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Journal Articles

The Development status of Generation IV reactor systems, 7; Sodium-cooled Fast Reactor (SFR)

Kamide, Hideki; Ito, Takaya*; Kotake, Shoji*

Nippon Genshiryoku Gakkai-Shi, 60(9), p.562 - 566, 2018/09

Sodium-cooled Fast Reactors (SFRs) have significant characteristics on sustainability as follows, highly effective utilization of Uranium resource, burning of TRU long-life nuclide, e.g., Plutonium, reduction of volume and toxicity of high level radioactive waste of spent fuels. SFRs are one of promising concepts at a step of demonstration phase of development. BN-800 in Russia has already started commercial operation. This is a great step toward the commercialization of SFRs. Russia stated that SFR entered the step of commercial use and next step was demonstration of safety and economy of SFRS by means of operation of BN-1200. Construction of a demo reactor of 600 MWe started in China. In India, operation of PFBR is planned near future and also constructions of 6 units of commercial reactors are also planned. In this report such SFR development plans of oversea countries are summarized including development status and future direction in Japan,

Journal Articles

Development of prototype reactor maintenance, 1; Application to piping system of sodium-cooled reactor prototype

Kotake, Shoji*; Chikazawa, Yoshitaka; Takaya, Shigeru; Otaka, Masahiko; Kubo, Shigenobu; Arai, Masanobu; Kunogi, Kosuke; Ito, Takaya*; Yamaguchi, Akira*

Proceedings of 2017 International Congress on Advances in Nuclear Power Plants (ICAPP 2017) (CD-ROM), 6 Pages, 2017/04

A maintenance management required to prototype nuclear power reactors is proposed. Monitoring and control of sodium impurity and thermal transient are extremely important for sodium boundary maintenance for sodium-cooled fast reactors. At the fast stage of the prototype reactor Monju operation, degradation mechanism on the piping should be demonstrated based on operation experiences. Therefore inspection on a representative position for crack indication and pipe thickness is proposed. Due to less experience of SFR plants, early detection of boundary failure is considered. For a matured operation stage, when degradation mechanism is well demonstrated based on inspection data, inspection cycle could be extended. And for commercial reactors, maintenance without inspection will be established based on accumulated operation experiences including those of the prototype reactor Monju.

Journal Articles

Development of prototype reactor maintenance, 2; Application to piping support of sodium-cooled reactor prototype

Arai, Masanobu; Kunogi, Kosuke; Aizawa, Kosuke; Chikazawa, Yoshitaka; Takaya, Shigeru; Kubo, Shigenobu; Kotake, Shoji*; Ito, Takaya*; Yamaguchi, Akira*

Proceedings of 2017 International Congress on Advances in Nuclear Power Plants (ICAPP 2017) (CD-ROM), 6 Pages, 2017/04

Applications for maintenance program on piping support of prototype fast breeder reactor Monju are studied. Based on degradation mechanism, snubbers in Monju primary cooling system showed lifetime more than the plant lifetime of 30 years by experiments conservatively. For the first step during construction, visual inspection on accessible all supports could be available. In that visual inspection, mounting conditions and damages of all accessible supports could be monitored. One of major features of the Monju primary piping system is large thermal expansion due to large temperature difference between maintenance and operation conditions. Thanks to that large thermal expansion, integrity of the piping support could be monitored by measuring piping displacement. When technologies of piping displacement monitoring are matured in Monju, visual inspection on piping support could be shifted to piping displacement monitoring. At that stage, the visual inspection could be limited only on representative supports.

