Constructing PWR plants - Primary equipment

The primary equipment of the PWR pressurized water reactor includes :

• the tank ;

• internal equipment made up of two sub-assemblies: lower internals and upper internals;

• control clusters and their control mechanisms ;

• steam generators ;

• primary piping ;

• primary pump units ;

• the pressurizer and pressure control and overpressure protection devices.

Primary equipment manufacturers have arrived at similar concepts, so we'll confine ourselves to a description of the achievements and practices of the French industry, although we'll mention the most notable differences that can be found abroad.

Given the importance of this equipment for safety, its design, materials of construction, manufacture and associated controls must comply with the RCC-M rules applicable to Class I equipment.

The equipment specification, established for each of them prior to their construction, defines in particular the service conditions, in normal, exceptional and accidental situations (cf. RCC-M vol. I, tome A), in accordance with the applicable regulations.

At the time of writing, the regulatory text applicable in France to primary equipment pressure vessels is the ESPN (nuclear pressure equipment) decree of December 12, 2005. In particular, it applies to primary equipment for the EPR™, currently under construction in France at the Flamanville site in the Manche département.

In this article:

• contents indicated are mass contents ;

• power ratings shown are nominal electrical ratings.

The material designations used in this article are those of the RCC-M. The RCC-M uses a different symbolism from the AFNOR standards to designate materials that are nevertheless related. This is justified by the fact that the requirements of the RCC-M are sometimes significantly different from those of the AFNOR standards.