PbLi Melting Charaterization and Basic Design for Tritium Extraction

Melting characteristics of Pb-15.7Li, which is a eutectic metal for the tritium breeding, is experimented. As expected, molten Pb-15.7Li, hereafter called PbLi, did not show any reactivity when mixed with water but only cooled by water addition. Composition also is found not to be changed by the water addition. Molten PbLi also was found not to show any reactivity when in the air atmosphere or change in composition. However, as PbLi can change its composition in the air atmosphere in the long term period by the reactivity of lithium, it would be safe to store PbLi in an inert atmosphere like argon gas. Literature data on hydrogen distribution equilibrium in PbLi is collected and compared. This literature data shows large discrepancies with 20 times in values between the data. This discrepancies are thought be coming from the permeation of hydrogen through wall of the reaction chambers. Thus it is concluded that hydrogen permeation through the walls should be suppressed by coating the walls of the PbLi container with alumina or tungsten. Various methods for the tritium extraction is surveyed, and one of them, countercurrent extraction, is chosen as our preference. Parts for the accomplishment of this method are: structured packing, porous metal sparger, evacuation system, hydrogen gas pressure measurements. Basic design of the counter-current extraction and necessary parts for it is performed. A brief introduction on the tritium separation and lithium isotope separation is also given