1. Secondary and auxiliary circuit materials for pressurized water reactors

The vast majority of PWR secondary circuit components are made of carbon or low-alloy steel, whose protection against corrosion and, in particular, erosion corrosion, dictates the principles of water treatment.

The other materials present in quantity in the secondary circuit are as follows:

• Nickel alloys for steam generator (SG) tubes: alloy 600, then alloy 690 since the late 1980s, or alloy 800 (iron-based, medium nickel content) in Germany and Canada;

• austenitic stainless steels type 18-10 (type 304) or 17-12-Mo (type 316) – which are used in the tubes of feedwater heaters, condensate coolers, dryer-superheater units and condensers. In France, the main austenitic stainless steel grades (304 and 316) have low carbon contents, below 0.03% (types 304L and 316L), guaranteeing good resistance...