ABSTRACT
The specification of fire areas must be carried out during the layout phase after having located the centers of danger for the following three effects: thermal radiation, release of dangerous substances, and explosions. The intensity radiation value which determines the border depends on the thermic exposure necessary for the fuel to catch fire. In nuclear plants fire presents serious risks because it can bring about the loss of components that are essential to safety and in particular those components that are necessary to shut down the core reactor and to cool it after the shutdown. The fire resistance of an element for building construction is represented by its attitude to preserve mechanical stability and tight and thermic insulation during the fire. The true behavior of a fire is defined by the thermic balance between the heat power developed in the combustion, and the heat taken away in the time unit.
