Thermal and structural analysis of the first wall in the SIRIUS-P reactor

The SIRIUS-P conceptual design study is of a 1.0 GWe laser driven inertial confinement fusion power reactor utilizing near symmetric illumination of direct drive targets. Sixty laser beams providing a total of 3.4 MJ of energy are used at a repetition rate of 6.7 Hz with a nominal target gain of 118. The spherical chamber has an internal radius of 6.5 m and consists of a first wall assembly made from carbon-carbon composite material, and a blanket assembly made of SiC composite material. The chamber is cooled by a flowing granular bed of solid ceramic materials, non-breeding TiO₂ for the first wall assembly and breeding Li₂O for the blanket assembly. Helium gas (P=0.15 MPa) is used in a fluidized bed outside the reactor to return the particles to the top of the reactor. A moving bed is chosen over a fluidized bed because of its superior heat transfer capability. The heat transfer in a moving bed depends on the level of agitation and on the effective thermal conductivity of the solid material and the interstitial gas, whereas in a fluidized bed, it is entirely dominated by the thermal conductivity of the carrier gas. This paper describes the two-dimensional thermo-structural steady state analysis of the first wall elements at several critical locations utilizing the finite element analysis code, ANSYS, with r-θ modeling. The stresses are dominated by bending due to the internal pressure of the He gas; modifying the shape of the tube from purely elliptical, while keeping the area constant reduces the stresses