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Am
O
at 1473, 1573, and 1673 KWatanabe, Masashi; Yokoyama, Keisuke; Vauchy, R.; Kato, Masato; Sugata, Hiromasa*; Seki, Takayuki*; Hino, Tetsushi*
Journal of Nuclear Materials, 599, p.155232_1 - 155232_5, 2024/10
Oxygen potential data of UAmO
were measured at 1473, 1573, and 1673 K by thermogravimetry. In U
An
O, where An stands for Pu or Am, and for a given value of y and Oxygen/Metal ratio, the oxygen potential of UAmO is higher than that of UPuO. The valence of cations in the hypostoichiometric region is similar to that of Nd-doped UO. At the stoichiometric composition, it is estimated to be Am
, U
, and U
(for charge compensation of Am). The experimental data were analyzed using a defect chemistry model, and a relationship connecting the oxygen-to-metal ratio, the temperature, and the equilibrium oxygen partial pressure was proposed.
Nakayama, Masataka; Abe, Yukiko; Atarashi-Andoh, Mariko; Tange, Takeshi*; Sawada, Haruo*; Liang, N.*; Koarashi, Jun
Applied Soil Ecology, 201, p.105485_1 - 105485_12, 2024/09
Nitrogen often limits plant growth in forest ecosystems. Plants, including trees, change vertical root distribution when nutrient competition is strong within surface soil layer and take up nitrogen even from subsurface soil layers in addition to the surface soil. However, there is still limited knowledge about nitrogen cycles within deeper soil layers. In this study, we investigated the vertical profiles (0-60 cm) of the net nitrogen mineralization and nitrification rates at four Japanese forest sites with two different soil types (Andosols and Cambisols). The partial least square path modeling (PLS-PM) was used to determine factors affecting nitrogen-cycling processes. The net nitrogen mineralization and nitrification rates per unit soil weight were considerably higher in surface soil layer than in deeper soil layers in Andosols but not in Cambisols. PLS-PM analysis showed that microbial biomass and soil organic matter quantities were the main factors influencing the net nitrogen mineralization and nitrification rates, indicating that a similar mechanism creating the spatial variations of nitrogen-cycling processes in surface soil layer predominantly regulates the processes in subsoil layers. Moreover, it was estimated that the net nitrogen mineralization rate could be comparable at all soil types and depths when the rate was expressed per unit soil volume. Therefore, our results suggest that subsoil layers are a quantitatively important nitrogen source for plant nutrients in Andosols and Cambisols, supporting high forest productivity.
Nakahara, Masaumi; Watanabe, So; Ishii, Yasuyuki*; Yamagata, Ryohei*; Yuri, Yosuke*; Yuyama, Takahiro*; Ishizaka, Tomohisa*; Koka, Masashi*; Yamada, Naoto*; Hagura, Naoto*
Nuclear Instruments and Methods in Physics Research B, 554, p.165449_1 - 165449_5, 2024/09
Ion beam induced luminescence analysis of lanthanide complexes in the organic solvents for minor actinides recovery process was carried out to investigate the structures of complexes. In this study, hydrogen ion beam obtained from the single-ended accelerator and argon ion beam obtained from the azimuthally varying field cyclotron were used in Takasaki Ion Accelerators for Advanced Radiation Application in National Institutes for Quantum Science and Technology. In the experiments, ion beam induced luminescence spectra of lanthanide complexes in the organic solvents were measured, and the relationship between the obtained spectra and the structures of complexes was studied.
Arai, Yoichi; Watanabe, So; Watanabe, Masayuki; Arai, Tsuyoshi*; Katsuki, Kenta*; Agou, Tomohiro*; Fujikawa, Hisaharu*; Takeda, Keisuke*; Fukumoto, Hiroki*; Hoshina, Hiroyuki*; et al.
