TABLE OF CONTENTS By necessity, a nuclear power plant is composed of the parts required to generate electric power (the process parts or systems) but also of a complexity of safety systems. The name safety systems here indicates all those systems which are not strictly necessary to the plant operation or to health protection under normal conditions, but rather to those that prevent the progression of accidents and therefore avert the large release of radioactive products. Accident prevention is a major activity of designers, operators and control bodies. Figure 3-1 will remind the reader of the components of a typical pressurized water reactor (the PWR the most common design in the world).
The process components are: the reactor (R) itself, where the nuclear chain reaction takes place and the heat is produced which will finally be transformed into electric energy; the steam generator (SG), where the heat is used to produce high pressure steam; the turbine (T), where the steam energy is transformed into mechanical rotation energy; and, finally, the electric generator (G), which produces the electric energy to be supplied to the grid.
As can be seen in the drawing, the process fluid, that is water in the form of liquid or vapour, circulates in two distinct systems, the primary and the secondary system, which mutually exchange heat in the steam generator.
Another important component of the primary system is the pressurizer (PR), whose function is that of...
