Spectral Element Methods for Liquid Metal Reactors Applications

Funded by the U.S. Department of Energy, the Nuclear Energy Advanced Modeling and Simulation (NEAMS) program aims to develop an integrated multiphysics simulation capability “pellet to plant” for the design and analysis of future generations of nuclear power plants. NEAMS embraces a multiresolution hierarchy designing the code suite structure to ultimately span the full range of length and time scales present in relevant reactor design and safety analyses. Advanced reactors, such as liquid metal reactors, rely on innovative component designs to meet cost and safety targets. Heuristic assumptions typically employed in the safety analysis of the current fleet are not likely be sufficient. In order to span a wider design range, advanced modeling and simulation capabilities that rely on minimal assumptions (i.e., fewer closure models) plays an important role in optimizing the design. Over the past several years the NEAMS program has developed the integrated multiphysics code suite SHARP [1] aimed at streamlining the prototyping of such components. The goal of developing such a tool is to perform multiphysics neutronics, thermal/fluid, and structural mechanics modeling of various reactor components at user-specified fidelity, with a focus on first principles approaches (“high fidelity”). The thermal-hydraulic philosophy in NEAMS relies on a hierarchical multiscale approach (Fig. 1) consistent with other programs, such as THINS. SHARP focus on the high-fidelity end, aiming primarily at turbulence-resolving techniques such large eddy simulation (LES) and direct numerical simulation (DNS). The computational fluid dynamics code (CFD) selected for SHARP is Nek5000 [2], a state-of-the-art highly scalable tool employing the spectral element method (SEM). In the following we review the method and its implementation in Nek5000 (Section 2). We also examine several applications (Section 3). In Section 4 we summarize our work.