Tritium removal by Y hot trap for purification of IFMIF Li target

The use of Li is expected for a flowing target in the International Fusion Materials Irradiation Facility (IFMIF) for high-intensity neutron generation. Tritium (T) of by-product is removed by a Y hot trap placed in a by-path position of the flowing Li target. Since the equilibrium pressure of hydrogen isotopes is extremely low, the removal rate of H isotopes is affected by coexisting other impurities such as N, C and O dissolved in Li. In the present study, the removal rate of H isotopes in Li is experimentally investigated under the three different methods or conditions: (i) measuring gravimetrically in a static Li + Y system with the supply of low-concentration H2 in Ar purge, (ii) counting the change of T radioactivity in a static Li + Y system after neutron irradiation and (iii) measuring the change of the H2 concentration in a stirred Li + Y system with the supply of low-concentration H2 in Ar purge. There was no corrosive action in the Li–Y interface observed after contact at 500 °C for 100 h. The present results are extended to design a Y hot trap for the IFMIF–EVEDA Li loop in order to remove H isotopes less than a specified concentration.