Current status and critical issues for development of SiC composites for fusion applications

Current status and recent research achievements in SiC/SiC composites

Tritium/hydrogen barrier development

Silicon carbide composites as fusion power reactor structural materials

Extensive progress and improvements have been made in the science and technology of gamma titanium aluminide alloys within the last decade. In particular, our understanding of their microstructural characteristics and property/microstructurc relationships has been substantially deepened. Based on these achievements, various engineering two-phase gamma alloys have been developed and their mechanical and chemical properties have been assessed. Aircraft and automotive industries arc pursuing their introduction for various structural components. At the same time, recent basic studies on the mechanical properties of two-phase gamma alloys, in particular with a controlled lamellar structure have provided a considerable amount of fundamental information on the deformation and fracture mechanisms of the two-phase gamma alloys. The results of such basic studies are incorporated in the recent alloy and microstructure design of two-phase gamma alloys. In this paper, such recent advances in the research and development of the two-phase gamma alloys and industrial involvement are summarized.

Gamma Titanium Aluminide Alloys

Poloidal field distribution studies in tokamak reactor

A feasibility study is presented of fast tokamak plasma terminations by means of high-Z impurity liquid jet injections in order to reduce the technological requirements of such terminations. The calculation was carried out by combining models described for the jet ablation and the current termination and taking into account the ionization of the jet material exposed to generated runaway electrons. The liquid jet was assumed to fragment and thus to deposit more massive impurity ions in the plasma. Although argon or krypton jet injection generates the runaway electron current, it decays in several hundred milliseconds with ionization of the residual jet material. These high-Z impurity jet injections would also be applicable for terminating or reducing the runaway electron current tails generated by major plasma disruptions.

Termination of Plasma Discharge by High- Z Liquid Impurity Jet Injection in a Tokamak Reactor

The radwaste generated from three fusion power reactors using ferritic steel, V-alloy and SiC/SiC composite were classified into low level waste (LLW) which can be disposed by shallow land burial (...

Effect of activation cross section change on the shallow land burial fraction of low activation materials for fusion reactors

The finite element analysis and calculation were performed for the blanket first-wall made of SiC/SiC composite material for Advanced Steady-state Tokamak Reactor 2, A-SSTR2, which at present is conceptually designed in Naka Fusion research establishment, JAERI. Comparison analysis and design window were analyzed using the finite element code ADINA 7.4. Through a 2D calculation for various geometrical configurations and sensitive material properties, a fundamental guideline for the first wall and blanket design are established with respect to maximum temperature, thermal and mechanical stress for many configurations. To satisfy hydrodynamic requirement, a4d4 (the dimension of coolant channel is 4 mm × 8 mm, and the distance between neighboring channels is 4 mm) was chosen as a design point for high thermal conductivity up to 50 W/m.K. In order to find a good solution for lower conductivity, more elaborate work should be done in the future. Nonetheless, the outline of design window for a specific structural material is very useful for the future A-SSTR2 first wall design.

http://iopscience.iop.org/article/10.1088/1009-0630/5/1/009/pdf

Satoshi Nishio

Papers

Poloidal field distribution studies in tokamak reactor

Termination of Plasma Discharge by High- Z Liquid Impurity Jet Injection in a Tokamak Reactor

Effect of activation cross section change on the shallow land burial fraction of low activation materials for fusion reactors

Thermo-Mechanical Design Considerations for First Wall of A-SSTR2

Composition adjustment of low activation materials for shallow land burial