The Nuclear Power Plant Beznau comprises two identical 380 MWe PWR units with two loops each, commissioned in 1969 and 1971. Westinghouse was responsible for the primary part of the plant and BBC, nowadays ABB for the secondary one. The original materials used in the secondary systems were lots of copper-based alloys, such as for the condensers, the low Pressure Preheaters and the Moisture Separator Reheater. The original SG tubes were made of Inconel 600 MA.

Regarding its age, Beznau has to be designated as an old plant. But in fact one should better talk about two young, "state of the art" units, taking into account the numerous back-fittings for which the owner spent about 1.5 billion Swiss francs. Important measures were the replacements of the steam generators (SGR) realized at unit 1 in 1993 and at unit 2 in 1999. But there were more changes in the secondary systems. Copper was banished from the system completely and replaced by stainless and chromium steel. The condensers were fitted with titanium tubes. New SG were installed with tubes from Inconel 690 TT. Of course, the water chemistry was also influenced by these changes and moved from Low-AVT with  a pH of  £ 9.3 step by step to High-AVT with a pH of 9.8 to 9.9 currently.

To ensure the integrity of the new Steam Generators as well as of the whole secondary system a corrosion product management was introduced in the end of the Nineties. Different investigations which are performed periodically are part of this measure. The program consist of analyses of corrosion products, measurements of sludge mass and composition, HOR-measurements and mass balance measurements of corrosion products in the whole circuit.

Objectives of these investigations are assessments of the efficiency of water chemistry regarding the origin and the transport of corrosion products and pollutants, populating into the steam generator, as well as of the potential danger of deposit, forming substances and stored or absorbed pollutants and an estimation of the material condition and trend considerations.

The main target of all measures is to avoid any chemical cleaning of the Steam Generators in the life time of the plant.

The current paper presents the plant experience since introduction of the corrosion product management program as well as the recent results of investigations.