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Journal Articles

Revaporization behavior of cesium and iodine compounds from their deposits in the steam-boron atmosphere

Rizaal, M.; Miwa, Shuhei; Suzuki, Eriko; Imoto, Jumpei; Osaka, Masahiko; Gou$"e$llo, M.*

ACS Omega (Internet), 6(48), p.32695 - 32708, 2021/12

JAEA Reports

Semi-autonomous remote-control technology of an articulated mobile robot to recover from stuck states (Contract research); FY2020 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; The University of Electro-Communications*

JAEA-Review 2021-025, 33 Pages, 2021/11

JAEA-Review-2021-025.pdf:1.68MB

The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2020. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2019, this report summarizes the research results of the "Semi- autonomous remote-control technology of an articulated mobile robot to recover from stuck states" conducted in FY2020. The purpose of this work is to establish a recovery method of an articulated mobile robot from stuck states. In this work, a control method of the robot to recover from stuck states by using redundancy of the system is proposed. In addition, we develop two interfaces. One is a display interface as an operator can understand the situation of the robot and surrounding terrain, and the other is a control interface to provide a target motion using the proposed control method. Finally, the effectiveness of them is demonstrated by experiments using an actual robot.

Journal Articles

The Impact of cement on argillaceous rocks in radioactive waste disposal systems; A Review focusing on key processes and remaining issues

Wilson, J.*; Bateman, K.; Tachi, Yukio

Applied Geochemistry, 130, p.104979_1 - 104979_19, 2021/07

 Times Cited Count:1 Percentile:0.56(Geochemistry & Geophysics)

The concept of deep geological disposal will include the multiple use of cement-based materials. In the case of argillaceous host rocks, the presence of hyperalkaline cement porefluid results in the destabilization of primary minerals in the argillite, resulting in the development of a zone of alteration at cement-rock interfaces. The process understanding gained from experimental, analogue, and modelling studies has been reviewed, and remaining areas of uncertainty identified. Although there is a reasonably good understanding of the mineral assemblages that are likely to occur due to cement-rock interactions, there are still some areas where a degree of uncertainty remains, in particular: the evolution of cement-argillite interfaces at T $$>$$ 25$$^{circ}$$C; the rates at which secondary minerals form; the extent of pore clogging due to secondary mineral precipitation; the implications of alteration for radionuclide transport.

Journal Articles

Surface complexation of Ca and competitive sorption of divalent cations on montmorillonite under alkaline conditions

Sugiura, Yuki; Ishidera, Takamitsu; Tachi, Yukio

Applied Clay Science, 200, p.105910_1 - 105910_10, 2021/01

 Times Cited Count:2 Percentile:0.03(Chemistry, Physical)

Journal Articles

Evaluation of acoustic anisotropy of granite by surface wave measurements

Okano, Aoi*; Kimoto, Kazushi*; Matsui, Hiroya

Dai-15-Kai Iwa No Rikigaku Kokunai Shimpojiumu Koen Rombunshu (Internet), p.633 - 636, 2021/01

This study evaluates the acoustic anisotropy of granite using surface waves. It is well-known that granite shows acoustic anisotropy due to preferentially oriented microcracks. Therefore it may be possible to gain information on the microcracks from the measurement of the acoustic anisotropy. In the conventional rock core elastic wave test, acoustic anisotropy has been evaluated by the ultrasonic transmission test. However, it is difficult to apply this method to field measurement and irregularly-shaped specimens. Therefore, in this study, we attempted to evaluate the acoustic anisotropy of granite using surface waves. By this method, the acoustic anisotropy was evaluated based on the changes in the surface wave amplitude, velocity, and frequency when the transmission direction was varied stepwise at a constant angle. As a result, the proposed surface wave technique evaluated acoustic anisotropy successfully. Furthermore, it was found that the acoustic anisotropy emerges because the microcracks change the apparent rigidity of the granite specimen.

