Tritium systems of fusion reactor

In a d-t fusion reactor, a large amount (10 kg/day) of tritium has to be supplied as a fuel. In order to avoid human radiation exposure in the plant, confinement of tritium inside the reactor vessel is crucial. The fuel cycle system of the d-t reactor consists of the gas exhaust, purifying and collecting units, the isotope separation unit and the fuel adjustment unit. In the present article, research activities on the development of the fuel cycle system for the d-t fusion reactor are reviewed. First a database on the retention, permeation and release of hydrogen isotopes in the form of water, water vapor and gas in metallic and organic materials was made. Next neutron irradiation effects on hydrogen isotopes in reactor materials were investigated. By incorporating coefficients and values derived from these experiments, the multi-scale simulation code to predict behaviors of hydrogen isotopes in reactor materials was successfully constructed. (author)