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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：44 Percentile：97.1(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.
Nakano, Masanao; Fujii, Tomoko; Nagaoka, Mika; Koike, Yuko; Yamada, Ryohei; Kubota, Tomohiro; Yoshii, Hideki*; Otani, Kazunori*; Hiyama, Yoshinori*; Kikuchi, Masaaki*; et al.
JAEA-Review 2020-070, 120 Pages, 2021/02
JAEA-Review-2020-070.pdf:2.47MB
Based on the regulations (the safety regulation of Tokai Reprocessing Plant, the safety regulation of nuclear fuel material usage facilities, the radiation safety rule, the regulation about prevention from radiation hazards due to radioisotopes, which are related with the nuclear regulatory acts, the local agreement concerning with safety and environment conservation around nuclear facilities, the water pollution control law, and by law of Ibaraki Prefecture), the effluent control of liquid waste discharged from the Nuclear Fuel Cycle Engineering Laboratories of Japan Atomic Energy Agency has been performed. This report describes the effluent control results of the liquid waste in the fiscal year 2019. In this period, the concentrations and the quantities of the radioactivity in liquid waste discharged from the reprocessing plant, the plutonium fuel fabrication facilities, and the other nuclear fuel material usage facilities were much lower than the limits authorized by the above regulations.
Nakano, Masanao; Fujii, Tomoko; Nagaoka, Mika; Inoue, Kazumi; Koike, Yuko; Yamada, Ryohei; Yoshii, Hideki*; Otani, Kazunori*; Hiyama, Yoshinori*; Kikuchi, Masaaki*; et al.
JAEA-Review 2019-045, 120 Pages, 2020/03
JAEA-Review-2019-045.pdf:2.54MB
Based on the regulations (the safety regulation of Tokai Reprocessing Plant, the safety regulation of nuclear fuel material usage facilities, the radiation safety rule, the regulation about prevention from radiation hazards due to radioisotopes, which are related with the nuclear regulatory acts, the local agreement concerning with safety and environment conservation around nuclear facilities, the water pollution control law, and by law of Ibaraki Prefecture), the effluent control of liquid waste discharged from the Nuclear Fuel Cycle Engineering Laboratories of Japan Atomic Energy Agency has been performed. This report describes the effluent control results of the liquid waste in the fiscal year 2018. In this period, the concentrations and the quantities of the radioactivity in liquid waste discharged from the reprocessing plant, the plutonium fuel fabrication facilities, and the other nuclear fuel material usage facilities were much lower than the limits authorized by the above regulations.
Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Arai, Takehiko*; Nakauchi, Yusuke*; Nakamura, Tomoki*; Matsuoka, Moe*; et al.
Science, 364(6437), p.272 - 275, 2019/04
Times Cited Count：262 Percentile：99.73(Multidisciplinary Sciences)The near-Earth asteroid 162173 Ryugu, the target of Hayabusa2 sample return mission, is believed to be a primitive carbonaceous object. The Near Infrared Spectrometer (NIRS3) on Hayabusa2 acquired reflectance spectra of Ryugu's surface to provide direct measurements of the surface composition and geological context for the returned samples. A weak, narrow absorption feature centered at 2.72 micron was detected across the entire observed surface, indicating that hydroxyl (OH)-bearing minerals are ubiquitous there. The intensity of the OH feature and low albedo are similar to thermally- and/or shock-metamorphosed carbonaceous chondrite meteorites. There are few variations in the OH-band position, consistent with Ryugu being a compositionally homogeneous rubble-pile object generated from impact fragments of an undifferentiated aqueously altered parent body.
Nakano, Masanao; Fujita, Hiroki; Mizutani, Tomoko; Nagaoka, Mika; Inoue, Kazumi; Koike, Yuko; Yamada, Ryohei; Yoshii, Hideki*; Hiyama, Yoshinori*; Otani, Kazunori*; et al.
JAEA-Review 2018-028, 120 Pages, 2019/02
JAEA-Review-2018-028.pdf:2.69MB
Based on the regulations (the safety regulation of Tokai Reprocessing Plant, the safety regulation of nuclear fuel material usage facilities, the radiation safety rule, the regulation about prevention from radiation hazards due to radioisotopes, which are related with the nuclear regulatory acts, the local agreement concerning with safety and environment conservation around nuclear facilities, the water pollution control law, and by law of Ibaraki Prefecture), the effluent control of liquid waste discharged from the Nuclear Fuel Cycle Engineering Laboratories of Japan Atomic Energy Agency has been performed. This report describes the effluent control results of the liquid waste in the fiscal year 2017. In this period, the concentrations and the quantities of the radioactivity in liquid waste discharged from the reprocessing plant, the plutonium fuel fabrication facilities, and the other nuclear fuel material usage facilities were much lower than the limits authorized by the above regulations.
Kitamura, Akihiro; Kurikami, Hiroshi; Yamaguchi, Masaaki; Oda, Yoshihiro; Saito, Tatsuo; Kato, Tomoko; Niizato, Tadafumi; Iijima, Kazuki; Sato, Haruo; Yui, Mikazu; et al.
