Experience with chemical control in the feed water and steam generators at MAPS

Sea water is used for cooling the main Condensers and the Process Sea Water Heat Exchangers at MAPS. In other PHWRs in India Lake/River water is used for cooling main condensers. Morpholine is used as an alkalising agent in the feed water and condensate system for maintaining the pH in the range 8.5-9.2 in all the Indian PHWRs. During the initial stages of operation of both the Units at MAPS, congruent phosphate control was adopted in the Steam Generators whenever condenser tube leak occurred to maintain the pH and to remove the scale forming ions by blowdown. As this treatment has not been found satisfactory, Condensate Polishing Plants were retrofitted in both the units at a later stage. The experience gained and the problems encountered in the operation of Condensate Polishing Plant with the imported and indigenous macroporous resins in the maintenance of chemical parameters in the Steam Generators are highlighted in this paper. (author)