29th Symposium on Fusion Technology (SOFT 2016)

P2.163 Thermal-hydraulic design of a DCLL breeding blanket for the EU DEMO

6 Sep 2016, 14:20

1h 40m

Foyer 2A (2nd floor), 3A (3rd floor) (Prague Congress Centre)

Board: 163

Poster H. Fuel Cycle and Breeding Blankets P2 Poster session

Speaker

Ivan Fernandez-Berceruelo (Fusion National Laboratory)

Description

The Dual Coolant Lead-Lithium (DCLL) is one of the breeding blanket concepts under investigation in EUROFusion. This concept is characterized by the use of self-cooled eutectic PbLi as neutron multiplier and tritium breeder and carrier, whereas supercritical helium is used to cool the first wall and other parts of the structure. The thermal-hydraulic (TH) design of the breeding blanket, as the main thermal source for power conversion, reveals itself as a key issue to counteract the influence of the foreseen low overall plant availability on the cost of electricity. In this sense, the decreased contribution of the non-breeding coolant in the DCLL presents clear advantages, like less dependence on the long-term availability of helium and lower recirculating power (recompression). The short operational range of temperature (300-550ºC) imposed by the use of RAFM steel is handled by adopting the Multi-Module Segment concept.  This allows lower PbLi velocities by arranging in parallel the circuits of different modules. In consequence, the magnetohydrodynamics phenomena and corrosion rates are diminished. The high Péclet numbers validate the use of simpler computational codes to couple thermally both coolants, taking advantage of assuming that the heat transfer between the structure and the fluids is one-dimensional. A TH code adapted to the transient behaviour of the pulsed operation of DEMO has been developed for sensitivity analyses. The results are compared to those obtained by FEM thermal analyses in which the PbLi and He streams are treated as fluid lines. On the other hand, the results of different CFD assessments on the performance of the helium cooling system are analyzed: the cooling of the first wall and the radial walls and the flow distribution in the general manifold. Besides, a preliminary study of the effects of the high heat generation gradient in the front poloidal PbLi channels is reported.