Patent Number: 045335141
Section: summary

This invention relates to a nuclear reactor degassing method and a degassing system therefor, and more particularly it relates to a degassing method and degassing system which can be advantageously adapted in nuclear reactors for lowering the dissolved oxygen concentration in the coolant in the reactor vessel. It is known that, in the water cooling type nuclear reactors, particularly in the boiling water type ones, the concentration of the oxidizing material such as dissolved oxygen in the coolant is a highly influential factor for the corrosion of feed water piping. In order to suppress the corrosion on feed water piping, it has been proposed to adjust the dissolved oxygen concentration in the coolant flowing in the piping (U.S. Pat. No. 3,663,725). Also, a nuclear reactor degassing method in which dissolved oxygen in the coolant in the nuclear reactor pressure vessel is removed at the time of start-up of the reactor to mitigate the risk of stress corrosion cracking of the pressure vessel and the structures therein was proposed in Japanese Laid-Open Patent Application No. 39791/79 (U.S. Pat. No. 4,293,382). An object of this invention is to decrease the dissolved oxygen concentration in the coolant in the nuclear reactor vessel during the reactor start-up period. Another object of this invention is to decrease the dissolved oxygen concentration in the coolant in the nuclear reactor vessel at the time of shutdown of the reactor. A salient feature of this invention resides in that the coolant in the nuclear reactor vessel is sprayed while in a highly heated state into the space in the vessel and the gas in the space is extracted from the nuclear reactor vessel.