A Modeling approach to estimate H discharge from rivers; Comparison of discharge from the Fukushima Dai-ichi and inventory in seawater in the Fukushima coastal region

Sakuma, Kazuyuki; Machida, Masahiko; Kurikami, Hiroshi; Iwata, Ayako; Yamada, Susumu; Iijima, Kazuki

Science of the Total Environment, 806(Part 3), p.151344_1 - 151344_8, 2022/02

https://doi.org/10.1016/j.scitotenv.2021.151344

Thermally altered subsurface material of asteroid (162173) Ryugu

Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Takagi, Yasuhiko*; Nakamura, Tomoki*; Hiroi, Takahiro*; Matsuoka, Moe*; et al.

Nature Astronomy (Internet), 5(3), p.246 - 250, 2021/03

https://doi.org/10.1038/s41550-020-01271-2

Here we report observations of Ryugu's subsurface material by the Near-Infrared Spectrometer (NIRS3) on the Hayabusa2 spacecraft. Reflectance spectra of excavated material exhibit a hydroxyl (OH) absorption feature that is slightly stronger and peak-shifted compared with that observed for the surface, indicating that space weathering and/or radiative heating have caused subtle spectral changes in the uppermost surface. However, the strength and shape of the OH feature still suggests that the subsurface material experienced heating above 300 C, similar to the surface. In contrast, thermophysical modeling indicates that radiative heating does not increase the temperature above 200 C at the estimated excavation depth of 1 m, even if the semimajor axis is reduced to 0.344 au. This supports the hypothesis that primary thermal alteration occurred due to radiogenic and/or impact heating on Ryugu's parent body.

Investigation of single-event damages on silicon carbide (SiC) power MOSFETs

Mizuta, Eiichi*; Kuboyama, Satoshi*; Abe, Hiroshi; Iwata, Yoshiyuki*; Tamura, Takashi*

IEEE Transactions on Nuclear Science, 61(4), p.1924 - 1928, 2014/08

https://doi.org/10.1109/TNS.2014.2336911

Si substrate suitable for radiation-resistant space solar cells

Matsuura, Hideharu*; Iwata, Hiroshi*; Kagamihara, So*; Ishihara, Ryohei*; Yoneda, Masahiko*; Imai, Hideaki*; Kikuta, Masanori*; Inoue, Yuki*; Hisamatsu, Tadashi*; Kawakita, Shiro*; et al.

Japanese Journal of Applied Physics, Part 1, 45(4A), p.2648 - 2655, 2006/04

https://doi.org/10.1143/JJAP.45.2648

no abstracts in English

Change of majority-carrier concentration in p-type silicon by 10 MeV proton irradiation

Iwata, Hiroshi*; Kagamihara, Satoshi*; Matsuura, Hideharu*; Kawakita, Shiro*; Oshima, Takeshi; Kamiya, Tomihiro

Proceedings of the 6th International Workshop on Radiation Effects on Semiconductor Devices for Space Application (RASEDA-6), p.143 - 146, 2004/10

no abstracts in English

Investigation research on the evaluation of a coupled thermo-hydro-mechanical-chemical phenomena; result report

Chijimatsu, Masakazu*; Neyama, Atsushi*; Ishihara, Yoshinao*; Amemiya, Kiyoshi*; ; Iwata, Hiroshi*

