Patent Number: 041815726
Section: claims

1. A closure head for a nuclear reactor comprising: a stationery outer ring disposed on a reactor vessel;  a first rotatable plug disposed within said stationery outer ring defining a first annulus therebetween for enclosing internals of said reactor vessel and for positioning refueling equipment;  a first bearing assembly mounted in said stationery outer ring and in contact with said first rotatable plug for supporting said first rotatable plug from said stationary outer ring;  first seal means disposed in said first annulus for preventing passage of gases through said first annulus;  first biasing means mounted on said stationery outer ring and near said first seal means for selectively contacting said first seal means and urging said first seal means into contact with said first rotatable plug thereby sealing said first annulus; and  first fluid means connected to said first annulus near said first bearing assembly for introducing a fluid into said first annulus and into contact with said first seal means causing said first seal means to compress said first biasing means and allowing said fluid to pass over said first seal means while forming a fluid layer between said first seal means and said first rotatable plug thereby sealing said first annulus.  second seal means disposed in said first annulus such that said first bearing assembly is disposed between said first seal means and said second seal means for preventing passage of gases through said first annulus; and  second biasing means mounted on said stationery outer ring and near said second seal means for selectively contacting said second seal means and urging said second seal means into contact with said first rotatable plug thereby sealing said first annulus, said first fluid means also causing said fluid to contact said second seal means and causing said second seal means to compress said second biasing means and allowing said fluid to pass over said second seal means while forming a fluid layer between said second seal means and said first rotatable plug thereby sealing said first annulus.  a first housing mounted on said stationery outer ring;  a first spring mounted in said first housing and extending toward said first tubular seal member; and  a first contact member mounted on said first spring near said first tubular seal member, said first spring causing said first contact member to contact said first tubular member thus forcing said first tubular member against said first rotatable plug.  a second housing mounted on said stationery outer ring;  a second spring mounted in said second housing and extending toward said first tubular seal member; and  a second contact member mounted on said second spring near said second tubular seal member, said second spring causing said second contact member to contact said second tubular member thus forcing said second tubular member against said first rotatable plug.  a fluid source;  an inlet conduit connected between said first annulus near said first bearing assembly and said fluid source for conducting said fluid from said fluid source to said first annulus;  a first return conduit connected at one end to said first annulus so that said first seal means is between said first bearing assembly and said first return conduit for conducting said fluid to said fluid source; and  a second return conduit connected at one end to said first annulus so that said second seal means is between said first bearing assembly and said second return conduit for conducting said fluid to said fluid source.  a pump connected in said inlet conduit for forcing said fluid through said inlet conduit; and  a recirculating system connected around said pump for maintaining a constant volume flow through said pump.  an outer race mounted in said first rotatable plug;  a bearing ball disposed in said outer race;  an inner race mounted in said stationery outer ring for supporting said bearing ball, said inner race having a clearance on its inner diameter between said inner race and said bearing ball for accommodating differential thermal expansion of the components of said closure head.  a gas inlet line connected to said first annulus for conducting a purge gas to said first annulus; and  a gas outlet line connected to said first annulus for conducting said purge gas from said first annulus thus purging said first annulus and removing contaminants therefrom.  a second rotatable plug disposed within said first rotatable plug defining a second annulus therebetween for enclosing said internals of said reactor vessel and for positioning said refueling equipment;  a second bearing assembly mounted in said first rotatable plug and in contact with said second rotatable plug for supporting said second rotatable plug from said first rotatable plug;  third seal means disposed in said second annulus for preventing passage of gases through said second annulus;  third biasing means mounted in said first rotatable plug and near said third seal means for selectively contacting said third seal means and urging said third seal means into contact with said second rotatable plug thereby sealing said second annulus; and  third fluid means connected to said second annulus near said second bearing assembly for introducing a second fluid into said second annulus and into contact with said third seal means causing said third seal means to compress said third biasing means and allowing said second fluid to pass over said third seal means while forming a fluid layer between said third seal means and said second rotatable plug thereby sealing said second annulus. 2. The closure head according to claim 1 wherein said closure head further comprises: 3. The closure head according to claim 2 wherein said first annulus has a portion formed into a dip seal between said first seal means and said second seal means for further preventing passage of said gases therethrough. 4. The closure head according to claim 3 wherein said first seal means comprises a first tubular seal member disposed in said first annulus and extending around the circumference of said first rotatable plug. 5. The closure head according to claim 4 wherein said second seal means comprises a second tubular seal member disposed in said first annulus and extending around the circumference of said first rotatable plug. 6. The closure head according to claim 5 wherein said first biasing means comprises: 7. The closure head according to claim 6 wherein said second biasing means comprises: 8. The closure head according to claim 7 wherein said first fluid means comprises: 9. The closure head according to claim 8 wherein said fluid source comprises: 10. The closure head according to claim 9 wherein said fluid is a lubricating liquid for lubricating said first bearing assembly while sealing said first annulus. 11. The closure head according to claim 10 wherein said lubricating liquid is silicone. 12. The closure head according to claim 11 wherein said first bearing assembly comprises: 13. The closure head according to claim 12 wherein said closure head further comprises: 14. The closure head according to claim 1 wherein said closure head further comprises: