Patent Number: 047864605
Section: claims

1. An installation for handling assemblies forming a core of a fast neutron nuclear reactor, between a primary station situated in a main vessel containing the core and a secondary station situated in an adjoining vessel, said installation comprising: at least one pivotable transfer hood, means for pivoting the hood around a vertical axis, two inclined ramps for connecting the hood to the primary station and the secondary station respectively, at least one pot for transporting an assembly, means for lifting said at least one pot along guiding means inside each of the ramps and the pivotable hood between the primary station and the secondary station, and means for closing the ramps at their top ends when the reactor is operating, comprising two flaps, the hood being attached to a rotary horizontal platform such that the hood and platform rotate as a unit around said vertical axis, said flaps being mounted on the platform in locations such that the flaps can be simultaneously placed above the top ends of the ramps by said means for pivoting the hood when the reactor is operating, said at least one pot comprising two pairs of wheels cooperating with the guiding means. 2. An installation according to claim 1, wherein the transfer hood comprises a thick tube inclined at an angle identical to that of the ramps, so that it can be placed in an extension of each of said ramps when the means for pivoting the hood are operated. 3. An installation according to claim 2, wherein the thick tube is lined externally with a heat insulation cooperating with the tube to bound an annular space for the circulation of a cooling fluid, openings bounded by windows formed at a top and bottom of the heat insulation being controlled by closure members. 4. An installation according to claim 3, wherein heating means are disposed around the thick tube in contact therewith. 5. An installation according to claim 1, wherein the rotary platform also bears a spare flap disposed beneath a demountable plug extending through the platform, a flap-receiving station formed by a recess formed on a fixed base plate disposed below the platform, thereby enabling one of the two flaps to be interchanged with the spare flap. 6. An installation according to claim 5, wherein the spare flap and the hood are disposed in two locations such that they can be placed simultaneously above the top ends of the ramps by the means for pivoting the hood when the reactor is shut down. 7. An installation according to claim 5, wherein a closure member adapted to be attached to an open bottom end of the hood is located in a recess formed in the base plate, the hood being demountably mounted on the rotary platform. 8. An installation according to claim 7, wherein the closure member is located in the recess in the flap-receiving station. 9. An installation according to claim 5, wherein the ramps rest on the base plate via swivel links and can expand freely downwards. 10. An installation according to claim 5, wherein the base plate rests via a swivel joint on a tube connected to a slab closing the main vessel, the tube enclosing the ramp connected to the primary station and the base plate moreover resting via sliding supports on a floor into which the ramp connected to the secondary station opens. 11. An installation according to claim 1, wherein the means for lifting the at least one pot comprise two cables wound at one end on two drums simultaneously actuated by a common motor assembly, the opposite end being attached to the at least one pot, means being provided, to detect any imbalance between the forces exerted on each of the cables. 12. An installation according to claim 1, wherein the guiding means inside each of the ramps and the pivotable hood are rails, the ends of the rails of the hood and of the rails of the ramps being separated by a limited clearance when such rails are aligned. 13. An installation according to claim 1, wherein each of the flaps is mounted on the rotary platform via a control mechanism enabling the flap to be moved between a top position in which the flap is retracted into a recess in the rotary platform and a bottom position in which the flap closes the end of one of the ramps, the control mechanism also comprising means for gripping the flap.