PANDORA Project for the study of photonuclear reactions below

Tamii, Atsushi*; Pellegri, L.*; Sderstrm, 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

https://doi.org/10.1140/epja/s10050-023-01081-w

no abstracts in English

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

https://doi.org/10.4028/www.scientific.net/MSF.778-780.414

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 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/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 -ray doses, and the channel mobility decreased. From this result, it is assumed that hydrogen atoms passivating C dangling bonds are released by -rays and the channel mobility decreases with increasing the C related defects.

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

https://doi.org/10.1073/pnas.0511264103

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 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.

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 -type and -typc arc prepared for UNIS-D. Thc sufficient consideration has also been made on the rc-assembling. A -type is the same compartment as the existing UNIS-B's and a -type is the newly designed one for UNIS-D. Three to five fuel pins are loaded into a -type compartment and only one pin is loadcd into a -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.

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.

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 Li(n, )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.

Study on the structure of Li rod using Zr particles for T-production in HTGR; Non-equilibrium Hydrogen absorption properties of Zr

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

no journal, , 

Currently, the method to reduce the spilled tritium by using the lithium rod with zirconium layer under the high temperature condition was proposed in the study of the tritium production by using high temperature gas-cooled reactor (HTGR). In this study, the experiments to evaluate the performance of hydrogen absorption in the zirconium layer were conducted. The experimental result concerning hydrogen absorption properties of zirconium will be presented and discussed.

Study of simulated fuel debris properties by spectroscopic analysis from micro to bulk range

Endo, Ryo*; Akiyama, Daisuke*; Yomogida, Takumi; Okamoto, Yoshihiro; Tanida, Hajime; Kirishima, Akira*

no journal, , 

In the Fukushima Daiichi Nuclear Power Plant accident, fuel debris were formed by the reaction of molten fuel and reactor structural materials. The fuel debris is composed of many elements and crystalline phases. Therefore, it is inevitable to study various solid phases for debris analysis. In this study, we focused on (U,Zr)O solid solution, which is assumed to be formed in the reactor by the reaction of molten nuclear fuel (UO) and oxide of cladding components (ZrO). First, the crystalline phase of (U,Zr)O solid solution in the bulk region were determined by X-ray diffraction. The elemental composition in the micro region was analyzed by scanning electron microscopy-energy dispersive X-ray spectroscopy, and the crystalline phase in the same region was analyzed by micro-Raman spectroscopy. In addition, local elemental and valence analyses of micro regions were performed by -XRD, -XRF, and -XAFS. The U valence determined by XANES spectra was compared to the crystalline phase of (U,Zr)O solid solution. The objective of this study is to develop techniques which determine the chemical state from multiple angles by combining multiple spectroscopic analyses.

Study on the Li loading rod irradiation test and granular Zr performance evaluation method using the HTTR

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

no journal, , 

Production of tritium using a high temperature gas-cooled reactor (HTGR) has been studied for a prior engineering test with tritium handling and for the startup operation of a demonstration fusion reactor. For this purpose, Li-loading rods are installed at the moderator region of the HTGR. The tritium retention capability of Li-loading rod would decline due to high temperature condition from 1100K to 1200K during HTGR rated power operation. Therefore, the zirconium is employed as tritium absorber which is granular and is coated with nickel to prevent from declining the tritium absorption capability due to zirconium oxidation and so on. In this presentation, the design concept of Li-loading rods with granular zirconium coated with nickel and the method of irradiation test by using the HTTR which is a test reactor of HTGR are presented.

Overview of HTGR Project in JAEA

Okamoto, Ryo; Tachibana, Yukio

no journal, , 

Japan aims to achieve carbon neutrality by 2050, with hydrogen utilization as a key measure. The requirements for hydrogen supply in a hydrogen society include domestic hydrogen production, large-scale and stable production, and being carbon-free. High-temperature gas reactors have been selected as one of five reactor types to be developed under the government's Green Transformation policy, with basic design starting in 2023 and operation targeted for the late 2030s. While there are challenges related to policy, society, and technology in the practical use of high-temperature gas reactors, we aim to resolve these through domestic demonstration projects and thermal utilization tests using HTTR. HTTR is the world's only block-type high-temperature gas reactor in operation, achieving a reactor outlet temperature of 950 degree, the highest globally, and has a record of safety validation tests. In these tests, we simulated the failure of control rod insertion and tripping helium gas circulation system, demonstrating that the reactor stabilizes due to physical phenomena even in accidents, proving the inherent safety of high-temperature gas reactors. We plan to connect a hydrogen production plant to HTTR, producing hydrogen using secondary system heat. The schedule includes submitting application for licensing within the 2024 fiscal year and starting hydrogen production tests in 2028. There are several candidates for hydrogen production methods, including methane steam reforming, high-temperature steam electrolysis, methane pyrolysis, and the IS process, and we will select the appropriate method for carbon-free hydrogen production using high-temperature gas reactors.