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Nishihara, Kenji; Sugawara, Takanori; Fukushima, Masahiro; Iwamoto, Hiroki; Katano, Ryota; Abe, Takumi
Progress in Nuclear Science and Technology (Internet), 8, p.185 - 190, 2025/09
A pilot plant for the accelerator-driven system is proposed as a scaled-down version of a lead-bismuth cooled ADS with 800 MW thermal output for transmutation of minor actinides. In this article, the design policy of the pilot plant is elaborated for each design area: safety, subcritical management, sub-critical core, accelerator, target and in-core components. The conceptual design of the pilot ADS is also presented: 200 MW of thermal output, keff below 0.95, introduction of control rod, 1.0 GeV-10mA accelerator and roughly-estimated size of in-core components.
Nishihara, Kenji; Sugawara, Takanori; Fukushima, Masahiro; Iwamoto, Hiroki; Katano, Ryota; Abe, Takumi
Proceedings of International Conference on Nuclear Fuel Cycle (GLOBAL2024) (Internet), 4 Pages, 2024/10
A pilot plant for the accelerator-driven system is proposed as a scaled-down version of a lead-bismuth cooled ADS with 800 MW thermal output for transmutation of minor actinides. In this presentation, the design policy of the pilot plant is presented.
Riyana, E. S.; Okumura, Keisuke; Sakamoto, Masahiro; Matsumura, Taichi; Terashima, Kenichi; Kanno, Ikuo
Journal of Nuclear Science and Technology, 61(2), p.269 - 276, 2024/02
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)Collaborative Laboratories for Advanced Decommissioning Science; Kyoto University*
JAEA-Review 2022-068, 90 Pages, 2023/05
JAEA-Review-2022-068.pdf:3.55MB
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 FY2018, this report summarizes the research results of the "Development of thin SiC neutron detector with high radiation resistance" conducted from FY2018 to FY2021 (this contract was extended to FY2021). Since the final year of this proposal was FY2021, the results for four fiscal years were summarized. In the works for debris retrieval, it is required to install subcritical surveillance radiation monitors that can surely work for long time under extremely high gamma-ray radiation environment. However, there have been problems such as remote control of conventional neutron detectors is difficult because heavy radiation shields are needed.
Yamane, Yuichi
Journal of Nuclear Science and Technology, 59(11), p.1331 - 1344, 2022/11
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)The reactivity was estimated from a time profile of neutron count rate or a simulated data in a quasi-steady state after sudden change of reactivity or external neutron source strength. The estimation was based on the equation of power in subcritical quasi-steady state. The purpose of the study is to develop the method of timely reactivity estimation from complicated time profile of neutron count rate. The developed method was applied to the data simulating neutron count rate created by using one-point kinetics code, AGNES, and Poisson-distributed random noise and to the transient subcritical experiment data measured by using TRACY. The result shows that the difference of the estimated and reference value was within about 5% or less for (
-1) for simulated data and within about 7% or less for 
-1.4 and -3.1 for the experimental data. It was also shown that the possibility of the reactivity estimation several ten seconds after the status change.
Riyana, E. S.; Okumura, Keisuke; Sakamoto, Masahiro; Matsumura, Taichi; Terashima, Kenichi
Journal of Nuclear Science and Technology, 59(4), p.424 - 430, 2022/04
Times Cited Count：1 Percentile：7.35(Nuclear Science & Technology)Katano, Ryota
Journal of Nuclear Science and Technology, 59(3), p.368 - 381, 2022/03
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)We propose a subcriticality determination methodology to be applied during fuel loading of an accelerator-driven system (ADS). In this methodology, subcriticality is determined via the area ratio method (via the proton accelerator) in the first step and by the neutron source multiplication method (through the spontaneous fission neutrons of minor actinides) in subsequent steps; then, the number of fuel assemblies to be loaded in the next step is predicted. We performed a numerical simulation of the proposed methodology, and the estimated subcriticalities agreed well with those obtained by eigenvalue calculations. We also conducted an uncertainty assessment of the proposed methodology and deduced a value of 1000 pcm for the 
uncertainty. The proposed methodology can be a candidate for practical subcriticality monitoring for ADS.
Collaborative Laboratories for Advanced Decommissioning Science; Kyoto University*
JAEA-Review 2020-057, 50 Pages, 2021/01
JAEA-Review-2020-057.pdf:2.82MB
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 FY2018, this report summarizes the research results of the "Development of Thin SiC Neutron Detector with High Radiation Resistance" conducted in FY2019. In the works for debris retrieval, it is required to install subcritical surveillance radiation monitors that can surely work for long time under extremely high gamma-ray radiation environment. However, there have been problems such as remote control of conventional radiation monitors is difficult because heavy radiation shields are needed. In the present study, we will develop a neutron detector using thin, light-weight and radiation-resistive silicon carbide (SiC) that has low sensitivity to gamma-rays as well as the data collection system in collaboration with the U.K.
