The viability of a fusion reactor is preeminently conditioned by the tritium self-sufficiency. An assessment of different parameters representing the tritium production, as the tritium breeding ratio (TBR), the tritium production rate (TPR) density and their poloidal and radial variations along the PbLi breeder zones has been performed for the last DCLL DEMO designs developed in the frame of the EUROfusion Programme. The final overall value of 1.104 obtained allows accomplishing the fuel self-sufficiency requirement. This TBR value includes not only the contribution of the breeding blanket (BB) modules but also of the back supporting structure (BSS). The BSS design resulted fundamental to reach the 1.1 criterion. Lastly, the influence of the integration in the reactor of the heating and current drive (H&CD) systems that will penetrate the breeder volume has been evaluated. Assuming different configurations for them, the TBR loss has been determined. All the calculations have entailed the use of the particle transport Monte Carlo code MCNP5.
Tritium well depth, tritium well time and sponge mechanism for reducing tritium retention