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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.
Fukushima, Manabu; Owada, Minoru; Ota, Kazunori; Takeuchi, Masaki; Goto, Shingo; Imahashi, Masaki; Terakado, Yoshibumi
JAEA-Technology 2010-028, 24 Pages, 2010/09
JAEA-Technology-2010-028.pdf:1.01MB
The cooling tower of the JRR-3's secondary cooling system is used to emit the heat from the core into the atmosphere. The appropriate maintenance of the cooling tower has helped the safe and stable reactor operation. Temperature of the secondary coolant had controlled constantly by changing the number of cooling fans. But, just after the number of fans changed, the temperature changed transiently and consequently the reactor thermal power changed. In order to amend this some weakness, the control system has improved to change the speed of fans constantly. The maintenance and improvement activities with the records of inspection are compiled to be utilized for future work.
Oba, Toshinobu; Fukushima, Manabu; Takeuchi, Masaki; Uno, Yuki; Owada, Minoru; Terakado, Yoshibumi
JAEA-Technology 2010-020, 31 Pages, 2010/07
JAEA-Technology-2010-020.pdf:1.33MB
Japan research reactor No.3 (JRR-3) has a heavy water tank. The heavy water tank surrounds the reactor core to use thermalize neutrons for experiments. The heavy water cooling system removes the heat generated by 
ray in the heavy water reflector. The heavy water cooling system is composed of the cooling system and the helium gas system. The helium gas system has an important role of helium gas circulation. The helium gas system also has a role to recombine deuterium gas and oxygen gas. We had overhauled the helium compressor regularly and replaced consumable parts. However, in recent year, the helium compressor had sometimes stopped by the leakage of seal oil. In 2007, we refurbished the helium compressor with new one. This report describes refurbishment of helium compressor.
Ota, Kazunori; Ikekame, Yoshinori; Owada, Minoru; Fukushima, Manabu; Oba, Toshinobu; Takeuchi, Masaki; Imahashi, Masaki; Murayama, Yoji
JAEA-Technology 2008-023, 31 Pages, 2008/03
JAEA-Technology-2008-023.pdf:3.3MB
JRR-3 uses shell and tube heat exchangers. The secondary coolant flushes into the tubes and the primary coolant flows outside of the tubes. The heat exchangers are cleaned with the ball-cleaning method, which is a method to clean inside of the tubes by passing the sponge balls with secondary coolant. Decline in the performance of heat exchanger could rise temperature of the primary coolant and then influence the safe and stable reactor operation. The effective way of ball-cleaning for JRR-3 heat exchangers is examined based on past cleaning data. The results show the optimal ball size and the way to determine the cleaning time.
Hama, Katsuhiro; Takahashi, Kazuharu; Ishii, Eiichi; Takeuchi, Ryuji; Sasaki, Manabu; Kunimaru, Takanori; Matsui, Hiroya
JNC TN5400 2003-002, 61 Pages, 2003/08
JNC-TN5400-2003-002.pdf:5.42MBJNC-TN5400-2003-002(errata).pdf:0.08MB
The working program for deep borehole investigations (HDB-6,7,8 boreholes).
Tobita, Kenji; Tani, Keiji; Neyatani, Yuzuru; A.A.E.VanBlokland*; *; Fujita, Takaaki; Takeuchi, Hiroshi; Nishitani, Takeo; Matsuoka, Mamoru; *
Physical Review Letters, 69(21), p.3060 - 3063, 1992/11
Times Cited Count：49 Percentile：86.13(Physics, Multidisciplinary)no abstracts in English
*; Minehara, Eisuke; *
JAERI-M 91-074, 28 Pages, 1991/05
no abstracts in English
superconductor powders*; *; *; Minehara, Eisuke
JAERI-M 91-029, 26 Pages, 1991/03
no abstracts in English
Minehara, Eisuke; *; *; *
J. Supercond., 3(3), p.277 - 280, 1990/00
no abstracts in English
superconductors to FEL accelerator componentsMinehara, Eisuke; *; *
Nuclear Instruments and Methods in Physics Research A, 296, p.707 - 709, 1990/00
Times Cited Count：1 Percentile：34.83(Instruments & Instrumentation)no abstracts in English
superconducting microwave elements and their measurements of the microwave propertiesMinehara, Eisuke; *; *
SCE-89-6, p.39 - 42, 1989/04
no abstracts in English
microwave cavity made of YBa
Cu
O
Minehara, Eisuke; *; *
Japanese Journal of Applied Physics, 28(1), p.L100 - L101, 1989/01
Times Cited Count：3 Percentile：23.67(Physics, Applied)no abstracts in English
Minehara, Eisuke; *; *
Dai-13-Kai Riniakku Kenkyukai Hokokushu, p.220 - 221, 1988/00
no abstracts in English
superconductorsMinehara, Eisuke; *; *
Proc. Surface Engineering Int. Conf., p.249 - 254, 1988/00
no abstracts in English
n eigenmode dampingMatsunaga, Go; Toi, Kazuo*; Ikeda, Ryosuke*; Takeuchi, Masaki*; Takechi, Manabu; Nakajima, Noriyoshi*; Fukuyama, Atsushi*
no journal, ,
no abstracts in English
Oba, Toshinobu; Owada, Minoru; Fukushima, Manabu; Takeuchi, Masaki; Uno, Yuki; Murayama, Yoji
no journal, ,
no abstracts in English
Ishizaki, Katsuhiko; Ota, Kazunori; Takeuchi, Masaki; Imahashi, Masaki; Fukushima, Manabu
no journal, ,
no abstracts in English
