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Journal Articles

A View of technology maturity assessment to realize fusion reactor by Japanese young researchers

Kasada, Ryuta*; Goto, Takuya*; Fujioka, Shinsuke*; Hiwatari, Ryoji*; Oyama, Naoyuki; Tanigawa, Hiroyasu; Miyazawa, Junichi*; Young Scientists Special Interest Group on Fusion Reactor Realization*

Purazuma, Kaku Yugo Gakkai-Shi, 89(4), p.193 - 198, 2013/04

Japanese young researchers who have interest in realizing fusion reactor have analyzed Technology Readiness Levels (TRL) in Young Scientists Special Interest Group on Fusion Reactor Realization. In this report, brief introduction to TRL assessment and a view of TRL assessment against fusion reactor projects conducting in Japan.

Journal Articles

Efforts towards improvement of systems codes for the Broader Approach DEMO design

Nakamura, Makoto; Kemp, R.*; Uto, Hiroyasu; Ward, D. J.*; Tobita, Kenji; Hiwatari, Ryoji*; Federici, G.*

Fusion Engineering and Design, 87(5-6), p.864 - 867, 2012/08

 Times Cited Count:14 Percentile:76.37(Nuclear Science & Technology)

For fusion research directed at electricity generation in the ITER and post-ITER era, it is necessary to define development targets toward DEMO including plasma parameters and engineering requirements such as magnetic field and divertor heat flux. In general as a first step of systematic reactor design, systems analysis is performed in order to estimate reactor operation windows with engineering constraints. Thus, evaluation of existing systems analysis codes or development of systems codes is essential for basis of fusion reactor plasma parameters and engineering requirements. In this paper we report recent our efforts towards improvement of systems codes for the BA DEMO design, i.e. benchmarking the two systems codes the Japan and EU home teams are managing. The main result is that calculation outputs from the two codes are in good agreement.

Journal Articles

Development of a methodology to evaluate characteristics of energy technology by conjoint analysis

Hiwatari, Ryoji*; Okano, Kunihiko*; Asaoka, Yoshiyuki*; Nagano, Koji*; Ogawa, Yuichi*; Kato, Takaaki*; Tobita, Kenji; Norimatsu, Takayoshi*

Denryoku Chuo Kenkyusho Hokoku (L07012), P. 34, 2008/07

Key to take public acceptance into account on the energy system is how to evaluate and compare quantitatively the merits and the demerits of each energy system from the public viewpoint. For this purpose, a method to evaluate the property of energy technology is developed based on the conjoint analysis technique. Based on the statistical method, utility values for energy abundance, environmental load (i.e. CO$$_{2}$$ emission), stability of supply, sense of security, and other features as well as economic performance, are estimated from several thousands of choice experiments to more than 1600 respondents volunteered in the study. The basic methodology developed in this study establishes the first step to assess energy technology quantitatively on a common standard, and needs further integration with other factors, such as waste generation other than CO$$_{2}$$ emission.

Journal Articles

Effect of SOL decay length on modeling of divertor detachment by using simple core-SOL-divertor model

Hiwatari, Ryoji*; Hatayama, Akiyoshi*; Takizuka, Tomonori

Contributions to Plasma Physics, 48(1-3), p.174 - 178, 2008/03

 Times Cited Count:0 Percentile:0.01(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Challenge to innovative technologies and the expected market appeal

Tobita, Kenji; Konishi, Satoshi*; Tokimatsu, Koji*; Nishio, Satoshi; Hiwatari, Ryoji*

Purazuma, Kaku Yugo Gakkai-Shi, 81(11), p.875 - 891, 2005/11

no abstracts in English

Journal Articles

Path toward commercial fusion power plants

Okano, Kunihiko*; Kikuchi, Mitsuru; Tobita, Kenji; Hiwatari, Ryoji*

Purazuma, Kaku Yugo Gakkai-Shi, 81(11), p.839 - 848, 2005/11

no abstracts in English

Journal Articles

Experimental validation of beam particle self interaction in JT-60U by use of N-NB

Okano, Kunihiko*; Suzuki, Takahiro; Umeda, Naotaka; Hiwatari, Ryoji*; Masaki, Kei; Tobita, Kenji; Fujita, Takaaki

Purazuma, Kaku Yugo Gakkai-Shi, 81(8), p.579 - 580, 2005/08

In a toroidal system, circulating fast ions generated by neutral beam injection affect the beam stopping cross-section of the neutral beam itself. This effect is called "beam particle self-interaction (BPSI)". In a recent experiment in JT-60U with 350 keV H$$^{0}$$ beam, an indication of this BPSI effect has been found for the first time. In a low density discharge at about 1$$times$$10$$^{19}$$m$$^{-3}$$, the beam shine-through decreased by about 35% within several hundred msec after beam injection. This result is consistent with a prediction by the BPSI theory.

