The slight-alkalization of generator internal cooling water (GICW) is widely used to inhibit the corrosion of hollow copper conductor and thereby ensure the safe operation of the generator. CO

2

inleakage is increasingly identified as a potential security risk for GICW system. In this paper

the influence of CO

2

inleakage on the slight-alkalization of GICW was theoretically discussed. Based on the equilibriums of the CO

2

-NaOH-H

2

O system

CO

2

inleakage saturation was derived to quantify the amount of the dissolved CO

2

in GICW. This parameter can be directly calculated with the measured conductivity and the [Na

+

]

of GICW. The influence of CO

2

inleakage on the slight-alkalization conditioning of GICW and the measurement of its water quality parameters were then analyzed. The more severe the inleakage

the narrower the water quality operation ranges of GICW

resulting in the more difficult the slight-alkalization conditioning of GICW. The temperature calibrations of the conductivity and the pH value of GICW show non-linear correlations with the amount of CO

2

inleakage and the NaOH dosage. This study provides insights into the influence of CO

2

inleakage on the slight-alkalization of GICW

which can serve as the theoretical basis for the actual slight-alkalization when CO

2

inleakage occurs.