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Journal Articles

Neutron diffraction study of the crystal and magnetic structures of antiferromagnetic manganese deuteride at high temperatures and high pressures

Machida, Akihiko*; Saito, Hiroyuki*; Aoki, Katsutoshi*; Komatsu, Kazuki*; Hattori, Takanori; Sano, Asami; Funakoshi, Kenichi*; Machida, Shinichi*; Sato, Toyoto*; Orimo, Shinichi*

Physical Review B, 111(22), p.224413_1 - 224413_6, 2025/06

 Times Cited Count:1

The crystal and magnetic structures of antiferromagnetic Mn deuterides formed by hydrogenating Mn metal at high temperature and high pressure, fcc $$gamma$$-MnDx and hcp $$epsilon$$-MnDx, were investigated by in-situ neutron powder diffraction. Deuterium atoms partially occupied the octahedral interstitial positions of the fcc and hcp metal lattices. The site occupancies increased rapidly with decreasing temperature from $$sim$$700 to $$sim$$450 K and remained down to 300 K. N$'{e}$el temperature of 543(10) K was determined for $$gamma$$-MnD$$_{0.34}$$. For $$epsilon$$-MnD$$_{0.62}$$, saturation magnetic moment and N$'{e}$el temperature were determined to be 0.82(1) $$mu_B$$ and 347(3) K, respectively. The N$'{e}$el temperatures determined for $$gamma$$-MnD$$_{0.34}$$ and $$epsilon$$-MnD$$_{0.62}$$ are consistent with those predicted by the respective Slater-Pauling curves proposed in previous studies. The updated N$'{e}$el temperatures provide insights into the development of more accurate Slater-Pauling curves based on electronic band structure calculations.

Journal Articles

Effect of temperature on bentonite deformation

Takayama, Yusuke; Sato, Daisuke*; Sugita, Yutaka

Kansai Geo-Symposium 2024; Chikasui Jiban Kankyo, Bosai, Keisoku Gijutsu Ni Kansuru Shinpojiumu Rombunshu, p.115 - 119, 2024/11

During the initial phases after closure of a high-level radioactive waste repository, the temperature of the buffer material will increase. Therefore, fundamental properties regarding the temperature dependence of bentonite, which is the main material of the buffer material, have been tested. The number of tests for the temperature dependence of displacement behavior is less than the number of tests for the temperature dependence of swelling pressure and permeability. In this paper, two tests were conducted using a consolidation test device that can control temperature conditions. One is a cyclic loading and unloading test under temperature conditions from room temperature to 80 $$^{circ}$$C. The second is a temperature rise and fall test from room temperature to 80 $$^{circ}$$C under stable loading condition. It was clarified that large deformations occur in the specimen under high temperature conditions, that the deformation associated with temperature changes is affected by the past stress path, and that irreversible deformation occurs under normal consolidation conditions.

Journal Articles

Novel first-order phase transition and critical points in SU(3) Yang-Mills theory with spatial compactification

Fujii, Daisuke; Iwanaka, Akihiro*; Kitazawa, Masakiyo*; Suenaga, Daiki*

Physical Review D, 110(9), p.094016_1 - 094016_16, 2024/11

 Times Cited Count:1 Percentile:35.96(Astronomy & Astrophysics)

We investigate the thermodynamics and phase structure of $$SU(3)$$ Yang-Mills theory on $$mathbb{T}^2timesmathbb{R}^2$$ in Euclidean spacetime in an effective-model approach. The model incorporates two Polyakov loops along two compactified directions as dynamical variables, and is constructed to reproduce thermodynamics on $$mathbb{T}^2timesmathbb{R}^2$$ measured on the lattice. The model analysis indicates the existence of a novel first-order phase transition on $$mathbb{T}^2timesmathbb{R}^2$$ in the deconfined phase, which terminates at critical points that should belong to the two-dimensional $$Z_2$$ universality class. We argue that the interplay of the Polyakov loops induced by their cross term in the Polyakov-loop potential is responsible for the manifestation of the first-order transition.

