Eventhough OD IGA/SCC of SG tubing remains limited in the French plants compared to foreign units, EDF is concerned by its extend. Hence, several studies have been performed on materials, chemistry in operation, hideout returns during shutdown, and maintenance, getting to preventive or remedial actions. It can be noted that no 600 TT nor 690 alloy SG tube is affected by secondary side corrosion in EDF units. Aside from SG tubing physical and mechanical properties influencing IGA/SCC, the secondary side chemistry in EDF plants has always been satisfactory enough not to enhance rapid corrosion growth. However, chemistry has been progressively improved: limitation of pollutants ingress into SGs, optimization of the secondary system conditioning, boric acid addition,... Other studies are conducted in order to prevent SGs fouling by sludge and scale accumulation removal: physico-chemical characterization of deposits, detection of deposits by non destructive examination, study of a chemical fouling indicator, study of the physical and chemical parameters influencing sludge production, modelization of the deposition mechanisms and study of the influence of parameters in order to propose preventive methods against fouling. Chemical cleaning could be implemented in Chinon Bl in the next future with two main objectives: to restore the heat transfer coefficient and to limit the progression of IGA/SCC at TSP level.
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