[en] The Steam generator condition is a key factor for plant performance, high plant availability, possible life time extension and plant safety. Its major safety function is to act as a barrier between the radioactive primary side and the non-radioactive secondary side of pressurized water reactors. Any degradation mechanism, which impairs this barrier function, is a significant safety concern. The main reason for SG tube failure is known to be the accumulation of deposits contributing to formation of local aggressive conditions. Furthermore deposits on primary as well as secondary side of SG tubes reduce the heat transfer performance. A SG cleanliness management program is therefore mandatory to ensure high plant performance regarding efficiency as well as component integrity. Cleaning measures of steam generator are essential parts of the cleanliness management program. Mechanical cleaning, e.g. tubesheet and inner bundle lancing or upper bundle flushing are efficient methods for removal of local loose deposits. But a chemical cleaning is the only method to remove deposits from the complete SG. AREVA is providing with its C³ (customized chemical cleaning) concept a tool box of chemical cleaning methods, to adapt to plant specific needs and requirements. (author)