During AP1000 operation,the water itself in the primary loop and special nuclides added in the water will be activated by neutrons.Tritium is main activation product and it is drawing more and more attention as they are almost discharged into environment in form of gas or liquid.Therefore,it's essential to study tritium generation in the primary coolant.In this paper,the tritium generation and consumptionmechanism of the primary coolant in AP1000 nuclear power plant was studied and the tritium calculation m...