System and method for evaporating moisture from a gap defined between a heat transfer tube surrounding a repair sleeve in a nuclear steam generator. The nuclear steam generator has a heat transfer tube surrounding a repair sleeve that has been hydraulically expanded into engagement with the tube. The tube and the sleeve define a gap therebetween having moisture residing therein. The system includes an air compressor in communication with the gap for supplying air to the gap and a dryer in communication with the air compressor for drying the gas supplied to the gap. A heater in communication with the air compressor may also be provided for heating the air supplied to the gap, so that the moisture residing in the gap evaporates into the heated air. A vacuum pump in communication with the gap may be provided for decreasing the pressure of the heated air in the gap, so that substantially all the moisture evaporates from the gap and into the heated air.