System transient include 3D phenomena Transient simulation for safety require low CPU to allow many runs for UQ Coupling between reactor circuits, containment and passive systems may be necessary Many types of 3D simulation tools exist (CFD in open medium, porous body CFD, 3D modules of system codes? Multi-1D+crossflows) with many options for physical models (e.g. turbulence model) How to select the right 3D tool depending on the objective? FONESYS Meeting, June 2020, Mixing problems are encountered in reactor thermalhydraulics which may require 3D modelling of some components: MSLB, Boron dilution, H2 mixing, PTS, passive systems,… Turbulence controls the efficiency of the mixing Buoyancy effects and density stratification may play a role Predicting turbulence mixing requires CFD with very fine nodalization in all shear layers, high order numerical schemes and needs very high CPU cost 3D models of system codes use coarse nodalization and first order numerical schemes: low CPU cost When buoyancy effects are dominant or sufficiently high, the mixing may be low and a coarse nodalization may predict the behavior rather well

Proposed activity on 3D modeling of passive systems and other mixing problems using coarse nodalization

D'Auria F.
Co-primo
Supervision
;
2020-01-01

Abstract

System transient include 3D phenomena Transient simulation for safety require low CPU to allow many runs for UQ Coupling between reactor circuits, containment and passive systems may be necessary Many types of 3D simulation tools exist (CFD in open medium, porous body CFD, 3D modules of system codes? Multi-1D+crossflows) with many options for physical models (e.g. turbulence model) How to select the right 3D tool depending on the objective? FONESYS Meeting, June 2020, Mixing problems are encountered in reactor thermalhydraulics which may require 3D modelling of some components: MSLB, Boron dilution, H2 mixing, PTS, passive systems,… Turbulence controls the efficiency of the mixing Buoyancy effects and density stratification may play a role Predicting turbulence mixing requires CFD with very fine nodalization in all shear layers, high order numerical schemes and needs very high CPU cost 3D models of system codes use coarse nodalization and first order numerical schemes: low CPU cost When buoyancy effects are dominant or sufficiently high, the mixing may be low and a coarse nodalization may predict the behavior rather well
2020
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11568/1064100
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