The radial dose rate distributions D(rd) around a cask can be described well by the following relation: where H is the cask height, rs is the radius of the cask surface, and rd is the distance between the cask axis and the detector position. The quantity J is described by elliptic integrals of the first kind. This expression is a generating function for an empirical description of the rd dependence of the radiation dose rate distributions around a cask.