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Journal Articles

Heat transfer characteristics of downward saturated boiling flow in vertical round pipes

Wada, Yuki; Shibamoto, Yasuteru; Hibiki, Takashi*

International Journal of Heat and Mass Transfer, 239, p.126598_1 - 126598_18, 2025/04

 Times Cited Count:0

Journal Articles

High-pressure polymerization of phenol toward degree-4 carbon nanothread

Yang, X.*; Che, G.*; Wang, Y.*; Zhang, P.*; Tang, X.*; Lang, P.*; Gao, D.*; Wang, X.*; Wang, Y.*; Hattori, Takanori; et al.

Nano Letters, 25(3), p.1028 - 1035, 2025/01

 Times Cited Count:0

Saturated sp$$^3$$-carbon nanothreads (CNTh) have garnered significant interest due to their predicted high Young's modulus and thermal conductivity. While the incorporation of heteroatoms into the central ring has been shown to influence the formation of CNTh and yield chemically homogeneous products, the impact of pendant groups on the polymerization process remains underexplored. In this study, we investigate the pressure-induced polymerization of phenol, revealing two phase transitions occurring below 0.5 and 4 GPa. Above 20 GPa, phenol polymerizes into degree-4 CNThs featuring hydroxyl and carbonyl groups. Hydrogen transfer of hydroxyl groups was found to hinder the formation of degree-6 nanothreads. Our findings highlight the crucial role of the hydroxyl group in halting further intracolumn polymerization and offer valuable insights for future mechanism research and nanomaterial synthesis.

Journal Articles

A Key element of internal dosimetry for members of the public

Endo, Akira

Annals of the ICRP, 52(4), p.5 - 7, 2024/12

In its Publication 155, International Commission on Radiological Protection (ICRP) has developed data on the Specific Absorbed Fraction (SAF) for reference males and females at ages of newborn, 1 year, 5 years, 10 years, and 15 years. The SAF represents the fraction of energy emitted within a source region which is absorbed in a target region per mass of the target region and is essential for calculating absorbed doses in organs or tissues for internal exposure. By combining the data of Publication 155 with the SAF data for reference adult males and females already published as Publication 133, an SAF dataset for the calculation of age-dependent dose coefficients for members of the public for environmental intakes of radionuclides has been completed. This, together with revised biokinetic models and nuclear decay data, means that the key building blocks for calculating new dose coefficients are in place. The outcome will soon be available in a series of ICRP Publications of Dose Coefficients for Intakes of Radionuclides by Members of the Public.

Journal Articles

$$^{149}$$Sm synchrotron-radiation-based M$"{o}$ssbauer spectroscopy of Sm-based heavy fermion compounds

Tsutsui, Satoshi; Higashinaka, Ryuji*; Mizumaki, Masaichiro*; Kobayashi, Yoshio*; Nakamura, Jin*; Ito, Takashi; Yoda, Yoshitaka*; Matsuda, Tatsuma*; Aoki, Yuji*; Sato, Hideyuki*

Interactions (Internet), 245(1), p.9_1 - 9_10, 2024/12

Journal Articles

$$^{149}$$Sm synchrotron-radiation-based M$"{o}$ssbauer and $$mu^+$$SR studies of Sm$$_3$$Ru$$_4$$Ge$$_{13}$$

Tsutsui, Satoshi; Ito, Takashi; Nakamura, Jin*; Yoshida, Mio*; Kobayashi, Yoshio*; Yoda, Yoshitaka*; Nakamura, Jumpei*; Koda, Akihiro*; Higashinaka, Ryuji*; Aoki, Dai*; et al.

