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Lind, T.*; Kalilainen, J.*; Marchetto, C.*; Beck, S.*; Nakamura, Koichi*; Kino, Chiaki*; Maruyama, Yu; Kido, Kentaro; Kim, S. I.*; Lee, Y.*; et al.
Proceedings of 20th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-20) (Internet), p.4796 - 4809, 2023/08
Maruyama, Koichi*; Nakamura, Junya*; Yoshimi, Kyosuke*; Nagae, Yuji
Advances in Materials Technology for Fossil Power Plants; Proceedings from the 8th International Conference (EPRI 2016), p.467 - 478, 2016/00
Ajimura, Shuhei*; Bezerra, T. J. C.*; Chauveau, E.*; Enomoto, T.*; Furuta, Hisataka*; Harada, Masahide; Hasegawa, Shoichi; Hiraiwa, T.*; Igarashi, Yoichi*; Iwai, Eito*; et al.
Progress of Theoretical and Experimental Physics (Internet), 2015(6), p.063C01_1 - 063C01_19, 2015/06
Times Cited Count：6 Percentile：45.25(Physics, Multidisciplinary)The J-PARC E56 experiment aims to search for sterile neutrinos at the J-PARC Materials and Life Science Experimental Facility (MLF). In order to examine the feasibility of the experiment, we measured the background rates of different detector candidate sites, which are located at the third floor of the MLF, using a detector consisting of plastic scintillators with a fiducial mass of 500 kg. The gammas and neutrons induced by the beam as well as the backgrounds from the cosmic rays were measured, and the results are described in this article.
Ioki, Kimihiro*; Akiba, Masato; Barabaschi, P.*; Barabash, V.*; Chiocchio, S.*; Daenner, W.*; Elio, F.*; Enoeda, Mikio; Ezato, Koichiro; Federici, G.*; et al.
Journal of Nuclear Materials, 329-333(1), p.31 - 38, 2004/08
Times Cited Count：14 Percentile：66.09(Materials Science, Multidisciplinary)The preparation of the procurement specifications is being progressed for key components. Progress has been made in the preparation of the procurement specifications for key nuclear components of ITER. Detailed design of the vacuum vessel (VV) and in-vessel components is being performed to consider fabrication methods and non-destructive tests (NDT). R&D activities are being carried out on vacuum vessel UT inspection with waves launched at an angle of 20 or 30 degree, on flow distribution tests of a two-channel model, on fabrication and testing of FW mockups and panels, on the blanket flexible support as a complete system including the housing, on the blanket co-axial pipe connection with guard vacuum for leak detection, and on divertor vertical target prototypes. The results give confidence in the validity of the design and identify possibilities of attractive alternate fabrication methods.
-ray emission source developmentArisawa, Takashi; Matoba, Toru; Yamakawa, Koichi; Maruyama, Yoichiro; Sasuga, Tsuneo; Wakaida, Ikuo; Nakajima, Kazuhisa*; Sasaki, Akira; Minehara, Eisuke; Oshima, Masumi
Proc. of the 1st International Induced Gamma Emision Workshop, p.29 - 41, 1999/00
no abstracts in English
Sawada, Kota; Maruyama, Koichi; Komine, Ryuji; Nagae, Yuji
PNC TN9410 98-018, 32 Pages, 1998/02
Mod.9Cr-1Mo steel has a martensitic lath structure. Recovery of the lath structure takes place hl the course of creep. Microstructural degradation due to the recovery results in the acceleration of creep rate and the subsequent failure of a specimen. Change of lath width during creep of the steel was quantitatively investigated to propose a residual life assessment methodology based on the recovery process. Since the steel was tempered at 1053K, the lath structure is thermally stable at the testing temperatures (848K
923K). However, recovery of lath structure readily takes place during creep, indicating that the recovery is induced by creep deformation. Lath width 
increases with creep strain and saturates to a value 
determined by creep stress. The increase of is faster at a higher stress and temperature. A normalized ehange in lath width, 
/, was introduced to explain the variation of lath growth rate with creep stress and temperature. is the change in lath width from the initial value 
, and is the difference between and . / is uniquely related to creep strain 
and the relationship is independent of creep stress as well as ereep temperature. This /- relationship obtained by an accelerated creep test at a higher temperature or stress is applicable to any creep condition including service conditions of engineering plants. Creep strain can be evaluted from the measurement of / based on the /- relationship. A creep curve under any creep condition can readily be calculated by creep data of the steel. Combining these information one can assess residual life of a structural component made of the steel.
Sawada, Kota; Maruyama, Koichi; Komine, Ryuji; Nagae, Yuji
PNC TN9410 97-035, 41 Pages, 1997/03
Several microstructural changes take place in a material during the course of creep. These changes can be a measure of creep life consumption. In this paper, microstructural changes in Mod.9Cr-1Mo steel were studied in order to examine their ability as the measure of crecp life consumption. Macroscopic structural changes, such as void growth, rotation of lath structure toward the tensile axis and elongation of grains, are evident only in the necked portion of ruptured specimens. These macroscopic structural changes are not useful for creep life assessment. Lath width increases and dislocation density within lath decreases with increasing creep duration. These changes in dislocation substructure start in the early stage of creep life, and cause the increase of strain rate in the tertiary creep stage. The lath width and the dislocation density reach a stationary value before rupture. The stationary values are independent of temperature, and uniquely related to creep stress normalized by shear modulus. The extent of these microstructural changes are greater at lower stresses under which the material is practically used. These facts suggest that the lath width and the dislocation density within lath can be a useful measure of creep life consumption. Hardness of crept specimens is closely related to the lath width and the dislocation density within lath. The changes of these microstructural features can be evaluated by the measurement of handness.
