Evaluation of Detached Eddy Simulation Applicability to Random Hydraulic Load Analysis for Reactor Vessel Internals

The US NRC Regulatory Guide 1.20 requires the comprehensive vibration assessment program (CVAP) to verify the structural integrity of the reactor vessel internals (RVIs) against flow-induced vibration. The CVAP consists of analysis, measurement, inspection, and evaluation programs. In the conventional analysis, the deterministic hydraulic loads and the random hydraulic loads were predicted by the analytical equations and compensating the correlated random hydraulic function from mock-up test results. Recently, the revised Regulatory Guide 1.20 allows the usage of CFD code and recommends large eddy simulation (LES) for the unsteady simulation of flow turbulence. However, LES is not efficient because many grids and time steps are required to predict the flow turbulence for the reactor vessel internals 3D model. This paper presents the evaluation results on the applicability of the detached eddy simulation (DES) instead of LES to predict the flow turbulence for the RVIs. Therefore, the flow turbulence in a simple duct was calculated by using DES and LES to evaluate the applicability