Shape optimization of an upper plenum of a PBMR using 3D-RANS analysis and surrogate modeling

Shape optimization of an upper plenum of a PBMR type gas cooled nuclear reactor has been performed by using three-dimensional Reynolds-Averaged Navier-Stokes (RANS) analysis and surrogate modeling technique. Shear stress transport (SST) turbulence model is used as a turbulence closure. The objective function is defined as a linear combination of uniformity of flow distribution in the core and pressure drop in the upper plenum and the core. Three geometric design variables viz., the ratio of thickness of slot to diameter of rising channels, ratio of height of upper plenum to diameter of rising channels, and ratio of height of the slot at inlet to that at outlet, are used for optimization. Design points are selected by Latin-hypercube sampling. The optimal point is determined through surrogate-based optimization method which use RANS derived calculations at design points. The results show that the optimization improves considerably both the flow uniformity and the friction performance. (authors)