Journal Articles

Design features and cost reduction potential of JSFR

Kato, Atsushi; Hayafune, Hiroki; Kotake, Shoji*

Nuclear Engineering and Design, 280, p.586 - 597, 2014/12

 Times Cited Count:3 Percentile:68.51(Nuclear Science & Technology)

To improve the economic competitiveness of the Japan Sodium-cooled Fast Reactor (JSFR), several innovative designs have been introduced, e.g. reduction of number of main cooling loop, shorter pipe arrangement by adopting thermally durable material, a compact reactor vessel (RV), integration of a primary pump and an intermediate heat exchanger (IHX). A new approach for construction cost estimation has been introduced to handle innovative technologies, for example, concerning different kinds of material, fabrication processes of equipment etc. As results of cost estimations and the latest conceptual JSFR design, economic goals of Generation IV nuclear energy systems can be achieved by expecting the following cost reduction effects: commodity reduction by adopting innovative design, economy of scale by power generation increase, learning effect etc.

JAEA Reports

Preliminary conceptual design of the secondary sodium circuit-eliminated JSFR (Japan Sodium Fast Reactor) adopting a supercritical CO$$_{2}$$ turbine system, 2; Turbine system and plant size

Kisohara, Naoyuki; Sakamoto, Yoshihiko; Kotake, Shoji*

JAEA-Research 2014-016, 60 Pages, 2014/09

JAEA-Research-2014-016.pdf:22.38MB

JAEA has performed a design study of an S-CO$$_{2}$$ gas turbine system applied to the JSFR. In this study, the S-CO$$_{2}$$ cycle turbine system was directly connected to the primary sodium system of the JSFR to eliminate the secondary sodium circuit, aiming for further economical improvement. This report describes the system configuration, heat/mass balance, and main components of the S-CO$$_{2}$$ turbine system, based on the JSFR specifications. The layout of components and piping in the reactor and turbine buildings were examined and the dimensions of the buildings were estimated. The study has revealed that the reactor and turbine buildings could be reduced by 7% and 40%, respectively, in comparison with those in the existing JSFR design with the secondary sodium circuit employing the steam turbine. The cycle thermal was also calculated as 41.9-42.3%, which is nearly the same as that of the JSFR with the water/steam system.

JAEA Reports

Preliminary conceptual design of the secondary sodium circuit-eliminated JSFR (Japan Sodium Fast Reactor) adopting a supercritical CO$$_{2}$$ turbine system, 1; Sodium/CO$$_{2}$$ heat exchanger

Kisohara, Naoyuki; Sakamoto, Yoshihiko; Kotake, Shoji*

JAEA-Research 2014-015, 33 Pages, 2014/09

JAEA-Research-2014-015.pdf:27.33MB

JAEA has performed a design study of an S-CO$$_{2}$$ gas turbine system applied to the JSFR. In this study, the S-CO$$_{2}$$ cycle turbine system was directly connected to the primary sodium system of the JSFR to eliminate the secondary sodium circuit, aiming for further economical improvement. The Na/CO$$_{2}$$ heat exchanger is one of the key components, and this report describes its structure and the safety in case of CO$$_{2}$$ leak. A Printed Circuit Heat Exchanger (PCHE) is employed to the heat exchanger. A SiC/SiC ceramic composite material is used for the PCHE to prevent crack growth and to reduce thermal stress. The Na/CO$$_{2}$$ heat exchanger has been designed in such a way that a number of small heat transfer modules are combined in the vessel in consideration of manufacture and repair. CO$$_{2}$$ leak events in the heat exchanger have been also evaluated, and it revealed that no significant effect has arisen on the core or the primary sodium boundary.

Journal Articles

Radioactivity evaluation of the secondary sodium in DRACS of the Japan Sodium-cooled Fast Reactor

Sasaki, Kenji*; Naito, Katsuaki*; Oki, Shigeo; Okubo, Tsutomu; Kotake, Shoji*

Progress in Nuclear Science and Technology (Internet), 4, p.94 - 98, 2014/04

This paper evaluates the amount of activation of the secondary sodium in Direct Heat Exchanger (DHX) by neutrons leaked from the core, the radioactivity density, and the dose rate around the secondary sodium pipes in Direct Reactor Auxiliary Cooling System (DRACS) and confirms that the requirements in radioactivity free areas are satisfied by improving the exactness of calculation model with Monte Carlo Methodology.

