• Condensation
• TRioCFD

Recently, nuclear power has taken into its burden factors of global importance such
as climate change problem and the reduction of CO_2 emissions. The key factors that
influence the development and deployment of nuclear reactors can be emphasized in
four of them: cost-effectiveness, safety, security and management of the fuel cycle.
Mainly, nuclear reactor safety has been and is still an issue to be improved, that
affects not only the current Gen-II systems but also the new and upcoming designs
which offer passive safety and inherent means and measures to prevent as well mit-
igate the consequences of nuclear accidents.
The improvement of Gen-III/Gen-III+ systems, like AP1000 and EBR designs, over
Gen-II designs is the incorporation in some designs of passive safety features that
do not require active controls or operator intervention but instead rely on gravity or
natural convection to mitigate the impact of abnormal events.
Following a loss of coolant accident, steam can be released into the containment
where it mixes with non-condensible gases. Steam condensation can limit the pres-
sure excursion in the containment and influence the distribution of Hydrogen gas.
Since Steam condensation on containment walls is an important phenomenon for
mitigating severe accident in light water reactors. The French Atomic Energy Com-
mission, CEA-Saclay and specifically LMSF Laboratory has initiated a project con-
cerning in-depth study of condensation phenomenon in an open cavity using a CFD
model implemented in TrioCFD code.
In this thesis, a model based on the analogy of heat and mass transfer with the
aid of wall functions has been developed in TrioCFD code, in which condensation
rates, heat fluxes and the surface temperatures of the solid walls are computed and
compared with the experimental data available by the CONAN test facility. The
experimental data were part of the SARnet condensation benchmarks in which an
analysis of different models allows identifying the main strategies adopted for the
purpose of condensation modeling in CFD and the most relevant experiences by
which the models capabilities have been checked.