Nuclear Instruments and Methods in Physics Research B, 554, p.165448_1 - 165448_10, 2024/09
He, X.*; Kagi, Hiroyuki*; Komatsu, Kazuki*; Iizuka, Riko*; Okajima, Hajime*; Hattori, Takanori; Sano, Asami; Machida, Shinichi*; Abe, Jun*; Goto, Hirotada*; et al.
Journal of Molecular Structure, 1310, p.138271_1 - 138271_8, 2024/08
High-pressure responses of the O-D
F hydrogen bonds in deuterated magnesium hydroxyfluoride were investigated using neutron powder diffraction and Raman spectroscopy. The Rietveld analysis at ambient conditions revealed a chemical formula of Mg(OD)
F
and hydroxyl group/fluorine disorder (OD/F disorder) in the crystal structure, which gave rise to two hydrogen-bonding configurations. The Rietveld analysis showed the hydrogen-bonding geometries remains up to 9.8 GPa, indicating no pressure-induced strengthening of hydrogen bonds. The Raman spectra at ambient conditions showed three hydroxyl stretching bands at 2613, 2694, and 2718 cm
. The high frequencies of the O-D stretching modes indicated that the hydroxyls should be involved in weak or none hydrogen-bonding interactions. Up to 20.2 GPa, the mode initially centered at 2694 cm displayed a pressure-induced blue shift, revealing no strengthening of hydrogen bonds under compression. We discuss the existence of hydrogen bonds and the causes of the blue-shifting hydroxyls at ambient and at high pressures.
Lan, Z.*; Arikawa, Yasunobu*; Mirfayzi, S. R.*; Morace, A.*; Hayakawa, Takehito*; Sato, Hirotaka*; Kamiyama, Takashi*; Wei, T.*; Tatsumi, Yuta*; Koizumi, Mitsuo; et al.
Nature Communications (Internet), 15, p.5365_1 - 5365_7, 2024/07
Nemoto, Takahiro; Fujiwara, Yusuke; Arakawa, Ryoki; Choyama, Yuya; Nagasumi, Satoru; Hasegawa, Toshinari; Yokoyama, Keisuke; Watanabe, Masashi; Onishi, Takashi; Kawamoto, Taiki; et al.
JAEA-Technology 2024-003, 17 Pages, 2024/06
JAEA-Technology-2024-003.pdf:1.91MB
In order to investigate the cause of the increase in differential pressure in the primary helium circulator filter that occurred during the RS-14 cycle, a clogged filter was investigated. As a result of the investigation, deposits caused by silicone oil were confirmed on the surface of the filter element. These results revealed that the cause of filter clogging was silicone oil mixed into the primary system due to performance deterioration of the charcoal filter in the gas circulator of primary helium purification system. As a measure to prevent the recurrence of this event, in addition to the conventional management based on operating hours for replacing of charcoal filter in the gas circulator of primary helium purification system, we have established a new replacement plan for every three years.
O
/U
O
redox equilibrium in [emim]TfN-based liquid electrolytes towards uranium redox-flow batteryTakao, Koichiro*; Ouchi, Kazuki; Komatsu, Atsushi; Kitatsuji, Yoshihiro; Watanabe, Masayuki
European Journal of Inorganic Chemistry, 27(14), p.e202300787_1 - e202300787_7, 2024/05
Electrochemical behavior of U
O/U
O in 1-ethyl-3-methylimidazolium bis(trifluoromethyl)sulfonylamide ([emim]TfN) ionic liquid was studied to clarify what are required to attain its redox reversibility for utilizing depleted U as an electrode active material in a redox flow battery. As a result, reversibility of the UO/UO redox reaction was successfully achieved in use of a glassy carbon working electrode under presence of Cl
in [emim]TfN. To improve diffusivity of solutes, [emim]TfN diluted with an auxiliary molecular solvent, N,N-dimethylformamide (DMF). We have succeeded in demonstrating a reversible redox reaction of [UOCl
]
+ e = [UOCl]
in the 50:50 v/v [emim]TfN-DMF liquid electrolyte containing Cl.
