Use of mesh based variance reduction technique for shielding calculations of the stellarator power reactor HELIAS

摘要

The shielding capability is an important aspect of a fusion power plant. The neutron flux decreases in areas far away from the plasma chamber while at the same time the statistical error in Monte Carlo particle transport simulations increases significantly in such regions. This requires variance reduction methods to guide the particles in regions of interest and improve the statistical accuracy. The mesh based weight window technique, applied with ADVANTG, is investigated in this paper and successfully applied for the first neutronic investigation of the shielding performance for the HELIAS stellarator. The obtained results are in an area with high neutron wall load and reduced material thickness. They will be evaluated against the design requirements specified for the EU DEMO tokamak fusion reactor. The results show that the current HELIAS design cannot fulfill the shielding limits specified for DEMO in the investigated area, which is mainly due to the limited space available in the stellarator and should be overcome by improved design solutions for blanket and shield.