Interactions (Internet), 245(1), p.55_1 - 55_9, 2024/12

JAEA Reports

Heat transfer coefficients model for SIMMER-III and SIMMER-IV

Brear, D. J.*; Kondo, Satoru; Sogabe, Joji; Tobita, Yoshiharu*; Kamiyama, Kenji

JAEA-Research 2024-009, 134 Pages, 2024/10

JAEA-Research-2024-009.pdf:2.45MB

The SIMMER-III/SIMMER-IV computer codes are being used for liquid-metal fast reactor (LMFR) core disruptive accident (CDA) analysis. The sequence of events predicted in a CDA is often influenced by the heat exchanges between LMFR materials, which are controlled by heat transfer coefficients (HTCs) in the respective materials. The mass transfer processes of melting and freezing, and vaporization and condensation are also controlled by HTCs. The complexities in determining HTCs in a multi-component and multi-phase system are the number of HTCs to be defined at binary contact areas of a fluid with other fluids and structure surfaces, and the modes of heat transfer taking into account different flow topologies representing flow regimes with and without structure. As a result, dozens of HTCs are evaluated in each mesh cell for the heat and mass transfer calculations. This report describes the role of HTCs in SIMMER-III/SIMMER-IV, the heat transfer correlations implemented and the calculation of HTCs in all topologies in multi-component, multi-phase flows. A complete description of the physical basis of HTCs and available experimental correlations is contained in Appendices to this report. The major achievement of the code assessment program conducted in parallel with code development is summarized with respect to HTC modeling to demonstrate that the coding is reliable and that the model is applicable to various multi-phase problems with and without reactor materials.

JAEA Reports

Opposing mixed convection heat transfer for turbulent single-phase flows (Contract research, Translated document)

Motegi, Kosuke; Shibamoto, Yasuteru; Hibiki, Takashi*; Tsukamoto, Naofumi*; Kaneko, Junichi*

JAEA-Review 2024-039, 45 Pages, 2024/09

JAEA-Review-2024-039.pdf:2.23MB

Several heat transfer correlations have been reported related to single-phase opposing flow; however, these correlations are based on experiments conducted in various channel geometries, working fluids, and thermal flow parameter ranges. Therefore, establishing a guideline for deciding which correlation should be selected based on its range of applicability and extrapolation performance is important. This study reviewed the existing heat transfer correlations for turbulent opposing-flow mixed convection. Furthermore, the authors evaluated the predictive performance of each correlation by comparing them with the experimental data obtained under various experimental conditions. The Jackson and Fewster, Churchill, and Swanson and Catton correlations can accurately predict all the experimental data. The authors confirmed that heat transfer correlations using the hydraulic-equivalent diameter as a characteristic length can be used for predictions regardless of channel-geometry differences. Furthermore, correlations described based on nondimensional dominant parameters can be used for predictions regardless of the differences in working fluids.

Journal Articles

Antiferromagnetism and phase stability of CrMnFeCoNi high-entropy alloy

Zhu, L.*; He, H.*; Naeem, M.*; Sun, X.*; Qi, J.*; Liu, P.*; Harjo, S.; Nakajima, Kenji; Li, B.*; Wang, X.-L.*

Physical Review Letters, 133(12), p.126701_1 - 126701_6, 2024/09

 Times Cited Count:1

Journal Articles

Elasto-plastic mechanical analysis considering thermal and hydraulic effects for the in-situ experiment for full-scale engineered barrier system performance experiment at Horonobe Underground Research Laboratory

Ito, Shinji*; Shimizu, Hiroyuki*; Ono, Shintaro*; Takayama, Yusuke

Doboku Gakkai Rombunshu (Internet), 80(8), p.24-00030_1 - 24-00030_18, 2024/08

In the design consideration of a geological disposal facility for radioactive waste, it is essential to perform a mechanical evaluation that takes into account phenomena that may occur from construction and operation to post-closure. With this background, we have developed the long-term mechanical analysis system MACBECE. In this research, we have built an analysis system that can consistently evaluate the mechanical behavior considering the thermal and hydraulic evolution after the closure of the repository by incorporating the constitutive model for unsaturated soils and coupling with the thermal-hydraulic analysis. As a validation, a mechanical analysis was conducted for the in-situ experiment for full-scale engineered barrier system performance experiment at Horonobe URL. Despite some discrepancies due to constraints in two-dimensional analysis, the extended functionality of the analysis code was confirmed to effectively repro-duce the measured data.

