In the course of a LOCA accident, the fuel rod can be deformed and thus, it is important to be able to predict the coolability of these regions. One issue of a LOCA is the coolability of the blockage zone. In order to experimentally analyze the influences of the cladding deformation on the heat transfer, different vertical tubes are used to study different blockage ratio. A first section of constant diameter equal to the hydraulic diameter of a sub-channel PWR is followed by a smaller part which is representative of a significant deformation (blockage ratio between 61% and 90%), with different lengths of this section. In the last part of the tube, the hydraulic diameter gradually increases to represent the output of the ballooned area and ends with the same diameter as the inlet. The two-phase flow injected is a controlled flow of superheated steam with polydispersed water droplets produced by a piezoelectric injector. The tube (i.e. test section) will be heated up to 800°C to be representative of the temperature of the fuel rod during the reflood. At the inlet and outlet of the deformed zone of the tube, measurements will be carried out using optical metrology techniques such as Phase Doppler Anemometry (PDA) and Laser Induced Fluorescence (LIF) to characterize the droplet’s flow. Along the deformed region, temperature measurements will be performed using infrared thermography. This paper presents the test section with its instrumentation. The different thermal hydraulic parameters will be complementary to the COAL experiments where knowledge at the sub-channel scale to characterize steam/droplets flow and heat transfer with the purpose to better understand the coolability during a LOCA