically detected magnetic spectroscopy on interface defects in 4H-SiC (000-1) C-face metal-oxide-semiconductor field effect transistors

Umeda, Takahide*; Sato, Yoshihiro*; Arai, Ryo*; Okamoto, Mitsuo*; Harada, Shinsuke*; Kosugi, Ryoji*; Okumura, Hajime*; Makino, Takahiro; Oshima, Takeshi

no journal, , 

no abstracts in English

Oral presentation

Electrically detected magnetic resonance study on hydrogen depassivation from C-face interface defects in 4H-SiC(000$$bar{1}$$) metal-oxide-semiconductor field effect transistors

Arai, Ryo*; Umeda, Takahide*; Sato, Yoshihiro*; Okamoto, Mitsuo*; Harada, Shinsuke*; Kosugi, Ryoji*; Okumura, Hajime*; Makino, Takahiro; Oshima, Takeshi

no journal, , 

no abstracts in English

Oral presentation

International review on safety requirements for Monju

Nakai, Ryodai; Saito, Shinzo; Yamaguchi, Akira*; Okamoto, Koji*; Kani, Yoshio*

no journal, , 

In response to the lessons learned from the serious nuclear accidents at the TEPCO's Fukushima Daiichi Nuclear Power Stations, the report "Safety Requirements Expected to the Prototype Fast Breeder Reactor Monju" was issued taking into account the SFR specific safety characteristics. The report was reviewed by the leading international and domestic experts on SFR safety in order to obtain independent and objective evaluation. As a result the basic concept for prevention of severe accidents and mitigation of their consequences of Monju is appropriate in consideration of SFR specific safety characteristics, and is in accordance with international common understanding.

Oral presentation

Study on lithium rod test module and irradiation method of tritium production using high temperature gas-cooled reactor; Evaluation of test module with Zr layer

Ida, Yuma*; Matsuura, Hideaki*; Nagasumi, Satoru*; Koga, Yuki*; Okamoto, Ryo*; Katayama, Kazunari*; Otsuka, Teppei*; Goto, Minoru; Nakagawa, Shigeaki; Ishitsuka, Etsuo

no journal, , 

Tritium production method using HTGRs (High Temperature Gas-cooled reactors) is studied as the tritium supplying method for initial D-T fusion reactors. In this method, tritium is produced by $$^{6}$$Li (n,$$alpha$$)T reaction. The amount of tritium production and the tritium confinement capability were evaluated in case of the irradiation capsule including the Li compound is installed into the HTGRs in the past. In this study, the tritium confinement capability is evaluated for the irradiation capsule with ZrC layer by performing calculations of the amount of tritium leakage. The calculation results showed that the amount of tritium leakage is decreased to one fifth with the ZrC layer.

Oral presentation

Study on tritium confinement method using Li rod with Zr in very high temperature gas-cooled reactor; Hydrogen storage properties of Zr in high temperature (700$$sim$$850$$^{circ}$$C) conditions

Okamoto, Ryo*; Matsuura, Hideaki*; Ida, Yuma*; Koga, Yuki*; Katayama, Kazunari*; Otsuka, Teppei*; Goto, Minoru; Nakagawa, Shigeaki; Ishitsuka, Etsuo; Nagasumi, Satoru; et al.

no journal, , 

Currently, many researches to achieve DT nuclear-fusion power generation are under proceeding but the method to provide initial tritium loaded to fusion prototype reactor is not clear. The method of tritium production by using high temperature gas-cooled reactor (HTGR) was proposed. In this method, lithium rods are loaded to the reactor core of HTGR and tritium is produced by $$^{6}$$Li(n,$$alpha$$)T reaction. And the method to reduce the spilled tritium by using the lithium rod with zirconium layer was proposed. In this study, the experiments to evaluate the performance of hydrogen absorption in the zirconium layer were conducted under the temperature condition more than 700$$^{circ}$$C which is the normal operation condition for the very high temperature gas-cooled reactor (VHTR). The experimental result concerning solubility and diffusion factor of hydrogen in the zirconium layer will be presented and discussed.

