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Nuga, Hideo; Matsuyama, Akinobu; Yagi, Masatoshi; Fukuyama, Atsushi*
Plasma and Fusion Research (Internet), 10, p.1203006_1 - 1203006_2, 2015/01
Kikuchi, Mitsuru; Fasoli, A.*; Takizuka, Tomonori*; Diamond, P.*; Medvedev, S.*; Duan, X.*; Zushi, Hideki*; Furukawa, Masaru*; Kishimoto, Yasuaki*; Wu, Y.*; et al.
no journal, ,
Power and particle control is challenging for standard D-shaped H-mode scenario in tokamak. Possibility of negative triangularity as innovative tokamak concept is discussed by Kikuchi et al. Experimental and numerical studies of negative triangular plasma at CRPP-EPFL success-fully demonstrated improved connement and the weakening of the SOL flow acceleration is implied for the negative triangularity. Recent studies on mechanism of type II and grassy ELM show importance of closure of second stability access to achieve small ELM regimes and also kinetic effects. Medvedev showed that closure of second stability also occurs for negative triangularity. But the MHD stability in negative triangularity is a bit more complicated so that closure of second stability does not imply easy access to small ELM regimes. We discuss critical elements behind.
Takase, Haruhiko; Tobita, Kenji; Sakamoto, Yoshiteru; Uto, Hiroyasu; Mori, Kazuo; Kudo, Tatsuya
no journal, ,
Analysis of plasma position control is one of important issues for design of DEMO reactor on Broader Approach (BA). Especially, plasma performance, blanket design and maintenance scheme influence the plasma position control mutually. Therefore, we made a numerical simulation code that consists of plasma equilibrium analysis, eddy current analysis and plasma motion analysis. Since we analyzed several cases of design using this numerical simulation code, the results will be shown.
Rivas, J. C.*; Nakamura, Makoto; Someya, Yoji; Takase, Haruhiko; Tobita, Kenji; de Blas, A.*; Dies, J.*; Fabbri, M.*; Riego, A.*
no journal, ,
Safety studies of plasma-wall transients have been performed with AINA code for the Japanese DEMO design (water cooled pebble bed). The AINA code has been adapted from its original mission of performing safety studies for ITER to this new mission. A breeding blanket model has been implemented in code. The configuration has been changed to implement the design parameters of DEMO reactor. First analyses performed show the behavior of the reactor during ex-vessel LOCA transients and during overpower events.
Nuga, Hideo; Matsuyama, Akinobu; Shibata, Yoshihide; Yagi, Masatoshi; Kawano, Yasunori; Fukuyama, Atsushi*
no journal, ,
no abstracts in English
Nuga, Hideo; Matsuyama, Akinobu; Yagi, Masatoshi; Fukuyama, Atsushi*
no journal, ,
no abstracts in English
Rivas, J. C.*; Nakamura, Makoto; Someya, Yoji; Takase, Haruhiko; Tobita, Kenji; Dies, J.*; Blas, A. de*; Fabbri, M.*; Riego, A.*
no journal, ,
In the frame of JAPAN-EU collaborative work for development of AINA code in 2014-2016, a version of AINA code has been developed for the Japanese DEMO WCPB design. During 2014, the AINA code was adapted from ITER to this new mission. A breeding blanket model was implemented in code. The configuration was changed to implement the design parameters of DEMO reactor. Finally, safety studies of plasma-wall transients affecting blanket region were performed. During 2015, plasma models were improved both for plasma core and for divertor (improved SOL model). Safety analyses affecting divertor were performed, considering thermohydraulic accidents and plasma transients where loss of control function was assumed. First analyses performed for the Japanese DEMO design show the behavior of the reactor during Ex-Vessel LOCA and during overpower events. The preliminary conclusions point to the possibility of considering the plasma control system as a safety important component.
Takase, Haruhiko; Uto, Hiroyasu; Sakamoto, Yoshiteru; Mori, Kazuo; Kudo, Tatsuya; Tobita, Kenji
no journal, ,
Pre-conceptual design of DEMO reactor has been preceded under collaboration Japan and Europe (Broader Approach activities (BA)). In the case of DEMO reactor, it is important for design of plasma position control to take into account the actual shape of vacuum vessel and in-vessel components precisely since the design condition of DEMO reactor is different from current tokamak devices and ITER (for example, installation of maintenance ports). To consider the DEMO design condition, the numerical simulation that consists of three modules has been developed. As results, (1) The time constants of eddy current in the breeding blankets are less than 10ms and there is no influence to passive stabilization effect. (2) The stabilization effect of conducting components decreases by considering installation of vertical maintenance port. The adoption of vertical port is related to the choice of the maintenance scenario.
