A removable storage device intended to be housed in a cavity of a form of packaging for transporting and/or storing radioactive materials, including several substructures movable relative to one another, positioned around a longitudinal axis, and defining multiple adjacent recesses for radioactive materials, together with means for deployment of the substructures including actuation means acting by shape collaboration on the substructures through a bearing surface having, in a section according to any plane passing through longitudinal axis, the shape of a segment inclined relative to this axis, such that displacement of actuation means in a first direction parallel to longitudinal axis causes a displacement of the substructures radially towards the exterior relative to longitudinal axis.