Oral presentation

The Study on lithium rod test module and irradiation method for tritium production using high temperature gas-cooled reactor

Ida, Yuma*; Matsuura, Hideaki*; Nagasumi, Satoru; Okamoto, Ryo*; Koga, Yuki*; Katayama, Kazunari*; Otsuka, Teppei*; Goto, Minoru; Nakagawa, Shigeaki; Ishitsuka, Etsuo; et al.

no journal, , 

Large quantity of tritium is demanded for starting up of fusion reactor and engineering test using tritium for fusion blanket system. However, tritium is very rare and kg order of tritium must be produced artificially. Tritium production, by $$^{6}$$Li(n,$$alpha$$)T reaction using the high temperature gas-cooled reactor (HTGR), has been proposed. In this method, loading of Li rods into burnable poison (BP) holes in HTGR is considered. In this paper, the Li rod suited to the demand for the utilization in High Temperature engineering Test Reactor (HTTR) is designed, and tritium production and leakage from Li-rod capsule are evaluated by adjusting the thickness of LiAlO$$_{2}$$, alumina, and Zr layers. A scenario of irradiation test supposed to be conducted at HTTR for demonstration of the tritium production and containment performance of the Li rod is presented.

Oral presentation

Study on tritium confinement method using Li rod with Zr in HTGR; Hydrogen absorption properties of Zr in high temperature (700-900$$^{circ}$$C) conditions

Okamoto, Ryo*; Matsuura, Hideaki*; Ida, Yuma*; Koga, Yuki*; Suganuma, Takuro*; Katayama, Kazunari*; Otsuka, Teppei*; Goto, Minoru; Nakagawa, Shigeaki; Ishitsuka, Etsuo; et al.

no journal, , 

It has been proposed that lithium rods, which are cylindrical lithium compounds, are loaded into a HTGR and tritium for initial fusion reactors is produced by $$^{6}$$Li(n,$$alpha$$)T reaction. In this study, it was discussed that the lithium rods are covered with zirconium layers to prevent the produced tritium leak. The solubility and diffusion coefficient of hydrogen in zirconium were measured and the effectiveness of the zirconium layers on prevention of tritium leakage was estimated with the measured values. As a result, the tritium leakage ratio with the zirconium layers was estimated two orders lower than that without the zirconium layers, and hence it was considered that the zirconium layer is very effective on the prevention of the tritium leakage.

Oral presentation

Study on lithium rod module and irradiation method for tritium production using high temperature gas-cooled reactor

Koga, Yuki*; Matsuura, Hideaki*; Okamoto, Ryo*; Ida, Yuma*; Katayama, Kazunari*; Otsuka, Teppei*; Goto, Minoru; Nakagawa, Shigeaki; Ishitsuka, Etsuo; Nagasumi, Satoru; et al.

no journal, , 

Large quantity of tritium is demanded for starting up of fusion reactor and engineering test using tritium for fusion blanket system. Tritium production, by $$^{6}$$Li(n, $$alpha$$)T reaction using the high temperature gas-cooled reactor (HTGR), has been proposed and the method to produce tritium by loading the lithium rods as burnable poison in the reactor core has been studied. In this presentation, the design of lithium rods to be loaded to High Temperature engineering Test Reactor (HTTR) and its irradiation test plan to demonstrate tritium production are presented.

Oral presentation

The Influence of hydrogen absorption performance of Zr on tritium confinement properties of Li rod in HTGR

Okamoto, Ryo*; Matsuura, Hideaki*; Ida, Yuma*; Koga, Yuki*; Katayama, Kazunari*; Otsuka, Teppei*; Goto, Minoru; Nakagawa, Shigeaki; Ishitsuka, Etsuo; Nagasumi, Satoru

no journal, , 

A study on tritium production using a high-temperature gas-cooled reactor has been carried out and it was proposed that zirconium is loaded into the lithium irradiation capsule to confine tritium within the irradiation capsule under high temperature condition. In this study, zirconium loading method was examined by numerical calculations to improve the tritium confinement. As a result, it was found that improvement in the tritium confinement can be expected by loading spherical zirconium into the irradiation capsule.

Oral presentation

Deuterium absorption properties of Zr in Li rod for high temperature gas-cooled reactor

Suganuma, Takuro*; Matsuura, Hideaki*; Okamoto, Ryo*; Koga, Yuki*; Katayama, Kazunari*; Otsuka, Teppei*; Goto, Minoru; Nakagawa, Shigeaki; Tobita, Kenji*

no journal, , 

A study on the confinement of tritium, which is a fuel for fusion reactors and is produced by a HTGR, has been conducted for high temperature condition. The tritium is confined in the irradiation capsule with a zirconium layer. The relation between a H/Zr ratio and an apparent diffusion coefficient of tritium in the zirconium layer is needed to evaluate the tritium confinement performance of the irradiation capsule. This relation was examined with a experiment using deuteron. As a result, the apparent diffusion coefficient deceases with an increase of the H/Zr ratio. This phenomena should be caused by a generation of hydrogen. After that, the analysis for an amount of the release of the tritium from the irradiation capsule will be calculated using obtained data to evaluate the containment performance of the irradiation capsule.

22 (Records 1-20 displayed on this page)