Tritium transport modeling for breeding blanket: State of the art and strategy for future development in the EU fusion program

The design of the Test Blanket Modules for ITER and the breeding blanket for DEMO requires robust and accurate modeling tools. Transport phenomena through the blanket tritium cycle are complex and involve a large number of physical properties and parameters, many of which have not been determined yet with a level of accuracy adequate for design optimization. Similarly, the use of simplified models with experimentally determined lumped coefficients allows satisfactory predictions only in very limited range of operative conditions, strongly reducing their potential to be relevant to the DEMO design. Within the European Union fusion program a road map to develop such modeling tools has been defined with the purpose of supporting the design of the ITER Tritium Blanket System and to exploit the TBM experimental testing for extrapolation to DEMO. The roadmap includes the development of the simulation tools as well as the supporting validation and verification experiments that must be carried out in parallel. This paper gives an overview of the state of the art of tritium modeling tools for blanket design, proposes a structure of the tritium modeling tools in order to facilitate their development and identifies a realistic work plan to achieve their final delivery.