European numerical code for fire scenario simulations

The computer code ECART is dedicated to predict the consequences of an accident in a risk installation. It was originally created to calculate the concentration of airborne radiotoxic substances inside nuclear power plants in the case of a severe accident. As it is not related to a specific design, nuclear or not, it can simulate the airborne transport of dangerous substances throughout a generic system of rooms, pipes or plant components, together with the removal and the re-entrainment mechanisms which may occur in the presence of structures, liquid sumps or water sprays.

The problem of integral analysis of complex systems or industrial installations is still quite difficult using CFD codes that are suitable for the detection of fluid motion field, but are too heavy to run detailed simulations of fire propagation through several rooms, corridors or tunnels, accounting the flame and smoke propagation, or the chemistry of combustion together with the thermodynamic response of atmosphere and structures.

The possibility offered by the lumped parameter approach of ECART appears interesting for the simulation of fires within close environments. As a matter of fact, the development of multi-phase simulation tools, accounting both gaseous and aerosol transport in fire incidents, is still the object of investigations, where the aerosol physics is of great importance to analyze the diffusion and removal of airborne toxic substances, or to monitor the risk of deflagration of combustible dust or droplets.

The models of this code are quite useful for the evaluation of fire consequences, emergency procedures and safety systems, as they can predict the thermal conditions of cables and concrete walls, the concentration of carbon monoxide and the visibility reduction.

ECART belongs to the category of “eulerian” and “mechanistic” analyzers. Eulerian because it traces the transport of radiotoxic species taking the plant as the reference system, in order to give, as a function of time, concentrations and physical forms along the followed pathways. Mechanistic because it follows, whenever possible, physical and chemical laws, avoiding the use of assumptions of limited applicability.

This computer tool is currently developed by CESI RICERCA of Milan, Italy (contact flavio.parozzi@cesiricerca.it) and has been also supported by Italian Government, national agency ENEA, University of Pisa, Politecnico di Milano and Torino, French EDF and the European Union.

Significant efforts were spent to extend its modelling to fire phenomenology in the recent years in cooperation with the Department of Energy of Politecnico di Milano (ref: giovanni.manzini@polimi.it; luca.iannantuoni@polimi.it), paying particular attention to modelling pool fires and water mist phenomenology.

This work has been financed by the Research Fund for the Italian Electrical System under the Contract Agreement between CESI RICERCA and the Ministry of Economic Development–General Directorate for Energy and Mining Resources stipulated on June 21, 2007 in compliance with the Decree n.73 of June 18, 2007.

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