Journal Articles

Chapter 18, Moving particle semi-implicit method

Wang, Z.; Duan, G.*; Koshizuka, Seiichi*; Yamaji, Akifumi*

Nuclear Power Plant Design and Analysis Codes, p.439 - 461, 2021/00

JAEA Reports

Semi-autonomous remote-control technology of an articulated mobile robot to recover from stuck states (Contract research); FY2019 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; The University of Electro-Communications*

JAEA-Review 2020-025, 34 Pages, 2020/12

JAEA-Review-2020-025.pdf:2.73MB

The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2019. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2019, this report summarizes the research results of the "Semiautonomous Remote-control Technology of an Articulated Mobile Robot to Recover from Stuck States". The purpose of this work is to establish a recovery method of an articulated mobile robot from stuck states. In this work, a control method of the robot to recover from stuck states by using redundancy of the system is proposed. In addition, we develop two interfaces. One is a display interface as an operator can understand the situation of the robot and surrounding terrain, and the other is a control interface to provide a target motion using the proposed control method. Finally, the effectiveness of them is demonstrated by experiments using an actual robot.

Journal Articles

Water distribution in Nafion thin films on hydrophilic and hydrophobic carbon substrates

Ito, Kanae; Harada, Masashi*; Yamada, Norifumi*; Kudo, Kenji*; Aoki, Hiroyuki; Kanaya, Toshiji*

Langmuir, 36(43), p.12830 - 12837, 2020/11

 Times Cited Count:2 Percentile:21.55(Chemistry, Multidisciplinary)

Journal Articles

Acceleration of fusion plasma turbulence simulations using the mixed-precision communication-avoiding Krylov method

Idomura, Yasuhiro; Ina, Takuya*; Ali, Y.*; Imamura, Toshiyuki*

Proceedings of International Conference for High Performance Computing, Networking, Storage, and Analysis (SC 2020) (Internet), p.1318 - 1330, 2020/11

The multi-scale full-$$f$$ simulation of the next generation experimental fusion reactor ITER based on a five dimensional (5D) gyrokinetic model is one of the most computationally demanding problems in fusion science. In this work, a Gyrokinetic Toroidal 5D Eulerian code (GT5D) is accelerated by a new mixed-precision communication-avoiding (CA) Krylov method. The bottleneck of global collective communication on accelerated computing platforms is resolved using a CA Krylov method. In addition, a new FP16 preconditioner, which is designed using the new support for FP16 SIMD operations on A64FX, reduces both the number of iterations (halo data communication) and the computational cost. The performance of the proposed method for ITER size simulations with 0.1 trillion grids on 1,440 CPUs/GPUs on Fugaku and Summit shows 2.8x and 1.9x speedups respectively from the conventional non-CA Krylov method, and excellent strong scaling is obtained up to 5,760 CPUs/GPUs.

JAEA Reports

Review and evaluation on the surface area of vitrified products of high-level waste; Surface area increase factors due to fracturing and their bases for the performance assessment of geological disposal

Igarashi, Hiroshi

JAEA-Review 2020-006, 261 Pages, 2020/09

JAEA-Review-2020-006.pdf:4.42MB

A literature review was conducted on the increase in surface area of vitrified products of HLW due to the fracturing caused by cooling during glass pouring process and by mechanical impact, from the perspective of a parameter of the radionuclide release model in the performance assessment of geological disposal system studied overseas. The review was focused on the value of surface area increase factor set as a parameter in the model, the experimental work to evaluate an increase in surface area, and how the parameters on surface area were determined based on the experimental results. The surface area obtained from the experiments executed in Japan was also discussed in comparison with the overseas studies. On the basis of the investigation, the effects of various conditions on the surface area were studied, such as a diameter of vitrified product, cooling condition during and after the glass pouring, impact on vitrified products during their handling, environment after the closure of disposal facility, and others. The causes of fracturing are associated with the phenomena or events in the waste management process such as production, transport, storage, and disposal. The surface area increase factors set in the nuclide release model of the glass and their bases were reviewed. In addition, the measured values and the experimental methods for surface increase factors published so far were compared. Accordingly, the methods for measuring surface area as the bases were identified for these factors set in the models. The causes of fracturing and features of these factors were studied with respect to the relation with the waste management process. The results from the review and assessment can contribute to the expanding the knowledge for the conservative and realistic application of these factors to performance assessment, and to the developing and upgrading of safety case as a consequence.