Journal Articles

Research aimed at reducing radioactive wastes

Tobita, Kenji; Hiwatari, Ryoji*

Purazuma, Kaku Yugo Gakkai-Shi, 78(11), p.1179 - 1185, 2002/11

no abstracts in English

Journal Articles

Possible scenario to start up DT fusion plant without initial loading of tritium

Konishi, Satoshi; Asaoka, Yoshiyuki*; Hiwatari, Ryoji*; Okano, Kunihiko*

Purazuma, Kaku Yugo Gakkai-Shi, 76(12), p.1309 - 1312, 2000/12

no abstracts in English

Journal Articles

Transport simulation of JT-60U L-mode discharges

Hiwatari, Ryoji*; Ogawa, Yuichi*; Amano, Tsuneo*; Takizuka, Tomonori; Shirai, Hiroshi; *; Inoue, Nobuyuki*

Journal of the Physical Society of Japan, 67(1), p.147 - 157, 1998/01

 Times Cited Count:1 Percentile:15.97(Physics, Multidisciplinary)

no abstracts in English

Oral presentation

Present status of BA DEMO design activity

Tobita, Kenji; Nishio, Satoshi; Nishitani, Takeo; Ozeki, Takahisa; Araki, Masanori; Okano, Kunihiko*; Hiwatari, Ryoji*; Ogawa, Yuichi*

no journal, , 

During the first three years of BA DEMO design activity, exchange of opinions is carried out between Japanese and European experts in a workshop style. In the previous two workshops, the both parties were devoted to discussions on definition of DEMO, role of DEMO in their fusion development program, requirements for DEMO and issues on DEMO physics and engineering. Throughout the discussion, common design issues which are not independent DEMO design concepts, including (1) divertor, (2) maintenance, (3) superconducting magnet, (4)current drive (steady state operation), etc. Key issues regarding each subject are removal of high heat load in the divertor under severe neutron environment, maintenance scheme which could provide high availability, need for high field superconducting magnet, and current drive schemes favorable in the aspects of the current drive efficiency and the controllability of current profile.

Oral presentation

Japanese contribution to BA DEMO design activity

Tobita, Kenji; Asakura, Nobuyuki; Uto, Hiroyasu; Okano, Kunihiko*; Ogawa, Yuichi*; Nishitani, Takeo; Hiwatari, Ryoji*; Nakamura, Makoto*

no journal, , 

In the Phase One of the Broader Approach (BA) DEMO design activity, we have proceeded with the exchange of technical informations in the workshop style to enhance mutual understanding on DEMO design. The discussion was mainly focused on (1) role of DEMO and (2) engineering issues on DEMO. This presentation will introduce the Japanese contribution to the activity.

Oral presentation

Design concept of conducting shell for remote maintenance scheme in DEMO reactor

Uto, Hiroyasu; Takase, Haruhiko; Sakamoto, Yoshiteru; Tobita, Kenji; Hiwatari, Ryoji; Mori, Kazuo; Kudo, Tatsuya; Someya, Yoji; Asakura, Nobuyuki

no journal, , 

This presentation describes conceptual design of in-vessel component including conducting shell in DEMO design activities, in order to propose feasible DEMO reactor from plasma vertical stability and engineering viewpoint. The conducting shell design for plasma vertical stability was clarified from the plasma vertical stability analysis, and a conceptual design divided in the toroidal direction for the blanket remote maintenance was proposed. We evaluated dependence of the plasma vertical stability on the conducing shell parameters and electromagnetic force at plasma disruption by using a numerical simulation code (EDDYCAL) with actual shape and position of the vacuum vessel and in-vessel components. The calculation results showed that the double-loop shell has the most effect on plasma vertical stability. On the other hand, while the electromagnetic force at the plasma disruption is a few times larger than no conducting shell case because of larger eddy current on conducting shell.

Oral presentation

Analysis of plasma position control for DEMO reactor

Takase, Haruhiko; Uto, Hiroyasu; Sakamoto, Yoshiteru; Mori, Kazuo; Kudo, Tatsuya; Hiwatari, Ryoji; Tobita, Kenji

no journal, , 

Plasma position control for DEMO reactor has been studied using numerical simulation, which consists of plasma equilibrium, eddy current and active feedback control analyses. The stabilization effect of in-vessel components, the influence on the magnetic detector and the power of active feedback control coils are evaluated. Especially, the influence on plasma position control by installation of the breeding blanket modules is shown in this paper.

