The invention relates to an assembly consisting of a plurality of packaging bottles (1) for conditioning, storing and transporting radioactive bars or tubes, hereinafter called fagot assembly (2), wherein: said bottles (1) are identical and interchangeable; and said bottles are attached to each other in order to form a fagot or a bundle (2), by means of quick-fastening means (3), said fagot (2) comprising N bottles, N≧2; characterised in that said bottles (1) are formed from steel and are thicker at one of the two ends thereof, over a certain length.