Patent Number: 
Section: claims

1. A boiling water nuclear power plant comprising:a nuclear reactor building including a reactor containment vessel and a reactor pressure vessel;an external building which is installed independently outside the nuclear reactor building, which includes a power source and an operating panel independent of the nuclear reactor building, and which has an anti-hazard property;a water injection pump installed inside the external building;a water injection pipe configured to perform water injection on at least the reactor pressure vessel or the reactor containment vessel in the nuclear reactor building from the water injection pump; anda valve connected to the water injection pipe;wherein the valve connected to the water injection pipe includes valves arranged inside the nuclear reactor building and valves arranged outside the nuclear reactor building, and the valves arranged inside the nuclear reactor building include a valve operated to be kept constantly open and a check valve which are arranged outside the reactor containment vessel; andwherein the check valve allows water injection from the outside into the nuclear reactor building and prevents backward flow. 2. The boiling water nuclear power plant according to claim 1, wherein a branching-off pipe is provided at one of the water injection pipes; and a hose connection portion allowing connection of a hose of a pumper vehicle is provided at an end of the branching-off pipe. 3. The boiling water nuclear power plant according to claim 2, wherein the branching-off pipe is provided inside the external building; and the hose connection portion is arranged inside the external building. 4. The boiling water nuclear power plant according to claim 2, wherein the branching-off pipe is provided inside the external building; and the hose connection portion is arranged outside the external building. 5. The boiling water nuclear power plant according to claim 2, wherein the branching-off pipe is provided inside the nuclear reactor building; and the hose connection portion is arranged outside the nuclear reactor building. 6. The boiling water nuclear power plant according to claim 2, wherein the external building includes a garage storing the pumper vehicle. 7. The boiling water nuclear power plant according to claim 1, wherein:the plurality of water injection pipes includes a first water injection pipe performing water injection on the reactor pressure vessel, and a second water injection pipe performing water injection on other portions of the boiling water nuclear power plant; andthe boiling water nuclear power plant includes a bypass pipe performing water injection on the first water injection pipe from the second water injection pipe, and a valve installed at the bypass pipe. 8. The boiling water nuclear power plant according to claim 2, comprising, at a position different from the external building, a garage storing the pumper vehicle. 9. A boiling water nuclear power plant comprising:a nuclear reactor building including a reactor containment vessel and a reactor pressure vessel;an external building which is installed independently outside the nuclear reactor building, which includes a power source and an operating panel independent of the nuclear reactor building, and which has an anti-hazard property;a water injection pump installed inside the external building;a water injection pipe configured to perform water injection on at least the reactor pressure vessel or the reactor containment vessel in the nuclear reactor building from the water injection pump; anda valve connected to the water injection pipe;wherein the valve connected to the water injection pipe includes valves arranged inside the nuclear reactor building and valves arranged outside the nuclear reactor building, the valves arranged inside the nuclear reactor building including a valve operated to be kept constantly open and a check valve which are arranged outside the reactor containment vessel, and the valves arranged inside the nuclear reactor building are connected to a water injection port inside the nuclear reactor building via an up-grade water injection pipe;wherein the check valve allows water injection from the outside into the nuclear reactor building and prevents backward flow; anda water discharge mechanism including a flow rate restrictor is provided at the lowermost point of the up-grade water injection pipe in the nuclear reactor building. 10. The boiling water nuclear power plant according to claim 9, wherein a branching-off pipe is provided at the water injection pipe; and a hose connection portion allowing connection of a hose of a pumper vehicle is provided at an end of the branching-off pipe. 11. The boiling water nuclear power plant according to claim 10, wherein the branching-off pipe is provided inside the external building; and the hose connection portion is arranged inside the external building. 12. The boiling water nuclear power plant according to claim 10, wherein the branching-off pipe is provided inside the external building; and the hose connection portion is arranged outside the external building. 13. The boiling water nuclear power plant according to claim 10, wherein the branching-off pipe is provided inside the nuclear reactor building; and the hose connection portion is arranged outside the nuclear reactor building. 14. The boiling water nuclear power plant according to claim 10, wherein the external building includes a garage storing the pumper vehicle. 15. The boiling water nuclear power plant according to claim 9, wherein:the water injection pipe includes a first water injection pipe performing water injection on the reactor pressure vessel, and a second water injection pipe performing water injection on other portions of the boiling water nuclear power plant; andthe boiling water nuclear power plant includes a bypass pipe performing water injection on the first water injection pipe from the second water injection pipe, and a valve installed at the bypass pipe. 16. The boiling water nuclear power plant according to claim 10, comprising, at a position different from the external building, a garage storing the pumper vehicle.