Patent Number: 
Section: claims

1. A pressure suppression and decontamination apparatus for a reactor container including a dry well space having an upper dry well and a lower dry well, the reactor container housing therein a reactor pressure vessel containing nuclear core fuel, said apparatus comprising:a dry well cooling unit configured to cool a gas in the dry well space and produce a condensate of the gas;a circulation device configured to circulate the gas in the dry well space through said dry well cooling unit;a sprayer head connected to an outlet of a pump, disposed in the upper dry well, and configured to cool the reactor container;a drain pipe extending from said dry well cooling unit to the lower dry well, said drain pipe being configured to discharge the condensate from said dry well cooling unit, the drain pipe being directly connected to a changeover device, the changeover device being directly connected to the cooling unit; anda sprinkling device connected to said drain pipe and configured to sprinkle condensate in the dry well space, the sprinkling device being disposed lower than the dry well cooling unit and connected to receive condensate from the cooling unit via the drain pipe. 2. The pressure suppression and decontamination apparatus according to claim 1, wherein said changeover device connects said sprinkling device with said drain pipe, and wherein said changeover device includes a changeover panel that has a first position that allows the condensate to flow from said dry well cooling unit to an end of said drain pipe in the lower dry well and a second position that allows the condensate to flow from said dry well cooling unit to said sprinkling device. 3. The pressure suppression and decontamination apparatus according to claim 2, wherein said changeover panel is in the second position when said circulation device is in an emergency state. 4. The pressure suppression and decontamination apparatus according to claim 3, wherein said changeover panel is in the second position when a temperature of said changeover device is higher than a melting temperature of an adhesive metal in the changeover device. 5. The pressure suppression and decontamination apparatus according to claim 3, wherein said changeover panel is configured to move between the first position and the second position by mechanical means. 6. The pressure suppression and decontamination apparatus according to claim 1, wherein said sprinkling device is provided with a plurality of sprinkling holes at an end thereof. 7. The pressure suppression and decontamination apparatus according to claim 1, wherein said sprinkling device is provided with a collision plate, against which a flow of the condensate collides. 8. The pressure suppression and decontamination apparatus according to claim 1, wherein said sprinkling device is provided with a sprinkling blade configured to scatter a flow of the condensate. 9. The pressure suppression and decontamination apparatus according to claim 1, further comprising:a rotating mechanism configured to rotate through with a flow of the condensate flowing through said sprinkling device;a shut-off plate provided at an opening of a casing of said dry well cooling unit and an exhaust fan provided adjacent to said shut-off plate; anda connecting shaft connecting said rotating mechanism and said exhaust fan. 10. The pressure suppression and decontamination apparatus according to claim 9, wherein said shut-off plate is configured to be in a closed position during operation of said circulation device and configured to be in an open position during stoppage of said circulation device. 11. The pressure suppression and decontamination apparatus according to claim 1, wherein said sprinkling device is provided in the bottom dry well. 12. The pressure suppression and decontamination apparatus according to claim 1, wherein said sprinkling device is provided in the upper dry well. 13. A pressure suppression and decontamination apparatus for a reactor container including a dry well space having an upper dry well and a lower dry well, the reactor container housing therein a reactor pressure vessel containing nuclear core fuel, said apparatus comprising:means for cooling a gas in the dry well space to produce a condensate of the gas;a sprayer head connected to an outlet of a pump, disposed in the upper dry well, and configured to cool the reactor container;a drain pipe extending from said means for cooling to the lower dry well, said drain pipe being configured to discharge the condensate from said means for cooling, the drain pipe being directly connected to a changeover device, the changeover device being directly connected to the means for cooling; andmeans for sprinkling the condensate in the dry well space, said means for sprinkling being connected to said changeover device, the means for sprinkling being disposed lower than the means for cooling and connected to receive condensate from the means for cooling via the changeover device. 14. The pressure suppression and decontamination apparatus according to claim 13, wherein the changeover device fluidly connects said means for cooling to either an end of said drain pipe in the lower dry well or said means for sprinkling. 15. The pressure suppression and decontamination apparatus according to claim 1, wherein the sprayer head is connected to the pump via a residual heat removing line connected to the outlet of the pump and extending upward from the pump toward the sprayer head.