The TOSQAN project has been created to perform separate-effect tests that are representative of typical post-accident thermal-hydraulic flow conditions in the reactor containment. After a wall condensation programme, the TOSQAN spray programme is performed with a high density of instrumentation (gas temperature, steam concentration, droplet velocities and diameters).
The main thermalhydraulic phenomena when water sprays are used in a containment are the mixing induced by spray entrainment and the heat and mass transfer on droplets and walls. In order to improve the latter phenomena, a code benchmark exercise has been initiated, based on the TOSQAN test 101. In this test a cold water spray is injected into the steam/air-filled vessel, resulting in partial depressurization. The first phase in 2004 was blind, and the second phase in 2005, was open. The codes involved in this exercise are either lumped-parameter-codes or Multi-Dimensional codes: ACACIA-1D (IRSN), ASTEC/CPA-0D (IRSN), GASFLOW-MultiD (FZK), GOTHIC-MultiD (AECL), TONUS-MultiD (CEA) and TONUS-0D (CEA). Results of the two phases will be presented. The major observations of this benchmark concern the comparison between the modeled phenomena and the real phenomena involved when spray is injected in the TOSQAN vessel. It is shown that results, such as the depressurization curve, are very sensitive to the modelling, depending on how the vaporization of droplets, in the gas or on the structures, is taken into account.
This benchmark is still open to new partners: the next phase is a second post-calculation of this test, on the basis of an analysis of the energy balance in the experiment. Furthermore, a new “cold spray test”, TOSQAN test 113, has been proposed in order to evaluate the mixing effect of a spray in a cold air-helium stratified environment.
(1) : IRSN
(2) : AUSY –France
(3) : AECL, Chalk River
(4) : CEA/DEN
(5) : FZK