The steam generator of fast breeder test reactor (FBTR) at Kalpakkam (India) is an once through type sodium heated Steam Generator (OSTG). Therefore, the feed water is maintained at a high purity level. To achieve this, all volatile treatment (AVT) for maintaining water chemistry is adopted and a full-flow deep bed Condensate Polishing Unit (CPU) has been installed in the circuit and has been in operation for the last seven years. However, operational problems 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 several occasions leading to deterioration in the feed water quality. This paper describes the modification that were carried out in the steam water circuit to overcome the above mentioned problems. The experience in operating the CPU and further modifications to enhance the performance are discussed in this paper.
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