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.

Design of HTTR-GT/H test plant

Yan, X.; Sato, Hiroyuki; Sumita, Junya; Nomoto, Yasunobu*; Horii, Shoichi*; Imai, Yoshiyuki; Kasahara, Seiji; Suzuki, Koichi*; Iwatsuki, Jin; Terada, Atsuhiko; et al.

Nuclear Engineering and Design, 329, p.223 - 233, 2018/04

https://doi.org/10.1016/j.nucengdes.2017.10.009

The pre-licensing design of an HTGR cogeneration test plant to be coupled to JAEA's existing test reactor HTTR is presented. The plant is designed to demonstrate the system of JAEA commercial plant design GTHTR300C. With construction planned to be completed around 2025, the test plant is expected to be the first-of-a-kind nuclear system operating on two of the advanced energy conversion systems attractive for the HTGR closed cycle helium gas turbine for power generation and thermochemical iodine-sulfur water-splitting process for hydrogen production.

Crystal structures and magnetic properties of nickel chain compounds PbMNiTeO (M = Mn, Cd)

Doi, Yoshihiro*; Suzuki, Ryo*; Hinatsu, Yukio*; Kodama, Katsuaki; Igawa, Naoki

Inorganic Chemistry, 54(22), p.10725 - 10731, 2015/11

https://doi.org/10.1021/acs.inorgchem.5b01619

Enhancement of the methodology of repository design and post-closure performance assessment for preliminary investigation stage, 3; Progress report on NUMO-JAEA collaborative research in FY2013 (Joint research)

Shibata, Masahiro; Sawada, Atsushi; Tachi, Yukio; Makino, Hitoshi; Wakasugi, Keiichiro; Mitsui, Seiichiro; Kitamura, Akira; Yoshikawa, Hideki; Oda, Chie; Ishidera, Takamitsu; et al.

JAEA-Research 2014-030, 457 Pages, 2015/03

JAEA-Research-2014-030.pdf:199.23MB

JAEA and NUMO have conducted a collaborative research work which is designed to enhance the methodology of repository design and post-closure performance assessment in preliminary investigation stage. With regard to (1) study on rock suitability in terms of hydrology, based on some examples of developing method of hydro-geological structure model, acquired knowledge are arranged using the tree diagram, and model uncertainty and its influence on the evaluation items were discussed. With regard to (2) study on scenario development, the developed approach for "defining conditions" has been reevaluated and improved from practical viewpoints. In addition, the uncertainty evaluation for the effect of use of cementitious material, as well as glass dissolution model, was conducted with analytical evaluation. With regard to (3) study on setting radionuclide migration parameters, based on survey of precedent procedures, multiple-approach for distribution coefficient of rocks was established, and the adequacy of the approach was confirmed though its application to sedimentary rock and granitic rock. Besides, an approach for solubility setting was developed including the procedure of selection of solubility limiting solid phase. The adequacy of the approach was confirmed though its application to key radionuclides.

Gap junction communication and the propagation of bystander effects induced by microbeam irradiation in human fibroblast cultures; The Impact of radiation quality

Autsavapromporn, N.*; Suzuki, Masao*; Funayama, Tomoo; Usami, Noriko*; Plante, I.*; Yokota, Yuichiro; Muto, Yasuko*; Ikeda, Hiroko; Kobayashi, Katsumi*; Kobayashi, Yasuhiko; et al.

Radiation Research, 180(4), p.367 - 375, 2013/10

https://doi.org/10.1667/RR3111.1

We investigated the role of gapjunction intercellular communication (GJIC) in the propagation of stressful effects in confluent normal human fibroblast cultures wherein only 0.036-0.144% of cells in the population were traversed by primary radiation tracks. Confluent cells were exposed to graded doses from X ray, carbon ion, neon ion or argon ion microbeams in the presence or absence of an inhibitor of GJIC. After 4 h incubation, the cells were assayed for micronucleus (MN) formation. Micronuclei were induced in a greater fraction of cells than expected based on the fraction of cells targeted by primary radiation, and the effect occurred in a dose-dependent manner with any of the radiation sources. Interestingly, the inhibition of GJIC depressed the enhancement of MN formation in bystander cells from cultures exposed to high-LET radiation but not low-LET radiation. The results highlight the important role of radiation quality and dose in the observed effects.

Enhancement of the methodology of repository design and post-closure performance assessment for preliminary investigation stage; Progress report on NUMO-JAEA collaborative research in FY2011 (Joint research)

Shibata, Masahiro; Sawada, Atsushi; Tachi, Yukio; Makino, Hitoshi; Hayano, Akira; Mitsui, Seiichiro; Taniguchi, Naoki; Oda, Chie; Kitamura, Akira; Osawa, Hideaki; et al.

