Nuclear plant operators have noticed a significant increase of the force needed to open cold wedge gate valves closed during a temperature transient. This phenomenon is known as "Thermal-Binding". At extreme ends, valves can't be opened. The consequences are an important risk for the safety of the unit and a decrease of its availability. The goal of this study is to obtain an analytical, experimental and numerical analysis of this phenomenon. This allows to determine the requirements needed to avoid this situation. The main part of this work is devoted to the calculation of the opening force after closure during a cooling transient. This can be divided in three phases: to begin with, an analytical model is set up. At the same time, the situation in a plant is reproduced on a loop. This gives some foundations to the model in several cases. Finally, the numerical simulation helps to investigate, other scenarios and to have a deeper understanding of the phenomenon. The main result is that there is a good agreement between experiment and numerical simulation either in the case where there is some binding or in the case where there isn't.
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