Containment thermal-hydraulics remains an open question to predict the local distribution of hydrogen, steam and air inside a Pressurized Water Reactor in case of severe accident. The objective of the ISP 47, proposed by OECD-CSNI, is a computer code exercise based on experimental facilities in order to assess the actual capability of CFD and Lumped parameter codes to predict local gas distributions. The first phase of the ISP deals with a steam injection in air performed in the TOSQAN experimental facility and the code benchmark is performed in an open exercise on these experimental results. For both codes CFD and lumped parameter, comparisons are focused in one hand, on pressure, mean temperature and mean steam concentration and, in an other hand, on temperature and steam concentration vertical and radial profiles. Velocity radial profiles are also compared with CFD codes predictions. The TOSQAN test is simulated by 21 participants, 13 participants have performed calculations using a lumped parameter approach and 8 have used a CFD code. The main result of the first phase of the ISP shows that, on an open exercise, quite all the codes are able to calculate with a fairly good accuracy the different mean values and they reproduce in a satisfactory way the vertical and radial profiles.