Experimental Study on Deoxidization of the Chemical and Volume Control Tank by the Nitrogen Purging Method

Deoxidization of the chemical and volume control tank of nuclear power plant by the nitrogen purging method is of great significance for inhibiting oxygen corrosion of equipment and ensuring the safe operation of nuclear power plant. In this paper, the experimental study on nitrogen purging process of the lifting and lowering liquid level of the volume control tank was carried out. The experimental results indicate that the oxygen concentration is basically the same at different points in the gas space of the chemical and volume control tank during the purging process. In the purging process, the higher the high liquid level, the lower the pressure after exhaust, the higher the pressure at the end of purging, and the better the purging effect. A gas oxygen concentration change model of lifting and lowering liquid level purging was established. The calculated results of the model are in good agreement with the experimental results. The analysis shows that measures such as reducing the pressure after exhaust, increasing the pressure at the end of purging, increasing the high liquid level and reducing the low liquid level, can effectively reduce the gas oxygen concentration and improve the purge effect, but increase the nitrogen consumption for the lifting and lowering liquid level purging. This study could provide a basis for the optimization of the nitrogen purging method of the chemical and volume control tank and has important guiding significance for the purging strategy of the chemical and volume control tank in nuclear power plants.