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Journal Articles

Study on eutectic melting behavior of control rod materials in core disruptive accidents of sodium-cooled fast reactors, 1; Project overview and progress until 2019

Yamano, Hidemasa; Takai, Toshihide; Furukawa, Tomohiro; Kikuchi, Shin; Emura, Yuki; Kamiyama, Kenji; Fukuyama, Hiroyuki*; Higashi, Hideo*; Nishi, Tsuyoshi*; Ota, Hiromichi*; et al.

Proceedings of 28th International Conference on Nuclear Engineering; Nuclear Energy the Future Zero Carbon Power (ICONE 28) (Internet), 11 Pages, 2021/08

One of the key issues in a core disruptive accident (CDA) evaluation in sodium-cooled fast reactors is eutectic reactions between boron carbide (B$$_{4}$$C) and stainless steel (SS) as well as its relocation. Such behaviors have never been simulated in CDA numerical analyses in the past, therefore it is necessary to develop a physical model and incorporate the model into the CDA analysis code. This study focuses on B$$_{4}$$C-SS eutectic melting experiments, thermophysical property measurement of the eutectic melt, and physical model development for the eutectic melting reaction. The eutectic experiments involve the visualization experiments, eutectic reaction rate experiments and material analyses. The thermophysical properties are measured in a range from solid to liquid state. The physical model is developed for a CDA computer code based on the measured data of the eutectic reaction rate and the physical properties. This paper describes the project overview and progress of experimental and analytical studies conducted until 2019. Specific results in this paper are the validation of physical model describing B$$_{4}$$C-SS eutectic reaction in the CDA analysis code, SIMMER-III, through the numerical analysis of the B$$_{4}$$C-SS eutectic melting experiments in which a B$$_{4}$$C block was placed in a SS pool.

JAEA Reports

Proceedings of debriefing session on JAEA's Underground Research Laboratory Projects, 2020

Shimizu, Mayuko; Amano, Kenji; Mizuno, Takashi; Hama, Katsuhiro

JAEA-Review 2021-004, 92 Pages, 2021/07

JAEA-Review-2021-004.pdf:10.33MB

Japan Atomic Energy Agency (JAEA) has been conducting research and development (R&D) on geological disposal technology in order to establish a scientific and technological basis for the geological disposal of HLW. "Debriefing Session on JAEA's Underground Research Laboratory" was held online on December 1, 2020 by live stream on YouTube, in order to widely disseminate the results of R&D themes ("Important issues") that we have been focusing on from fiscal year 2015 to 2019 and the plans for 2020 and beyond, and to further enhance the research plan. This document summarizes the overview of the debriefing session and the presentation materials.

Journal Articles

A Proposed method to discriminate a gas derived from deep underground by focusing on the relationship between changes in methane and carbon dioxide concentrations in the atmosphere

Miyakawa, Kazuya; Shimo, Michito*; Niwa, Masakazu; Amano, Kenji; Tokunaga, Tomochika*; Tonokura, Kenichi*

Fukada Chishitsu Kenkyujo Nempo, (22), p.139 - 153, 2021/00

no abstracts in English

Journal Articles

Estimation of gas migration pathways around faults based on the distribution of atmospheric methane near ground surface

Shimo, Michito*; Niwa, Masakazu; Miyakawa, Kazuya; Amano, Kenji; Tonokura, Kenichi*; Tokunaga, Tomochika*

Fukada Chishitsu Kenkyujo Nempo, (22), p.119 - 137, 2021/00

no abstracts in English

Journal Articles

Rapid identification of water-conducting fractures using a trace methane gas measurement

Niwa, Masakazu; Amano, Kenji; Takeuchi, Ryuji; Shimada, Koji

Groundwater Monitoring & Remediation, 41(3), p.41 - 50, 2021/00

 Times Cited Count:0 Percentile:0.01(Water Resources)

Identification of water-conducting fractures is important for the safety assessment of underground projects in crystalline rocks at geological disposal sites. We applied a portable methane gas analyzer by wavelength-scanned cavity ring-down spectroscopy to detect the water-conducting fractures in an underground tunnel excavated in granite with CH$$_{4}$$-rich groundwater. Two approaches were taken to obtain the profile of CH$$_{4}$$ concentration along the gallery walls: (1) Scan by walking at the speed of 0.5 m/s and (2) monitoring for 30 s at 0.5 or 1-m intervals. In the Scan by walking approach, the peaks of the CH$$_{4}$$ concentration corresponded well with the occurrence of high water flow rate fractures. Thus, this method is useful for rapid identification of major water-conducting fractures. Monitoring at constant intervals takes more time than the Scan by walking approach; however, this method can largely detect occurrences of fractures with low fluid fluxes.

