Assessment of neptune_cfd applied to the study of a passive safety condenser: Modeling and first validation elements

Innovative systems are being considered for its application in Generation III and III+ concepts aiming safety enhancement and cost reduction by means of decreasing operator intervention dependency, maintenance and the redundancies of active systems. Several passive systems designs are studied such as a particular solution of a safety condenser where the residual decay heat of the core is removed by condensing the steam from the secondary circuit through a tube bundle submerged in a cooling pool. The application of numerical tools (such as the system code CATHARE) in the study of safety related transients with these systems is led by CEA, EDF and FRAMATOME in a conjointly effort. Development and validation steps are taken towards the codes qualification on the condensation physics. On a numerical multiscale approach, CFD solutions are being assessed as well, foreseeing an eventual up-scaling to system codes to enrich the validation process. In this work, first steps aiming the application of neptune_cfd for a safety condenser configuration are presented, including a contribution to its condensation model validation by confronting it against experimental data. The model implemented in the code for the condensation within tubes is described, and some selected experiences from the separate effects test bench COTURNE are chosen to be simulated. Results of the simulations are presented from which some conclusions are drawn, in addition, perspectives for further validation are discussed.