Journal Articles

Selection of sodium coolant for fast reactors in the US, France and Japan

Sakamoto, Yoshihiko; Garnier, J.-C.*; Rouault, J.*; Grandy, C.*; Fanning, T.*; Hill, R.*; Chikazawa, Yoshitaka; Kotake, Shoji*

Nuclear Engineering and Design, 254, p.194 - 217, 2013/01

 Times Cited Count:9 Percentile:37.16(Nuclear Science & Technology)

This trilateral study confirms that the fundamental mission of the fast reactor is to achieve significant uranium utilization and waste management goals. Thus, fast spectrum reactor concepts are vital for nuclear fuel cycle sustainability goals. The trilateral countries agree that SFR, GFR and LFR are capable to achieve the goals. However SFR is the most matured technology from the view point of industrial deployment while GFR and LFR still require long term development before a test reactor project could begin. The trilateral common view supports fast reactor project situations in each country.

Journal Articles

Evaluation of JSFR key technologies

Chikazawa, Yoshitaka; Aoto, Kazumi; Hayafune, Hiroki; Kotake, Shoji; Ono, Yushi; Ito, Takaya*; Toda, Mikio*

Nuclear Technology, 179(3), p.360 - 373, 2012/09

 Times Cited Count:9 Percentile:34.7(Nuclear Science & Technology)

Key technologies for Japan Sodium-cooled Fast Reactor (JSFR) have been evaluated. The ten technologies: high burn-up fuel, safety enhancement, compact reactor vessel, two-loop cooling system using high chromium steel, integrated intermediate heat exchanger/pump component, reliable steam generator, natural circulation decay heat removal system, simplified fuel handling system, containment vessel made of steel plate reinforced concrete and advanced seismic isolation system have been confirmed to be feasible to be installed a conceptual design of demonstration JSFR to be ready for large scale demonstration experiments.

Journal Articles

Current status of SFR development in Japan

Ieda, Yoshiaki; Chikazawa, Yoshitaka; Kotake, Shoji*

ATW; International Journal for Nuclear Power, 57(3), p.163 - 168, 2012/03

Fast reactor development experiences and status in Japan are summarized. The undergoing FaCT project is pursuing commercialization of fast reactor cycle system around 2050 under cooperation of MEXT, METI, utilities, venders and JAEA. As results of the FaCT Phase I, feasibility of the key technologies for JSFR has been evaluated and the project is waiting for launching the phase II due to the Tohoku large earthquake. It is considered that the nuclear development policy might be affected by the Tohoku large Earthquake/Tsunami in Japan. Nevertheless the significance of nuclear energy will not be changed and thus we will focus on the issues learnt from Fukushima accidents and reflect into the improvement of the safety of Monju and the safety design criteria for the next generation fast reactor systems.

Journal Articles

Comparison of sodium-cooled reactor fuel-handling systems with and without an ex-vessel storage tank

Chikazawa, Yoshitaka; Uzawa, Masayuki*; Usui, Shinichi*; Tozawa, Katsuhiro*; Kotake, Shoji

Nuclear Technology, 177(3), p.293 - 302, 2012/03

 Times Cited Count:3 Percentile:69.14(Nuclear Science & Technology)

JSFR is a concept of a commercial sodium-cooled fast reactor which has been being studied in Fast Reactor Cycle Technology Development (FaCT) project since 2006. For the JSFR fuel handling, various fuel handling systems (FHSs) were investigated and an advanced FHS with an ex-vessel storage tank (EVST) has been selected. The other FHS concepts investigated are evolutional FHSs without an EVST. The result has indicated that the construction cost of the evolutional systems do not reduce the construction cost dramatically, which is mainly due to additional safety measures required higher decay heat handling in gas atmosphere and due to the necessity of separated fresh and failed fuel storage. From an economical point of view, a longer plant outage of the evolutional systems offsets its advantage of the lower construction cost. On the basis of the results of this comparative study, JSFR has selected the FHS with an EVST.

