Patent Number: 
Section: claims

1. A system for storing spent nuclear fuel comprising: a lid having a side wall with substantially horizontal ventilation means extending through the side wall, the lid having a bottom surface;  a ventilated vertical overpack having a body including lower ventilation ducts, a bottom, a top surface, and a chamber formed by the body and the bottom adapted for receiving a canister of spent nuclear fuel; and  wherein the lid is secured to the overpack by a plurality of fasteners so that the bottom surface of the lid and the top surface of the overpack form an interface comprising a substantially horizontal section. 2. A system for storing spent nuclear fuel comprising: a lid having a side wall with substantially horizontal ventilation means extending through the side wall, the lid having a bottom surface;  a ventilated vertical overpack having a body including lower ventilation ducts a bottom, a top surface, and a chamber formed by the body and the bottom adapted for receiving a canister of spent nuclear fuel;  a lid shear ring having a lower surface attached to the bottom surface of the lid;  a body shear ring having an upper surface attached to the top surface of the overpack; and  the lid being secured to the overpack by a plurality of fastener so that the upper surface of the body shear ring contacts the bottom surface of the lid forming a first substantially horizontal interface and the lower surface of the lid shear ring contacts the top surface of the overpack forming a second substantially horizontal interface. 3. The system of  claim 1  wherein when the canister of spent nuclear fuel is received in the overpack and the lid is secured, air within the chamber is warmed by heat from the spent nuclear fuel, cold air entering through the lower ventilation ducts and warmed air exiting through the ventilation means of the lid. claim 1 4. A method of storing spent nuclear fuel comprising: placing a canister of spent nuclear fuel in a chamber of an overpack of a system comprising a lid having a side wall with substantially horizontal ventilation means extending through the side wall, the lid having a bottom surface, the overpack having a body including lower ventilation ducts, a bottom, and a top surface, the chamber being formed by the body and the bottom, wherein the lid is secured to the overpack by a plurality of fasteners; and  securing the lid to the overpack so that the bottom surface of the lid and the top surface of the overpack form an interface comprising at least one substantially horizontal section so that air within the chamber is warmed by heat from the spent nuclear fuel, cold air entering through the lower ventilation ducts and warmed air exiting through the ventilation means. 5. The method of  claim 4  wherein the fasteners are bolts and the securing step comprises bolting the lid to the overpack. claim 4 6. The system of  claim 1  wherein the lower ventilation ducts are located in the body near the bottom and no upper ventilation ducts are included in the body of the overpack. claim 1 7. The system of  claim 2  wherein the lower ventilation ducts are located in the body near the bottom and no upper ventilation ducts are included in the body of the overpack. claim 2 8. The system of  claim 2  wherein the body of the overpack is cylindrical. claim 2 9. The system of  claim 1  wherein the lid comprises a lid cap and a lid body. claim 1 10. The system of  claim 9  wherein the lid body is an annular ring. claim 9 11. The system of  claim 1  wherein the body of the overpack is cylindrical. claim 1 12. The system of  claim 1  wherein the fasteners are bolts extending through the lid and threadily engaging the overpack. claim 1 13. The system of  claim 1  wherein the ventilation means are four ventilation ducts. claim 1 14. The system of  claim 2  wherein the lid shear ring engages the body shear ring so as to prevent lateral movement of the lid with respect to the overpack. claim 2 15. The system of  claim 2  wherein the lid comprises a lid body and a lid cap. claim 2 16. The system of  claim 15  wherein the lid body is an annular ring. claim 15 17. The system of  claim 2  wherein the fasteners are bolts extending through the lid and threadily engaging the overpack. claim 2 18. The system of  claim 2  wherein the ventilation means are four ventilation ducts. claim 2 19. A method of storing spent nuclear fuel comprising: placing a canister of spent nuclear fuel in a chamber of an overpack of a system comprising a lid having a side wall with substantially horizontal ventilation means extending through the side wall, the lid having a bottom surface and a lid shear ring having a lower surface attached to the bottom surface, the overpack having a body including lower ventilation ducts, a bottom, a top surface, and a body shear ring having an upper surface attached to the top surface, the chamber being formed by the body and the bottom; and  securing the lid to the overpack with a plurality of fasteners so that the lower surface of the lid shear ring contacts the top surface of the overpack forming a first substantially horizontal interface, and the upper surface of the body shear ring contacts the bottom surface of the lid forming a second substantially horizontal interface so that air within the chamber is warmed by heat from the spent nuclear fuel, cold air entering through the lower ventilation ducts and warmed air exiting through the ventilation means. 20. The method of  claim 19  wherein the fasteners are bolts and the securing step comprises bolting the lid to the overpack. claim 19