Journal Articles

Plastic constraint correction factor $$chi$$ for brittle fracture in ductile-brittle transition temperature region

Hojo, Kiminobu*; Hirota, Takatoshi*; Nagoshi, Yasuto*; Fukahori, Takuya*; Shimizu, Kazuma*; Shimodaira, Masaki; Ogawa, Takuya*; Yashirodai, Kenji*; Ohata, Mitsuru*; Minami, Fumiyoshi*

Proceedings of ASME 2024 Pressure Vessels & Piping Conference (PVP 2024) (Internet), 9 Pages, 2024/07

no abstracts in English

Journal Articles

Influence of temperature on stress corrosion cracking susceptibility of carbon steel in sodium hydrogen carbonate aqueous solution assuming upper limit of carbonate concentration in geological disposal environment

Takahashi, Rieko*; Taniguchi, Naoki

Zairyo To Kankyo, 73(6), p.153 - 163, 2024/06

Carbon steel is one of the candidate materials for overpacks in geological disposal of high-level radioactive waste, and is known to susceptible to stress corrosion cracking(SCC) depending on the condition in carbonate environment. In order to understand the influence of temperature on the SCC susceptibility of carbon steel, slow strain rate test (SSRT) of rolled steel were performed in NaHCO$$_{3}$$ aqueous solution with varying temperature in the range of 303-393K for conditions of 0.1-0.5 mol/dm$$^{3}$$, which is assumed to be the upper limit of carbonate concentration in groundwater in a geological disposal environment. As the results, no obvious influence of temperature on mechanical properties such as fracture strain ratio and reduction area ratio were observed, but SCC susceptibility based on SCC fracture ratio increased at relatively low temperatures of 303K and 323K. It was suggested that the reason for the higher SCC sensitivity at lower temperatures was due to slower repassivation at lower temperatures. Regarding the type of SCC, intergranular SCC was dominant at low temperatures and tended to transition to intergranular SCC at higher temperatures. Transgranular SCC tended to be observed at lower potentials than those at which intergranular SCC was observed.

Journal Articles

Crystallization processes of quartz in a granitic magma; Implications for the magma chamber processes of Okueyama granite, Kyushu, Japan

Yuguchi, Takashi*; Kato, Takenori*; Ogita, Yasuhiro; Watanabe, Minori*; Yamazaki, Hayato*; Kato, Asuka*; Ito, Daichi*; Yokoyama, Tatsunori; Sakata, Shuhei*; Ono, Takeshi*

Journal of Asian Earth Sciences, 265, p.106091_1 - 106091_13, 2024/04

 Times Cited Count:2 Percentile:36.99(Geosciences, Multidisciplinary)

Journal Articles

Magnetic structures and spin-wave excitations in rare-earth iron garnets near the compensation temperature

Mori, Michiyasu; Ziman, T.*

IEEE Transactions on Magnetics, 59(11), p.1300505_1 - 1300505_5, 2023/11

 Times Cited Count:1 Percentile:14.55(Engineering, Electrical & Electronic)

Journal Articles

Application of 1D-CFD coupling method to unprotected loss of heat sink event in EBR-II focusing on thermal stratification in cold pool

Yoshimura, Kazuo; Doda, Norihiro; Fujisaki, Tatsuya*; Igawa, Kenichi*; Tanaka, Masaaki; Yamano, Hidemasa

Proceedings of 29th International Conference on Nuclear Engineering (ICONE 29) (Internet), 10 Pages, 2022/08

To confirm the applicability of the reactivity model, the authors have been conducting the benchmark exercises of the unprotected loss of heat sink event tests in a pool-type experimental fast reactor EBR-II. In the blind phase in the benchmark analyses using the plant dynamics analysis (1D) code in which the cold pool was modeled by means of the perfect mixing volume, it was found the increase of the core inlet temperature was evaluated lower than that of the measured data and the feedback reactivity was underestimated, because the thermal stratification in the cold pool was ignored. Then, the detailed model of the cold pool for the computational fluid dynamics (CFD) code was introduced and the 1D-CFD codes coupling method was applied to the benchmark analyses. It was confirmed that both the thermal stratification in the cold pool and the increase of the core inlet temperature were successfully reproduced.

