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Koizumi, Mitsuo; Ito, Fumiaki*; Lee, J.; Hironaka, Kota; Takahashi, Tone; Suzuki, Satoshi*; Arikawa, Yasunobu*; Abe, Yuki*; Wei, T.*; Yogo, Akifumi*; et al.
Dai-45-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 4 Pages, 2024/11
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
Times Cited Count：2 Percentile：82.00(Materials Science, Multidisciplinary)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.
Ishikawa, Akihisa; Tanaka, Hiroki*; Nakamura, Satoshi*; Kumada, Hiroaki*; Sakurai, Yoshinori*; Watanabe, Kenichi*; Yoshihashi, Sachiko*; Tanagami, Yuki*; Uritani, Akira*; Kiyanagi, Yoshiaki*
Journal of Radiation Research (Internet), 11 Pages, 2024/10
Times Cited Count：0Yoshida, Naoki; Ono, Takuya; Amano, Yuki; Yoshida, Ryoichiro; Abe, Hitoshi; Yamane, Yuichi
Nuclear Technology, 210(10), p.1999 - 2007, 2024/10
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)A malfunction of the cooling system of high-level liquid waste (HLLW) and failure of countermeasures may lead to the "evaporation to dryness due to the loss of cooling functions" (EDLCF) of HLLW. In the EDLCF, ruthenium (Ru) can be released at a greater fraction to initial amount than other elements in HLLW by forming gaseous Ru. It is important to identify the chemical form of the released gaseous Ru to achieve a comprehensive understanding of the events impacting the source term assessment of Ru in this accident, such as particle formation, gas absorption and deposition on migration pathways. In this study, we observed the ultraviolet/visible spectroscopy of the off-gas generated during the heating of an HLLW simulant. Employing a program that allows the separation and quantification of known components within the spectrum (ruthenium tetroxide (RuO
), nitrogen dioxide, and nitric acid), we attempted to analyze the composition of gaseous Ru within the generated off-gas. Our findings reveal RuO as the main component of the gaseous Ru in off-gas after comparing the total amount of released Ru and the RuO released amount obtained via spectroscopic analysis.
Nishino, Hiroyuki; Kurisaka, Kenichi; Futagami, Satoshi; Watakabe, Tomoyoshi; Yamano, Hidemasa
Proceedings of Probabilistic Safety Assessment and Management & Asian Symposium on Risk Assessment and Management (PSAM17 & ASRAM2024) (Internet), 10 Pages, 2024/10
The reactor vessel (RV) buckling was a dominant contributor to core damage. However, even if the RV is buckled due to seismic shaking, it is expected that the RV maintains stable state without unstable failure such as rupture, collapse. Realistic consideration of the post-buckling behavior is regarded as a measure for improving the resilience in this study. The purpose of this study is to understand the post-buckling deformation behavior of the RV and to evaluate the RV fragility based on fatigue failure. This study performed structural analysis using a finite element method to quantify time histories of displacement, strain, etc. As the result of the analysis, wrinkles of the buckling appeared at the elevation higher than the liquid level in the RV. The largest strain value was also indicated around this elevation. The cumulative fatigue damage fraction was evaluated in this analysis to evaluate the fragility of fatigue failure in addition to the buckling fragility. The result showed that the seismic intensity for the median fragility of the fatigue failure was about six times larger than the design-basis ground motion. This is 1.2 times larger than the buckling-based result, which suggests that realistic evaluation of the post-buckling behavior could contribute to improving the resilience of the nuclear structure.
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
Times Cited Count：0 Percentile：0.00(Soil Science)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.
Sato, Nobuaki*; Kameo, Yutaka; Sato, Soichi; Kumagai, Yuta; Sato, Tomonori; Yamamoto, Masahiro*; Watanabe, Yutaka*; Nagai, Takayuki; Niibori, Yuichi*; Watanabe, Masayuki; et al.
Introduction to Dismantling and Decommissioning Chemistry, 251 Pages, 2024/09
This book focuses on the dismantling and decommissioning of nuclear facilities and reactors that have suffered severe accidents. In Part 1, we introduce basic aspects ranging from fuel chemistry, analytical chemistry, radiation chemistry, corrosion, and decontamination chemistry to waste treatment and disposal. Then, Part 2 covers the chemistry involved in the decommissioning of various nuclear facilities, and discusses what chemical approaches are necessary and possible for the decommissioning of TEPCO's Fukushima Dai-ichi Nuclear Power Plants, how decommissioning should be carried out, and what kind of research and development and also human resource development are required for this.
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
Times Cited Count：0 Percentile：0.00(Instruments & Instrumentation)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
Times Cited Count：0 Percentile：0.00(Instruments & Instrumentation)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.
Koizumi, Mitsuo; Ito, Fumiaki*; Lee, J.; Hironaka, Kota; Takahashi, Tone; Suzuki, Satoshi*; Arikawa, Yasunobu*; Abe, Yuki*; Lan, Z.*; Wei, T.*; et al.
