Modélisation de l'aspersion dans TOSQAN à l'aide du code ASTEC

Titre du congrès :NURETH-12 (Nuclear Reactor Thermal Hydraulics) Ville du congrès :Pittsburgh Date du congrès :30/09/2007

Spray systems are emergency systems designed for preserving the integrity of the containment that constitutes the last barrier to the release of fission products into the environment in case of a severe accident in a Light Water Reactor. These systems are used in the reactor containment in order to prevent overpressure, to remove fission products and to enhance the gas mixing in case of the presence of hydrogen. The evaluation of the spray efficiency in containment depressurization, gas mixing and removal of fission products relies on the modelling of various phenomena, namely the droplet kinetic and thermal relaxation, the gravitational coagulation, the aerosol particle captation, and the gaseous species mass transfer and chemical transformation. Models describing these phenomena have been developed and implemented in the ASTEC integral code. Recently, the French Institute of Radioprotection and Nuclear Safety (IRSN) performed new spray tests on a 7 m3 facility, called TOSQAN and located in SACLAY (France). The reduced size of TOSQAN allows a high density of instrumentation for a better analysis of the involved phenomena. Non intrusive instrumentation is also used to characterize the spray droplets. In this paper, we propose to investigate two separate effect tests that have been proposed for benchmarking in the frame of the European SARNET project using ASTEC code. The first test is relative to the thermodynamic of sprays, i.e. the droplet heat and mass transfer modelling and the gas thermodynamical modelling. The second test is relative to the gas entrainment and atmosphere mixing induced by a spray, avoiding heat and mass transfer exchanges. Calculated total pressure, droplet size, vertical and horizontal profiles of velocity and temperature, steam concentration are compared to experimental results and analysed.