Journal Articles

Safety design approach for a large-scale Japan Sodium-cooled Fast Reactor (JSFR)

Kotake, Shoji*; Yamano, Hidemasa; Sagayama, Yutaka

Fusion Science and Technology, 61(1T), p.137 - 143, 2012/01

 Times Cited Count:1 Percentile:87.51(Nuclear Science & Technology)

The present paper describes safety goals and principles for Generation IV energy systems, with emphasis on prevention and mitigation against severe accidents in the safety design corresponding to Level 4 of the defense-indepth architecture. Consistent with them, a deterministic safety design approach has been applied to the Japan Sodium-cooled Fast Reactor (JSFR) with the complimentary use of probabilistic approach. The JSFR safety design principle has also been developed with safety design features corresponding to essential safety functions, such as reactor shutdown, decay heat removal and containment. Design principle against chemical activity of sodium is also discussed both on the isolation from the reactor core safety and the contribution to the plant reliability.

Journal Articles

Safety design requirements for safety systems and components of JSFR

Kubo, Shigenobu*; Shimakawa, Yoshio*; Yamano, Hidemasa; Kotake, Shoji

Proceedings of International Conference on Fast Reactors and Related Fuel Cycles (FR 2009) (CD-ROM), 12 Pages, 2012/00

In order to embody a safety design, a higher level safety principle was broken down into a set of design requirements for each safety related system, structure and component (SSC). This paper will present an output of the safety requirements for safety related SSCs of JSFR.

Journal Articles

Comparison of pool/loop configurations in the JAEA feasibility study 1999-2006

Chikazawa, Yoshitaka; Kotake, Shoji; Sawada, Shusaku*

Proceedings of International Conference on Fast Reactors and Related Fuel Cycles (FR 2009) (CD-ROM), 12 Pages, 2012/00

Journal Articles

Development of FR construction cost estimation method in FaCT project

Kato, Atsushi; Kotake, Shoji; Yoshiuji, Takahiro*

Proceedings of International Conference on Fast Reactors and Related Fuel Cycles (FR 2009) (CD-ROM), 11 Pages, 2012/00

Within the FaCT project, commodities shall be reduced by introducing innovative technologies. In order to evaluate the economy for the Japan Sodium-cooled Fast Reactor (JSFR), the account code named SCALLE (Sum of Cost Account Leading to future Logistics Economy) has been developed, in which the basic methodology is bottom up of component costs based on amounts of material and corresponding unit costs.

Journal Articles

Development of transfer pot for JSFR ex-vessel fuel handling

Hirata, Shingo; Chikazawa, Yoshitaka; Kato, Atsushi; Uto, Nariaki; Obata, Hiroyuki*; Kotake, Shoji*

Proceedings of International Conference on Fast Reactors and Related Fuel Cycles (FR 2009) (CD-ROM), 10 Pages, 2012/00

In Fast Reactor Cycle Technology Development (FaCT) project, Japan Sodium-cooled Fast Reactor (JSFR) is going to adopt an advanced fuel handling system. As for ex-vessel spent fuel handling, a pot which contains two fuel subassemblies simultaneously and is applicable size to compact reactor vessel, has been developing so as to shorten a refueling period leading to an improvement of plant availability. The pot is required to provide sufficient cooling capability even in case of transportation malfunction during transportation of spent fuel subassemblies with high decay heat. In the present study, experimental and analytical studies to evaluate the cooling capacity of the pot are summarized.

Journal Articles

In-service inspection and repair program for commercialized sodium-cooled fast reactor

Nishiyama, Noboru; Kotake, Shoji*; Uzawa, Masayuki*

Proceedings of International Conference on Fast Reactors and Related Fuel Cycles (FR 2009) (CD-ROM), 9 Pages, 2012/00

Japan Sodium-cooled Fast Reactor (JSFR) adopts a compact design to reduce construction cost as a commercialized reactor. A commercialized fast reactor is also expected to be excellent in operation and maintenance for high availability. From the study for JSFR, in-service inspection and repair program necessary for JSFR has been developed. Major component design has been improved considering ISI accommodation, and the required ISI devices have been specified according to the proposed ISI program. To increase maintainability of JSFR, such approaches are employed at the conceptual design stage.

