Effects of Spilled Chemicals on Fouling, Heat Transfer and Corrosion in the Cooling Water Systems of NPPs

摘要

Undisturbed function of cooling systems is of utmost importance for nuclear power plants to operate safely. The main problems that can affect the operation of a cooling water system are linked to fouling or scaling of surfaces which, in turn, may cause a reduction in heat-transfer or increase the risk of corrosion. In cooling water systems operating with natural waters, some fouling and scaling occurs naturally. In addition, oil spill or release of other chemicals into the water in case of a tanker accident, for example, may cause an unexpected intrusion of chemicals into the system. This paper presents the results of studies concerning the effect of ethanol, sodium hydroxide, phosphoric acid and phenol as well as rapeseed oil on fouling, heat transfer and corrosion of heat exchanger material (titanium) in synthetic brackish water simulating Baltic Sea water. The chosen chemicals are among the most frequently transported chemicals on Baltic Sea. They were chosen to this study based on their possibility to get carried to the cooling water system as well as their potential to be harmful to the system. Rapeseed oil was chosen as a representative of oily products. A specialised flow-through cell was developed for the studies allowing on-line monitoring of a heated sample by methods such as electrochemical impedance spectroscopy (EIS) and linear polarisation resistance (LPR). The risk evaluation was based on the corrosion rates measured.