3Importance of Coupling Systems Analysis Codes to CFD Codes widely recognized … IAEA recently hosted a meeting to discuss: “…interest in the application of 3-dimensional CFD software as a supplement to or in combination with system codes, which provide the boundary conditions for CFD codes.” Problems under discussion include: · Evaluation of performance of passive safety features;· Local phenomena leading to cladding ruptures;· Multidimensional TH in various components;· Liquid/gas stratification and interface tracking; and· Bubble dynamics in suppression pools.”
13Fluid Behavior in Lower Plenum Need: Preliminary evaluation of turbulent intensity and mixing characteristics likely to be present in lower plenum (LP) at rated condition.Use existing CFD model of LP with most representative turbulence model and perform preliminary evaluation of fluid behavior as function of location in LP.Helium gas entering domain around core support postsHelium gas exiting domain via Hot DuctFluid DomainCore support post
14Validation of LP Flow Model Objective: The flow in the lower plenum of the NGNP will involve multiple jets entering from the core into a crossflow moving toward the exit duct and having to negotiate the presence of rows of support pillars. The modeling strategies (turbulence model, grid characteristics, time stepping, etc.) for simulating this complex turbulent flow must be validated.