Journal Articles

Crystallization processes of quartz in a granitic magma; Cathodoluminescence zonation pattern controlled by temperature and titanium diffusivity

Yuguchi, Takashi*; Ogita, Yasuhiro; Kato, Takenori*; Yokota, Rintaro*; Sasao, Eiji; Nishiyama, Tadao*

Journal of Asian Earth Sciences, 192, p.104289_1 - 104289_16, 2020/05

 Times Cited Count:6 Percentile:28.44(Geosciences, Multidisciplinary)

Quartz from a granitic pluton is found to have formed through sequential growth events under different mechanisms and crystallization temperatures, which can provide new insights into magmatic processes of granitic magmas that were eventually consolidified into plutons. The events were identified using (1) the description of crystal shape and occurrence, (2) the study of the internal structure with cathodoluminescence (CL), and (3) derivation of the crystallization temperatures based on TitaniQ thermometry. The magmatic quartz crystals from the Toki granite, central Japan, are characterized as having the following internal structures: oscillatory zonation, no-oscillatory zonation with luminescence graduation (gradational zonation), and heterogeneous CL. The quartz crystals with oscillatory zonation were formed in the temperature range of about 800 $$^{circ}$$C to below 700 $$^{circ}$$C, which is referred to as oscillatory zoning temperature (OZT) conditions. The CL zonation pattern was controlled by the temperature conditions and titanium diffusivity in the melt (magma). The crystallization process of quartz within the Toki granite reveals the cooling processes of the granitic pluton; the lithofacies with a high frequency of oscillatory-zoned quartz underwent slower cooling under the OZT conditions than those in other lithofacies.

JAEA Reports

Influence factors on temperature behavior of robot test pool

Arakawa, Ryoki; Nosaki, Nobuhisa

JAEA-Technology 2019-018, 157 Pages, 2020/03

JAEA-Technology-2019-018.pdf:12.97MB

The Naraha Center for Remote Control Technology Development has various test facilities for the decommissioning work after the accident of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, and is now promoting external use. In the test facilities, the robot test pool for the underwater robot can be used in different temperature conditions from room temperature to 60$$^{circ}$$C, maximum setting temperature. In order to clarify the temperature behavior in heating condition, a heating test from room temperature to 60$$^{circ}$$C was performed. The data was obtained this way. From the data, a heat transfer model for evaluating the temperature behavior was investigated, and the temperature evaluation method for the robot test pool was developed. By using the developed evaluation method, the influence of various factors such as flow rate and humidity on the temperature behavior was investigated for the condition of temperature heating, holding (test condition) and cooling. From the investigation, the temperature behavior of the robot test pool was analytically clarified, and a reasonable operation method was proposed. This report summarizes the results of analytical study at the temperature heating, holding and cooling condition.

Journal Articles

Microstructural features and ductile-brittle transition behavior in hot-rolled lean duplex stainless steels

Takahashi, Osamu*; Shibui, Yohei*; Xu, P. G.; Harjo, S.; Suzuki, Tetsuya*; Tomota, Yo*

Quantum Beam Science (Internet), 4(1), p.16_1 - 16_15, 2020/03

JAEA Reports

Development of temperature evaluation method for robot test pool

Arakawa, Ryoki; Nosaki, Nobuhisa

JAEA-Technology 2018-013, 51 Pages, 2019/02

JAEA-Technology-2018-013.pdf:7.75MB

The Naraha Center for Remote Control Technology Development has various test facilities for the decommissioning work after the accident of the Fukushima Daiichi Nuclear Power Station, TEPCO Holdings, and is now promoting external use. In the test facilities, the robot test pool for the underwater robot can be used in different temperature conditions from room temperature to 60$$^{circ}$$C, maximum setting temperature. In order to clarify the temperature behavior in heating condition, a heating test from room temperature to 60$$^{circ}$$C was performed, and obtained the data. From the obtained temperature data, a heat transfer model for evaluating the temperature behavior was investigated, and the temperature evaluation method for the robot test pool was developed. This report summarizes the developed heat transfer model, and also summarizes the temperature evaluation method during heating and cooling conditions. Moreover, user's manual for the temperature evaluation code was also created.