Nuclear Science and Engineering, 179(1), p.104 - 118, 2015/01
Times Cited Count：8 Percentile：55.87(Nuclear Science & Technology)The prediction of the distribution and fate of radioactive materials eventually deposited at surface in the Fukushima area is one of the main objectives and expected to be achieved in an efficient manner. In order to make such prediction, a number of mathematical models of radioactive contaminants, with particular attention on cesium, on the land and in rivers, lakes, and estuaries in the Fukushima area are developed. Simulation results are examined with the field investigations simultaneously implemented. The basic studies of the adsorption/absorption mechanism of cesium and soils have been performed to shed light on estimating distribution coefficient between dissolved contaminant and particulate contaminant.
Murakami, Hiroshi; Sada, Tomoko*; Yamada, Masako*; Harada, Masafumi*
Physical Review E, 88(5), p.052304_1 - 052304_8, 2013/11
Times Cited Count：3 Percentile：23.18(Physics, Fluids & Plasmas)no abstracts in English
Itazu, Toru; Inagaki, Manabu; Kato, Tomoko; Suzuki, Yuji*; Oyamada, Kiyoshi*; Ebashi, Takeshi; Kawamura, Makoto; Ebina, Takanori*; Miyahara, Kaname
JAEA-Review 2009-015, 59 Pages, 2009/07
JAEA-Review-2009-015.pdf:10.84MB
The project of high-level radioactive waste disposal is in the stage of site selection in Japan, and the site-specific performance assessment using the methodology of site-generic study has been developed after the publication of the second progress report (H12). In the same way, biosphere assessment using the behavior of radionuclides, which depends on the site-specific condition, has been started. In this paper, the following issues have been addressed. (1) Survey of the foreign literature relating to the surface and near- surface hydrology for biosphere assessments. (2) Survey of the domestic literature of flow and transport in subsurface systems valuable for biosphere assessments. (3) Trial of transport analysis in surface and near-surface environment of the model site. (4) The setting and boundary conditions of model used for the surface and near-surface hydrological analysis. About the fist issue, from literature of Sweden, we studied the calculation of the dose with account to radionuclides migration in the Quaternary. Concerning the second item, collecting and compiling the useful information for the surface and near-surface hydrological analysis from literature related to groundwater flow and pollution survey in Japan, we learned about the environmental tracer method and so on. Concerning the third point, transport analysis in surface and near-surface environment using site-specific data for sensitivity analysis after this has been carried out to check out the influence of some parameters on transport phenomena, and the relative high sensitivity of the difference of the source positions were shown. Concerning the fourth item, we examined the setting and the boundary conditions of model whose outputs include groundwater flow and transport rate into river, lake, sea. These outputs are used as inputs of biosphere assessment model.
X-ray diffraction study of the size dependence of pressure-induced structural transformation in amorphous silica nanoparticlesUchino, Takashi*; Aboshi, Atsuko*; Yamada, Tomoko*; Inamura, Yasuhiro; Katayama, Yoshinori
Physical Review B, 77(13), p.132201_1 - 132201_4, 2008/04
Times Cited Count：8 Percentile：37.23(Materials Science, Multidisciplinary) X-ray diffraction study of nanometer-size amorphous silica particles was carried out at pressures up to 7.4 GPa. An energy dispersive synchrotron radiation technique was used. It was found that silica nanoparticles exhibit pressure-induced structural changes, which eventually lead to a permanent densification. The transformation occurs at much lower pressures than what occurs in a bulk silica glass. A new window for amorphous-amorphous transformation at room temperature is provided by decreasing the size.
Yamada, Hidenori*; Tamada, Taro; Kosaka, Megumi*; Miyata, Kohei*; Fujiki, Shinya*; Tano, Masaru*; Moriya, Masayuki*; Yamanishi, Mamoru*; Honjo, Eijiro; Tada, Horiko*; et al.
Protein Science, 16(7), p.1389 - 1397, 2007/07
Times Cited Count：39 Percentile：59.5(Biochemistry & Molecular Biology)In an attempt to control protein incorporation in a crystal lattice, a leucine zipper-like hydrophobic interface (comprising four leucine residues) was introduced into a helical region (helix 2) of the human pancreatic ribonuclease 1 (RNase 1) that was predicted to form a suitable crystallization interface. Although crystallization of wild type RNase 1 has not yet been reported, the RNase 1 mutant having four leucines (4L-RNase 1) was successfully crystallized under several different conditions. The crystal structures were subsequently determined by X-ray crystallography by molecular replacement using the structure of bovine RNase A. The overall structure of 4L-RNase 1 is quite similar to that of the bovine RNase A, and the introduced leucine residues formed the designed crystal interface. To further characterize the role of the introduced leucine residues in crystallization of RNase 1, the number of leucines was reduced to three or two (3L- and 2L-RNase 1, respectively). Both mutants crystallized and a similar hydrophobic interface as in 4L-RNase 1 was observed. A related approach to engineer crystal contacts at helix 3 of RNase 1 (N4L-RNase 1) was also evaluated. N4L-RNase 1 also successfully crystallized, and formed the expected hydrophobic packing interface. These results suggest that appropriate introduction of a leucine zipper-like hydrophobic interface can promote intra molecular symmetry for more efficient protein crystallization in crystal lattice engineering efforts.
