Patent Number: 044850689
Section: summary

BACKGROUND OF THE INVENTION The present invention relates to an installation for the storage and/or transfer of dangerous products such as those presenting an irradiation hazard (radioactive waste, feed materials, sources, etc), or chemical contamination (plutonium, liquid effluents, etc) or such as explosives. More specifically, the invention relates in preferred manner an installation for the storage and/or transfer of irradiated fuel assemblies in the core of a fast neutron nuclear reactor. It is known that irradiated fuel assemblies in the core of a fast neutron nuclear reactor are located in a tightly sealed sheath containing liquid sodium as soon as they are removed from the reactor cylinder, in order that the calories which the fuel continues to dissipate are removed under favourable conditions, despite the absence of storage in the reactor vessel. Another solution consists of transforming the assemblies under water or some other liquid (e.g. sodium.) after washing on leaving the reactor cylinder. It is also known that the irradiated fuel is reprocessed with minimum delay. However, it may be necessary to provide for a provisional storage of the fuel assemblies, particularly when there is a difference between the time in which the reactor is put into operation and that in which the reprocessing plant is put into operation. Moreover, even when the reactor and reprocessing plant are both operating, the storage of the irradiated assemblies awaiting reprocessing is virtually indispensible due to the significant difference between the removal speeds from the reactor cylinder during an irradiated fuel replacement phase and the reprocessing possibilities of the reprocessing plant. As the reprocessing plant is not in principle installed on the site on the reactor, it is possible to store the irradiated fuel on the same site as the reactor or on the site of the reprocessing plant. Technical problems are simplified by the first solution which makes it possible to defer the assembly transportation operations, thus reducing costs. For this reason, the storage installation according to the invention is preferably located on the site of the reactor. However, this location is not limitative and it is to be understood that the invention also covers the case when the storage installation is located on the site of the reprocessing plant. BRIEF SUMMARY OF THE INVENTION The present invention therefore relates to an installation for the storage and/or transfer of dangerous products, wherein it comprises a storage enclosure defining at least one loading and unloading station and a plurality of storage stations, modules each of which receives the dangerous products such as fuel assemblies (exposed or in sheets) each of these modules being located in one of the stations defined in the enclosure, the number of modules being less than that of the stations, lifting means for creating a fluid cushion below at least part of the modules in order to raise the latter within the enclosure and means for moving the modules between the different stations when they are raised by the lifting means. According to a secondary feature of the invention, the loading and storage stations are aligned in rows in accordance with two different directions, the lifting means acting independently in each of the said rows, and the means for moving the modules acting simultaneously on all the modules of the same row. According to a particular embodiment of the invention, the loading and storage stations are aligned in rows in two orthogonal directions, the storage enclosure then being rectangular and the module square. Preferably, means are provided for guiding the modules during their movements between the different stations. When these stations are aligned in rows, these module guidance means can comprise guide rails located on the periphery of the storage enclosure and between certain of the rows, except at each of the ends of the rows, and lateral rollers located on each module to cooperate with the guide rails and with adjacent modules. Preferably, the means for moving the modules are constituted by jacks located outside the enclosure at least at one end of at least part of said rows. According to another secondary feature of the invention, the lifting means comprise parallel pipes arranged level with the base of the enclosure and incorporating uniformly distributed support nozzles, the pipes being supplied with a pressurized fluid such as gas or liquid. When the installation is a fuel assembly storage installation located on the site of the reactor, it is important to provide a circuit making it possible to remove the calories diffused by the fuel assemblies. This circuit can be supplied in preferred manner by a cooled fluid such as gas or liquid. According to another secondary feature of the invention, each module then comprises an upper plate, means for supporting the fuel assemblies, a lower plate whose lower face is flat so as to permit the lifting of the module by the lifting means and an intermediate ferrule surrounding the fuel assemblies and defining in the vicinity of each of the plates a passage enabling the cooled fluid to enter and leave the module.