Journal Articles

Continuous and discontinuous yielding behaviors in ferrite-cementite steels

Wang, Y.*; Tomota, Yo*; Omura, Takahito*; Gong, W.*; Harjo, S.; Tanaka, Masahiko*

Acta Materialia, 196, p.565 - 575, 2020/09

 Times Cited Count:6 Percentile:69.06(Materials Science, Multidisciplinary)

Journal Articles

J-PARC 3-GeV RCS; 1-MW beam operation and beyond

Hotchi, Hideaki; Harada, Hiroyuki; Hayashi, Naoki; Kinsho, Michikazu; Okabe, Kota; Saha, P. K.; Shobuda, Yoshihiro; Tamura, Fumihiko; Yamamoto, Kazami; Yamamoto, Masanobu; et al.

Journal of Instrumentation (Internet), 15(7), p.P07022_1 - P07022_16, 2020/07

 Times Cited Count:1 Percentile:27.17(Instruments & Instrumentation)

no abstracts in English

JAEA Reports

Long-term monitoring of the stability of the gallery in Horonobe Underground Research Laboratory

Aoyagi, Kazuhei; Sakurai, Akitaka; Miyara, Nobukatsu; Sugita, Yutaka

JAEA-Research 2020-004, 68 Pages, 2020/06

JAEA-Research-2020-004.pdf:6.4MB
JAEA-Research-2020-004-appendix1(DVD-ROM).zip:636.84MB
JAEA-Research-2020-004-appendix2(DVD-ROM).zip:457.72MB
JAEA-Research-2020-004-appendix3(DVD-ROM).zip:595.19MB

In construction and operational phase of a high-level radioactive waste disposal project, it is necessary to monitor on mechanical stability of underground facility for long term. In this research, we measured the displacement of the rock around the gallery and the stress acting on support materials. Furthermore, we investigated the durability of measurement sensor installed in the rock mass and the support material such as concreate lining and steel support. As a result, optical fiber sensor is appropriate for measurement of the displacement of rock mass around the gallery, while it is enough to apply the conventional electric sensor for the measurement of stress acting on the support material in the geological environment (soft rock and low inflow). The result of the measurement in the fault zone in 350 m gallery, show that the stresses acting on both shotcrete and steel arch lib exceeded the value which will cause the instability of the gallery. However, as, we found no crack on the surface of the shotcrete. By observation on the surface of shotcrete, thus, it was concluded that careful observation of shotcrete around that section in addition to the monitoring the measured stress was necessary to continue. In other measurement sections, there was no risk for the instability of the gallery as a result of the investigation of the measurement result.

JAEA Reports

Poro-elastic parameter acquisition test using siliceous mudstone (Wakkanai formation)

Aoki, Tomoyuki*; Tani, Takuya*; Sakai, Kazuo*; Koga, Yoshihisa*; Aoyagi, Kazuhei; Ishii, Eiichi

JAEA-Research 2020-002, 83 Pages, 2020/06

JAEA-Research-2020-002.pdf:8.25MB
JAEA-Research-2020-002-appendix(CD-ROM).zip:6.63MB