Journal Articles

Compact and transportable system for detecting lead-shielded highly enriched uranium using $$^{252}$$Cf rotation method with a water Cherenkov neutron detector

Tanabe, Kosuke*; Komeda, Masao; Toh, Yosuke; Kitamura, Yasunori*; Misawa, Tsuyoshi*; Tsuchiya, Kenichi*; Sagara, Hiroshi*

Scientific Reports (Internet), 14, p.18828_1 - 18828_10, 2024/08

 Times Cited Count:0 Percentile:0.00(Multidisciplinary Sciences)

JAEA Reports

Proceedings of the 12th International Conference on Nuclear Criticality Safety (ICNC2023); October 1-6, 2023, Sendai International Center, Sendai, Miyagi, Japan

Suyama, Kenya; Gunji, Satoshi; Watanabe, Tomoaki; Araki, Shohei; Fukuda, Kodai; Shimada, Kazuya; Fujita, Tatsuya; Ueki, Taro; Nguyen, H.

JAEA-Conf 2024-001, 40 Pages, 2024/07

JAEA-Conf-2024-001.pdf:1.28MB
JAEA-Conf-2024-001-appendix(CD-ROM).zip:163.97MB

The 12th International Conference on Nuclear Criticality Safety (ICNC2023) was held from October 1 to October 6, 2023, at the Sendai International Center (Aobayama, Aoba-ku, Sendai, Miyagi-prefecture 980-0856, Japan), organized by Japan Atomic Energy Agency (JAEA) and co-organized by the Reactor Physics Division of the Atomic Energy Society of Japan (AESJ) and the Nuclear Energy Agency of the Organization for Economic Co-operation and Development (OECD/NEA). 224 presentations passed peer review and 273 technical session registrations, bringing the total number of registered participants to 289, including accompanying persons. Technical tours were also conducted to i) Fukushima Daiichi Nuclear Power Station of TEPCO holdings and Interim Storage Facility Information Center, ii) Nuclear Science Research Institute of JAEA (STACY Renewable Reactor and FCA), iii) NanoTerasu of Tohoku University (synchrotron radiation facility) and Onagawa Nuclear Power Station of Tohoku Electric Power Co., Inc. This report summarizes the conference and compiles the papers that were presented and agreed to be published in the Proceedings.

JAEA Reports

Differential pressure rise event for filters of HTTR primary helium gas circulators, 2; Investigation of filter deposits and recurrence prevention measures

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.

Journal Articles

Existence of local polar domains in perovskite oxyfluoride, BaFeO$$_2$$F

Katsumata, Tetsuhiro*; Suzuki, Ryo*; Sato, Naoto*; Oda, Ryoya*; Motoyama, Shingo*; Suzuki, Shumpei*; Nakashima, Mamoru*; Inaguma, Yoshiyuki*; Mori, Daisuke*; Aimi, Akihisa*; et al.

Chemistry of Materials, 36(8), p.3697 - 3704, 2024/04

 Times Cited Count:0 Percentile:0.00(Chemistry, Physical)

A perovskite-type oxynitride BaFeO$$_2$$F was prepared by high-pressure synthesis. Since the SHG signal was observed in the obtained material, suggesting the existence of spontaneous polarization, the mechanism of polarization was investigated by synchrotron high-energy X-ray diffraction. The obtained pair distribution functions were fitted, and a local polarization mechanism with different orientations was found. Since BaFeO$$_2$$F is also a magnetic material, a magnetic domain and a ferroelectric domain are considered to coexist.

Journal Articles

Total and double differential scattering cross-section measurements of isotropic graphite

Kimura, Atsushi; Endo, Shunsuke; Nakamura, Shoji

EPJ Web of Conferences, 294, p.01002_1 - 01002_7, 2024/04

Journal Articles

Field-induced insulator-metal transition in EuTe$$_2$$

Takeuchi, Tetsuya*; Honda, Fuminori*; Aoki, Dai*; Haga, Yoshinori; Kida, Takanori*; Narumi, Yasuo*; Hagiwara, Masayuki*; Kindo, Koichi*; Karube, Kosuke*; Harima, Hisatomo*; et al.

