Progress on water chemistry control in domestic PWR plants

Every possible efforts on water chemistry control of both primary and secondary water have been made to improve the plant reliability for these ten years. The calm technical responses for the quiet behavior of primary water and the dynamic responses for the unstable behavior of secondary water have been done as the water chemistry control techniques, which are presented here. For the secondary system, the water chemistry has been charged from phosphate treatment to all volatile treatment and new all domestic PWR plants are controlled by this treatment. Consequently, the excellent secondary water conditions have been maintained with the installation of the condensate polisher and the careful water chemistry control. On the other hand, for the primary system, the water chemistry has been finely controlled by settling not only the standard value but also the limiting value. The water chemistry control for reducing radioactive corrosion products, the automatization of chemical analyses and new corrosion inhibiter for component cooling water system are also reported here. (author)