A decade''s experience in chemistry maintenance of once through steam generator of fast breeder test reactor

The steam generator of fast breeder test reactor (FBTR) at Kalpakkam (India) is a once through Steam Generator (OTSG) which requires the feed water at high purity level. Therefore, for maintaining feed water chemistry, all volatile treatment (AVT) is adopted along with a full-flow deep bed Condensate Polishing Unit (CPU) in the steam water system. Operational difficulties such as premature termination of operation cycle of the CPU, enhanced impurity pickup resulting in increased load for CPU, early silica breakthrough, etc. were observed on occasions. This paper describes the modifications carried out in the steam water circuit to overcome these problems. A decade's experience in operating the CPU and maintaining the feed water quality is also discussed.