Wall resolved large eddy simulation of reactor core flows with the spectral element method

•The spectral element methods is used to model the flow in reactor cores.•Applications to wire-wrapped rod bundles, PWR bundles and MSRs.•Coherent structure are observed in the simulation of an MSR graphite block. Numerical simulation is an intrinsic part of nuclear engineering research supporting the design of nuclear power plants. With the advent of Petascale computing (i.e., computers capable of more than 1 PFlop), the simulation of portions of reactor components with turbulence-resolving techniques is now possible. These simulations can provide invaluable insight into the flow dynamics, which is difficult or often impossible to obtain with experiments alone. The spectral element method in particular has emerged as a powerful method to deliver massively parallel calculations at high fidelity by using Large Eddy Simulation or Direct Numerical Simulation. In this work we review the fundamentals of the method and the reasons it is compelling for the simulation of nuclear reactor core flows. We review a series of wall-resolved large eddy simulations of reactor cores applied to three reactor types. In particular we discuss the simulation of the flow in a 17 × 17 rod bundle related to light water reactor (LWR) applications; the flow in a 37-pin wire-wrapped rod bundle related to liquid metal reactor (LMR) applications and the flow through a graphite block with application to molten salt reactors (MSR).