Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Machida, Masahiko; Yamada, Susumu; Kim, M.; Okumura, Masahiko; Miyamura, Hiroko; Shikaze, Yoshiaki; Sato, Tomoki*; Numata, Yoshiaki*; Tobita, Yasuhiro*; Yamaguchi, Takashi; et al.
RIST News, (69), p.2 - 18, 2023/09
The contamination of radioactive materials leaked from the reactor has resulted in numerous hot spots in the Fukushima Daiichi Nuclear Power Station (1F) building, posing obstacles to its decommissioning. In order to solve this problem, JAEA has conducted research and development of the digital technique for inverse estimation of radiation source distribution and countermeasures against the estimated source in virtual space for two years from 2021 based on the subsidy program "Project of Decommissioning and Contaminated Water Management" performed by the funds from the Ministry of Economy, Trade and Industry. In this article, we introduce the results of the project and the plan of the renewal project started in April 2023. For the former project, we report the derivative method for LASSO method considering the complex structure inside the building and the character of the source and show the result of the inverse estimation using the method in the real reactor building. Moreover, we explain the platform software "3D-ADRES-Indoor" which integrates these achievements. Finally, we introduce the plan of the latter project.
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：43 Percentile：96.93(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.
Sakurai, Hideyuki*; Okamoto, Masahiko*; Shin, Masako*; Takeuchi, Aiko*; Hasegawa, Masatoshi*; Sato, Takahiro; Oikawa, Masakazu*; Kamiya, Tomihiro; Arakawa, Kazuo; Nakano, Takashi*
no journal, ,
no abstracts in English
Al-Jahdari, W. S.*; Suzuki, Yoshiyuki*; Yoshida, Yukari*; Hamada, Nobuyuki*; Okamoto, Masahiko*; Noda, Shinei*; Funayama, Tomoo; Sakashita, Tetsuya; Kobayashi, Yasuhiko; Nakano, Takashi*
no journal, ,
Okamoto, Masahiko*; Sakurai, Hideyuki*; Shin, Masako*; Hasegawa, Masatoshi*; Oikawa, Masakazu*; Sato, Takahiro; Kamiya, Tomihiro; Arakawa, Kazuo; Nakano, Takashi*
no journal, ,
no abstracts in English
Hasegawa, Masatoshi*; Sakurai, Hideyuki*; Shin, Masako*; Okamoto, Masahiko*; Ishiuchi, Shogo*; Asakawa, Isao*; Tamamoto, Tetsuo*; Ono, Tatsuya*; Oikawa, Masakazu*; Kamiya, Tomihiro; et al.
no journal, ,
no abstracts in English