Oral presentation

Numerical analysis of divertor erosion for Demo

Homma, Yuki; Hoshino, Kazuo; Yamoto, Shohei*; Asakura, Nobuyuki; Tokunaga, Shinsuke; Hatayama, Akiyoshi*; Sakamoto, Yoshiteru; Hiwatari, Ryoji; Tobita, Kenji

no journal, , 

no abstracts in English

Oral presentation

The Analysis of the surface heat load on the Demo first wall

Miyoshi, Yuya; Takase, Haruhiko; Hiwatari, Ryoji; Hoshino, Kazuo; Asakura, Nobuyuki; Someya, Yoji

no journal, , 

For the Demo reactor, the blanket design is one of the most important issue and the analysis of the surface heat load on the first wall for that design is essential. The neutron load, radiation load and the ion heat load are the main contributing factor of the first wall heat load. In this conference, the ion heat load is mainly considered. The analysis of the relationships between the form of the Demo first wall module and the ion heat load will be presented.

Oral presentation

Design of Limiter for a fusion demo reactor

Kudo, Hironobu; Watanabe, Kazuhito; Hiwatari, Ryoji; Asakura, Nobuyuki; Tokunaga, Shinsuke; Someya, Yoji; Nozawa, Takashi; Tanigawa, Hiroyasu

no journal, , 

In a fusion demo reactor, a rump-up scenario of the plasma is studied. The plasma is growing up and contacting on the first wall surface (limiter-phase) before shifting to diverter phase. Heat load of this time is a transient thing of the dozens seconds. However, it is bigger than the heat load which the first wall receives at the steady state. Therefore there are two idea to be taken with a demo reactor for this heat load. One is that addition a function of limiter to blanket oneself. Another one is design limiter as the independent structure. It is necessary to finally compare the superiority and inferiority of both in TBR (Tritium Breeding ratio) influenced by thickness of the surface tungsten layer and occupation area. This study perform conceptual design of independent limiter.

Oral presentation

Study on operation plan for a fusion DEMO plant

Hiwatari, Ryoji; Watanabe, Kazuhito; Aoki, Akira; Tobita, Kenji; Demo Design Joint Special Team

no journal, , 

The conceptual design activity for a fusion Demo plant by the DEMO design joint special team has been started according to the report by the Joint-Core Team for the establishment of technology based required for the development of a Fusion DEMO reactor. One of the main subjects will be the operation plan for DEMO in the intermediate check and review around 2020. In this presentation, the present result on the operation plan for DEMO is reported. Three categories are considered; (1) Operation plan for demonstration of electric generation, (2) Operation plan for demonstration of feasibility of fusion energy, (3) Data acquisition plan. From those view points, experimental subjects, technical skill and acquisition data are listed up as for core plasma, in-vessel components (blanket and divertor), fuel cycle system, plant operation, remote maintenance and inspection, safety system, environmental effect. A preliminary operation plan for DEMO based on the Monju operation plan will be reported.

Oral presentation

Shutdown dose rate assessment during replacement of in-vessel components for a multi-module-segments maintenance scheme-based fusion DEMO reactor

Someya, Yoji; Uto, Hiroyasu; Hiwatari, Ryoji; Tanigawa, Hisashi; Tobita, Kenji

no journal, , 

3D radiation map analyses were conducted using a code of DCHAIN-SP2001 on the basis of provisional water cooled fusion DEMO reactor as fusion power of 1.5 GW and major radius of 8.2 m. This analysis was performed assuming a divertor exposed for 1.0 FPY (full power year) and a blanket exposed for 4 FPY, respectively. As a result, after 1 month after shutdown the dose rate at the plasma center was 10$$^{4}$$ Sv/h. It dropped to 100 Sv/h at replacement port (upper and bottom). It was found that replacement of in-vessel components for DEMO could be possible. This is reason that the replacement method for fusion DEMO reactor can lower environment dose rate than the replacement method for shielding blankets in vacuum vessel for ITER by limiting a movable range of the remote handling equipment in maintenance port for DEMO.

Oral presentation

Estimation of recirculating power in fusion DEMO reactor

Sakamoto, Yoshiteru; Someya, Yoji; Uto, Hiroyasu; Nakamura, Makoto; Miyoshi, Yuya; Aoki, Akira; Hiwatari, Ryoji; Tobita, Kenji

no journal, , 

no abstracts in English

24 (Records 1-20 displayed on this page)