Modeling of the chemical behavior of sodium fire aerosols during atmospheric dispersion

Alice Plantamp (1, 2) , Thierry Gilardi (1, 2) , Hervé Muhr (3) , Christophe Perrais (1, 2)

1 CEA-DES (ex-DEN) - CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire)
2 SMTA - Service Mesures et modélisation des Transferts et des Accidents graves
3 LRGP - Laboratoire Réactions et Génie des Procédés

The use of liquid sodium as a coolant in sodium-cooled fast reactors (SFR) circuits requires studying the consequences of a sodium fire for safety analysis, and particularly the toxicological impact of sodium fire aerosols. More particularly, the carbonation of sodium fire aerosols from sodium hydroxide (NaOH) to sodium carbonate (Na$_2$CO$_3$) is investigated. A new kinetic model, based on the CO$_2$ reactive absorption and the two-film theory, is developed to describe the carbonation process of NaOH solutions, taking into account the NaOH aerosols' initial characteristics in equilibrium with the atmosphere. This model is applied for the case of NaOH aerosols considering the CO$_2$ absorption at the particle external surface. The estimation for the model parameters is detailed as function of NaOH degree of conversion, relative humidity (RH), and temperature. By comparisons with available experimental data, the absorption interfacial area is empirically estimated over the studied range of RH and initial particle diameter. The global sensitivity study of the model confirms its capabilities to describe NaOH aerosols' carbonation, waiting for new experimental data for validation.

Keywords: liquid sodium; reactive absorption; sodium fire; carbonation; aerosol

Domains: Nuclear Theory [nucl-th]; Nuclear Experiment [nucl-ex]

Alice Plantamp, Thierry Gilardi, Hervé Muhr, Christophe Perrais. Modeling of the chemical behavior of sodium fire aerosols during atmospheric dispersion. Aerosol Science and Technology, 2016, 50 (7), pp.705-716. ⟨10.1080/02786826.2016.1178852⟩. ⟨cea-02384087⟩