Monday, March 23, 2009: 1:30 PM
C301 (Georgia World Congress Center)
Some PWR plants have introduced ethanol-amine (ETA) injection for the purpose of decreasing iron transfer in steam generator (SG). The ETA injection is supposed to decrease flow accelerated corrosion (FAC) rate, because of secondary system pH increase. But the water chemistry in the secondary system is very complicated. So water chemistry following ETA injection and the effect of ETA injection on FAC rate have not been studied systematically. To assess the influence of ETA injection on FAC rate, it is assumed that the FAC rate is proportional to the concentration gradient of magnetite. Then chemical concentration and magnetite solubility of the secondary system are calculated and the change of FAC rate is evaluated in the outline. It has been clarified that the effect of ETA injection reduces the FAC rate to about 1/3 - 1/22 of that of ammonia. In some portions of the secondary system, the effects of ETA injection have been measured experimentally by rotary disk test. Almost FAC rate decrease under ETA conditions. The peak FAC rate to shift to higher temperature after ETA injection. At 274 °C, the FAC rates are nearly same under high pH of ETA and ammonia and low pH of ammonia conditions.