Yamane, Yuichi
Journal of Nuclear Science and Technology, 57(8), p.926 - 931, 2020/08
Times Cited Count：1 Percentile：7.19(Nuclear Science & Technology)An equation of power in subcritical quasi-steady state has been derived based on one-point kinetics equations for the purpose of utilizing it for the development of timely reactivity estimation from complicated time profile of neutron count rate. It linearly relates power, 
, to a new variable 
, which is a function of time differential of the power. It has been confirmed by using one-point kinetics code, AGNES, that the calculated points (
) are perfectly in a line described by the new equation and that points () calculated from transient subcritical experiments by using TRACY made a line with a slope indicated by the new equation.
Collaborative Laboratories for Advanced Decommissioning Science; Kyoto University*
JAEA-Review 2019-042, 43 Pages, 2020/03
JAEA-Review-2019-042.pdf:25.64MB
JAEA/CLADS, had been conducting the Center of World Intelligence Project for Nuclear Science/Technology and Human Resource Development (hereafter referred to "the Project") in FY2018. The Project aims to contribute to solving problems in nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. 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. Among the adopted proposals in FY2018, this report summarizes the research results of the "Development of Thin SiC Neutron Detector with High Radiation Resistance". In the works for debris retrieval, it is required to install subcritical surveillance radiation monitors that can surely work for long time under extremely high gamma-ray radiation environment. However, there have been problems such as remote control of conventional radiation monitors is difficult because heavy radiation shields are needed. In the present study, we will develop a neutron detector using thin, light-weight and radiation-resistive silicon carbide (SiC) that has low sensitivity to gamma-rays as well as the data collection system in collaboration with the U.K. Using this system, the performance tests will be conducted supposing the real debris retrieval including the irradiation tests. Based on the results, we will conduct research and development aiming to make the system ready for use in real decommissioning works.
Yamane, Yuichi
Nihon Genshiryoku Gakkai-Shi ATOMO
, 62(1), p.42 - 46, 2020/01
The combination of philosophy and technology to keep safety against the risk specific to the facility containing nuclear fuel materials is criticality safety. The first target of criticality safety is to keep subcriticality. Its essence is to make the subcriticality condition clear and to keep that condition. Criticality safety control utilizes the leak and absorption of neutrons. From the view point of the improvement of risk assessment, it is expected to study the relation between inhomogeniety and subcriticality condition.
Katano, Ryota; Yamanaka, Masao*; Pyeon, C. H.*
Nuclear Science and Engineering, 193(12), p.1394 - 1402, 2019/12
Times Cited Count：6 Percentile：42.77(Nuclear Science & Technology)The author proposed the linear combination method as a subcriticality measurement method which estimates the prompt neutron decay constant (alpha) correlated with the subcriticality using measurement results obtained at multiple detector positions. In this study, we conduct the pulsed neutron experiment at Kyoto University Critical Assembly (KUCA) and measure alpha by the linear combination method using measured neutron counts. Through experiment, we experimentally show that the linear combination method can reduce the higher-mode effect compared to the conventional method. In addition, experimentally show that the linear combination has capability of the different mode extraction.
Katano, Ryota
Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 6 Pages, 2019/05
no abstracts in English
Katano, Ryota
Nuclear Science and Engineering, 193(4), p.431 - 439, 2019/04
Times Cited Count：6 Percentile：42.77(Nuclear Science & Technology)We proposed "linear combination method" to reduce the higher order mode effect on the prompt neutron decay constant measured by the pulsed neutron experiment. When the spatial higher order mode effect is taken into account, the time evolution of the neutron counts after the pulsed neutron injection is given by linear combination of multiple exponential functions. However, the measurement results by the conventional method include the systematic error derived from the higher order mode effect because the conventional method fit the neutron counts with a single exponential function. The proposed method extract the single exponential function of the fundamental mode by linear combination of the neutron counts at multiple detectors, thus the proposed method reduces the higher order mode effect. As the verification, we applied the proposed method to the numerical simulation. The results indicate that the proposed method can reduce the higher order mode effect by linear combination.
Eguchi, Yuta; Sugawara, Takanori; Nishihara, Kenji; Tazawa, Yujiro; Tsujimoto, Kazufumi
Proceedings of 26th International Conference on Nuclear Engineering (ICONE-26) (Internet), 8 Pages, 2018/07
In order to investigate the basic neutronics characteristics of the accelerator-driven subcritical system (ADS), JAEA has a plan to construct a new critical assembly in the J-PARC project, Transmutation Physics Experimental Facility (TEF-P). This study aims to evaluate the natural cooling characteristics of TEF-P core which has large decay heat by minor actinide (MA) fuel, and to achieve a design that does not damage the core and the fuels during the failure of the core cooling system. In the evaluation of the TEF-P core temperature, empty rectangular lattice tube outer of the core has a significant effect on the heat transfer characteristics. The experiments by using the mockup device were performed to validate the heat transfer coefficient and experimental results were obtained. By using the obtained experimental results, the three-dimensional heat transfer analysis of TEF-P core were performed, and the maximum core temperature was obtained, 294
C. This result shows TEF-P core temperature would be less than 327C that the design criterion of temperature.
Iwamoto, Hiroki; Nishihara, Kenji; Yagi, Takahiro*; Pyeon, C.-H.*
Journal of Nuclear Science and Technology, 54(4), p.432 - 443, 2017/04
Times Cited Count：20 Percentile：83.01(Nuclear Science & Technology)Tsujimoto, Kazufumi; Oigawa, Hiroyuki; Ouchi, Nobuo; Kikuchi, Kenji; Kurata, Yuji; Mizumoto, Motoharu; Sasa, Toshinobu; Nishihara, Kenji; Saito, Shigeru; Umeno, Makoto*; et al.
