Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
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
Times Cited Count：27 Percentile：97(Astronomy & Astrophysics)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.
Kaneko, Makoto*; Iwata, Hajime; Shiotsu, Hiroyuki; Masaki, Shota*; Kawamoto, Yuji*; Yamasaki, Shinya*; Nakamatsu, Yuki*; Imoto, Jumpei*; Furuki, Genki*; Ochiai, Asumi*; et al.
Frontiers in Energy Research (Internet), 3, p.37_1 - 37_10, 2015/09
The mobility of the aggregates of submicron-sized sheet aluminosilicate in the surface environment is a key factor controlling the current Cs migration in Fukushima.
Doi, Reisuke; Iwata, Hajime; Kitamura, Akira
JAEA-Review 2014-014, 27 Pages, 2014/05
JAEA-Review-2014-014.pdf:1.77MB
The solubility method is one of the most powerful tools to obtain reliable thermodynamic data for (1) solubility products of discrete solids and double salts, (2) complexation constants for various ligands, (3) development of data in a wide range of pH values, (4) evaluation of data for metals that form very insoluble solids (e.g. tetravalent actinides), (5) determining solubility-controlling solids in different types of wastes and (6) elevated temperatures for redox sensitive systems. This document is focused on describing various aspects of obtaining thermodynamic data using the solubility method. This manuscript deals with various aspects of conducting solubility studies, including selecting the study topic, modeling to define important variables, selecting the range of variables and experimental parameters, anticipating results, general equipment requirements, conducting experiments, and interpreting experimental data.
(
,
)
and (,)
reactions for 
=1.5-2.4 GeVZegers, R. G. T.*; Sumihama, Mizuki*; Ahn, D. S.*; Ahn, J. K.*; Akimune, Hidetoshi*; Asano, Yoshihiro; Chang, W. C.*; Dat
, S.*; Ejiri, Hiroyasu*; Fujimura, Hisako*; et al.
Physical Review Letters, 91(9), p.092001_1 - 092001_4, 2003/08
Times Cited Count：128 Percentile：95.06(Physics, Multidisciplinary)no abstracts in English
= +1 Baryon resonance in photoproduction from the neutronNakano, Takashi*; Ahn, D. S.*; Ahn, J. K.*; Akimune, Hidetoshi*; Asano, Yoshihiro; Chang, W. C.*; Date, S.*; Ejiri, Hiroyasu*; Fujimura, Hisako*; Fujiwara, Mamoru; et al.
Physical Review Letters, 91(1), p.012002_1 - 012002_4, 2003/07
Times Cited Count：1003 Percentile：99.87(Physics, Multidisciplinary)no abstracts in English
Ueno, Fumiyoshi; Kano, Shigeki; Fujita, Mitsutane*; Kurihara, Yutaka*; Nakajima, Hajime*; Yokoyama, Norio*; Iwata, Shuichi*
Journal of Nuclear Science and Technology, 31(12), p.1314 - 1324, 1994/00
None
Fujita, Mitsutane*; *; Nakajima, Hajime; *; Ueno, Fumiyoshi*; Kano, Shigeki*; Iwata, Shuichi*
Computer Aided Innovation of New Materials,II,Pt. 1, p.81 - 84, 1993/00
no abstracts in English
Fujita, Mitsutane*; Nakajima, Hajime; Ueno, Fumiyoshi*; Iwata, Shuichi*
Genshiryoku Kogyo, 39(10), p.53 - 57, 1993/00
no abstracts in English
Fujita, Mitsutane*; *; Nakajima, Hajime; *; Ueno, Fumiyoshi*; *; Iwata, Shuichi*
Proc. of the 4th Int. Symp. on Advanced Nuclear Energy Research (JAERI-CONF 1/JAERI-M 92-207), p.402 - 409, 1992/12
no abstracts in English
Nakajima, Hajime; ; *; Ueno, Fumiyoshi*; Fujita, Mitsutane*; *; Iwata, Shuichi*
Journal of Nuclear Materials, 191-194, p.1046 - 1050, 1992/00
Times Cited Count：4 Percentile：42.27(Materials Science, Multidisciplinary)no abstracts in English
Fujita, Mitsutane*; *; Nakajima, Hajime; *; Ueno, Fumiyoshi*; Kano, Shigeki*; Iwata, Shuichi*
Proc. of the Int. Symp. on Material Chemistry in Nuclear Environment, p.601 - 611, 1992/00
no abstracts in English
Fujita, Mitsutane*; Nakajima, Hajime; *; Iwata, Shuichi*
Computer Aided Innovation of New Materials, p.25 - 28, 1991/00
no abstracts in English
Fujita, Mitsutane*; *; Nakajima, Hajime; *; *; Ueno, Fumiyoshi*; Iwata, Shuichi*
Genshiro Zairyo Dai-122 Iinkai Heisei-2-Nendo Dai-5-Kai Iinkai Shiryo (Nihon Gakujutsu Shinkokai), p.7 - 14, 1991/00
no abstracts in English
Iwata, Hajime*; Sakamaki, Keiko*; Yasuda, Kenichiro; Onuki, Toshihiko; Utsunomiya, Satoshi*
no journal, ,
The aim of this study is to understand the fate of plutonium derived from atomic bomb, which has been preserved in the bottom sediment for 60 years, based on the investigation of the speciation and size distribution of plutonium. Approximately 60 % of plutonium is present as bound to organic matters and 30 % is present as insoluble species such as Pu oxides. Our results also suggest that the fast transformation of plutonium to the species bound to the organic matter for the period of 60 years, evidencing the important role of the natural organic matters on the plutonium speciation in the environment.
Sakamaki, Keiko; Iwata, Hajime*; Utsunomiya, Satoshi*
no journal, ,
no abstracts in English
Iwata, Hajime*; Kawamoto, Yuji*; Sakamaki, Keiko; Yasuda, Kenichiro; Onuki, Toshihiko; Utsunomiya, Satoshi*
no journal, ,
no abstracts in English
Iwata, Hajime; Kitamura, Akira
no journal, ,
The solubility of Nb(V) under atmosphere control by using oversaturation and undersaturation method. In the obtained results, Significant difference is observed in the solubility of Nb, and at high pH, the effect of colloid was not observed. These results were compared with the existing thermodynamic data.
Iwata, Hajime; Kitamura, Akira
no journal, ,
The solubility of Nb was measured using oversaturation and undersaturation method. Compared with the values evaluated using JAEA-TDB, in the OS method a similar solubility was observed, and the measured values in the US method were around three orders magnitude below the evaluated values. It suggests that the solubility limiting solid differ between OS and US method.
Iwata, Hajime; Kitamura, Akira
no journal, ,
The solubility of Nb was measured using oversaturation and undersaturation method. Compared with the values evaluated using JAEA-TDB, in the OS method a similar solubility was observed, and the measured values in the US method were around three orders magnitude below the evaluated values. It suggests that the solubility limiting solid differ between OS and US method.
Iwata, Hajime; Sekine, Nobuyuki*; Mitsui, Seiichiro
no journal, ,
Static leaching tests of simulated nuclear waste glass were carried out at 90C in an air atmosphere using a MgCl
solution and deionized water. As a result, in the MgCl solution, temporal plateau and following resumption of glass dissolution were observed, while an ordinary dissolution behavior, which shows rate decrease with time, was observed in the deionized water. It is considered that these unique dissolution behavior in MgCl solution may be related to the evolution of the Mg-containing mineral species deposited on the glass surface.