JAEA Reports

Heating test of robot test pool

Arakawa, Ryoki; Nosaki, Nobuhisa; Hirata, Yuji*

JAEA-Technology 2018-009, 28 Pages, 2019/01

JAEA-Technology-2018-009.pdf:2.94MB

The Naraha Center for Remote Control Technology Development consists of a mock-up test building and a research management building, and various test facilities are installed in them for the decommissioning work after the accident of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings. In the test facilities, the robot test pool for the underwater robot can be tested under temperature conditions raised from room temperature to 60$$^{circ}$$C. Then, for the purpose of grasping the temperature distribution inside of the pool and the temperature rising behavior in temperature raising condition, a temperature heating test with room temperature to 60$$^{circ}$$C. (maximum setting temperature) was performed, and as well as an analytical study was performed. This report summarizes the obtained both experimental and analytical studies.

Journal Articles

Temperature measurement for in-situ crack monitoring under high-frequency loading

Naoe, Takashi; Xiong, Z.*; Futakawa, Masatoshi

Journal of Nuclear Materials, 506, p.12 - 18, 2018/08

BB2016-1012.pdf:0.95MB

 Times Cited Count:9 Percentile:60.52(Materials Science, Multidisciplinary)

A mercury target for neutron source (made of 316L SS) suffers not only proton and neutron radiation damage, but also cyclic impact stress caused by pressure waves. In the previous study, we carried out an ultrasonic fatigue test to investigate the gigacycle fatigue strength of 316L SS, concluding that specimen surface temperature rose abruptly more than 300$$^{circ}$$C just before failure. In this study, to clarify the mechanism of the temperature rise, we measured temperature distribution with a thermography during the fatigue test. The experimental results showed that the temperature rose locally only at the crack tip and the peak position moved with the crack propagation. We also carried out a nonlinear structural analysis by LS-DYNA to estimate the temperature rise with strain energy of elements. The analytical result showed that the heat due to plastic deformation at the crack tip is dominant for the temperature rise rather than the friction between crack surface.

Journal Articles

Temperature measurement of control rod using melt wire in High-Temperature Engineering Test Reactor (HTTR)

Hamamoto, Shimpei; Tochio, Daisuke; Ishii, Toshiaki; Sawahata, Hiroaki

Nihon Genshiryoku Gakkai Wabun Rombunshi, 16(4), p.169 - 172, 2017/12

A melt wire was installed at the tip of the control rod in order to measure the temperature of High Temperature engineering Test Reactor (HTTR). After experience with reactor scrum from the state of reactor power 100%, the melt wire was taken out from the control rod and appearance has been observed visually. It was confirmed that the melt wires with a melting point of 505 $$^{circ}$$C or less were melted, and the melt wires with a melting point of 651 $$^{circ}$$C or more were not melted. Therefore, it was found that the highest arrival temperature of tip of the control rods where the melt wires are installed reaches within the range of 505 to 651 $$^{circ}$$C. And it was found that the control rod temperature at the time of reactor scram does not exceed the using temperature criteria (900 $$^{circ}$$C) of Alloy 800H of the control rod sleeve.

Journal Articles

Saturation behavior of thermal ratcheting strain due to long range travel of temperature distribution

Okajima, Satoshi; Wakai, Takashi

Nihon Kikai Gakkai 2017-Nendo Nenji Taikai Koen Rombunshu (DVD-ROM), 5 Pages, 2017/09

It was reported that the long distance travel of temperature distribution causes a new type of thermal ratcheting, even in the absence of primary stress. In this paper, based on the results of inelastic finite element analyses, we investigated saturation behavior of thermal ratcheting strain due to long range travel of temperature distribution. As a result, we revealed that the long distance travel of temperature distribution generates plastic strain distribution made maximum at the central part. Because of the shape of the generated strain distribution, the residual stress accumulates even at the central part of the region passed through the temperature distribution. In the case with excessive long traveling of temperature distribution, the region with plastic deformation extended to the surrounding region. Otherwise, sufficient magnitude of residual stress to cause shakedown behavior accumulated on entire region, and the accumulation of the plastic strain saturated.

