ABSTRACT
Large number of features is common to all types of nuclear power plants. They will be the subject of the first three sections, which treat, respectively, the structure of reactors, problems of thermo hydraulics, and problems of reactor control. The structure of every reactor, going from the center to the periphery, consists of: an approximately cylindrical active core in which the chain reaction takes place, reflectors, means of control, a tank containing all the foregoing, and various thermal and biological shields. Biological here means that the operating personnel can approach the reactor block without danger, or, if one prefers, that the biological doses to which they submitted remain admissible. In the same way, when the vessel is of prestressed concrete, it assures biological protection. But in this case a thermal protection must cover its inner surface. The repetitive pattern or elementary cell thus consists of all the elements necessary to the neutronic and thermo hydraulic functioning of the reactor.