JAEA Reports

Hydrochemical investigation at the Mizunami Underground Research Laboratory; Compilation of groundwater chemistry data in the Mizunami Group and the Toki Granite (fiscal year 2019)

Fukuda, Kenji; Watanabe, Yusuke; Murakami, Hiroaki; Amano, Yuki; Aosai, Daisuke*; Hara, Naohiro*

JAEA-Data/Code 2020-012, 80 Pages, 2020/10

JAEA-Data-Code-2020-012.pdf:3.55MB

Japan Atomic Energy Agency has been investigating groundwater chemistry to understand the influence of excavation and maintenance of underground facilities as part of the Mizunami Underground Research Laboratory (MIU) Project in Mizunami, Gifu, Japan. In this report, we compiled data of groundwater chemistry and microbiology obtained at the MIU in the fiscal year 2019. In terms of ensuring traceability of data, basic information (e.g. sampling location, sampling time, sampling method and analytical method) and methodology for quality control are described.

Journal Articles

Study on eutectic melting behavior of control rod materials in core disruptive accidents of sodium-cooled fast reactors, 1; Project overview and progress until 2018

Yamano, Hidemasa; Takai, Toshihide; Furukawa, Tomohiro; Kikuchi, Shin; Emura, Yuki; Kamiyama, Kenji; Fukuyama, Hiroyuki*; Higashi, Hideo*; Nishi, Tsuyoshi*; Ota, Hiromichi*; et al.

Proceedings of 2020 International Conference on Nuclear Engineering (ICONE 2020) (Internet), 10 Pages, 2020/08

One of the key issues in a core disruptive accident (CDA) evaluation in sodium-cooled fast reactors is eutectic reactions between boron carbide (B$$_{4}$$C) and stainless steel (SS) as well as its relocation. Such behaviors have never been simulated in CDA numerical analyses in the past, therefore it is necessary to develop a physical model and incorporate the model into the CDA analysis code. This study focuses on B$$_{4}$$C-SS eutectic melting experiments, thermophysical property measurement of the eutectic melt, and physical model development for the eutectic melting reaction. The eutectic experiments involve the visualization experiments, eutectic reaction rate experiments and material analyses. The thermophysical properties are measured in a range from solid to liquid state. The physical model is developed for a severe accident computer code based on the measured data of the eutectic reaction rate and the physical properties. This paper describes the project overview and progress of experimental and analytical studies conducted until 2018. Specific results in this paper are boron concentration distributions of solidified B$$_{4}$$C-SS eutectic sample in the eutectic melting experiments, which would be used for the validation of the eutectic physical model implemented into the computer code.

JAEA Reports

Hydrochemical investigation at the Mizunami Underground Research Laboratory; Compilation of groundwater chemistry data in the Mizunami group and the Toki granite (fiscal year 2018)

Fukuda, Kenji; Watanabe, Yusuke; Murakami, Hiroaki; Amano, Yuki; Aosai, Daisuke*; Kumamoto, Yoshiharu*; Iwatsuki, Teruki

JAEA-Data/Code 2019-019, 74 Pages, 2020/03

JAEA-Data-Code-2019-019.pdf:3.53MB

Japan Atomic Energy Agency has been investigating groundwater chemistry to understand the influence of excavation and maintenance of underground facilities as part of the Mizunami Underground Research Laboratory (MIU) Project in Mizunami, Gifu, Japan. In this report, we compiled data of groundwater chemistry and microbiology obtained at the MIU in the fiscal year 2018. In terms of ensuring traceability of data, basic information (e.g. sampling location, sampling time, sampling method and analytical method) and methodology for quality control are described.

Journal Articles

Study on eutectic melting behavior of control rod materials in core disruptive accidents of sodium-cooled fast reactors, 1; Project overview

Yamano, Hidemasa; Takai, Toshihide; Furukawa, Tomohiro; Kikuchi, Shin; Emura, Yuki; Kamiyama, Kenji; Fukuyama, Hiroyuki*; Higashi, Hideo*; Nishi, Tsuyoshi*; Ota, Hiromichi*; et al.

