During a severe accident in a water-cooled nuclear facility, a large amount of water vapour can be released into the containment, and the corresponding pressure increase may damage containment walls and safety systems. Two main phenomena can limit this pressure increase: wall condensation, and water spray. The walls of the containment and the metal structures are significantly cooler than the gas, and thus condense the water vapour and limit the increase of the pressure. Similarly, the injection of droplets with a spray system leads to bulk condensation on the droplets, and to a decrease of the pressure.In order to carry out these safety studies, the numerical results obtained with the neptune_cfd software were compared to the experimental results of the CEA with the MISTRA facility, a 1:10 scale model of a French Pressurized Water Reactor. We showed that the numerical results were in good agreement with the experiment for the condensation cases, and in excellent agreement with the experiment for the spray cases. Furthermore, sensitivity studies showed that spraying was a much more powerful phenomenon than wall condensation, and that the droplet diameter was a very important parameter when studying spraying.