Scientific Reports (Internet), 14, p.21916_1 - 21916_9, 2024/09
Times Cited Count：0Endo, Shunsuke; Abe, Ryota*; Fujioka, Hiroyuki*; Ino, Takashi*; Iwamoto, Osamu; Iwamoto, Nobuyuki; Kawamura, Shiori*; Kimura, Atsushi; Kitaguchi, Masaaki*; Kobayashi, Ryuju*; et al.
European Physical Journal A, 60(8), p.166_1 - 166_10, 2024/08
Times Cited Count：0 Percentile：0.00(Physics, Nuclear)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
Times Cited Count：0 Percentile：0.00(Chemistry, Physical)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.
Arai, Yoichi; Hasegawa, Kenta; Watanabe, So; Watanabe, Masayuki; Minowa, Kazuki*; Matsuura, Haruaki*; Hagura, Naoto*; Katsuki, Kenta*; Arai, Tsuyoshi*; Konishi, Yasuhiro*
Journal of Radioanalytical and Nuclear Chemistry, 333(7), p.3585 - 3593, 2024/07
Times Cited Count：1 Percentile：41.04(Chemistry, Analytical)Watanabe, Tsutomu*; Ishikawa, Shuhei*; Kawashima, Masayuki*; Shimoyama, Ko*; Onodera, Naoyuki; Hasegawa, Yuta; Inagaki, Atsushi*
Journal of Wind Engineering and Industrial Aerodynamics, 250, p.105783_1 - 105783_17, 2024/07
Times Cited Count：1 Percentile：0.00(Engineering, Civil)This paper presents simulations of drifting snow using a Lagrangian particle dispersion model coupled with a large-eddy simulation code. The model accurately replicates observed features such as mass transport rate dependency on flow velocity and variations in particle size distribution. It also shows that the saltation layer height increases monotonically with flow velocity, contrary to conventional estimates. Additionally, the study confirms the transition from saltation to suspension near the estimated saltation layer height and finds that dense snow streamers are linked to small-scale low-speed streaks in near-surface flows.
Sanada, Yukihisa; Urabe, Yoshimi*; Saito, Madoka*; Shiribiki, Takehiko*; Misono, Toshiharu; Funaki, Hironori
Kankyo Gijutsu, 53(4), p.188 - 193, 2024/07
no abstracts in English
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
and 
reactions and its implications for a phenomenological reaction modelNakada, Hibiki*; Nakayama, Shinsuke; Yoshida, Kazuki; Watanabe, Yukinobu*; Ogata, Kazuyuki*
Physical Review C, 110(1), p.014616_1 - 014616_8, 2024/07
Times Cited Count：0 Percentile：0.00(Physics, Nuclear)Previous studies have revealed the importance of introducing surface correction into a phenomenological model for inclusive 
and reactions, and these findings have contributed significantly to the improvement of nuclear data evaluation. However, the necessity for the surface correction in an inclusive reaction has hardly been investigated. The energy spectra and their radial distributions for the and reactions are calculated by the one-step semiclassical distorted wave model. The radial distribution of the energy spectra for the reaction is shifted toward the outer region of the nucleus compared to the reaction. Based on this finding, we consider a larger surface correction into a phenomenological model for the reaction than that for the reaction, and calculated values reproduce the experimental spectra well. The peripherality of the reaction is more prominent than that of the reaction. The stronger surface correction thus should be introduced for the reaction than for the reaction.
Nakamura, Izumi*; Takito, Kiyotaka; Shimazu, Ryuya*; Okuda, Yukihiko; Sakai, Michiya*; Otani, Akihito*; Watakabe, Tomoyoshi; Okuda, Takahiro; Shibutani, Tadahiro*; Shiratori, Masaki*
Proceedings of ASME 2024 Pressure Vessels & Piping Conference (PVP 2024) (Internet), 9 Pages, 2024/07
Watakabe, Tomoyoshi; Yamamoto, Tomohiko; Okamura, Shigeki; Miyazaki, Masashi; Miyagawa, Takayuki; Uchita, Masato*; Hirayama, Tomoyuki*; Somaki, Takahiro*; Yukawa, Masaki*; Fukasawa, Tsuyoshi*; et al.
Proceedings of ASME 2024 Pressure Vessels & Piping Conference (PVP 2024) (Internet), 10 Pages, 2024/07
To secure the seismic safety of the thin-walled mechanical components and piping under a severe design earthquake level, employing a three-dimensional (3D) seismic isolation system has been planned in a sodium-cooled fast reactor. The development results of the 3D isolation system have been reported in previous papers so far. Its update is reported in Part 7 to Part 9. Part 7 describes the overview of the development, the test plan of the isolation system in the assembled state of each element, and the performance of individual isolation elements. In part 8, the performance of the isolation device that each element was assembled into was investigated through loading tests. Part 9 reports analytical studies by an analysis model validated based on the insight of the test results.
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.
