Optimization process for the design of the DCLL blanket for the European DEMOnstration fusion reactor according to its nuclear performances

The research study focuses on the neutronic design analysis and optimization of one of the options for a fusion reactor designed as DCLL (dual coolant lithium-lead). The main objective has been to develop an efficient and technologically viable modular DCLL breeding blanket (BB) using the DEMO generic design specifications established within the EUROfusion Programme. The final neutronic design has to satisfy the requirements of: tritium self-sufficiency; BB thermal efficiency; preservation of plasma confinement; temperature limits imposed by materials; and radiation limits to guarantee the largest operational life for all the components. Therefore, a 3D fully heterogeneous DCLL neutronic model has been developed for the DEMO baseline 2014 determining its behaviour under the real operational conditions of the DEMO reactor. Consequent actions have been adopted to improve its performances. Neutronic assessments have specially addressed tritium breeding ratio, multiplication energy factor, power density distributions, damage and shielding responses. The model has then been adapted to the subsequent DEMO baseline 2015 (with a more powerful and bigger plasma, smaller divertor and bigger blanket segments), implying new design choices to improve the reactor nuclear performances.