A canister for transporting and/or storing radioactive materials, the canister comprising two concentric shells between which is housed a radiological protection device comprising at least a first and a second metal components adjacent along a circumferential direction. According to the invention, the first component is supported against the outer shell and at a distance from the inner shell, whereas the second component is supported against the shell and at a distance from the shell. In addition, the components are in contact with each other along an interface taking, in section along any plane orthogonal to the longitudinal axis and crossing this interface, the form of a straight line segment defining with a radial straight line crossing it at its centre an acute angle (A).