The International Thermonuclear Experimental Reactor (ITER) plays a pivotal role in energy fusion research based on tokamak technology and will magnetically confine a hot toroidal plasma, whose heat exhausted will impact the internal surface of the tokamak chamber closest to the plasma itself, namely the First Wall (FW), potentially leading to accidental conditions. The FW will be protected in real-time (RT) by the First Wall Heat Load Controller (FWHLC), which evaluates its surface temperature through a combination of measurements from infrared (IR) cameras and reconstruction of the impacting heat load thanks to the coupling with a thermal model, which is the focus of this thesis.