Abstract
Some pressurized water reactor (PWR) plants have switched to ethanol-amine (ETA) injection to reduce iron transfer in the steam generator (SG). ETA injection is supposed to reduce the rate of flow accelerated corrosion (FAC) by increasing the pH of the secondary system. However, the effect of ETA injection on FAC rate have not been studied systematically. To assess the influence of ETA injection on FAC rate, first the water chemistries in secondary systems were calculated considering thermal decomposition of hydrazine in SG and vapor/liquid distribution of ammonia, ETA and hydrazine in SG and MSR. Then change in FAC rate was evaluated using magnetite solubility changes before and after ETA injection. Evaluation from calculated magnetite solubility shows that ETA injection reduces the FAC rate of the secondary system. In some portions of the secondary system, we also measured the FAC rate experimentally by the rotating disk test to examine the effect of ETA injection. The peak of FAC rate shifted to a higher temperature after ETA injection. At 274°C, the FAC rates were nearly the same under the conditions of high pH of ETA and conventional low pH of all volatile treatment (AVT). Same pH dependence was observed in ETA and ammonia treatment.
