Nuclear analysis of the HCLL blanket for the European DEMO
Résumé
The EUROfusion Consortium aims at developing a conceptual design of a fusion power demonstrator (DEMO). The breeding blanket facing the plasma is one of the key components of DEMO. It must ensure tritium self-sufficiency and heat removal functions. The Helium Cooled Lithium Lead (HCLL) blanket concept is one the four breeding blanket concepts investigated for DEMO. It uses the liquid lithium lead eutectic as tritium breeder and neutron multiplier and helium gas as coolant for both the Eurofer structure and the breeder. Within the EUROfusion organisation CEA, with the support of Wigner-CR and IPP-CR, is in charge for the design of the HCLL blanket.
This paper presents the nuclear analysis carried out for a new DEMO baseline with HCLL blanket. This baseline has a bigger minor radius and a smaller divertor that give extra space for the breeding blanket. The tritium breeding ratio obtained with the previous baseline and the HCLL blanket was below the 1.1 target (1.08). Different HCLL breeding blanket design options were investigated to increase the TBR. The helium manifold architecture was improved to increase the breeding zone. The number of cooling plates was reduced. The vertical stiffening plate removal was studied. The objective was to reduce the steel amount in the breeding zone. The TBR achieved with these new HCLL designs and new DEMO baseline present comfortable margins (1.15 to 1.23). The studies of DEMO-HCLL-2014 showed a nuclear heating in coils (100 W/m3) above the limit (50 W/m3). To improve the radiation stopping power of the HCLL blanket a shielding block (in Eurofer and other investigated material) is added in the manifold. The shielding block volume is taken from the breeding zone and the manifold region. Finally, the obtained HCLL design is a compromise between the tritium production and the shielding capability.
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