Ishikado, Motoyuki*; Takahashi, Ryuta*; Yamauchi, Yasuhiro*; Nakamura, Masatoshi*; Ishimaru, Sora*; Yamauchi, Sara*; Kawamura, Seiko; Kira, Hiroshi*; Sakaguchi, Yoshifumi*; Watanabe, Masao; et al.
JPS Conference Proceedings (Internet), 41, p.011010_1 - 011010_7, 2024/05
Sanada, Yukihisa; Abe, Tomohisa; Sasaki, Miyuki; Kanno, Marina*; Yamada, Tsutomu*; Nakasone, Takamasa*; Miyazaki, Nobuyuki*; Oshikiri, Keisuke*; Watabe, Hiroshi*
Journal of Nuclear Science and Technology, 61(5), p.693 - 702, 2024/05
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)The "treated water" from which the main radioactive materials were removed contains tritium, and stakeholders in Japan have been debating how to treat it. The amount of treated water stored in the facility has reached its limit, and the Japanese government has decided that the treatment method will be to discharge the water into the ocean by FY 2023 (FY: Fiscal Year). The present research developed a simple and practical tritium monitor for the Fukushima Daiichi Nuclear Power Station (FDNPS) tritiated water release. A simple and practical tritium monitor was developed for FDNPS tritiated water release based on thin plastic scintillator sheets. The developed devices were calibrated using standard tritium solutions and a method for calculating the minimum detectable activity. Fifteen 0.25 mm-thick scintillators can be placed in the 0.26 L flow cell where the sample water is fed, yielding an active surface area of 3,200 mm
. The efficiency of tritiated water with full water is 0.000035 cps Bq. The minimum detectable activity under simple shielding conditions was 7,800 Bq L (Measurement time was 3,600 s).
Kato, Masato; Oki, Takumi; Watanabe, Masashi; Hirooka, Shun; Vauchy, R.; Ozawa, Takayuki; Uwaba, Tomoyuki; Ikusawa, Yoshihisa; Nakamura, Hiroki; Machida, Masahiko
Journal of the American Ceramic Society, 107(5), p.2998 - 3011, 2024/05
Times Cited Count：0 Percentile：0.01(Materials Science, Ceramics)Sanada, Yukihisa; Oshikiri, Keisuke*; Kanno, Marina*; Abe, Tomohisa
Nuclear Instruments and Methods in Physics Research A, 1062, p.169208_1 - 169208_7, 2024/05
As part of the decommissioning work at the Fukushima Daiichi Nuclear Power Plant (FDNPP), the release of stored treated water began in 2023. In this study, we developed a practical tritium monitor to continuously monitor the concentration of tritiated water, as confirmed by batch sampling measurements at the FDNPP. The monitor is arranged with a flow cell detector comprising inexpensive plastic scintillator pellets and incorporating simultaneous measurements by three detectors, a veto detector, and lead shielding to reduce the influence of environmental 
-rays. The system reached a detection limit of 911 Bq L-1 with a measurement time of 30 min, which is lower than the discharge standard for tritiated water of 1,500 Bq L-1. The system can also qualitatively distinguish the presence of disturbances due to interfering radionuclides other than tritium or background radiation using the 
-ray spectrum.
Be and 
Al under direct muon-induced spallation in granite quartz and its implications for past high-energy cosmic ray fluxesSakurai, Hirohisa*; Kurebayashi, Yutaka*; Suzuki, Soichiro*; Horiuchi, Kazuho*; Takahashi, Yui*; Doshita, Norihiro*; Kikuchi, Satoshi*; Tokanai, Fuyuki*; Iwata, Naoyoshi*; Tajima, Yasushi*; et al.
