[en] Following the depressurization of a postulated break in the primary system of a pressurized nuclear reactor, the core becomes uncovered and the fuel rods overheat rapidly due to the decay heat and poor heat transfer. To prevent fuel failure, emergency coolant is injected in the lower plenum of the pressure vessel. To understand the phenomena of reflooding and quenching the hot fuel rods, experimental work is essential, as a purely theoretical treatment is inadequate due to the extreme complexity of the process. Heat losses were measured during preliminary experiments and fitted by a numerical expression, which was then later used in the analysis of the main tests. These heat-losses, together with the wall temperature distribution, were required for the solution of the energy balance in the wall to determine the heat transferred from the wall to the fluid. In order to describe the transport phenomena in the two-phase flow, one-dimensional mass and energy conservation equations have been combined with a transient conduction model for the liquid to calculate the liquid temperature. The steam temperature has less influence on the heat transfer than the fluid temperature, but is still needed to describe the thermal non-equilibrium. However, a simple approximation was sufficient. The simultaneous numerical integration of the conservation and conduction equations gives local and temporal distributions of the flow parameter during reflooding. By means of parameter sensitivity analysis, nonlinear regression relationships were developed to correlate heat transfer as a function of the flow parameters. The recommended correlations are valid in the unwetted part of the cooling channel and fit the experimental results with acceptable accuracy. (author)