Hydrogen extraction characteristics of high-temperature proton conductor ceramics for hydrogen isotopes purification and recovery

To develop high-efficiency and economical hydrogen isotope purification and recovery processes for a tritium extraction system in a fusion reactor, hydrogen extraction characteristics of an electrochemical hydrogen pump using high-temperature proton conductors were studied. The driving forces of hydrogen transportation in the proton conductors are electric potential difference, which can extract hydrogen isotopes selectively from a solid breeder blanket purge gas with low-pressure hydrogen isotope gas. In the experiments, a one-end closed tube made of proton-conducting ceramic CaZr0.9In0.1O3−α (effective electrode area: 160 cm2) was developed because of its high chemical stability, mechanical strength, and durability in a series of perovskite-type proton conductors. The hydrogen pumping characteristics were evaluated over the temperature range from 923 K to 1073 K by extraction of 664–1200 ppm H2 balanced with He, H2 was selectively extracted from and the mixture of He and H2 at the rate of Faradayʹs Law under an applied voltage of 3.5 V DC. In the case of He with 0.12% H2 at 1023 K and at 1.15 V DC, the maximum hydrogen evolution rate was 0.12 ml/min, the hydrogen recovery efficiency was more than 99%, suggesting the extraction of hydrogen could be operated with a current efficiency close to unity. The possible application of hydrogen pumps for the TES of CIPITISE at CIAE has been estimated.