(FT/P2-12) Studies and Developments of Tritium Recovery System for Blanket of Fusion Reactor in Japan Atomic Energy Agency

Y. Kawamura1), K. Isobe1), Y. Iwai1), H. Nakamura1), K. Kobayashi1), T. Hayashi1), T. Yamanishi1)
 
1) Japan Atomic Energy Agency, Tokai, Ibaraki, Japan

Abstract.  Tritium technology has reached the level where they allow us to design the main fuel cycle of ITER. On the other hand, for the blanket tritium recovery system, a series of fundamental studies have still been carried out even though the system is essential to realize the fusion reactor from the viewpoint of the fuel production. In the case of a water cooling solid breeder blanket, the blanket tritium recovery system will be composed of three processes: tritium recovery from the helium sweep gas as hydrogen, that as water vapor and tritium recovery from the coolant water. For these processes, the present authors have proposed a set of advanced systems, and have proved that the proposed systems would be feasible for a DEMO reactor. For tritium recovery as hydrogen, an electrochemical hydrogen pump with a ceramic proton conductor has been proposed. In this work, the correlation between the proton concentration in the ceramic and the hydrogen pressure in the gas phase has been investigated to describe the proton conductivity specifically. And then, it has been shown that the partial pressures of hydrogen and water vapor control the proton concentration in the ceramic as a key parameter of the system. A ceramic electrolysis cell has been proposed to process the tritiated water vapor. In this work, the present authors have developed a new electrode that contained the cerium oxide, and it has shown a fairly large current density. The performance of the ceramic electrolysis cell would be largely improved by using this electrode. For tritium recovery from the coolant water, the reduction of the processing water by tritium condensation is necessary. The present authors have studied about the fixed-bed adsorption process of synthesis zeolite, and the development of the adsorbent that can release water vapor easily is required. In this work, the effect of the silica/alumina ratio of the adsorbent on the separation factor was examined. NAY10.0 (faujasite-type, silica/alumina = 10.0) showed quite unique characteristics for the water adsorption and desorption. The system size is expected to decrease significantly by using NAY10.0.

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