Journal Articles

JSFR design study and R&D progress in the FaCT project

Aoto, Kazumi; Uto, Nariaki; Sakamoto, Yoshihiko; Ito, Takaya*; Toda, Mikio*; Kotake, Shoji*

Proceedings of International Conference on Fast Reactors and Related Fuel Cycles (FR 2009) (CD-ROM), 11 Pages, 2012/00

In the FaCT project, SFR with 1,500 MWe is a target for the commercialization. R&D on innovative technologies to achieve the economic competitiveness and enhance the reliability and safety is carried out. A compact RV without wall-cooling layer is pursued in consideration of seismic reliability. For a two-loop cooling system with shortened high chromium steel piping, studies on the hydraulics in the pipe elbow and the fabrication capability of the pipes are being performed. A double-walled straight tube SG is investigated to enhance the reliability against sodium/water reaction, and developmental works are progressing including the thermal-hydraulic design and trial manufacturing for components. SASS is being developed with safety analysis of the applicability for JSFR and experimental demonstration in JOYO. An advanced fuel handling system is also pursued. Discussion on whether the innovative technologies can be adopted for JSFR is in progress to be finalized in 2010.

Journal Articles

Conceptual design study of JSFR, 2; Reactor system

Eto, Masao*; Kamishima, Yoshio*; Okamura, Shigeki*; Watanabe, Osamu*; Oyama, Kazuhiro*; Negishi, Kazuo; Kotake, Shoji*; Sakamoto, Yoshihiko; Kamide, Hideki

Proceedings of International Conference on Fast Reactors and Related Fuel Cycles (FR 2009) (CD-ROM), 10 Pages, 2012/00

In the JSFR design, the diameter of the Reactor Vessel (RV) shall be minimized and the reactor internal structures shall be simplified for reduction in construction cost. The reduction in the RV diameter is achieved by adopting an advanced refueling system and the hot RV with high temperature wall. The flow velocity in the reactor upper plenum increases because the diameter of the RV is decreased. As the result, the coolant flow field in reactor upper plenum is severe. The optimization of the coolant flow field in the reactor upper plenum was carried out for prevention the cover gas entrainment and the vortex cavitations at the hot leg intake. In addition, structural integrities for seismic loadings and thermal loadings were evaluated because the design seismic loading was highly increased and the vessel wall is directly exposed to the thermal transients of the upper plenum. This paper describes the characteristics and the results of the design study of the reactor system.

Journal Articles

Seismic isolation design for JSFR

Okamura, Shigeki*; Eto, Masao*; Kamishima, Yoshio*; Negishi, Kazuo; Sakamoto, Yoshihiko; Kitamura, Seiji; Kotake, Shoji*

Proceedings of International Conference on Fast Reactors and Related Fuel Cycles (FR 2009) (CD-ROM), 10 Pages, 2012/00

This paper describes the seismic design of JSFR, which includes the seismic condition, the seismic isolation system and the seismic evaluation of primary component. JSFR employs a seismic isolation system to mitigate the earthquake force. The design seismic loading is made more severe than ever since Niigata-ken Chuetsu-oki Earthquake in 2007. The earthquake force loaded on the primary components has to be mitigated more than that of the previous seismic isolation system. We examined the advanced seismic isolation system by optimizing the performance of the previous seismic isolation system considering the natural frequency of the primary components. The advanced seismic isolation system for SFR was adopted laminated rubber bearings which are thicker than that of the previous, as well as oil dampers. The seismic evaluation of nuclear reactor components under applying the advanced seismic isolation system was performed; the performance of the system was confirmed.

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