Sawada, Kota*; Maruyama, Koichi*; Komine, Ryuji; Nagae, Yuji
Tetsu To Hagane, 83(7), p.466 - 471, 1997/00
None
Takeda, Nobukazu; Kakudate, Satoshi; Shibanuma, Kiyoshi; Tsuji, Koichi*; Kubo, Tomomi*; Maruyama, Kensuke*; Kondo, Mitsunori*
no journal, ,
no abstracts in English
Maruyama, Koichi*; Nogami, Masanobu*; Ikeda, Yasuhisa*; Nishimura, Kenji*; Morita, Yasuji
no journal, ,
Radiation and heat resistance of low coordinate and hydrophobic pyrrolidone derivatives, NProP and NBP, which are selective precipitants for U(VI), was examined by -irradiation and heating of the 3M nitric and solutions of the precipitants. Test results of radiation resistance of NProP and NBP showed that the ability to make precipitate of U(VI) was kept until 0.5 MGy of irradiation. After the heating of the 3M nitric and solutions of NProP and NBP at 50 
C, the molecular structures of NBP and NProP were changed within 4 days and 10days, respectively. It was found that the change of the structure does not weaken but reinforce the ability to make precipitate of U(VI), which would due to the increase of the hydrophobicity.
Noda, Kyoko*; Takao, Koichiro*; Sugiyama, Yuichi*; Harada, Masayuki*; Nogami, Masanobu*; Maruyama, Koichi*; Takahashi, Hiroaki*; Kim, S.-Y.; Sato, Makoto; Mineo, Hideaki; et al.
no journal, ,
We have been developing an advanced reprocessing system for spent FBR fuels based on precipitation method using pyrrolidone derivatives. In previous investigation, N-cyclohexyl-2-pyrrolidone (NCP) is used as a precipitant, which is able to precipitate selectively UO
ions in HNO
solution, and a process consisting of two separation steps; selective U precipitation step and U-Pu co-precipitation step, was developed. In order to make the process more effective and more economical, we are now studying precipitation of U and Pu with other pyrrolidone derivatives. The outline of the study and main results obtained until now are shown in this presentation.
Watanabe, Hisao*; Usui, Nobuhiko*; Maruyama, Fumi*; Kimura, Koichi
no journal, ,
no abstracts in English
Mitsumoto, Rika; Kimura, Koichi; Tamayama, Kiyoshi; Maruyama, Fumi*
no journal, ,
no abstracts in English
Maruyama, Koichi*; Nakamura, Junya*; Sekido, Nobuaki*; Yoshimi, Kyosuke*; Nagae, Yuji
no journal, ,
no abstracts in English
Amamoto, Ippei; Oyama, Koichi; Nagano, Yuichi*; Nagao, Saichi*; Kitajima, Hideki*; Taneda, Naoki*; Maruyama, Tsutomu*; Sakai, Mitsuyoshi*; Nishikawa, Nobutaka*
no journal, ,
MATRIX database has been constructed to obtain experimental phase diagram using Interglad. It also possesses functions such as literature search, construction of computational phase diagrams by the thermodynamic method using FactSage as well as estimation of viscosity, density and/or electric resistance of certain glasses by neural network method.
Yoshida, Hidekazu*; Yamamoto, Koshi*; Maruyama, Ippei*; Asahara, Yoshihiro*; Minami, Masayo*; Shirono, Shinichi*; Hasegawa, Hitoshi*; Katsuta, Nagayoshi*; Nishimoto, Shoji*; Muramiya, Yusuke*; et al.
no journal, ,
no abstracts in English
Yoshida, Hidekazu*; Yamamoto, Koshi*; Maruyama, Ippei*; Karukaya, Koichi*; Nakayama, Masashi; Sakurai, Akitaka; Sato, Toshinori
no journal, ,
Spherical, isolated carbonate concretions occur throughout the world in marine argillaceous sedimentary rocks of widely varying geological ages. These concretions are characteristically highly enriched in CaCO compared to the surrounding sedimentary rock matrices and are commonly containing the well-preserved fossils inside. Recently the process of the enrichment of CaCO has been revealed and synthetic concretion materials are developed. Here we will introduce the in-situ experiment with the synthetic concretion material for EDZ sealing carried out in Horonobe Underground Research Laboratory and the preliminary results of the EDZ sealing process and their sealing effectiveness.
Uno, Koichiro*; Nakao, Atsushi*; Okumura, Masahiko; Kogure, Toshihiro*; Yamaguchi, Akiko; Takeda, Hikaru*; Maruyama, Hayato*; Shinano, Takuro*; Yanai, Junta*
no journal, ,
Biotite inhibits radiocesium (RCs) transfer from soil to plants by two functions of selective adsorption of radiocesium (Cs) between layers (Cs adsorption ability) and K supply from between layers (K supply ability). However, it was difficult to distinguish between the two. In this study, the authors succeeded in preparing biotite in which both functions are variously different by preparing weathered biotite in which interlayer pottasium (K) was replaced with rubidium (Rb) to lose K supply ability. By systematically comparing these biotites, the authors clarified the effects of Cs adsorption ability and K supply ability on Cs transfer to plants.