JAEA-Research 2012-032, 298 Pages, 2012/09

JAEA-Research-2012-032.pdf:33.68MB

JAEA and NUMO have conducted a collaborative research work which is designed to enhance the methodology of repository design and performance assessment in preliminary investigation phase. The topics and the conducted research are follows; (1) Study on selection of host rock: in terms of hydraulic properties, items for assessing rock property, and assessment methodology of groundwater travel time has been organized with interaction from site investigation. (2) Study on development of scenario: the existing approach has been embodied, in addition, the phenomenological understanding regarding dissolution of and nuclide release from vitrified waste, corrosion of the overpack, long-term performance of the buffer are summarized. (3) Study on setting nuclide migration parameters: the approach for parameter setting has been improved for sorption and diffusion coefficient of buffer/rock, and applied and tested for parameter setting of key radionuclides. (4) Study on ensuring quality of knowledge: framework for ensuring quality of knowledge has been studied and examined aimed at the likely disposal facility condition.

Residual stress measurement of large scaled welded pipe using neutron diffraction method; Effect of SCC crack propagation and repair weld on residual stress distribution

Suzuki, Hiroshi; Katsuyama, Jinya; Tobita, Toru; Morii, Yukio*

Yosetsu Gakkai Rombunshu (Internet), 29(4), p.294 - 304, 2011/12

https://doi.org/10.2207/qjjws.29.294

The RESA-1 neutron engineering diffractometer in the JRR-3 (Japan Research Reactor No.3) at the Japan Atomic Energy Agency, which is used for stress measurements, was upgraded to realize residual stress measurements of large scaled mechanical components. A series of residual stress measurements was made to obtain through-thickness residual stress distributions in a Type 304 stainless steel butt-welded pipe of 500A-sch.80 using the upgraded RESA-1 diffractometer. We evaluated effects of crack propagation such as stress corrosion cracking (SCC) and a part-circumference repair weld on the residual stress distributions induced by girth welding. Measured residual stress distributions near original girth weld revealed good agreement with typical results shown in some previous works using finite element method, deep hole drilling as well as neutron diffraction. After introducing a mock crack with 10 mm depth in heat affected zone on the inside wall of the pipe by electro discharge method, the axial residual stresses were found to be released in the part of the mock crack. However, changes in the through-wall bending stress component and the self-equilibrated stress component were negligible and hence the axial residual stress distribution in the ligament was remained in the original residual stresses near girth weld without the mock crack. Furthermore, changes in hoop and radial residual stress were also small. The residual stress distributions after a part repair welding on outer circumference of girth weld were significantly different from residual stress distributions near the original girth weld. Membrane residual stress was increased in the axial direction since the bending moment near the heat affected zone was changed due to repair weld. Throughout above studies, we evidenced that the neutron diffraction technique is useful and powerful tool for measuring residual stress distributions in large as well as thick mechanical components.

Development of new molybdenum adsorbent

Kimura, Akihiro; Tanimoto, Masataka; Ishida, Takuya; Tsuchiya, Kunihiko; Hasegawa, Yoshio*; Hishinuma, Yukio*; Suzuki, Masashi*

JAEA-Technology 2011-012, 17 Pages, 2011/06

JAEA-Technology-2011-012.pdf:1.72MBJP, 2010-263801   Patent publication (In Japanese)

PZC (Poly-Zirconium Compound) was developed as adsorbent of molybdenum for Mo-Tc generator. However, PZC has some faults. So, new adsorbent based on titanium (PTC), was developed for getting rid of faults. This time, Mo adsorption and Tc elution tests with PZC and PTC were carried out. As a result, the Mo adsorption performance of the PTC was lower than PZC, on the other hand, Tc elution performance of the PTC was higher than PZC.

Report of ITPA (International Tokamak Physics Activity) meetings, 21

Kawahata, Kazuo*; Kawano, Yasunori; Kusama, Yoshinori; Mase, Atsushi*; Sasao, Mamiko*; Ide, Shunsuke; Oikawa, Toshihiro; Suzuki, Takahiro; Takase, Yuichi*; Nakamura, Yukio*; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 84(5), p.297 - 298, 2008/05

http://www.jspf.or.jp/Journal/PDF_JSPF/jspf2008_05/jspf2008_05-297.pdf

no abstracts in English

Report of meetings of ITPA (International Tokamak Physics Activity), 19

Sasao, Mamiko*; Kusama, Yoshinori; Kawano, Yasunori; Kawahata, Kazuo*; Mase, Atsushi*; Sugie, Tatsuo; Fujita, Takaaki; Fukuda, Takeshi*; Fukuyama, Atsushi*; Sakamoto, Yoshiteru; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 83(9), p.779 - 782, 2007/09

http://ci.nii.ac.jp/naid/40015654514

This is a report of highlights from 2007 spring meetings of seven Topical Groups (TG) of International Tokamak Physics Activity (ITPA). In each meeting, high priority issues in physics of International Thermonuclear Experimental Reactor (ITER) and other burning plasma experiments have been discussed and investigated. Twenty-seven scientists from Japan have participated in those meetings. Dates and places of the meetings are shown below. (1) Diagnostics TG: 26-30 March, Princeton (USA), (2) Transport Physics TG: 7-10 May, Lausanne (Switzerland), (3) Confinement Database and Modeling TG: 7-10 May, Lausanne (Switzerland), (4) Edge Pedestal Physics TG: 7-10 May, Garching (Germany) (5) Steady State Operation TG: 9-11 May, Daejeon (South Korea), (6)MHD TG: 21-24 May, San Diego (USA), (7) Scrape-off-layer and Divertor Physics TG: 7-10 May, Garching (Germany).