Patent Number: 054065968
Section: claims

1. In a pressurized-water nuclear vessel, having a head, a plurality of tubular adapters, each fixed into an opening traversing said head, and at least one instrumentation column passing though one adapter of said plurality of adapters, a device for sealed clamping of said instrumentation column against a support surface of a tubular support assembly fixed to an end of said one adapter located outside said head and in an extension of said one adapter, said clamping device comprising: (a) a pressure plate having a central opening through which said instrumentation column can pass;  (b) a removable supporting end piece coming to rest on an end of said support assembly opposite to said adapter having a central opening for passage of said instrumentation column;  (c) an odd number of lifting screws, each lifting screw being engaged in a tapped hole traversing said pressure plate and comprising a supporting end bearing on said supporting end piece and an opposite end constituting an engagement means for rotating said lifting screw, said lifting screws being distributed about an axis of symmetry of said central opening of said pressure plate and parallel to said axis;  (d) a pull-ring comprising two half rings coming to bear between a radially projecting part of said instrumentation column and said pressure plate;  (e) a tightening assembly including a mounting plate having an opening for passage of said instrumentation column and an odd number at least equal to three of tightening spindles distributed around and parallel to an axis of said opening of said mounting plate, each of said spindles having an end configured for engaging an engagement means for rotating one lifting screw of said pressure plate, each of said spindles being mounted rotationally on said mounting plate and securely fastened to gears in kinematic connection so as to be rotated in a same direction upon rotation of one of said spindles, called a driving spindle, which includes a shaped drive part; and,  (f) a tool for rotationally driving said driving spindle. 2. Device according to claim 1, wherein said supporting end piece and said pressure plate have the shape of a regular polygon with an odd number of sides. 3. Device according to claim 2, wherein said supporting end piece and said pressure plate have the shape of equilateral triangles with rounded corners. 4. Device according to claim 3, wherein each said tapped hole traversing said pressure plate is located adjacent said rounded corners. 5. Device according to any one of claims 1 to 3, wherein said tightening assembly comprises three spindles each securely fastened to identical gears, said driving spindle including the shaped drive part being kinematically linked to each of two other tightening spindles, by a kinematic chain of an odd number of gears, identical to gears securely fastened to the three tightening spindles and meshing successively with one another and with the gears of the tightening spindles. 6. Device according to claim 5, wherein each of the kinematic chains for driving said tightening spindles includes three gears securely fastened to shafts mounted so as to idle on said mounting plate of said tightening assembly. 7. Device according to claim 5, wherein said tool for rotationally driving said driving spindle including said shaped part is a torque wrench. 8. Device according to claim 5, wherein said tightening assembly includes two manipulating handles attached to said mounting plate. 9. Device according to claim 1, wherein said removable supporting end piece includes a top support surface containing at least three recesses receiving supporting ends of said lifting screws of said pressure plate.