Proceedings of International Nuclear Fuel Cycle Conference / Light Water Reactor Fuel Performance Conference (Global/Top Fuel 2019) (USB Flash Drive), p.418 - 427, 2019/09

Eutectic reactions between boron carbide (B$$_{4}$$C) and stainless steel (SS) as well as its relocation are one of the key issues in a core disruptive accident (CDA) evaluation in sodium-cooled fast reactors. Since such behaviors have never been simulated in CDA numerical analyses, it is necessary to develop a physical model and incorporate the model into the CDA analysis code. This study is focusing on B$$_{4}$$C-SS eutectic melting experiments, thermophysical property measurement of the eutectic melt, and physical model development for the eutectic melting reaction. The eutectic experiments involve the visualization experiments, eutectic reaction rate experiments and material analyses. The thermophysical properties are measured in the range from solid to liquid state. The physical model is developed for a severe accident computer code based on the measured data of the eutectic reaction rate and the physical properties. This paper describes the project overview and progress of experimental and analytical studies by 2017. Specific results in this paper is boron concentration distributions of solidified B$$_{4}$$C-SS eutectic sample in the eutectic melting experiments, which would be used for the validation of the eutectic physical model implemented into the computer code.

JAEA Reports

Hydrochemical investigation at the Mizunami Underground Research Laboratory; Compilation of groundwater chemistry data in the Mizunami group and the Toki granite (fiscal year 2017)

Fukuda, Kenji; Watanabe, Yusuke; Murakami, Hiroaki; Amano, Yuki; Hayashida, Kazuki*; Aosai, Daisuke*; Kumamoto, Yoshiharu*; Iwatsuki, Teruki

JAEA-Data/Code 2018-021, 76 Pages, 2019/03

JAEA-Data-Code-2018-021.pdf:3.78MB

Japan Atomic Energy Agency has been investigating groundwater chemistry to understand the influence of excavation and maintenance of underground facilities as part of the Mizunami Underground Research Laboratory (MIU) Project in Mizunami, Gifu, Japan. In this report, we compiled data of groundwater chemistry and microbiology obtained at the MIU in the fiscal year 2017. In terms of ensuring traceability of data, basic information (e.g. sampling location, sampling time, sampling method and analytical method) and methodology for quality control are described.

Journal Articles

Determination of fusion barrier distributions from quasielastic scattering cross sections towards superheavy nuclei synthesis

Tanaka, Taiki*; Narikiyo, Yoshihiro*; Morita, Kosuke*; Fujita, Kunihiro*; Kaji, Daiya*; Morimoto, Koji*; Yamaki, Sayaka*; Wakabayashi, Yasuo*; Tanaka, Kengo*; Takeyama, Mirei*; et al.

Journal of the Physical Society of Japan, 87(1), p.014201_1 - 014201_9, 2018/01

 Times Cited Count:10 Percentile:72.43(Physics, Multidisciplinary)

Excitation functions of quasielastic scattering cross sections for the $$^{48}$$Ca + $$^{208}$$Pb, $$^{50}$$Ti + $$^{208}$$Pb, and $$^{48}$$Ca + $$^{248}$$Cm reactions were successfully measured by using the gas-filled recoil-ion separator GARIS. Fusion barrier distributions were extracted from these data, and compared with the coupled-channels calculations. It was found that the peak energies of the barrier distributions for the $$^{48}$$Ca + $$^{208}$$Pb and $$^{50}$$Ti + $$^{208}$$Pb systems coincide with those of the 2n evaporation channel cross sections for the systems, while that of the $$^{48}$$Ca + $$^{248}$$Cm is located slightly below the 4n evaporation ones. This results provide us helpful information to predict the optimum beam energy to synthesize superheavy nuclei.