Physical Review D, 109(10), p.102005_1 - 102005_18, 2024/05
Secular variations of galactic cosmic rays (GCRs) are inseparably associated with the galactic activities and should reflect the environments of the local galactic magnetic field, interstellar clouds, and nearby supernova remnants. The high-energy muons produced in the atmosphere by high-energy GCRs can penetrate deep underground and generate radioisotopes in the rock. As long lived radionuclides such as Be and Al have been accumulating in these rocks, concentrations of Be and Al can be used to estimate the long-term variations in high-energy muon yields, corresponding to those in the high-energy GCRs over a few million years. This study measured the production cross sections for muon induced Be and Al by irradiating positive muons with the momentum of 160 GeV/c on the synthetic silica plates and the granite core at the COMPASS experiment line in CERN SPS. In addition, it the contributions of the direct muon spallation reaction and the nuclear reactions by muon-induced particles on the production of long lived radionuclides in the rocks were clarified.
Deng, Y.*; Watanabe, Yukinobu*; Manabe, Seiya*; Liao, W.*; Hashimoto, Masanori*; Abe, Shinichiro; Tampo, Motonobu*; Miyake, Yasuhiro*
IEEE Transactions on Nuclear Science, 71(4, Part 2), p.912 - 920, 2024/04
With the miniaturization of semiconductors and the decrease in operating voltage, there is a growing interest and discussion in whether the muons in cosmic rays may be the source of single event upsets (SEUs). In the case of neutron-induced SEUs, it was reported that the irradiation side has the impact on SEU cross sections. Here, to investigate the impact of irradiation direction on muon-induced SEUs, we have measured and simulate muon-induced SEUs in 65-nm bulk SRAMs with different muon irradiation directions. It was found that the peak SEU cross section for the package side irradiation is about twice large as that for the board side irradiation. We also revealed that the difference in observed SEU cross sections between the package side and the board side irradiation is caused by differences in energy straggling due to changes in penetration depth depending on the incident direction.
Hasegawa, Kenta; Goto, Ichiro*; Miyazaki, Yasunori; Ambai, Hiromu; Watanabe, So; Watanabe, Masayuki; Sano, Yuichi; Takeuchi, Masayuki
Mechanical Engineering Journal (Internet), 11(2), p.23-00407_1 - 23-00407_8, 2024/04
Watanabe, So; Takahatake, Yoko; Hasegawa, Kenta; Goto, Ichiro*; Miyazaki, Yasunori; Watanabe, Masayuki; Sano, Yuichi; Takeuchi, Masayuki
Mechanical Engineering Journal (Internet), 11(2), p.23-00461_1 - 23-00461_10, 2024/04
Funakoshi, Tomomasa; Watanabe, So; Arai, Yoichi; Iwamoto, Toshihiro; Watanabe, Masayuki; Nishimoto, Yoshihiro*; Yasuda, Makoto*
Mechanical Engineering Journal (Internet), 11(2), p.23-00445_1 - 23-00445_7, 2024/04
Iwamoto, Toshihiro; Saito, Madoka*; Takahatake, Yoko; Watanabe, So; Watanabe, Masayuki; Naruse, Atsuki*; Tsukahara, Takehiko*
Mechanical Engineering Journal (Internet), 11(2), p.23-00444_1 - 23-00444_7, 2024/04
-odd/
-odd interactions on the 0.75 eV 
-wave resonance in 
+
forward transmission determined using a pulsed neutron beamNakabe, Rintaro*; Auton, C. J.*; Endo, Shunsuke; Fujioka, Hiroyuki*; Gudkov, V.*; Hirota, Katsuya*; Ide, Ikuo*; Ino, Takashi*; Ishikado, Motoyuki*; Kambara, Wataru*; et al.
Physical Review C, 109(4), p.L041602_1 - L041602_4, 2024/04
-wave resonance of 
+
Okudaira, Takuya*; Nakabe, Rintaro*; Auton, C. J.*; Endo, Shunsuke; Fujioka, Hiroyuki*; Gudkov, V.*; Ide, Ikuo*; Ino, Takashi*; Ishikado, Motoyuki*; Kambara, Wataru*; et al.
Physical Review C, 109(4), p.044606_1 - 044606_9, 2024/04
