Our laboratory focuses on the research that handles hydrogen isotopes including tritium which is fuel of a fusion reactor.We aim to understand elemental phenomena that are required to develop fusion reactor, fission reactor and next-generation energy system utilizing hydrogen, and to optimize these systems as an aggregate of elements. Scientific education and research about experiment and numerical analysis are conducted from the viewpoint of process engineering.
Tritium experimental room
 A lot of findings have been obtained through the tritium experiment.Recently, we are working on the quantitative understanding of the tritium behavior in concrete materials and plasma facing materials, in addition to tritium breeding materials.

Tritium trapping on the surface of SiC Release of tritium impranted into JT60 graphite tile

Study on behavior of hydrogen isotopes in liquid blanket.
  The blanket in a fusion reactor plays very important roles, (i) tritium breeding for fuels supply, (ii) heat exchange for energy, (iii) shielding radiation for safety. Liquid blanket system has some advantages such as simple blanket structure, a high tritium-breeding ratio, a high thermal conductivity. Candidate materials of liquid blankets are Li, Li17Pb83, FLiBe, and so on. We study about the behavior of hydrogen isotopes in their material, especially Li and Li17Pb83 in order to construct a reliable tritium recovery system with low tritium leakage. The use of Li is expected for a flowing target in the International Fusion Materials Irradiation Facility (IFMIF) for high-intensity neutron generation. IFMIF is designed to test materials durability under high intensity neutron-irradiation conditions of the future commercial fusion reactors. Our research group has been developed a Y hot trap for remove tritium from Li loop. Li17Pb83 is one of the most promising candidate materials for liquid blankets in fusion reactors. We are studying about tritium behavior in Li-Pb blanket for design the tritium recovery system.

Study on tritium behavior in solid breeder materials.
under construction.
Study on tritium behavior in re-deposited layer
  The plasma facing wall is eroded by interaction with high-energy particles and impure particles are emitted to the plasma. A part of the emitted impurities returns to the surface of the wall via some interactions with the plasma and it forms a re-deposition layer or dust containing fuel atoms. From D-T experiments such as Joint European Torus (JET) or Tokamak Fusion Test Reactor (TFTR), it has been revealed that a large amount hydrogen isotope is retained in carbon-based co-deposition. From the viewpoint of fuel recycling and assurance of tritium safety, it is essential to understand the sorption and desorption behavior of tritium from not only plasma facing materials but also re-formed materials. However, discussions about tritium behavior in tungsten a re-deposition layer have not been performed sufficiently. In this study, we made various re-deposited layers by a sputtering method using hydrogen RF plasma. The amount of hydrogen isotopes trapped in the layer is quantified.
Study on desorption of hydrogen, helium and methane from cryo-sorption pump
  A key issue to establish the tritium (T) fuel cycle of fusion reactor systems such as DEMO or the future commercial reactors is to reduce tritium inventory for increasing potential safety of D-T fusion reactors. In order to do that it is necessary to constitute a self-sufficient reactor system.The first process of the fuel cycle after D-T burning is the evacuation of gas mixtures including hydrogen isotopes, helium and impurities by cryo-sorption pumps or turbo molecular pumps.The cryo-sorption pump has be used for the evacuation system for the reasons that high magnetism tolerance and high vacuum speed of all gases. However, the process of regeneration to discharge the gases saved up is needed for cryo-sorption pump because that is a pump of the saving up type. Therefore, it is necessary to examine several gas discharge behavior from the cryo-sorption pump under various conditions.