A study on enrichment and volume reduction of tritiated water in a fusion reactor using photocatalysis

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It is important to establish a safety process of enrichment or volume reduction of tritiated water for promoting safety of a fusion reactor and public acceptance.Tentative storage of tritium water in a vessel is not final measures. Water distillation needs a large energy and has an economical problem. Titanium oxide (anatase) of photocatalysis is expected to decompose air pollutantor to dissociate water into hydrogen and oxygen. Since there may be a small difference in dissociation energy between light water and heavy or tritiated water, enrichment of tritium in waste water expected to be exhausted from a fusion reactor was experimentally investigated by using a photocatalysis.In the first year of the present research, we manufactured photocatalyses by means of nonelectrolysis gilding under different conditions of temperature and concentration. The catalysis was manufactured by plating nickel oxide on titanium oxide.Then the photocatalysis dipped in water in a glass cell was put undera … More n ultraviolet light from a xenon lamp. Part of tritiated water dissociated to hydrogen and oxygen on the anatase photocatalysis, and they recombined on nickel oxide. A difference in rate of dissociation and recombination between tritiated water and light water brought a certain enrichment of tritium in non-dissociated water. Since a key to enrich tritiated water by photocatalysis is to manufacture a high-efficient catalyst, many catalyses were tested under various plating conditions. Although.titanium oxides and nickel oxides were working, the yield was comparatively small.So, in the second year of the present research, another nonelectrolysis gilding in palladium chloride.solution was tested. Tritium enrichment by anatase-palladium catalysis was investigated under ultraviolet light. The yield increased and the isotope separation factor was around 1.1. In order to apply the present method to industrial scale it is necessary to make contact well among solid (catalysis), liquid (water) and gas (vapor, hydrogen and oxygen). A trickle bed system was found to be optimum for maintaining the good contact. It was concluded that the trickle system should be investigated in the next study. Part of the results was presented in scientific journals and the rest will be presented in the near future. Less