Patent Number: 053012151
Section: claims

1. A building for enclosing a nuclear reactor comprising: a containment vessel for surrounding said reactor;  a wetwell disposed inside said containment vessel and including an inner wall, an outer wall, a floor, and a roof defining a wetwell pool, for containing wetwell water at a predetermined level from said wetwell floor, and a suppression chamber disposed above said wetwell pool;  said wetwell and said containment vessel defining a drywell for surrounding said reactor, said drywell including a gas;  a plurality of vents disposed in said wetwell pool and in flow communication with said drywell for channelling steam releasable in said drywell from said reactor for condensing said steam;  a shell disposed inside said wetwell and extending into said wetwell pool to define a dry gap devoid of said wetwell water and disposed in flow communication with said suppression chamber;  said shell being spaced from at least one of said wetwell inner and outer walls to define said dry gap;  said shell extending from said wetwell floor and into said suppression chamber; and  said wetwell roof comprising a slab disposed above a plurality of spaced apart support beams, said beams defining therebetween an auxiliary chamber disposed in flow communication with said suppression chamber.  a containment vessel for surrounding said reactor and sized for containing a maximum pressure therein;  a wetwell of predetermined size disposed inside said containment vessel and including an inner wall, an outer wall, a floor and roof defining a wetwell pool, for containing wetwell water at a predetermined level above said wetwell floor, and a suppression chamber disposed above said predetermined level of the wetwell water in the wetwell pool of a predetermined volume such that a pressure margin between an actual pressure in the suppression chamber and the maximum pressure is maintainable;  said wetwell and said containment vessel defining a drywell for surrounding said reactor, said drywell including a gas;  a plurality of vents disposed in said wetwell pool and in flow communication with said drywell for channeling steam releasable in said drywell from said reactor to said wetwell pool for condensing said steam; and  a shell disposed inside said wetwell and extending into said wetwell pool to define a dry gap devoid of said wetwell water and disposed in flow communication with said suppression chamber, said dry gap extending a vertical height substantially corresponding to the vertical height of said wetwell including said wetwell pool and said suppression chamber and at a corresponding elevation as said wetwell such that the volume of the suppression chamber is increased by said dry gap from said predetermined volume to a volume in excess thereof and the pressure margin in the suppression chamber given said actual pressure is increased without change in the sizes of the containment vessel and the wetwell. 2. A nuclear reactor building according to claim 1 wherein said shell extends upwardly to said support beams and said dry gap is disposed in flow communication with said auxiliary chamber. 3. A nuclear reactor building according to claim 2 wherein said shell is spaced inwardly from said wetwell outer wall to define said dry gap therebetween. 4. A nuclear reactor building according to claim 3 wherein said wetwell and said shell are annular, and said dry gap extends circumferentially therebetween. 5. A nuclear reactor building according to claim 4 wherein said support beams are equiangularly circumferentially spaced apart from each other and extend from said wetwell inner wall to said wetwell outer wall. 6. A nuclear reactor building according to claim 5 wherein said shell includes a top edge disposed adjacent to bottom ends of said support beams and spaced inwardly from said wetwell outer wall to define an annular inlet therebetween, said inlet being disposed in flow communication with said auxiliary chamber. 7. A nuclear reactor building according to claim 6 wherein said wetwell has a predetermined volume and contains said wetwell water, said wetwell water has a predetermined minimum level above said horizontal vents, and said predetermined minimum level with said shell displaying a portion of said wetwell water is substantially the same as a predetermined minimum level without said shell within said wetwell. 8. A building for enclosing a nuclear reactor comprising: 9. A nuclear reactor building according to claim 8 wherein said wetwell roof comprises a slab disposed above a plurality of spaced apart support beams, said beams defining therebetween an auxiliary chamber disposed in flow communication with said suppression chamber. 10. A nuclear reactor building according to claim 9 wherein said shell extends upwardly to said support beams and said dry gap is disposed in flow communication with said auxiliary chamber. 11. A nuclear reactor building according to claim 8 wherein said shell is spaced inwardly from said wetwell outer wall to define said dry gap therebetween. 12. A nuclear reactor building according to claim 8 wherein said wetwell and said shell are annular, and said dry gap extending circumferentially therebetween. 13. A nuclear reactor building according to claim 8 wherein said wetwell roof comprises a slab disposed above a plurality of spaced apart support beams, said beams defining therebetween an auxiliary chamber disposed in flow communication with said suppression chamber, said support beams being equiangularly circumferentially spaced apart from each other and extending from said wetwell inner wall to said wetwell outer wall. 14. A nuclear reactor building according to claim 13 wherein said shell includes a top edge disposed adjacent to bottom ends of said support beams and spaced inwardly from said wetwell outer wall to define an annular inlet therebetween, said inlet being disposed in flow communication with said auxiliary chamber. 15. A nuclear reactor building according to claim 8 wherein said wetwell has a predetermined volume and contains said wetwell water, said wetwell water having a predetermined minimum level above said horizontal vents, and said predetermined minimum level with said shell displacing a portion of said wetwell water is substantially the same as a predetermined minimum level without said shell within said wetwell. 16. A nuclear reactor building according to claim 8 wherein said suppression chamber is sealed from said drywell.