Patent Number: 052727378
Section: claims

1. A nuclear reactor installation, said nuclear reactor installation comprising a reactor pressure vessel containing a reactor core; a concrete structural portion enclosing and holding said reactor pressure vessel; a dry well formed within said concrete structural portion and enclosing said reactor pressure vessel, said dry well having an upper portion and a lower portion; a primary containment vessel enclosing therein said concrete structural portion; a pressure suppression chamber having therein a pressure suppression pool, a vent tube communicating between said dry well and said suppression pool and having an upper outlet; and an accumulator-type emergency core cooling system, a gravity-driven emergency core cooling system and an equalizing system for submerging said reactor core, which are mounted within said primary containment vessel; said accumulator-type emergency core cooling system including a pressure accumulator tank holding cooling water under a predetermined accumulation pressure, and first closing and opening means communicated with said pressure accumulator tank, said first closing and opening means being opened when the pressure in said reactor pressure vessel decreases below said predetermined accumulation pressure in the event of a coolant loss accident, thereby supplying the cooling water from said pressure accumulator tank into said reactor pressure vessel to cool said reactor core;  said gravity-driven emergency core cooling system including a cooling water pool provided above said reactor core, and second closing and opening means communicated with said cooling water pool, said second closing and opening means being opened when the pressure in said reactor pressure vessel decreases to a certain level below said predetermined pressure, thereby supplying the cooling water from said cooling water pool into said reactor pressure vessel under gravity, and the cooling water fed from said cooling water pool overflowing said reactor pressure vessel to fill in the lower portion of said dry well, and then flowing into said suppression pool so as to raise the water level of said suppression pool;  said equalizing system including third closing and opening means which is opened when the water level of said suppression pool increases above a predetermined level, so as to feed the cooling water from said suppression pool into said reactor pressure vessel, thereby submerging said reactor core to cool the same.  a pressure suppression chamber enclosing a reactor pressure vessel and having therein a pressure suppression pool and a gas-phase space above said pressure suppression pool;  an operation floor;  a primary containment vessel made of steel and enclosing said pressure suppression chamber and said operation floor, and having upper and lower portions, and an interior;  partition means dividing the interior of said primary containment vessel into a first space containing said gas-phase space of said pressure suppression chamber and a second space containing said operation floor in such a manner that said first and second spaces are isolated from each other, said partition means sealing said first and second spaces, relative to each other;  at least one opening and closing means provided in said partition means, for communication the first and second spaces with each other when said opening and closing means is opened upon an accident;  an outer pool surrounding said lower portion of said primary containment vessel; and  an air-cooling means surrounding said upper portion of said primary containment vessel. 2. A nuclear reactor installation according to claim 1, wherein said primary containment vessel is made of steel, an outer pool is provided, surrounding the lower portion of said primary containment vessel, for cooling said suppression pool. 3. A nuclear reactor installation according to claim 2, wherein said concrete structural portion includes an outer peripheral wall having a lower portion, said suppression pool is divided by said outer peripheral wall into an outer portion and an inner portion, said outer portion and said inner portion being communicated with each other via upper and lower communication holes formed through the lower portion of said outer peripheral wall. 4. A nuclear reactor installation according to claim 3, wherein said upper communication holes are located above the outlet of said vent tube and above a normal water level of said suppression pool, and said lower communication holes are located below the outlet of said vent tube and below the normal water level of said suppression tube. 5. A nuclear reactor installation according to claim 3, wherein said upper communication holes are disposed below a normal water level of said suppression pool, steam fed from said reactor pressure vessel into the inner portion of said suppression pool is condensed in the case of emergency and also increases the pressure in said inner portion of said suppression pool, so that the cooling water in the inner portion of said suppression pool is urged by said increased pressure into the outer portion of said suppression pool to raise the water level of said outer portion of said suppression pool. 6. A nuclear reactor installation according to claim 2, wherein a heat accumulator is provided in said outer pool. 7. A nuclear reactor installation according to claim 1, wherein a steam condenser is provided in said cooling water pool, steam being fed from said reactor pressure vessel to said condenser, so that said steam is condensed into condensate, said condensate being returned to said reactor pressure vessel, and gas contained in said steam and not condensed being discharged to an inner portion of said suppression pool. 8. A nuclear reactor installation according to claim 2, wherein a heat-exchange between the cooling water in said cooling water pool and the cooling water in said suppression pool is effected through a heat exchanger. 9. A nuclear reactor installation according to claim 2, wherein a cooling water supply system having closing and opening means is provided in said outer pool, said closing and opening means of said cooling water supply system being opened upon an accident, so as to replenish said outer pool with cooling water, thereby raising the level of the cooling water in said outer pool. 10. A nuclear reactor installation according to claim 2, in which air-cooling means using the ambient air is provided at an upper portion of said primary containment vessel. 11. A nuclear reactor installation comprising: 12. A nuclear reactor installation according to claim 11, wherein said air-cooling means comprises a plurality of natural ventilation ducts covering the upper portion of said primary containment vessel. 13. A nuclear reactor installation according to claim 11, wherein said opening and closing means comprises a valve openable by a pressure difference between said first and second spaces. 14. . A nuclear reactor installation according to claim 12, wherein said openable valve has a rupture disk.