Patent ID: 7509731

Claim:
Method for manufacturing non-contaminated MOX fuel rods, from pellets, in a containment enclosure under a depression, the method comprising the following operations for one rod: loading of the pellets in successive columns into a cladding previously provided with a first plug at one of its two ends; loading of various structural components, including a retaining spring; fitting of a second plug at the other end of the cladding; peripheral welding of said second plug; and at least one cleaning and at least one checking of the contamination of the parts of said cladding or respectively of the rod which have been exposed to contamination, the method being characterised in that it comprises: division of the containment enclosure into a number of successive compartments; connection of each compartment to its neighbour for a tight passage for the cladding, at least certain of said passages being aligned in order to allow a movement of the cladding along a longitudinal axis; introduction of the cladding to be loaded, said other end in front, into a first compartment through a sealed passage or an input aperture thereto; axial driving of the cladding between successive compartments until said other end reaches the last compartment; loading of the pellets in the last compartment, and if applicable also various structural components other than the retaining spring, into the cladding through said other; partial axial withdrawal of the cladding, when the loading is finished, so as to convey said other end into a preceding compartment; in this preceding compartment, cleaning and a possible contamination check of at least the part of the cladding exposed to contamination by the pellets in the process of being loaded or by the atmosphere of the last compartment; after this cleaning, axial movement of the cladding so that said other end is positioned in another compartment; loading of the retaining spring and fitting of the second plug in said other end, in this other compartment; after this fitting, carrying out of possible other operations in the same compartment or in yet another compartment, with a possible additional movement; contamination checking of the parts of the rod exposed to the contamination of the last compartments and possible cleaning if necessary, in the first or the second compartment; withdrawal of the rod out of the first compartment or a transverse transfer to another containment enclosure via a first compartment connecting the enclosures to one another; stepping of the contaminations between the various compartments, starting from the non-contaminated or the very slightly contaminated in the first compartment to the most contaminated in the last compartment; selection of gases supplying the compartments, chosen from amongst the group formed by: air, nitrogen, helium, argon, vacuum; stepping depressions in the compartments, in order to organise any leaks, from a weakest depression in the first compartment to a strongest depression in the last compartment.