The Japan Atomic Energy Agency (JAEA) has conducted with the Horonobe Underground Research Project in Horonobe, Teshio-gun, Hokkaido for the purpose of research and development related to geological disposal technology for high-level radioactive wastes in sedimentary soft rocks. The geology around the Horonobe Underground Research Laboratory (HURL) is composed of the Koetoi diatomaceous mudstone layer and the Wakkanai siliceous layer, both of which contain a large amount of diatom fossils. Since these rocks exhibit relatively high porosity but low permeability, it is important to investigate the poro-elastic characteristics of the rock mass. For this objective, it is necessary to measure parameters based on the poro-elastic theory. However, there are few measurement results of the poro-elastic parameters for the geology around HURL, and the characteristics such as dependence on confining pressure are not clearly understood. One of the reasons is that the rocks show low permeability and the pressure control during testing is difficult. Therefore, a poro-elastic parameter measurement test was conducted on the siliceous mudstone of the Wakkanai formation to accumulate measurement results on the poro-elastic parameters and to examine the dependence of the parameters on confining pressure. As a result, some dependency of the poro-elastic parameters on confining pressure was observed. Among the measured or calculated poro-elastic parameters, the drained bulk modulus increased, while the Skempton's pressure coefficient, and the Biot-Wills coefficient in the elastic region decreased with the increase in confining pressure. The measurement results also inferred that the foliation observed in the rock specimens might impact a degree of dependency of those parameters on confining pressure.

Journal Articles

Development of a user-friendly interface IRONS for atmospheric dispersion database for nuclear emergency preparedness based on the Fukushima database

El-Asaad, H.*; Nagai, Haruyasu; Sagara, Hiroshi*; Han, C. Y.*

Annals of Nuclear Energy, 141, p.107292_1 - 107292_9, 2020/06

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

Atmospheric dispersion simulations can provide crucial information to assess radioactive plumes in the environment for nuclear emergency preparedness. However, it is a difficult and time-consuming task to make simulations assuming many possible scenarios and to derive data from a vast number of results. Therefore, an interface was developed to assist users in conveying characteristics of plumes from simulation results. The interface uses a large database that contains WSPEEDI-II simulations for the first 20-days of radioactive release from the Fukushima Daiichi Nuclear Power Plant, and it displays essential quantitative data to the user from the database. The user may conduct sensitivity analysis with the help of the interface by changing release condition to generate many different case scenarios.

Journal Articles

Vertical and horizontal distributions of $$^{137}$$Cs on paved surfaces affected by the Fukushima Dai-ichi Nuclear Power Plant accident

Yoshimura, Kazuya; Watanabe, Takayoshi; Kurikami, Hiroshi

Journal of Environmental Radioactivity, 217, p.106213_1 - 106213_6, 2020/06

 Times Cited Count:3 Percentile:39.03(Environmental Sciences)

Journal Articles

Numerical simulation of two-phase flow in 4$$times$$4 simulated bundle

Ono, Ayako; Yamashita, Susumu; Suzuki, Takayuki*; Yoshida, Hiroyuki

Mechanical Engineering Journal (Internet), 7(3), p.19-00583_1 - 19-00583_12, 2020/06

JAEA is implementing the 3D detailed nuclear-thermal-coupled analysis code to analyze the transition state of the core and to reduce the likelihood of the design. In the development plan, the computational fluid dynamics code based on the VOF method, JUPITER, is applied for TH part of the 3D detailed nuclear-thermal-coupled analysis code.

Journal Articles

Observation of aerosol particle capturing behavior near gas-liquid interface

Uesawa, Shinichiro; Yoshida, Hiroyuki

Mechanical Engineering Journal (Internet), 7(3), p.19-00539_1 - 19-00539_9, 2020/06

Journal Articles

Development of FRENDY nuclear data processing code; Generation capability of multi-group cross sections from ACE file

Yamamoto, Akio*; Endo, Tomohiro*; Tada, Kenichi

Transactions of the American Nuclear Society, 122(1), p.714 - 717, 2020/06

A generation capability of multi-group cross sections from point-wise cross sections in ACE files is being developed as a function of the nuclear data processing code FRENDY. This presentation describes features of this function and comparison of the processing results between this function and GROUPR module in NJOY.

Journal Articles

Effects of the Montague resonance on the formation of the beam distribution during multiturn injection painting in a high-intensity proton ring

Hotchi, Hideaki

Physical Review Accelerators and Beams (Internet), 23(5), p.050401_1 - 050401_13, 2020/05

 Times Cited Count:3 Percentile:71.11(Physics, Nuclear)

no abstracts in English

663 (Records 1-20 displayed on this page)