The present invention relates to a system and method for removing dissolved gas from makeup water in a water-cooled nuclear reactor. The present invention includes a storage tank for containing the makeup water that includes the dissolved gas, a membrane system positioned downstream of the storage tank to at least partially remove the dissolved gas from the makeup water; and a transport mechanism to transfer the makeup water from an outlet of the membrane system for use in the water-cooled nuclear reactor. The dissolved gas can include at least one of dissolved oxygen, dissolved nitrogen, dissolved argon and mixtures thereof.