During an accident causing loss of the coolant of the primary circuit (LOCA) in a pressurized water reactor, partial or even complete drying of the fuel assemblies may lead to the fuel temperature increase, significant deformation and, consequently the rupture of the fuel rod claddings. In addition to the restriction of the flow area, the fragmented fuel relocation within the ballooned zone leads to an increase of the local residual power. The COAL experiments will focus on the outstanding issue of the coolability of a partially deformed fuel assembly, in particular the study of the thermo hydraulic behavior during the cooling phase by water injection with the safety systems. Competing influences due to the presence of a blockage will be evaluated through integral experiments using a 7x7 bundle of electrically heated rods. In one hand, the reduction of the cross-section between the deformed fuel rods will increase the flow velocity and consequently the heat transfer. On the other hand, the flow bypass of the blocked region, towards the periphery of the fuel assembly will lead to a reduction of mass flow in the sub channels of the blockage and therefore the cooling capacity. This paper presents the scenario and the pre-calculations of the COAL experiments using the 3D DRACCAR code coupled to the CESAR thermal hydraulics module developed by IRSN. The effect of the flow blockage (intact geometry up to long ballooning with different blockage ratios 80 to 90%) will be evaluated for various mass flow rates and different pressures representative to Large (LBLOCA) and Medium break size (MBLOCA) configuration.