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Emura, Yuki; Takai, Toshihide; Kikuchi, Shin; Kamiyama, Kenji; Yamano, Hidemasa; Yokoyama, Hiroki*; Sakamoto, Kan*
Journal of Nuclear Science and Technology, 10 Pages, 2023/00
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)Yamaguchi, Akinori*; Yokotsuka, Muneyuki*; Furuta, Masayo*; Kubota, Kazuo*; Fujine, Sachio*; Mori, Kenji*; Yoshida, Naoki; Amano, Yuki; Abe, Hitoshi
Nihon Genshiryoku Gakkai Wabun Rombunshi (Internet), 21(4), p.173 - 182, 2022/09
Risk information obtained from probabilistic risk assessment (PRA) can be used to evaluate the effectiveness of measures against severe accidents in nuclear facilities. The PRA methods used for reprocessing facilities are considered immature compared to those for nuclear power plants, and to make the methods mature, reducing the uncertainty of accident scenarios becomes crucial. In this paper, we summarized the results of literature survey on the event progression of evaporation to dryness caused by boiling of high-level liquid waste (HLLW) which is a severe accident in reprocessing facilities and migration behavior of associated radioactive materials. Since one of the important characteristics of Ru is its tendency to form volatile compounds over the course of the event progression, the migration behavior of Ru is categorized into four stages based on temperature. Although no Ru has been released in the waste in the high temperature region, other volatile elements such as Cs could be released. Sufficient experimental data, however, have not been obtained yet. It is, therefore, necessary to further clarify the migration behavior of radioactive materials that predominantly depends on temperature in this region.
Emura, Yuki; Kamiyama, Kenji; Yamano, Hidemasa
Dai-26-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Koen Rombunshu (Internet), 4 Pages, 2022/07
no abstracts in English
Ohshima, Hiroyuki; Morishita, Masaki*; Aizawa, Kosuke; Ando, Masanori; Ashida, Takashi; Chikazawa, Yoshitaka; Doda, Norihiro; Enuma, Yasuhiro; Ezure, Toshiki; Fukano, Yoshitaka; et al.
Sodium-cooled Fast Reactors; JSME Series in Thermal and Nuclear Power Generation, Vol.3, 631 Pages, 2022/07
This book is a collection of the past experience of design, construction, and operation of two reactors, the latest knowledge and technology for SFR designs, and the future prospects of SFR development in Japan. It is intended to provide the perspective and the relevant knowledge to enable readers to become more familiar with SFR technology.
Bachrata, A.*; Gentet, D.*; Bertrand, F.*; Marie, N.*; Kubota, Ryuzaburo*; Sogabe, Joji; Sasaki, Keisuke; Kamiyama, Kenji; Yamano, Hidemasa; Kubo, Shigenobu
Proceedings of International Conference on Fast Reactors and Related Fuel Cycles; Sustainable Clean Energy for the Future (FR22) (Internet), 9 Pages, 2022/04
In the frame of France-Japan collaboration, one of the objectives is to define and assess the calculation methodologies, and to investigate the phenomenology and the consequences of severe accident scenarios in sodium fast reactors (SFRs). A methodology whose purpose is to assess the loadings of the structures induced by a Fuel Coolant Interaction (FCI) taking place in the sodium plenum of SFR has been defined in the frame of the collaboration between France and Japan during 2014-2019. The work progress will be spread over the period 2020-2024 and the main objectives and milestones will be introduced in the paper. The objective of studies is to comprehensively address the margin between the limit of integrity of the main vessel structures and the loadings resulting from severe accidents. For this purpose, the SIMMER mechanistic calculation code simulates core disruptive accident sequences in SFRs. A fluid structure dynamics tool evaluates this interaction i.e. EUROPLEXUS is used in CEA studies and AUTODYN tool is used in JAEA studies. In the paper, a benchmark study is described in order to illustrate the evaluation of vapour expansion phase in the hot plenum. To do that, joint input data are used on the basis of an ASTRID 1500 MWth core degraded state after the power excursion which leads to vapour expansion. The most penalizing case was evidenced in this study by suppressing the action of transfer tube in-core mitigation devices in SIMMER input deck and thus privileging the upward molten core ejection. Even if the most penalizing case was evidenced in this paper, no significant RV deformation was observed in both EUROPLEXUS and AUTODYN calculation results. The assumed mechanical energy was small for the core expansion phase.
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 (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
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 BC-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 BC-SS eutectic reaction in the CDA analysis code, SIMMER-III, through the numerical analysis of the BC-SS eutectic melting experiments in which a BC block was placed in a SS pool.
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.
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
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
Niwa, Masakazu; Amano, Kenji; Takeuchi, Ryuji; Shimada, Koji
Groundwater Monitoring & Remediation, 41(3), p.41 - 50, 2021/00
Times Cited Count：1 Percentile：7.82(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-rich groundwater. Two approaches were taken to obtain the profile of CH 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 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.
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.
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 (BC) 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 BC-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 BC-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.
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.
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 (BC) 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 BC-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 BC-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.
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.
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：18 Percentile：74.14(Physics, Multidisciplinary)Excitation functions of quasielastic scattering cross sections for the 
Ca + 
Pb, 
Ti + Pb, and Ca + 
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 Ca + Pb and Ti + Pb systems coincide with those of the 2n evaporation channel cross sections for the systems, while that of the Ca + 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.
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 (BC) and stainless steel (SS) under a high temperature condition exceeding 1500
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 BC-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 BC 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 BC-SS eutectic in upper part of the solidified test piece due to the density separation.
Hama, Katsuhiro; Sasao, Eiji; Iwatsuki, Teruki; Onoe, Hironori; Sato, Toshinori; Fujita, Tomoo; 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).
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
Times Cited Count：24 Percentile：90.37(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.
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：27 Percentile：66.63(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.
