ICONE19-44016 SIMULATION OF NATURAL CIRCULATION IN ATMOSPHERE OF EXPERIMENTAL CONTAINMENT USING LUMPED-PARAMETER CONTAIN AND ASTEC CODES

Abstract

The possibility to adequately simulate the flow circulation in the atmosphere of a nuclear power plant containment at accident conditions using lumped-parameter codes is investigated. An experiment on containment atmosphere mixing and stratification, which was performed in the TOSQAN experimental facility at IRSN in Saclay (France), was considered. During some phases of the experiment, steady states were achieved by keeping the boundary conditions constant. Two steady states during which natural circulation was the dominant gas flow mechanism were simulated independently with the CFD code CFX4, whereas the entire transient was simulated with the lumped-parameter codes CONTAIN and ASTEC. The nodalisation of the lumped-parameter models was based on the flow pattern during the considered steady states, simulated with the CFD code. The lumped-parameter simulations succeeded in replicating the basic pattern of natural circulation in the vessel atmosphere during the two considered steady states, determined with the CFD code.