Calculating steam-water flows at large non-condensible gas concentration with severe accident code astec v2.2
Résumé
Large amount of non-condensible gas in a flow has an important impact on condensation and vaporisation process. In accident studies, such flow can be commonly encountered in various installations such as spent fuel pools but also in the primary loop of a Reactor Coolant System (RCS) of a pressurised water reactor. For example, high concentration of air can be found in case of accidents occurring during the cold shutdown of the reactor, throughout mid-loop operations, when the reactor coolant system has been partly drained. Such configurations are challenging to simulate with nuclear safety codes and require specific modelling.
To accurately represent the interfacial heat and mass transfer with non-condensible gas, the model presented in this paper, based on the diffusion layer approach, assumes that the interfacial heat transfer is mainly driven by the vapour diffusion in the gas phase. This model has been implemented in the severe accident code ASTEC v2.2.
Results of small scale experiments [1] are first used to test and validate the new model. The code new capability to calculate accident during cold shutdown states is then specifically assessed using experimental results obtained through the global scale facility BETHSY [2]. For the different considered experimental results, calculations with the new model are shown be in satisfactory agreement.
Domaines
Sciences de l'ingénieur [physics]
Origine : Fichiers produits par l'(les) auteur(s)