[en] High pressure feed water heater on unit 1 at Tarapur Atomic Power Station (TAPS) showed tube leaks in early 1972 after about two years of satisfactory operation. Subsequently the tube failures showed to be alarmingly high and confined to particular regions in the drain cooler zone. Problem of internal damage was suspected when recurring tube leak showed up. An attempt was made to withdraw the tube bundle, investigate for any generic problems and repair as possible. This exercise was carried out in the year 1977. The present paper describes the investigations earlier carried out and the rehabilitation attempts including changes in operating procedures made to extend the life of the heater tube bundle until re-tubing of the affected drain cooler region could be made. (author)