Effects of NaCl addition on magnetite deposition on the outer surfaces of steam generator tubes

During the operation of a steam generator (SG), NaCl can be introduced into the secondary system of a pressurized water reactor owing to the condenser inleakage. In this study, the effects of NaCl addition on magnetite deposition on SG tubes were investigated using a magnetite deposition test loop that can simulate the secondary side condition of SGs. The results showed that the deposited magnetite particles were polyhedral in shape regardless of NaCl, but the particles became smaller and more round with the addition of NaCl. The two-dimensional porosity of magnetite deposits decreased from 30.0% to 18.9% with the addition of NaCl. Furthermore, the amount of deposits was reduced by 46% with the addition of NaCl, which is discussed in terms of particle size, magnetite solubility, and zeta potential. The concentration factor of Na and Cl within the deposits were evaluated to be 6.2 x 10(5) and 1 x 10(4), respectively. (C) 2020 Elsevier Ltd. All rights reserved.