Patent Number: 
Section: claims

1. A unitary storage structure for storing spent nuclear fuel, the structure comprising:a metal shell forming a cavity configured to store a spent nuclear fuel canister, the shell having an open top end, a closed metal bottom plate seal welded to a bottom end of the shell to prevent the ingress of water and other fluids, a height, and an opening in a side wall of the shell;an elongated metal inlet ventilation duct disposed externally to the shell, the inlet ventilation duct having an inlet and an outlet in fluid communication with the cavity of the canister, the outlet being seal welded to the opening of the shell forming a sealed passageway from the inlet to the opening of the shell;the outlet of the inlet ventilation duct being positioned at a first vertical height above the bottom end of the shell and the inlet being positioned at a second vertical height above the bottom end of the shell, wherein the second vertical height is greater than the first vertical height;wherein the metal bottom plate has an extension portion that extends outwards beyond the shell, the inlet ventilation duct being seal welded to a top of the extension portion to prevent the ingress of water and other fluids;wherein the shell, metal bottom plate, and inlet ventilation duct form a self-supporting unitary storage structure. 2. The unitary storage structure of claim 1, wherein the inlet ventilation duct includes a vertical section that is spaced apart from the shell. 3. The unitary storage structure of claim 2, wherein the inlet ventilation duct includes a horizontal section fluidly coupled to the vertical section and to the opening of the shell. 4. The unitary storage structure of claim 1, wherein the second vertical height of the inlet of the inlet ventilation duct is higher than the top end of the shell. 5. The unitary storage structure of claim 1, wherein the shell has a cylindrical shape. 6. The unitary storage structure of claim 1, further comprising:a lid positioned atop the shell so as to substantially enclose the open top end of the shell, the lid being non-unitary with respect to the shell;the lid comprising an outlet ventilation duct forming a passageway from a top of the cavity to ambient atmosphere. 7. The unitary storage structure of claim 1, further comprising an outlet ventilation duct forming a passageway from a top of the cavity to ambient atmosphere. 8. A unitary storage structure for storing spent nuclear fuel, the structure comprising:a metal shell forming a cavity configured to store a spent nuclear fuel canister, the shell having an open top end, a closed metal bottom plate seal welded to a bottom end of the shell, a height, and an opening in a side wall of the shell;an elongated metal inlet ventilation duct disposed externally to the shell, the inlet ventilation duct having an inlet in fluid communication with ambient atmosphere and an outlet in fluid communication with the cavity of the canister, the outlet being seal welded to the opening of the shell forming a sealed passageway from the inlet to the opening of the shell;the outlet of the inlet ventilation duct being positioned at a first vertical height above the bottom end of the shell and the inlet being positioned at a second vertical height above the bottom end of the shell, wherein the second vertical height is greater than the first vertical height;wherein the inlet ventilation duct is seal welded to the bottom plate of the shell, the shell, bottom plate, and inlet ventilation duct forming a self-supporting unitary storage structure. 9. The unitary storage structure of claim 8, wherein the inlet ventilation duct is welded to the opening of the shell and bottom plate of the shell. 10. The unitary storage structure of claim 8, wherein the bottom plate has an extension portion that extends outwards beyond the shell, the inlet ventilation duct being welded to the extension portion. 11. The unitary storage structure of claim 8, wherein the inlet ventilation duct includes a vertical section that is spaced apart from the shell. 12. The unitary storage structure of claim 8, wherein the inlet ventilation duct includes a horizontal section fluidly coupled to the vertical second and to the opening of the shell. 13. A unitary storage structure for storing spent nuclear fuel, the structure comprising:a metal shell forming a cavity configured to store a spent nuclear fuel canister, the shell having an open top end, a closed metal bottom plate seal welded to a bottom end of the shell, a height, and an opening in a side wall of the shell;an elongated metal inlet ventilation duct disposed externally to the shell, the inlet ventilation duct having an inlet in fluid communication with ambient atmosphere and an outlet in fluid communication with the cavity of the canister, the outlet being seal welded to the opening of the shell forming a sealed passageway from the inlet to the opening of the shell;wherein the inlet ventilation duct includes a vertical section that is spaced apart from the shell and a horizontal section fluidly coupled to the vertical section and to the opening of the shell;wherein the horizontal section of the inlet ventilation duct is seal welded to the bottom plate of the shell and the shell forming a self-supporting unitary storage structure comprised of the inlet ventilation duct, bottom plate, and shell. 14. The unitary storage structure of claim 13, wherein the outlet of the inlet ventilation duct being positioned at a first vertical height above the bottom end of the shell and the inlet being positioned at a second vertical height above the bottom end of the shell, wherein the second vertical height is greater than the first vertical height. 15. The unitary storage structure of claim 13, wherein the inlet ventilation duct is welded to the opening of the shell and bottom plate of the shell. 16. The unitary storage structure of claim 13, wherein the bottom plate has an extension portion that extends outwards beyond the shell, the inlet ventilation duct being welded to the extension portion.