JNC TJ8400 2002-003, 155 Pages, 2002/02

JNC-TJ8400-2002-003.pdf:1.51MB

In order to realize a coupling analysis in the near field of the geological disposal system, this study has been studied on the addition of the mass transport model to the coupled thermo-hydro-mechanical analysis code (THAMES) and preliminary coupling analysis by using development environmental tool (Diffpack) for numerical analysis. (1)In order to prepare the strategy on the addition of the mass transport model to the coupled thermo-hydro-mechanical analysis code (THAMES), we have studied on the requirement of THAMES-Transport and methodology of coupling analysis. After that we set out modification plan by the Eulerian-Lagrangian (EL) method. (2)Based on the document of modification plan, we have done addition of the mass transport model to the coupled thermo-hydro-mechanical analysis code (THAMES) and carried out verification analysis in order to confirm on the accuracy of THAMES-Transport. (3)In order to understand on the behavior of NaCl in the porewater under the coupled thermo-hydro-mechanical phenomena in the HLW engineered barrier system, we have calculated coupling phenomenon by using THAMES-Transport. Transportation and concentration phenomena of NaCl are calculated but precipitation of NaCl is not occurred under the analysis conditions in this report. (4)In order to confirm about feasibility of coupling analysis under the development environmental tool (Diffpack) for numerical analysis, we have carried out on the design work and writing program of the preliminary coupling system. In this study, we have adopted existing transport model (HYDROGEOCHEM) and geochemical model (phreeqe60) for preliminary coupling system. (5)In order to confirm program correctness of preliminary coupling system, we have carried out benchmarking analysis by using existing reactive-transport analysiscode (HYDROGEOCHEM). (6)We have been prepared short-range development plan based on through the modification study of THAMES and writing program of the preliminary coupling ...

Investigation research of core-basic information associated with the coupling analysis; result report

Kataoka, Shinichi*; Kawahara, Kenichi*; Matsunaga, Kenichi*; Ishihara, Yoshinao*; Neyama, Atsushi*; Nakagawa, Koichi*; Iwata, Hiroshi*; Mori, Koji*

JNC TJ8400 2001-036, 202 Pages, 2001/03

JNC-TJ8400-2001-036.pdf:7.58MB

The newest literature information in the foreign countries was researched, and this research showed the basic concept of the coupling analysis code to realize coupling analysis in near field of the geological disposal system. The outline of this research is shown in the following. (1)The combination of M (Mechanical) and (Chemistry) is placed on the weak relations, Because coupling analysis of the United States Yucca Mountain limits a site and the specifications of engineered barrier. (2)One of the purposes of this research is information collecting about coupling analysis code NUFT-C adopted in the United States Yucca Mountain. Therefore, we carried out an information exchange with the United States Lawrence Livermore National Laboratory. We could collect the development purpose of analysis code, key function, and information such as a test case analysis. (3)The investigation of the analysis code concerned with the newest information of coupling analysis which contains the geochemistry process and 2 phase system was done based on the public information for the purpose of building some concept of the coupling analysis code, the extraction of the development issues. It could be understood about the future development strategy and the precaution in addition to a phenomenon to deal with, the current status of the coupling analysis technique as a result of the investigation. (4)It was cleared about the mission of the coupling analysis code and the requirement items (function, quality) by this research. Then, some development options were presented. (5)It was studied about the procedure of developing it to satisfy the above requirement toward the conditions that a site isn't selected, the short development. The tool (Diffpack) which could cope with the speed-up of the calculation time and visualization flexibly was effective, and it was summarized about the test case by using this tool, the key function of this tool as that result.

Ion irradiation effects in EuBaCuO thin film

; Iwase, Akihiro; Iwata, Tadao; Maeta, Hiroshi; ;

J. Supercond., 7(1), p.241 - 242, 1994/00

no abstracts in English

Evaluation of water chemistry in near-field by using reaction-path calculation; Effect of dissolued iron from overpack/HLW borosilicate glass on ligand concentrations

; Miyahara, Kaname; Iwata, Hiroshi*

Migration '93, 0 Pages, 1993/12

None

Radiation effect of YBaCuO irradiated by -rays and 14MeV neutrons

Kato, Teruo; Watanabe, Mitsuo; ; Naramoto, Hiroshi; Iwata, Tadao; Ikeda, Yujiro; Maekawa, Hiroshi; Nakamura, Tomoo

Japanese Journal of Applied Physics, 27(11), p.L2097 - L2099, 1988/11

https://doi.org/10.1143/JJAP.27.L2097

no abstracts in English