Journal Articles

Temperature performance of portable radiation survey instruments used for environmental monitoring and clean-up activities in Fukushima

Saegusa, Jun; Yanagisawa, Kayo; Hasumi, Atsushi; Shimizu, Takenori; Uchida, Yoshiaki*

Radiation Physics and Chemistry, 137, p.210 - 215, 2017/08

 Times Cited Count:1 Percentile:9.23(Chemistry, Physical)

Following the Fukushima Daiichi Nuclear Power Plant (NPP) accident, large-scale radiation monitoring and environmental clean-up activities have been conducted throughout the Fukushima region. Outside air temperatures there reach 40$$^{circ}$$C in summer and -20$$^{circ}$$C in winter, which are beyond the quoted range of many radiation survey instruments. For the purpose, temperature performances of four types of portable Japanese survey instruments which are widely used in Fukushima were experimentally investigated with a temperature-controlled chamber.

Journal Articles

Importance of temperature control in surrounding environment during permeability test for measuring hydraulic constants of rock

Kato, Masaji*; Nara, Yoshitaka*; Fukuda, Daisuke*; Kono, Masanori*; Sato, Toshinori; Sato, Tsutomu*; Takahashi, Manabu*

Zairyo, 65(7), p.489 - 495, 2016/07

Rock masses serve a vital function as natural barriers for geological disposal of radioactive waste; therefore, information on rock permeability is essential. Highly accurate measurement of permeability requires understanding of how temperature changes in the surrounding environment influence measurement results. We performed permeability measurement under conditions with dramatic changes of temperature in the surrounding environment to investigate the influence of such changes on the experimental results. Measurement of permeability with no temperature change was also conducted as reference. All measurements were conducted using the transient pulse method, and the sample material used was Toki granite obtained from Gifu Prefecture in central Japan. We found that temperature changes in the surrounding environment remarkably affected the pressure in reservoirs upstream and downstream, the pressure difference between them, and the confining pressure; all increased when temperature increased for our experimental system. Notably, pressure difference was affected immediately. This difference directly relates to estimation of permeability.

Journal Articles

SOL-divertor plasma simulations introducing anisotropic temperature with virtual divertor model

Togo, Satoshi*; Takizuka, Tomonori*; Nakamura, Makoto; Hoshino, Kazuo; Ogawa, Yuichi*

Journal of Nuclear Materials, 463, p.502 - 505, 2015/08

 Times Cited Count:10 Percentile:60.46(Materials Science, Multidisciplinary)

A 1D SOL-divertor plasma simulation code introducing the anisotropic ion temperature with virtual divertor model has been developed. By introducing the anisotropic ion temperature directly, the second-derivative parallel ion viscosity term in the momentum transport equation can be excluded and the boundary condition at the divertor plate becomes unnecessary. In order to express the effects of the divertor plate and accompanying sheath implicitly, the virtual divertor model has been introduced which has an artificial sinks of particle, momentum and energy. The virtual divertor model makes the periodic boundary condition available. By using this model, SOL-divertor plasmas satisfying the Bohm condition has been successfully obtained. Also investigated are the dependence of the ion temperature anisotropy on the normalized mean free path of ion and the validity of the approximated parallel ion viscosity for the Braginskii expression and the limited one.

Journal Articles

Statistical characteristics of turbulent plasmas dominated by zonal flows

Matsumoto, Taro; Kishimoto, Yasuaki; Miyato, Naoaki; Li, J.*

Journal of Plasma Physics, 72(6), p.1183 - 1187, 2006/12

 Times Cited Count:6 Percentile:20.68(Physics, Fluids & Plasmas)

no abstracts in English

778 (Records 1-20 displayed on this page)