Lumped-parameter simulations of wall condensation and sump evaporation under typical thermal-hydraulic conditions of nuclear reactor containment severe accident

• Numerical calculations with lumped-parameter code ASTEC/CPA are presented.
• Simulations of several IRSN tests especially developed for containment studies are performed.
• Sump evaporation and wall condensation are studied here on the TOSQAN facility.

During the course of a severe accident in a Pressurized Water Reactor, pressurization of the containment occurs and hydrogen can be produced by the reactor core oxidation and distributed in the containment according to natural, mixed and forced convection flows induced by break flow, wall condensation and spray systems used in some reactors' containment to prevent overpressure. Because of these phenomena, water can be collected in the sump containment, inducing further heat and mass exchanges between the sump surface and the atmosphere. Considering the large volume of the reactor containment, LP (0D) codes are preferred to CFD calculations, which still remain a very challenging task to compute.The French IRSN has tested different tools for containment studies with lumped-parameter codes and the reference code is now ASTEC/CPA, so that mainly results of this code will be presented here. This paper focuses mainly on several IRSN tests especially developed for containment studies and the above mentioned thermal-hydraulical phenomena. The objective of this paper is to present the validations performed with LP codes on these different experimental tests. Experiments on the TOSQAN facility are considered.