Patent Number: 
Section: claims

1. A ventilated apparatus for transporting and/or storing radioactive materials comprising:an overpack body having an outer surface and an inner surface forming an internal cavity about a longitudinal axis;a base enclosing a bottom end of the cavity;a lid enclosing a top end of the cavity;a plurality of outlet ducts, each of the outlet ducts forming an air outlet passageway from a top portion of the cavity to an external atmosphere;a bottom portion of the overpack body formed by a plurality of curved segments, each of the curved segments extending circumferentially from a first end wall having a convex portion to a second end wall having a concave portion; andthe curved segments circumferentially surrounding the longitudinal axis and arranged in an intermeshing configuration such that for all adjacent curved segments: (1) the convex portion of the first end wall of one of the curved segments at least partially nests within the concave portion of the second end wall of an adjacent one of the curved segments; and (2) the convex portion of the first end wall of the one of the curved segments is spaced from the concave portion of the second end wall of the adjacent one of the curved segments, thereby forming an inlet duct forming an air inlet passageway 160 from the external atmosphere to a bottom portion of the cavity. 2. The ventilated apparatus according to claim 1 wherein each of the curved segments has a convex outer wall that forms a portion of the outer surface of the overpack body and a concave inner wall that forms a portion of the inner surface of the overpack body; and wherein the convex outer walls of the curved segments lie in a first reference cylinder and the concave inner walls of the curved segments lie in a second reference cylinder. 3. The ventilated apparatus according to claim 1 wherein, for each of the air inlet passageways, a line of sight does not exist from the cavity to the external atmosphere through the air inlet passageway. 4. The ventilated apparatus according to claim 1 wherein each of the air inlet passageways comprises a first radial section extending from the outer surface of the overpack body, a curved section extending from the first radial section, and a second radial section extending from the curved section to the inner surface of the overpack body. 5. The ventilated apparatus according to claim 1 wherein each of the curved segments is a singular uninterrupted member. 6. The apparatus according to claim 1 wherein the overpack body comprises an inner metal shell and an outer metal shell concentrically arranged so that a gap exists between the inner and outer shells, a concrete material provided in the gap. 7. The apparatus according to claim 6 further comprising a plurality of lower metal inter-shell connectors extending between the inner and outer metal shells, the lower metal inter-shell connectors defining the inlet ducts. 8. The apparatus according to claim 1 wherein each of the inlet ducts has a height and a width, and wherein a ratio of height to width is at least 10:1. 9. The apparatus according to claim 1 wherein the air outlet passageways of the outlet ducts are at least partially defined by an interface between the lid and the overpack body. 10. The apparatus according to claim 1 further comprising a hermetically sealed canister for containing radioactive materials positioned within the cavity so that a first reference plane that is perpendicular to the longitudinal axis of the overpack body intersects both the canister and the inlet ducts. 11. The apparatus of claim 10 further comprising a set of tubular shock absorbers coupled to the inner surface of the overpack body, the set of tubular shock absorbers positioned so that a second reference plane that is perpendicular to the longitudinal axis of the overpack body intersects both a lid of the canister and the set of tubular shock absorbers. 12. A ventilated apparatus for transporting and/or storing radioactive materials comprising:an overpack body having an outer surface and an inner surface forming an internal cavity about a longitudinal axis;a base enclosing a bottom end of the cavity;a lid enclosing a top end of the cavity;a plurality of outlet ducts, each of the outlet ducts forming an air outlet passageway from a top portion of the cavity to an external atmosphere;a bottom portion of the overpack body formed by a plurality of segments, each of the segments extending from a first end wall having a projection to a second end wall having a channel; andthe segments circumferentially surrounding the longitudinal axis and arranged in an intermeshing and spaced-apart configuration such that the projections of the first end walls of the segments project into the channels of the second end walls of adjacent ones of the segments, thereby forming an inlet duct between adjacent ones of the segments that includes an air inlet passageway from the external atmosphere to a bottom portion of the cavity through which a line of sight does not exist from the cavity to the external atmosphere. 13. The ventilated apparatus according to claim 12 wherein, for each of the segments, the channel and the projection extend along the entire height of the segment. 14. The ventilated apparatus according to claim 12 wherein, for each of the segments, the first end wall further comprises a first shoulder on a first side of the projection and a second shoulder on a second side of the projection opposite the first side. 15. The ventilated apparatus according to claim 12 wherein, for each of the segments, the second end wall comprises a first channel wall and a second channel wall that define the channel therebetween. 16. The ventilated apparatus according to claim 12 wherein each of the segments has a convex outer wall that forms a portion of the outer surface of the overpack body and a concave inner wall that forms a portion of the inner surface of the overpack body; and wherein the convex outer walls of the curved segments lie in a first reference cylinder and the concave inner walls of the curved segments lie in a second reference cylinder that is concentric to the first reference cylinder.