Patent Number: 044407181
Section: summary

FIELD OF THE INVENTION The invention relates to a device for the transfer of fuel assemblies for a fast neutron reactor, between a storage position adjacent to the tank of the reactor and a position for the evacuation and introduction of these assemblies. BACKGROUND Fast neutron reactors cooled with liquid sodium comprise a tank of large dimensions inside which is disposed the reactor core consisting of fuel assemblies immersed in the liquid sodium. In order to effect the recharging of the reactor core with fuel assemblies, it is necessary to remove the irradiated fuel assemblies from the tank, then to dispose them in a transport cask, generally after a more or less long period of storage during which the radioactivity of these fuel assemblies diminishes, for their evacuation to a reprocessing unit. Parallel to this evacuation of these irradiated assemblies, new assemblies are introduced into the nuclear reactor in the charging zone of the core where a transfer machine can pick them up to dispose them inside the core in place of the irradiated assemblies. A transfer machine is therefore available, situated above the core, enabling the assemblies to be removed from or introduced into the core and to be disposed in a storage zone disposed in the reactor tank. On the other hand, a transfer assembly is available comprising two inclined ramps and a loading-unloading lock which enables the fuel assemblies to be transported between the reactor tank containing the core and a storage zone close to this tank where the assemblies can remain for a more or less extended time during which their radioactivity decreases. For their passage from the storage zone to the transport cask, the fuel assemblies must be picked up by a complex handling and packaging assembly comprising travelling cranes or other handling machines. This complex assembly is installed in a part of the reactor specially provided for this purpose, thereby increasing the overall size and the cost of construction of the reactor building. On the other hand, it is at present being considered, for the installation of fast neutron nuclear reactors, to group a plurality of reactors on one and the same site, so as to facilitate shared use of certain subsidiary installations or items of equipment of these reactors. In the case of reactors grouped on one and the same site, the device for the transfer and storage of fuel assemblies as described in French Patent Application No. 80-02862 of the NOVATOME company is of great interest because it simplifies considerably the total of the devices necessary for the evacuation of the irradiated assemblies towards a reprocessing factory and for supplying the reactor with new assemblies. This device comprises, in particular, modules for the transfer and storage of the fuel assemblies, carried by transport vehicles travelling on the site where the reactors are installed. Nevertheless, in the case where an intermediate storage of the fuel assemblies is necessary after their removal from the reactor tank and before they are picked up by the transfer and storage modules, it is necessary to have available special installations integrated with the building of the reactor for the passage of the fuel assemblies between their storage position in the vicinity of the reactor tank and an evacuation position from which the assemblies can be picked up by the transfer module. SUMMARY OF THE INVENTION It is therefore the object of the invention to provide a transfer device for fuel assemblies for fast neutron nuclear reactors between a storage position in the vicinity of the reactor tank and an evacuation and introduction position from which the evacuation of the irradiated assemblies and the supplying of the reactor with new assemblies is effected, and this device should permit a simplification of the structure of the reactor and common use by other reactors disposed on the site. For this purpose, the transfer device according to the invention is dismountable and movable as a whole for its successive use with a plurality of nuclear reactors and comprises: a platform mounted for rotation, with the interposition of a joint, on a support adapted to rest on the structure of the reactor, the platform, pierced by at least one aperture, then being horizontal and movable about a vertical axis so as to bring the aperture successively into concordance with vertical shafts giving access to the storage and evacuation positions of the assemblies formed in the structure of the reactor and equipped, at their upper portion, with closing and connection devices, at least one hopper capable of containing an assembly in the vertical position, disposed on the upper surface of the platform round the aperture formed therein and equipped with a winch for the vertical displacement of the assemblies inside the shafts and the hopper when these come into the extension of one another by rotation of the platform, and at least one connecting device carried by the platform for the connection between the hopper and the shafts when these come into concordance. In order that the invention may be more clearly understood, two embodiments of a device according to the invention, used on a fast neutron nuclear reactor, will now be described by way of non-limiting example, with reference to the accompanying drawings.