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Journal Articles

A Study for establishment of passive creep-fatigue test techniques using the difference of thermal expansion coefficients of the materials

Wakai, Takashi; Ando, Masanori; Okajima, Satoshi; Toyota, Kodai; Onuma, Terumitsu*; Takahashi, Ryoya*; Asayama, Tai

Dai-29-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Yokoshu (Internet), 5 Pages, 2025/06

This paper describes an experimental study for establishing a passive creep-fatigue test technique that mainly utilizes the difference in thermal expansion coefficients of the materials as material surveillance test technique that can be applied to evaluate the structural integrity of the fast reactor components when the components are used beyond the period assumed in the design. Using the test article designed with the aid of a finite element analysis, a long-term creep-fatigue test data has been successfully obtained. In the designing of the test article, it was essential to generate a adequate strain at the gauge portion of the specimen due to the difference of thermal expansion coefficients of the materials, without buckling. After much trial and error, an optimal shape and dimensions of the test article and the cyclic thermal load conditions are established. In the future, miniaturization of the test article for applying the established test technique to the actual nuclear reactors will be required.

Journal Articles

Development of gas entrainment evaluation method in the hot plenum of sodium-cooled fast reactor

Ezure, Toshiki; Matsushita, Kentaro; Sasaki, Keisuke; Tanaka, Masaaki

Dai-29-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Yokoshu (Internet), 5 Pages, 2025/06

In the design of the pool-type demonstration sodium-cooled fast reactor (demonstration reactor), the prevention of gas entrainment in the hot plenum of the reactor vessel is one of important issues to be addressed in the conceptual design of demonstration reactor. Related to this problem, the authors have been developing an evaluation approach combining the analysis method of entrained gas-transport in the primary circuit, SYRENA, and the gas entrainment evaluation method, StreamViewer, at the free surface in the hot plenum of the demonstration reactor. In this study, a development plan of StreamViewer is presented toward application to the evaluation of the demonstration reactor design. Furthermore, an overview of scaled model water experiment of the pool-type demonstration reactor to obtain the validation date for StreamViewer is also presented.

Journal Articles

R&D on nuclear transmutation technology

Nishihara, Kenji

Enerugi, Shigen, 45(6), p.359 - 363, 2024/11

no abstracts in English

Journal Articles

Development of ARKADIA for the innovation of advanced nuclear reactor design process (Development status of the design optimization support tool, ARKADIA-Design)

Tanaka, Masaaki; Doda, Norihiro; Hamase, Erina; Kuwagaki, Kazuki; Mori, Takero; Okajima, Satoshi; Kikuchi, Norihiro; Yoshimura, Kazuo; Matsushita, Kentaro; Hashidate, Ryuta; et al.

Dai-28-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Koen Rombunshu (Internet), 5 Pages, 2024/06

To assist conceptual studies of various reactor systems conducted by private sectors in nuclear power innovation, development of an innovative design system named ARKADIA (Advanced Reactor Knowledge- and AI-aided Design Integration Approach through the whole plant lifecycle) is undergoing. In this paper, focusing on the ARKADIA-Design, achievements in the development of optimization processes in the fields of the core design, the plant structure design, and the maintenance schedule planning, as major function of ARKADIA-Design, and numerical analysis methods to be used for the detailed analysis to confirm the plant performance after optimization are introduced at this point in time.

Journal Articles

Numerical simulation of accidents involving core damage with integrative severe accident analysis code, SPECTRA

Ishida, Shinya; Uchibori, Akihiro; Okano, Yasushi

Dai-28-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Koen Rombunshu (Internet), 4 Pages, 2024/06

no abstracts in English

Journal Articles

Suggestions for energy storage best mix to achieve carbon neutrality, 1; Development of energy storage best mix

Kato, Yukitaka*; Yamano, Hidemasa

Dai-28-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Koen Rombunshu (Internet), 5 Pages, 2024/06

The research committee of energy storage technologies toward carbon neutrality developed four suggestions: 1) Development of energy storage best mix, 2) Transformation to green society, 3) utilization of heat storage technologies, and 4) Development of energy storage strategy beyond 2050. This paper describes suggestion 1) Development of energy storage best mix in response to large-scale deployments of variable renewable energy.

Journal Articles

Development of safety design technologies for sodium-cooled fast reactor coupled to thermal energy storage system with sodium-molten salt heat exchanger, 3; Reaction on sodium-nitrate molten salt

Kikuchi, Shin; Sato, Rika; Kondo, Toshiki; Umeda, Ryota; Yamano, Hidemasa

Dai-28-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Koen Rombunshu (Internet), 4 Pages, 2024/06

no abstracts in English

Journal Articles

System evaluation of power generation with thermal energy storage for massive variable renewable energy penetration

Fujii, Shoma*; Yamano, Hidemasa; Ohno, Shuji; Hayafune, Hiroki

Dai-28-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Koen Rombunshu (Internet), 4 Pages, 2024/06

A modified price-following model was developed to perform annual simulations, and case studies were performed for systems combining Solar power, wind, and SMR with thermal storage. The results show that, when comparing wind power and solar power as heat source, solar power is more effective in applying thermal energy storage technology because it allows for a larger price differential between heat charging and discharging. It was also found that a stable heat source such as SMRs allows a larger amount of electricity to be sold with the same amount of heat storage material.

