Abstract: A method for the manufacture of a package for the transport and/or storage of nuclear materials, where the package includes an inner ferrule, an outerferrule and means of thermal conduction, and where the method includes: the construction of an essentially circular casing having at least one lengthways slit defined by two facing lengthways edges; and the welding of the facing lengthways edges, in order to obtain the outer ferrule, where this step is accomplished such that the welding shrinkage causes a compression stress of the means of thermal conduction between the ferrules, in a radial direction, and such that each welding bead only fastens the two edges which it links one on to the other.