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

The Super-X Divertor (SXD), a robust axisymmetric redesign of the divertor magnetic geometry that can allow a fivefold increase in the core power density of toroidal fusion devices, is presented. With small changes in poloidal coils and currents for standard divertors, the SXD allows the largest divertor plate radius inside toroidal field coils. This increases the plasma-wetted area by 2–3 times over all flux-expansion-only methods (e.g., plate near main X point, plate tilting, X divertor, and snowflake), decreases parallel heat flux and hence plasma temperature at plate, and increases connection length by 2–5 times. Examples of high-power-density fusion devices enabled by SXD are discussed; the most promising near-term device is a 100 MW modular compact fusion neutron source “battery” small enough to fit inside a conventional fission blanket.

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Super-X divertors and high power density fusion devices

Design and material issues for high performance SiCf/SiC-based fusion power cores

Critical issues and current status of SiC/SiC composites for fusion

The limited thermal power handling capacity of the standard divertors (used in current as well as projected tokamaks) is likely to force extremely high (∼90%) radiation fractions frad in tokamak fusion reactors that have heating powers considerably larger than ITER [D. J. Campbell, Phys. Plasmas 8, 2041 (2001)]. Such enormous values of necessary frad could have serious and debilitating consequences on the core confinement, stability, and dependability for a fusion power reactor, especially in reactors with Internal Transport Barriers. A new class of divertors, called X-divertors (XD), which considerably enhance the divertor thermal capacity through a flaring of the field lines only near the divertor plates, may be necessary and sufficient to overcome these problems and lead to a dependable fusion power reactor with acceptable economics. X-divertors will lower the bar on the necessary confinement to bring it in the range of the present experimental results. Its ability to reduce the radiative burden impart...

On heat loading, novel divertors, and fusion reactors

Maintenance and material aspects of DREAM reactor

PROBLEM TO BE SOLVED: To provide an automatic screening system for disposing of radioactive waste by separating mixed metals from nonmetal and also classifying and discharging the metals by type SOLUTION: The system for screening radioactive waste is provided with a transfer machine (oscillating conveyer 6) for supplying radioactive waste; a turning machine 37 for aligning the attitude of the supplied radioactive waste; eddy current screening machines 7, 8, 9 for generating an AC magnetic field; and a plurality of recovery containers 22-26 The radioactive waste transferred from upstream by the transferring machine is aligned into a target attitude by the turning machine and supplied for the eddy current screening machine and separately collected to the recovery containers according to repulsion to the AC magnetic field by the eddy current screening machine COPYRIGHT: (C)2004,JPO

Seiichiro Yamazaki

Papers

Maintenance and material aspects of DREAM reactor

System for screening radioactive waste

Design study of helium-solid suspension cooled blanket and divertor plate for a tokamak power reactor

Development of high heat flux component fabrication technology

Electron beam heating tests of newly-developed C/C composites for application to JT-60U divertor plate