An assembly comprising: - a package for transporting radioactive materials, the package comprising a lateral body extending about a longitudinal axis of the package, the latter also including at least one shock absorbing cover arranged at a longitudinal end of said lateral body, each shock absorbing cover extending laterally beyond the lateral body, - a base platform delimiting a base surface located away from each shock absorbing cover; - raising means for raising the package relative to the base surface, in a vertical superimposition direction along which the base platform, said raising means, and the package are superimposed, with its longitudinal axis oriented substantially horizontally; and - means for holding the package on said raising means, characterised in that said raising means consist of the following elements: - an upper structure for supporting the lateral body of the package, said support upper structure extending at least partly under the lateral body of the package; - a plurality of raising lateral walls (26a, 26b), each lateral wall consisting of: - an upper portion for connection to the support upper structure, said upper portion forming a plastic deformation zone; - a bearing portion bearing against the base surface, the bearing portion of at least one of the raising lateral walls being fastened to this base surface; - a lower portion for connection to the bearing portion, said lower portion forming a plastic deformation zone; and - a main portion interconnecting the connection upper and lower portions (28, 32), each main portion extending downwards, in said superimposition direction, beyond each shock absorbing cover, and in that each main portion is formed by a single plate or by a plurality of plates (34a, 34b) interconnected end to end and tilted relative to one another, each plate being arranged so as to define a non-zero angle with the superimposition direction, in any sectional plane passing through the plate over its entire height and including the superimposition direction. - a package for transporting radioactive materials, the package comprising a lateral body extending about a longitudinal axis of the package, the latter also including at least one shock absorbing cover arranged at a longitudinal end of said lateral body, each shock absorbing cover extending laterally beyond the lateral body, - a base platform delimiting a base surface located away from each shock absorbing cover; - raising means for raising the package relative to the base surface, in a vertical superimposition direction along which the base platform, said raising means, and the package are superimposed, with its longitudinal axis oriented substantially horizontally; and - means for holding the package on said raising means, - an upper structure for supporting the lateral body of the package, said support upper structure extending at least partly under the lateral body of the package; - a plurality of raising lateral walls (26a, 26b), each lateral wall consisting of: - an upper portion for connection to the support upper structure, said upper portion forming a plastic deformation zone; - a bearing portion bearing against the base surface, the bearing portion of at least one of the raising lateral walls being fastened to this base surface; - a lower portion for connection to the bearing portion, said lower portion forming a plastic deformation zone; and - a main portion interconnecting the connection upper and lower portions (28, 32), each main portion extending downwards, in said superimposition direction, beyond each shock absorbing cover, and in that each main portion is formed by a single plate or by a plurality of plates (34a, 34b) interconnected end to end and tilted relative to one another, each plate being arranged so as to define a non-zero angle with the superimposition direction, in any sectional plane passing through the plate over its entire height and including the superimposition direction. - an upper portion for connection to the support upper structure, said upper portion forming a plastic deformation zone; - a bearing portion bearing against the base surface, the bearing portion of at least one of the raising lateral walls being fastened to this base surface; - a lower portion for connection to the bearing portion, said lower portion forming a plastic deformation zone; and - a main portion interconnecting the connection upper and lower portions (28, 32), each main portion extending downwards, in said superimposition direction, beyond each shock absorbing cover, and in that each main portion is formed by a single plate or by a plurality of plates (34a, 34b) interconnected end to end and tilted relative to one another, each plate being arranged so as to define a non-zero angle with the superimposition direction, in any sectional plane passing through the plate over its entire height and including the superimposition direction.