Journal Articles

Basic visualization experiments on eutectic reaction between boron carbide and stainless steel under sodium-cooled fast reactor conditions

Yamano, Hidemasa; Suzuki, Toru; Kamiyama, Kenji; Kudo, Isamu*

Proceedings of International Conference on Fast Reactors and Related Fuel Cycles; Next Generation Nuclear Systems for Sustainable Development (FR-17) (USB Flash Drive), 11 Pages, 2017/06

This paper describes basic visualization experiments on eutectic reaction and relocation of boron carbide (B$$_{4}$$C) and stainless steel (SS) under a high temperature condition exceeding 1500$$^{circ}$$C as well as the importance of such behaviors in molten core during a core disruptive accident in a Generation-IV sodium-cooled fast reactor (750 MWe class) designed in Japan. At first, a reactivity history was calculated using an exact perturbation calculation tool taking into account expected behaviors. This calculation indicated the importance of a relocation behavior of the B$$_{4}$$C-SS eutectic because its behavior has a large uncertainty in the reactivity history. To clarify this behavior, basic experiments were carried out by visualizing the reaction of a B$$_{4}$$C pellet contacted with molten SS in a high temperature-heating furnace. The experiments have shown the eutectic reaction visualization as well as freezing and relocation of the B$$_{4}$$C-SS eutectic in upper part of the solidified test piece due to the density separation.

JAEA Reports

Synthesized research report in the second mid-term research phase, Mizunami Underground Research Laboratory Project, Horonobe Underground Research Laboratory Project and Geo-stability Project (Translated document)

Hama, Katsuhiro; Sasao, Eiji; Iwatsuki, Teruki; Onoe, Hironori; Sato, Toshinori; Fujita, Tomo; Sasamoto, Hiroshi; Matsuoka, Toshiyuki; Takeda, Masaki; Aoyagi, Kazuhei; et al.

JAEA-Review 2016-014, 274 Pages, 2016/08

JAEA-Review-2016-014.pdf:44.45MB

We synthesized the research results from the Mizunami/Horonobe Underground Research Laboratories (URLs) and geo-stability projects in the second midterm research phase. This report can be used as a technical basis for the Nuclear Waste Management Organization of Japan/Regulator at each decision point from siting to beginning of disposal (Principal Investigation to Detailed Investigation Phase).

Journal Articles

Development of the evaluation methodology for the material relocation behavior in the core disruptive accident of sodium-cooled fast reactors

Tobita, Yoshiharu; Kamiyama, Kenji; Tagami, Hirotaka; Matsuba, Kenichi; Suzuki, Toru; Isozaki, Mikio; Yamano, Hidemasa; Morita, Koji*; Guo, L.*; Zhang, B.*

Journal of Nuclear Science and Technology, 53(5), p.698 - 706, 2016/05

AA2015-0794.pdf:2.46MB

 Times Cited Count:10 Percentile:78.98(Nuclear Science & Technology)

The in-vessel retention (IVR) of core disruptive accident (CDA) is of prime importance in enhancing safety characteristics of sodium-cooled fast reactors (SFRs). In the CDA of SFRs, molten core material relocates to the lower plenum of reactor vessel and may impose significant thermal load on the structures, resulting in the melt through of the reactor vessel. In order to enable the assessment of this relocation process and prove that IVR of core material is the most probable consequence of the CDA in SFRs, a research program to develop the evaluation methodology for the material relocation behavior in the CDA of SFRs has been conducted. This program consists of three developmental studies, namely the development of the analysis method of molten material discharge from the core region, the development of evaluation methodology of molten material penetration into sodium pool, and the development of the simulation tool of debris bed behavior.

Journal Articles

3D geostatistical modeling of fracture system in a granitic massif to characterize hydraulic properties and fracture distribution

Koike, Katsuaki*; Kubo, Taiki*; Liu, C.*; Masoud, A.*; Amano, Kenji; Kurihara, Arata*; Matsuoka, Toshiyuki; Lanyon, B.*

Tectonophysics, 660, p.1 - 16, 2015/10

 Times Cited Count:20 Percentile:68.73(Geochemistry & Geophysics)

This study integrates 3D models of rock fractures from different sources and hydraulic properties aimed at identifying relationships between fractures and permeability. A geostatistical method (GEOFRAC) that can incorporate orientations of sampled data was applied to 50,900 borehole fractures for spatial modeling of fractures over a 12 km by 8 km area, to a depth of 1.5 km. GEOFRAC produced a plausible 3D fracture model, in that the orientations of simulated fractures correspond to those of the sample data and the continuous fractures appeared near a known fault. Small-scale fracture distributions with dominant orientations were also characterized around the two shafts using fracture data from the shaft walls. By integrating the 3D model of hydraulic conductivity using sequential Gaussian simulation with the GEOFRAC fractures from the borehole data, the fracture sizes and directions that strongly affect permeable features were identified.