Proceedings of International Conference on Nuclear Energy System for Future Generation and Global Sustainability (GLOBAL 2005) (CD-ROM), 6 Pages, 2005/10
The Japan Atomic Energy Research Institute (JAERI) has been proceeding with the research and development (R&D) on accelerator-driven subcritical system (ADS). The ADS proposed by JAERI is a lead-bismuth (Pb-Bi) eutectic cooled fast subcritical core with 800 MWth. To realize such an ADS, some technical issues should be studied, developed and demonstrated. JAERI has started a comprehensive R&D program since the fiscal year of 2002 to acquire knowledge and elemental technology that are necessary for the validation of engineering feasibility of the ADS. The first stage of the program had been continued for three years. The program is conducted by JAERI, and many institutes, universities and private companies were involved. Items of R&D are concentrated on three technical areas peculiar to the ADS: (1) superconducting linear accelerator (SC-LINAC), (2) Pb-Bi eutectic as spallation target and core coolant, and (3) subcritical core design and technology. In the present work, the outline and the results in the first stage of the program are reported.
Oigawa, Hiroyuki; Tsujimoto, Kazufumi; Kikuchi, Kenji; Kurata, Yuji; Sasa, Toshinobu; Umeno, Makoto*; Saito, Shigeru; Nishihara, Kenji; Mizumoto, Motoharu; Takano, Hideki*; et al.
EUR-21227 (CD-ROM), p.483 - 493, 2005/00
JAERI is conducting the study on the dedicated transmutation system using the accelerator driven subcritical system (ADS). A subcritical reactor with the thermal power of 800 MW has been proposed. Many research and development activities including the conceptual design study are under way and planned at JAERI to examine the feasibility of the ADS. In the field of the proton accelerator, a superconducting LINAC is being developed. In the field of the spallation target using lead-bismuth eutectic (LBE), material corrosion, thermal-hydraulics, polonium behavior, and irradiation effect on materials are being studied. Moreover, in the framework of the J-PARC project, JAERI plans to construct the Transmutation Experimental Facility (TEF) to study the feasibility of the ADS using a high-energy proton beam and nuclear fuel and to establish the technology for the LBE spallation target and relevant materials.
Sasa, Toshinobu
Progress in Nuclear Energy, 47(1-4), p.314 - 326, 2005/00
Times Cited Count：17 Percentile：71.71(Nuclear Science & Technology)JAERI performs R&D of accelerator-driven systems (ADS) for transmutation of long-lived nuclides under national OMEGA program since 1988. To study the basic characteristics of ADS, Transmutation Experimental Facility is proposed under a framework of JAERI-KEK joint J-PARC project. A comprehensive R&D program for future ADS plant is also performed since 2002. R&D items are categorized into three fields, (1) accelerator (superconducting LINAC design), (2) lead-bismuth target/coolant (material compatibility, thermal-hydraulics around beam window and polonium behavior) and (3) subcritical core (system design, nuclear data, subcriticality measurement, and safety issues of ADS). First phase of the program will be done within three years. Assemble test of the cryomodule, heat transfer experiment using Pb-Bi thermal-hydraulics loop, cold test of polonium vaporization, design study of the 800MW ADS subcritical core are now underway. Part of this job was funded by the MEXT as one of the public offered R&D program for innovative nuclear systems.
Sasa, Toshinobu; Oigawa, Hiroyuki; Tsujimoto, Kazufumi; Nishihara, Kenji; Kikuchi, Kenji; Kurata, Yuji; Saito, Shigeru; Futakawa, Masatoshi; Umeno, Makoto*; Ouchi, Nobuo; et al.
Nuclear Engineering and Design, 230(1-3), p.209 - 222, 2004/05
Times Cited Count：39 Percentile：89.36(Nuclear Science & Technology)JAERI carries out research and development on accelerator-driven system (ADS) to transmute minor actinides and long-lived fission products. The system is composed of high intensity proton accelerator, lead-bismuth spallation target and lead-bismuth cooled subcritical core with nitride fuel. About 2,500 kg of minor actinide is loaded into the subcritical core. Annual transmutation amount using this system is 250 kg with 800MW of thermal output. A superconducting linear accelerator with the beam power of 30MW is connected to drive the subcritical core. Many research and development activities are under way and planned in the fields of subcritical core design, spallation target technology, lead-bismuth handling technology, accelerator development, and minor actinide fuel development. Especially, to study and evaluate the feasibility of the ADS from physics and engineering aspects, the Transmutation Experimental Facility (TEF) is proposed under a framework of the High-Intensity Proton Accelerator Project.
