Principles and plant system desingns of nuclear fusion power is described introductively. Taking mainly the D-T reaction as the most feasible reaction expected to be of practical use in near future, development status of fuel cycle processes of fusion reactor, such as fuel injection, separation of tritium from discharged plasma gases, production and recoveery of tritium in blanket, is reviewed. Since the burnup fraction per pass of injected tritium fuel will be only a few precent, it is important to recover unused tritium from discharged gaseous mixtures with very high recovery yield. Recovery processes, which are considered to be feasible, are palladium film permeation, diffusion-effusion, metal-sponge adsorption, laser method, oxidationelectro lysis, and cryogenic distillation method. For separating tritium produced in lithium metal blanket and lithium molten salt blanket, there seems to be several methods sucn as metalwindow method, molten salt extraction, heat-pipe method, lithium-getter method, gas sparging method and cold-trap method. Some feasible processes to recover tritium from potassium and helium coolants are also discussed. These include metal-window, solid adsorber, and cold trap and oxidation methods.
Then, significance of fusion energy as an alternative for the basic energy supply resources are compared with the other resources, such as fission and fossil fuels. In addition, it is noted that some artificial production of fairly large amount of tritium will be required for initial charge of fuels for developmental and first generation fullscale fusion reactors.
Finaly, regarding the safety and environment problems of fusion power reactors, production and release of radioactivity, especially of tritium, are examined for both situations of normal operation and design basis accident.
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