JAEA Reports

Synthesized research report in the second mid-term research phase; Mizunami Underground Research Laboratory Project, Horonobe Underground Research Laboratory Project and Geo-stability Project

Hama, Katsuhiro; Mizuno, Takashi; Sasao, Eiji; Iwatsuki, Teruki; Saegusa, Hiromitsu; Sato, Toshinori; Fujita, Tomo; Sasamoto, Hiroshi; Matsuoka, Toshiyuki; Yokota, Hideharu; et al.

JAEA-Research 2015-007, 269 Pages, 2015/08

JAEA-Research-2015-007.pdf:68.65MB
JAEA-Research-2015-007(errata).pdf:0.07MB

We have synthesised the research results from Mizunami/Horonobe URLs and geo-stability projects in the second mid-term research phase. It could be used as technical bases for NUMO/Regulator in each decision point from sitting to beginning of disposal (Principal Investigation to Detailed Investigation Phase). High quality construction techniques and field investigation methods have been developed and implemented and these will be directly applicable to the National Disposal Program (along with general assessments of hazardous natural events and processes). It will be crucial to acquire technical knowledge on decisions of partial backfilling and final closure by actual field experiments in Mizunami/Horonobe URLs as main themes for the next phases.

JAEA Reports

Precise topographic analysis using 10m grid DEM in the Horonobe area

Sakai, Toshihiro; Matsuoka, Toshiyuki; Amano, Kenji

JAEA-Data/Code 2014-005, 43 Pages, 2014/05

JAEA-Data-Code-2014-005.pdf:33.23MB
JAEA-Data-Code-2014-005-appendix(DVD).zip:940.62MB

The Horonobe Underground Research Laboratory (URL) Project is being pursued by the Japan Atomic Energy Agency (JAEA) at Horonobe-cho in Northern Hokkaido, Japan. One of the main goals of the URL project is to establish techniques for investigation, analysis and assessment of the deep geological environment. As a part of this URL project, we develop the geological environment modeling technique. 10m grid digital elevation model (DEM) had been published by Geographical Survey Institute in 2008. The use of 10m grid DEM has made possible examination of detailed topographical features in wide area. We created eighteen kinds of filterd image data using 10m grid DEM around the Horonobe-cho to obtain the basic information for evaluating topographical and geological features and constructing the geological environment model.

Journal Articles

A Scenario of core disruptive accident for Japan sodium-cooled fast reactor to achieve in-vessel retention

Suzuki, Toru; Kamiyama, Kenji; Yamano, Hidemasa; Kubo, Shigenobu; Tobita, Yoshiharu; Nakai, Ryodai; Koyama, Kazuya*

Journal of Nuclear Science and Technology, 51(4), p.493 - 513, 2014/04

 Times Cited Count:46 Percentile:98.08(Nuclear Science & Technology)

As the most promising concept of SFRs, the JAEA has selected the advanced loop-type fast reactor, so-called JSFR. The safety design requirements of JSFR for design extension condition are the prevention of severe accidents and the mitigation of severe-accident consequences. For the mitigation of severe-accident consequences, in particular, the In-Vessel Retention (IVR) against postulated Core Disruptive Accidents (CDAs) is required. In order to investigate the sufficiency of these safety requirements, a CDA scenario should be constructed, in which the elimination of power excursion and the in-vessel cooling of core materials are evaluated so as to achieve IVR. In the present study, the factors leading to IVR failure were identified by creating phenomenological diagrams, and the effectiveness of design measures against them were evaluated based on experimental data and computer simulations. This is an unprecedented approach to the construction of a CDA scenario, and is an effective method to objectively investigate the factors of IVR failure and design measures against them. It was concluded that mechanical/thermal failures of the reactor vessel could be avoided by adequate design measures, and a clear vision for achieving IVR was obtained.

Journal Articles

Modification and verification of regional groundwater flow model

Munakata, Masahiro; Amano, Kenji; Tanaka, Tadao

JNES-RE-2013-9032, p.36 - 54, 2014/02

no abstracts in English

Journal Articles

Construction of evaluation model for rainwater cultivation amount

Munakata, Masahiro; Amano, Kenji; Tanaka, Tadao

JNES-RE-2013-9032, p.63 - 78, 2014/02

no abstracts in English

169 (Records 1-20 displayed on this page)