Journal Articles

Suggestions for energy storage best mix to achieve carbon neutrality, 2; Transformation to green society by zero-carbon energy

Kato, Yukitaka*; Yamano, Hidemasa

Dai-28-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Koen Rombunshu (Internet), 5 Pages, 2024/06

The research committee of energy storage technologies toward carbon neutrality developed four suggestions: 1) Development of energy storage best mix, 2) Transformation to green society, 3) utilization of heat storage technologies, and 4) Development of energy storage strategy beyond 2050. This paper describes suggestion 2) Transformation to green society by zero-carbon energy, 3) further utilization of heat storage technologies in the industry and civil sectors, and 4) Development of energy storage strategy toward achievement of carbon negative emission beyond 2050.

Journal Articles

Development of safety design technologies for sodium-cooled fast reactor coupled to thermal energy storage system with sodium-molten salt heat exchanger, 1; Overview and Consideration on tube failure

Yamano, Hidemasa; Takano, Kazuya; Kurisaka, Kenichi; Kikuchi, Shin; Kondo, Toshiki; Umeda, Ryota; Sato, Rika; Shirakura, Shota*

Dai-28-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Koen Rombunshu (Internet), 5 Pages, 2024/06

This project studies investigation on safety design guideline and risk assessment technology for sodium-cooled fast reactor with the molten-salt heat storage system, development of evaluation method for heat transferring performance between sodium and molten-salt and improvement of the performance, and evaluation of chemical reaction characteristic between sodium and molten-salt and improvement of its safety. This paper describes the effect of sodium-molten salt heat transfer tube failure in addition to the project overview and progress.

Journal Articles

Development of safety design technologies for sodium-cooled fast reactor coupled to thermal energy storage system with sodium-molten salt heat exchanger, 2; Study on heat exchanger performance

Hayashi, Masaaki*; Nakahara, Hirotaka*; Abe, Takashi*; Matsunaga, Suhei*; Miyata, Hajime*; Shirakura, Shota*; Yamano, Hidemasa

Dai-28-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Koen Rombunshu (Internet), 5 Pages, 2024/06

This paper describes the study of the performance evaluation technology of a heat exchanger between sodium and molten salt and the confirmation of heat transfer improvement measures effects up to FY2023.

Journal Articles

Development of Accident Tolerant Fuel (ATF) claddings

Nemoto, Yoshiyuki

Kiho Enerugi Sogo Kogaku, 47(1), p.27 - 32, 2024/04

no abstracts in English

Journal Articles

Restoration project from the Fukushima Dai-ichi Nuclear Power Station Accident

Iijima, Kazuki

Enerugi, Shigen, 44(6), p.372 - 377, 2023/11

In the Fukushima Daiichi Nuclear Power Station accident, huge number of radioactive materials were released into the environment. We provided an overview of how issues have been tackled, with a focus on decontamination which was the pillar of large-scale reconstruction efforts.

Journal Articles

IAEA activities after Russia military invasion to Ukraine

Kobayashi, Naoki

Enerugi Rebyu, 43(11), p.18 - 21, 2023/10

no abstracts in English

Journal Articles

Development of safety design technologies for sodium-cooled fast reactor coupled to thermal energy storage system with sodium-molten salt heat exchanger; Project overview

Yamano, Hidemasa; Kurisaka, Kenichi; Takano, Kazuya; Kikuchi, Shin; Kondo, Toshiki; Umeda, Ryota; Shirakura, Shota*

Dai-27-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Koen Rombunshu (Internet), 5 Pages, 2023/09

This project studies investigation on safety design guideline and risk assessment technology for sodium-cooled fast reactor with the molten-salt heat storage system, development of evaluation method for heat transferring performance between sodium and molten-salt and improvement of the performance, and evaluation of chemical reaction characteristic between sodium and molten-salt and improvement of its safety. The project overview is presented in this report.

Journal Articles

Experiment on gas entrainment evaluation method from free liquid surface in a sodium-cooled fast reactor, 2; Measurement of gas core length by dynamic image processing

Endo, Kazuki*; Kobayashi, Shunsuke*; Jasmine, H.*; Sakai, Takaaki*; Matsushita, Kentaro; Ezure, Toshiki; Tanaka, Masaaki

Dai-27-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Koen Rombunshu (Internet), 5 Pages, 2023/09

Assuming gas entrainment (GE) to the main coolant circulation system from cover gas which is an inert gas to cover sodium coolant in a reactor vessel of the sodium cooled fast reactor, there is a concern that reactivity disturbance will occur when bubbles pass through the reactor core. Conventionally, an evaluation method based on static vortex extension theory has been employed for the GE prediction. However, it is known that the method gives rather overestimation for the GE occurrence from the unsteady traveling vortex dimple at the wide liquid surface. In order to contribute to understand the phenomena, experimental data have been accumulated by the basic water experiment. In this study, measurement was performed for the length of a gas cores that grew while moving on the free liquid surface by dynamic image processing, and the types of the GEs and the occurrence conditions were evaluated.

