A water cooled lithium–lead blanket without tritium permeation barriers: feasibility and economical analysis

In the reference design of the water cooled lithium–lead (WCLL) blanket for DEMO, tritium permeation into the primary coolant must be lowered as much as possible to keep the coolant specific activity not higher than 1 Ci/kg. This requires tritium permeation barriers to be applied on the cooling tubes in the blanket. Taking into account the aggressive environments and the huge surface to be coated, the technology of permeation barriers appears as a tough challenge. To evaluate if it is feasible to lower the requirements on the performance of tritium permeation barriers, thus accepting a higher tritium permeation rate into the coolant and imposing a higher capacity in extracting tritium from the primary coolant, a conceptual study has been performed, mainly focusing on economical aspects. The results, which seem up to now encouraging, are presented and discussed.