Tritium control modelling for a helium cooled lithium–lead blanket of a fusion power reactor

In this paper, we present computations linking the tritium release rate to the characteristics of lithium–lead and helium cooling circuits. Impacting component performances are evaluated such as tritium permeation towards the He coolant in the blanket modules, lithium–lead circulation rate, tritium extraction unit efficiency, tritium permeation in steam generator, helium coolant leak rate, helium purification unit maximum flow rate and efficiency. Safety considerations are also taken into account. A finite element model (FEM) for tritium permeation was developed considering various phenomena such as tritium transport by convection and diffusion in lithium–lead, MHD effects on liquid metal flows, tritium permeation in structures with temperature gradients. Other sub-system performances, like He leak rate and efficiency of tritium extraction systems, are discussed via an engineering approach. The results show that a reasonable compromise among the various requirements can be found, leading to technologically achievable requirements for tritium permeation barriers, tritium extraction systems both from Pb–17Li and He, and leak rates from the He cooling system.