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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:30 Percentile:96.87(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.
Nishihara, Kenji; Yamagishi, Isao; Yasuda, Kenichiro; Ishimori, Kenichiro; Tanaka, Kiwamu; Kuno, Takehiko; Inada, Satoshi; Goto, Yuichi
Journal of Nuclear Science and Technology, 52(3), p.301 - 307, 2015/03
Times Cited Count:17 Percentile:81.3(Nuclear Science & Technology)After the severe accident at the Fukushima-1 nuclear power plant, large amounts of contaminated stagnant water have accumulated in turbine buildings and their surroundings. This rapid communication reports calculation of the radionuclide inventory in the core, collection of measured inventory in the stagnant water, and estimation of radionuclide release ratios from the core to the stagnant water. This evaluation is based on data obtained before June 3, 2011. The release ratios of tritium, iodine, and cesium were several tens of percent, whereas those of strontium and barium were smaller by one or two orders of magnitude. The release ratios in the Fukushima accident were equivalent to those in the TMI-2 accident.
Nishihara, Kenji; Yamagishi, Isao; Yasuda, Kenichiro; Ishimori, Kenichiro; Tanaka, Kiwamu; Kuno, Takehiko; Inada, Satoshi; Goto, Yuichi
Nihon Genshiryoku Gakkai Wabun Rombunshi, 11(1), p.13 - 19, 2012/03
After the severe accident in the Fukushima-1 Nuclear Power Plant, large amount of contaminated stagnant water has been produced in turbine buildings and those surroundings. This rapid communication reports calculation of radionuclide inventory in the core, collection of measured inventory in the stagnant water, and estimation of radionuclide release ratios from the core to the stagnant water. The present evaluation is based on data obtained before June 3, 2011.
Ishihara, Takehiko
Genshiryoku Kogyo, 21(10), p.1 - 5, 1975/10
no abstracts in English
; Ishihara, Takehiko
JAERI-M 4751, 82 Pages, 1972/03
no abstracts in English
; Ishihara, Takehiko
JAERI-M 4497, 38 Pages, 1971/07
no abstracts in English
; Ishihara, Takehiko;
Journal of Nuclear Science and Technology, 4(6), p.317 - 318, 1967/00
no abstracts in English
; Ishihara, Takehiko
Journal of Nuclear Science and Technology, 4(7), p.353 - 360, 1967/00
Times Cited Count:6no abstracts in English
; ; Ishihara, Takehiko
Kogyo Kagaku Zasshi, 70(5), p.622 - 628, 1967/00
no abstracts in English
; Ishihara, Takehiko
Journal of Inorganic and Nuclear Chemistry, 28(10), p.2343 - 2345, 1966/00
Times Cited Count:7no abstracts in English
Ishihara, Takehiko;
Journal of Nuclear Science and Technology, 3(1), p.20 - 26, 1966/00
no abstracts in English
Ishihara, Takehiko;
Journal of Nuclear Science and Technology, 3(2), p.67 - 71, 1966/00
no abstracts in English
; Ishihara, Takehiko
Journal of Nuclear Science and Technology, 3(4), p.144 - 149, 1966/00
Times Cited Count:16no abstracts in English
Ishihara, Takehiko;
Journal of Nuclear Science and Technology, 3(6), p.243 - 248, 1966/00
no abstracts in English
; Ishihara, Takehiko
Journal of Nuclear Science and Technology, 3(8), p.320 - 325, 1966/00
Times Cited Count:19no abstracts in English
Ishihara, Takehiko;
Practices in the Treatment of Low- and Intermediate-Level Radioactive Wastes(IAEA), p.207 - 222, 1966/00
no abstracts in English
Ishihara, Takehiko
Genshiryoku Kogyo, 11(2), p.61 - 64, 1965/00
no abstracts in English
Ishihara, Takehiko
Genshiryoku Kogyo, 11(8), p.36 - 40, 1965/00
no abstracts in English
Ishihara, Takehiko
Genshiryoku Kogyo, 11(11), p.1 - 6, 1965/00
no abstracts in English
Ishihara, Takehiko;
Journal of Nuclear Science and Technology, 2(11), p.463 - 467, 1965/00
Times Cited Count:7no abstracts in English