Journal Articles

Experiment on gas entrainment evaluation method from free liquid surface in a sodium-cooled fast reactor, 1; Measurement of velocity distributions in the experimental flow area by PIV method

Kobayashi, Shunsuke*; Endo, Kazuki*; Jasmine, H.*; Sakai, Takaaki*; Matsushita, Kentaro; Ezure, Toshiki; Tanaka, Masaaki

Dai-27-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Koen Rombunshu (Internet), 5 Pages, 2023/09

Assuming gas entrainment (GE) to the main coolant circulation system from cover gas which is an inert gas to cover sodium coolant in a reactor vessel of the sodium cooled fast reactor, there is a concern that reactivity disturbance will occur when bubbles pass through the reactor core. Conventionally, an evaluation method based on static vortex extension theory has been employed for the GE prediction. However, it is known that the method gives rather overestimation for the GE occurrence from the unsteady traveling vortex dimple at the wide liquid surface. In order to contribute to understand the phenomena, experimental data have been accumulated by the basic water experiment. In this study, the velocity distributions were measured under the conditions where GE occurs by particle image velocity (PIV) measurement in an experimental system to observe the gas cores that grow from the unsteady traveling vortex dimple.

Journal Articles

Development of gas entrainment evaluation method considering three-dimensional pressure decrease distribution along the center of free surface vortex

Matsushita, Kentaro; Ezure, Toshiki; Imai, Yasutomo*; Fujisaki, Tatsuya*; Tanaka, Masaaki

Dai-27-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Koen Rombunshu (Internet), 5 Pages, 2023/09

In design of sodium-cooled fast reactors (SFRs), cover gas entrainment phenomena induced by vortex dimple at free surface in upper plena is an important thermal-hydraulic issue. Authors have developed an evaluation method of gas entrainment with an evaluation tool named "StreamViewer". In this study, modification of evaluation model to improve quantitatively prediction accuracy of gas core length was investigated. In this model, vortex center lines which elongated from suction port where entrance of gas to heat transport system, for instance, IHX inlet in pool type SFRs, to free surface in plenum were to be identified, and distribution of pressure decrease along vortex center line was calculated to judge possibility of gas entrainment in comparisons with hydraulic head. This evaluation model was applied to results of water experiment with a rectangular open channel, where unsteady vortices are generated. It was confirmed that this model can identify occurrence of gas entrainment.

Journal Articles

JSME series in thermal and nuclear power generation Vol.3 (Sodium-cooled fast reactor development; R&Ds on thermal-hydraulics and safety assessment towards social implementation)

Tanaka, Masaaki; Uchibori, Akihiro; Okano, Yasushi; Yokoyama, Kenji; Uwaba, Tomoyuki; Enuma, Yasuhiro; Wakai, Takashi; Asayama, Tai

Dai-27-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Koen Rombunshu (Internet), 5 Pages, 2023/09

The book, JSME Series in Thermal and Nuclear Power Generation Vol.3 Sodium-cooled Fast Reactor, was published as a 30th anniversary memorial project of Power & Energy Systems Division. This paper describes an introduction of the book on a part of key technologies regarding safety assessment, thermal-hydraulics, neutronics, and fuel and material development. This introductory paper also provides an overview of an integrated evaluation system named ARKADIA to offer the best possible solutions for challenges arising during the design process, safety assessment, and operation of a nuclear plant over its life cycle, in active use of the R&D efforts and knowledges on thermal-hydraulics and safety assessment with state-of-the-art numerical analysis technologies.

Journal Articles

Development of virtual plant model for design rationalization of fast reactors by multi-level simulation system; Confirmation of functionality in application to U.S. experimental fast reactor EBR-II

Yoshimura, Kazuo; Doda, Norihiro; Nakamine, Yoshiaki*; Fujisaki, Tatsuya*; Igawa, Kenichi*; Iida, Masaki*; Tanaka, Masaaki

Dai-27-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Koen Rombunshu (Internet), 5 Pages, 2023/09

In Japan Atomic Energy Agency, a virtual plant model of the sodium-cooled fast reactor plant composed in a computer is being developed to reduce the development cost, by replacing the experiments to the numerical simulations with coupled analyses of the physical phenomena accounting for the interaction between components under various plant conditions. Through the numerical analysis of the ULOHS test in the U.S. experimental fast reactor named EBR-II, applicability of the virtual plant model was confirmed in comparison with the measured data including the core inlet temperature and the reactor power.

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