The Conceptual Design Activities of the International Thermonuclear Experimental Reactor (ITER) were carried out jointly by the European Community, Japan, the Soviet Union and the United States of America, under the auspices of the International Atomic Energy Agency. The European Community provided the site for joint work sessions at the Max-Planck-Institut für Plasmaphysik in Garching, Germany. The Conceptual Design Activities began in the spring of 1988 and ended in December 1990. The objectives of the activities were to develop the design of ITER, to perform a safety and environmental analysis, to define the site requirements as well as the future research and development needs, to estimate the cost and manpower, and to prepare a schedule for detailed engineering design, construction and operation. On the basis of the investigation and analysis performed, a concept of ITER was developed which incorporated maximum flexibility of the performance of the device and allowed a variety of operating scenarios to be adopted. The heart of the machine is a tokamak having a plasma major radius of 6 m, a plasma minor radius of 2.15 m, a nominal plasma current of 22 MA and a nominal fusion power of 1 GW. The conceptual design can meet the technical objectives of the ITER programme. Because of the success of the Conceptual Design Activities, the Parties are now considering the implementation of the next phase, called the Engineering Design Activities.

The compact reversed shear tokamak CREST is a cost competitive reactor concept based on a reversed shear high β plasma and water cooled ferritic steel components. The moderate aspect ratio A = 3.4 and the elongation κ = 2.0 of CREST are very similar to the case of the ITER advanced mode plasma. Presentation of such a concept based on the ITER project should be worth while for formulating a fusion development strategy. The achievement of a competitive cost of electricity (COE) is the first priority for electric power industries. High β and high thermal efficiency are the most effective parameters for achieving a competitive COE. In order to achieve a high efficiency power plant, a superheated steam cycle has been adopted which permits a high thermal efficiency (η = 41%). Current profile control and high speed plasma rotation by neutral beam current drive stabilize the ideal MHD activity up to the Troyon coefficient βN = 5.5. A cost assessment has shown that CREST could generate about 1.16 GW(e) electric power at a competitive cost.

Joules) of energy. If one assumes that the future world population stabilizes at 10 billions, and the people consume a similar amount of energy per capita to that of the people in the presently developed countries, the world will need about 2 ZJ a year. A recent survey of the available future energy resources indicates that the energies recoverable from coal, oil and gas are only 23 ZJ, 6.7 ZJ and 6.4 ZJ, respectively. Other energy resources such as solar and wind have problems of fluctuation due to the weather conditions. However, the energy expected from known Uranium resources by breeder reactors is 227 ZJ and that from Lithium by fusion reactors is more than 175 ZJ. Therefore, it is important to make efforts to develop and use breeder reactors and fusion reactors to supply a major part of the energy need in the future.

ITER: CONCERT DEFINITION. On the basis of the results of the investigation carried out since May 1988, an ITER concept has been defined which incorporates the maximum possible flexibility and allows a variety of plasma configurations and operating scenarios. For technology experiments, with a full breeding blanket, the machine can be operated typically with a plasma of 18 MA at a major radius of 5.5 tn. For the plasma physics experiments the same machine can, if required, be cot@ured with a thinner shield and produce a plasma of 22 MA with fully inductive operation and higher currents under limited conditions. A list of important ITER specific physics and technology R&D tasks has been developed. Implementation of these tasks is now under way.

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