Patent Number: 039649652
Section: summary

BACKGROUND OF THE INVENTION A pressurized-water reactor installation includes the reactor pressure vessel containing the core which heats the pressurized-water coolant circulated through the pressure vessel via a pipeline loop extending through a steam generator producing steam as useful power, and from there via a main coolant pump, back to the pressure vessel. A branch pipeline loop shunts a portion of the circulating water coolant around the main coolant pump and through a water coolant purification system, about from 10 to 20% of the circulating water coolant passing continuously through this purification system during operation of the reactor. A part of this purification system is a degassing facility wherein the water coolant is decompressed and cooled so that gases separate. These gases are mainly hydrogen, nitrogen and oxygen. However, in addition to the above three gases the separated gases include the noble gases krypton and xenon which are present in volumes that are very small as compared to the volume of the other gases but which mandatorily prevent disposal of the separated gases by discharging them to the atmosphere. The one prior art suggestion has been to store the separated gases under pressure in decay tanks for a time depending on the half-life of the radioactive noble gases and to thereafter discharge the gases to the atmosphere via a tall exhaust air stack through which is also discharged the exhaust air from the spherical steel containment vessel enclosing the entire reactor installation. However, this practice has been prevented by current, more stringent environmental protection regulations. Therefore, the operation of a pressurized-water reactor installation has presented the problem of disposing of the gases separated from the water coolant during its purification, in a manner that is economically feasible and entirely safe from the environmental pollution viewpoint. SUMMARY OF THE INVENTION The object of the present invention is to provide a solution to the above problem and this has been achieved in the following manner: Basically, the concept of the invention is that separation and isolation of the noble gases permits the other gases to be disposed of free from problems connected with radioactivity. The noble gases are included by the other gases in such small amounts that their isolation might be effected by storage in a tank or tanks which may be of small volumetric capacity while still capable of accepting all of the noble gases resulting from full reactor operation periods which may extend for as much as one year. In the case of a pressurized-water reactor installation operating as a power reactor of 1000 MWe for an operational period of one year, the noble gases can be stored in a steel bottle containing activated carbon and having a volumetric capacity of less than 1m.sup.3, a volumetric capacity of 0.1m.sup.3 or smaller being preferred. This is a very miniaturized tank as compared to the decay tanks required for storage of the gases by the prior art proposal previously referred to. In addition to the above advantage, the invention further involves combining the separated oxygen with a portion of the hydrogen and sending the balance of the hydrogen to the water coolant gas-charging system to provide the coolant with the hydrogen excess desired in the case of light-water reactors in general, and in particular, a pressurized-water reactor. Nitrogen is also added to the coolant by this gas-charging system and the separated nitrogen may be sent to this system for use there, or safely discharged to the atmosphere.