[en] This paper presents a study about the Counter-Current Flow Limitation (CCFL) prediction in hot legs and steam generators (SG) in both system test facilities and pressurized water reactors. Experimental data are analyzed, particularly the recent MHYRESA test data. Geometrical and scale effects on the flooding behavior are shown. The CATHARE code modelling problems concerning the CCFL prediction are discussed. A method which gives the user the possibility of controlling the flooding limit at a given location is developed. In order to minimize the user effect, a methodology is proposed to the user in case of a calculation with a counter-current flow between the upper plenum and the SF U-tubes. The following questions have to be made clear for the user: when to use the CATHARE CCFL option, which correlation to use, and where to locate the flooding limit