Inagaki, Manabu; Kato, Tomoko; Yoshida, Hideji*; Oyamada, Kiyoshi*; Fukaya, Yukiko*; Suzuki, Yuji*; Oi, Takao
JAEA-Research 2007-029, 81 Pages, 2007/03
JAEA-Research-2007-029.pdf:10.88MB
The project of high-level radioactive waste disposal is in activity for the site selection of HLW disposal facility and the performance assessment should be more site-specific rather than site-generic, where the applicability of the achievement of site-generic study such as second progress report (H12) to the site specific is to be clarified. In the same way, it is necessary for biosphere assessment to incorporate the site specific condition to the model. The exposure pathway or concentration of the radio nuclides should be determined according to the site specific geological condition, for example. In this paper, following topics have been selected to start the study to reflect specific geological condition to the biosphere modeling. (1) The literature survey of international and national approaches and issues relating to the treatment of GBIs within biosphere assessments, (2) To develop methodology to estimate the release point of the deep groundwater to the shallow accessible groundwater. (3) To prepare information to estimate water balance this is, in turn, necessary to assess the dilution and/or dispersion of the radionuclides in the shallow accessible groundwater body.
Ohara, Kazuhiro*; Kusano, Joichi; Inoue, Hitoshi*; Takaishi, Kazutoshi*; Yamada, Takayuki*; Ouchi, Nobuo; Ota, Tomoko*
Dai-50-Kai Sosei Kako Rengo Koenkai Koen Rombunshu, p.199 - 200, 1999/10
no abstracts in English
Itazu, Toru; Kato, Tomoko; Inagaki, Manabu; Maekawa, Keisuke; Suzuki, Yuji*; Oyamada, Kiyoshi*
no journal, ,
On the performance assessment of HLW Geological Disposal, we must evaluate the human impact of radionuclides delivered to the ground surface by groundwater flow, which evaluation requires the setting of pathways of the radionuclides and the estimation of dilution effect. In this presentation, for development of methodology for biosphere assessment modeling including the dilution effect with the site-specific information in the stage of site selection, we show the examination of the methodology through trial of groundwater flow analysis in surface and near-surface environment of Horonobe by using existing literature.
Murakami, Hiroshi; Sada, Tomoko; Yamada, Masako*; Harada, Masafumi*
no journal, ,
no abstracts in English
Murakami, Hiroshi; Sada, Tomoko; Yamada, Masako*; Harada, Masafumi*
no journal, ,
no abstracts in English
Murakami, Hiroshi; Yamada, Masako*; Sada, Tomoko; Harada, Masafumi*
no journal, ,
no abstracts in English
Murakami, Hiroshi; Sada, Tomoko; Yamada, Masako*; Harada, Masafumi*
no journal, ,
no abstracts in English
Murakami, Hiroshi; Sada, Tomoko*; Yamada, Masako*; Harada, Masafumi*
no journal, ,
no abstracts in English
-Lactamase TOHO-1 determined by combined high-resolution neutron and X-ray crystallographyKurihara, Kazuo; Sunami, Tomoko; Yamada, Mitsugu; Nitanai, Yasushi*; Okazaki, Nobuo; Adachi, Motoyasu; Tamada, Taro; Shimamura, Tatsuro*; Miyano, Masashi*; Ishii, Yoshikazu*; et al.
no journal, ,
To help resolve questions regarding the catalytic activity of -lactamase, the crystal structure of an unliganded form of the -lactamase Toho-1 with double mutation R274N/R276N (Toho-1/NN) has been determined by the use of high-resolution neutron and X-ray diffraction data. A large single crystal of Toho-1/NN with a dimension of 2.6 
2.5 1.3 mm
was used to collect 100 K neutron diffraction data to 1.5 
resolution and X-ray diffraction data to 1.4 resolution. The structural model of Toho-1/NN was refined to an R-factor of 19.7% using a program PHENIX. The structure showed that Glu166, a catalytic residue of Toho-1, was protonated even at pH 7 nonetheless for the close location to the positively charged side chain amino group (-NH3
) of Lys73. It is also found that there is a hydration water network bridging between the protonated Glu166 and the oxyanion hole comprising two main chain nitrogen atoms of Ser70 and Ser237. The neutron structure analysis also revealed the clear configuration of the proposed catalytic water molecule bridging Glu166 and Ser70. These observations are important to understand the catalytic action of -lactamase Toho-1.
Murakami, Hiroshi; Sada, Tomoko*; Yamada, Masako*; Harada, Masafumi*
no journal, ,
no abstracts in English