Journal of the Physical Society of Japan, 93(4), p.044708_1 - 044708_10, 2024/04

 Times Cited Count:0 Percentile:0.00(Physics, Multidisciplinary)

Journal Articles

Kinetic analysis of mass transfer of Eu(III) in extractant-impregnated polymer-layered silica particle in multiple-ion distribution system

Miyagawa, Akihisa*; Hayashi, Naoki*; Iwamoto, Hibiki*; Arai, Tsuyoshi*; Nagatomo, Shigenori*; Miyazaki, Yasunori; Hasegawa, Kenta; Sano, Yuichi; Nakatani, Kiyoharu*

Analytical Sciences, 40(2), p.347 - 352, 2024/02

 Times Cited Count:0 Percentile:0.00(Chemistry, Analytical)

The Eu(III) distribution mechanism in single extractant-impregnated polymer-layered silica particle in a complex solution containing multiple lanthanide ions was investigated using fluorescence microspectroscopy. The rate-determining step was the reaction of Eu(III) with the two extractant molecules. The obtained mechanism and rate constants agreed with those of the single-ion distribution system, in which Eu(III) was distributed to the particles in the Eu(III) solution.

Journal Articles

A Side event at the IAEA 67th General Conference "Providing the best nuclear data for tomorrow's nuclear solutions; Challenges and opportunities"; For "visualization" of nuclear data usage

Fukahori, Tokio

Kaku Deta Nyusu (Internet), (137), p.1 - 10, 2024/02

At the request of the EC/Joint Research Center, the author attended on an EU-sponsored side event "Providing the best nuclear data for tomorrow's nuclear solutions: challenges and opportunities" held simultaneously at the IAEA 67th General Conference as a panelist. Presented were the prospects for nuclear data activities in Japan and discussed the sustainability and revitalization of nuclear data activities. In addition, based on the roundtable discussion at this side event, the Nuclear Data Section held a meeting consisting mainly of panelists to consider future responses. In this article, I would like to report on the side event and subsequent follow-up meetings and discuss the background of these meetings.

Journal Articles

An Analytical model to decompose mass transfer and chemical process contributions to molecular iodine release from aqueous phase under severe accident conditions

Zablackaite, G.; Shiotsu, Hiroyuki; Kido, Kentaro; Sugiyama, Tomoyuki

Nuclear Engineering and Technology, 56(2), p.536 - 545, 2024/02

 Times Cited Count:1 Percentile:75.38(Nuclear Science & Technology)

Journal Articles

Chiral Dirac fermion in a collinear antiferromagnet

Zhang, A.*; Deng, K.*; Sheng, J.*; Liu, P.*; Kumar, S.*; Shimada, Kenya*; Jiang, Z.*; Liu, Z.*; Shen, D.*; Li, J.*; et al.

Chinese Physics Letters, 40(12), p.126101_1 - 126101_8, 2023/12

 Times Cited Count:8 Percentile:83.51(Physics, Multidisciplinary)

Journal Articles

Eu(III) transfer in single $$N,N,N',N'$$-tetraoctyldiglycolamide-impregnated polymer-coated silica particle using fluorescence microspectroscopy; Transfer mechanism and effect of polymer crosslinking degree

Miyagawa, Akihisa*; Takahashi, Takumi*; Kuzure, Yoshiaki*; Iwamoto, Hibiki*; Arai, Tsuyoshi*; Nagatomo, Shigenori*; Watanabe, So; Sano, Yuichi; Nakatani, Kiyoharu*

Analytical Sciences, 39(11), p.1929 - 1936, 2023/11

 Times Cited Count:1 Percentile:17.17(Chemistry, Analytical)

In this study, we revealed the Eu(III) distribution in a single diglycolamide-derivative extractant (TODGA)-impregnated polymer-coated silica particle. The reaction of Eu(III) with two TODGA molecules in the polymer layer was the rate-limiting process, as evidenced by the absence of any correlation between the rate constants (k$$_{1}$$ and k$$_{-1}$$) and concentrations of Eu(III) and HNO$$_{3}$$.

986 (Records 1-20 displayed on this page)