Patent Number: 
Section: claims

1. A method of transferring high level radioactive waste comprising:a) loading high level radioactive waste into a water-filled cavity of a canister body having an open top end at a first location;b) coupling a lid to the canister body to enclose the open top end;c) removing a volume of water from the cavity so that a water level of the water within the cavity is above a top end of the high level radioactive waste and a space exists between the water level and a bottom surface of the lid;d) hermetically sealing the cavity; ande) transferring the canister to a second location, the water level remaining above the top end of the high level radioactive waste during the transfer. 2. The method of claim 1 wherein the first location is a submerged environment and the second location is a submerged environment. 3. The method of claim 2 wherein the first location is a first pool and the second environment is a second pool. 4. The method of claim 1 wherein the water in the cavity is the water from the first pool. 5. The method of claim 1 wherein step c) comprises backfilling the space with a gas to pressurize the space. 6. The method of claim 5 therein the gas is steam. 7. The method of claim 1 wherein the lid comprises a chamber and a pressure relief device hermetically sealing an opening into the chamber, and wherein step e) further comprises upon the pressure within the cavity exceeding a predetermined threshold, the pressure relief device automatically opening so as to firm a passageway from the cavity into the chamber, thereby relieving, pressure within the cavity. 8. The method of claim 1 wherein the canister body is thermally conductive. 9. The method of claim 8 wherein the canister body is constructed of lead and steel. 10. The method of claim 1 further comprising a fuel basket located within the cavity, the fuel basket comprising a gridwork of plates forming a plurality of axially extending cells. 11. The method of claim 10 wherein step c) comprises a bottom plenum of water being formed at a bottom end of the cavity, a top plenum of water being formed below the water level, and one or more downcomer passageways adjacent an inner surface of the cavity that extend between the top plenum and the bottom plenum, and wherein during step e), thermosiphon flow of the water occurs within the cavity. 12. A method of transferring spent nuclear fuel from a first body of water to a second body of water comprising:a) submerging a canister into the first body of water, the canister having a cavity having, an open top end and a closed bottom end, the water filling the cavity;b) loading spent nuclear fuel into the cavity of the submerged canister:c) positioning a lid atop the loaded canister to enclose the open top end of the cavity;d) removing the loaded canister from the first body of water, the spent nuclear fuel remaining submerged in the water within the cavity;e) hermetically sealing the cavity;f) transferring and submerging the loaded canister to the second body of water;g) removing the lid from the loaded canister; andh) removing the spent nuclear fuel from the submerged canister. 13. The method of claim 12 wherein step d) further comprises draining a portion of the water from the cavity so that the spent nuclear fuel remains submerged in the water and a portion of the cavity is free of the water. 14. The method of claim 12 wherein step d) further comprises backfilling the portion of the cavity that is free of the water with steam and hermetically sealing the cavity. 15. The method of claim 12 wherein the lid comprises a chamber and a pressure relief device hermetically sealing an opening into the chamber, and wherein step f) further comprises upon the pressure within the cavity exceeding a predetermined threshold, the pressure relief device automatically opening so as to form a passageway from the cavity into the chamber, thereby relieving pressure within the cavity. 16. The method of claim 12 wherein the canister body is thermally conductive. 17. The method of claim 12 further comprising a fuel basket located within the cavity, the fuel basket comprising a gridwork of plates forming a plurality of axially extending cells, and wherein step b) comprises loading the spent nuclear fuel into the cells. 18. The method of claim 17 wherein step d) further comprises draining a portion of the water from the cavity so that the spent nuclear fuel remains submerged in the water and a portion of the cavity is free of the water, a bottom plenum of water being formed at a bottom end of the cavity, a top plenum of water being formed below a water level, and one or more downcomer passageways being formed adjacent an inner surface of the cavity that extend between the top plenum and the bottom plenum, and wherein during, step 5), a thermosiphon flow of the water occurs within the cavity. 19. A canister apparatus for transferring spent nuclear fuel comprising:a tubular body forming a cavity for receiving spent nuclear fuel, the tubular body having a longitudinal axis, a floor enclosing a bottom end of the tubular body, an open top end;a lid detachably coupled to the tubular body that encloses the open top end of the tubular body and hermetically seals the cavity, the lid comprising a chamber and a pressure relief device hermetically sealing an opening into the chamber, the pressure relief device automatically opening upon the pressure within the cavity exceeding a predetermined threshold so as to form a passageway from the cavity into the chamber; andwherein the cavity, the passageway, and the chamber collectively form a hermetically sealed volume when the pressure relief device is open. 20. The canister apparatus of claim 19 wherein the lid comprises: a body portion having a bottom surface and a top surface, the bottom surface of the body portion of the lid forming a roof of the cavity; and a dome portion attached to the top surface of the body portion, the dome portion forming the chamber. 21. The canister apparatus of claim 20 wherein the opening extends from the bottom surface of the body portion of the lid into the chamber, the pressure relief device coupled to the body portion of the lid. 22. The canister apparatus of claim 20 wherein the body portion of the lid and the tubular body are multi-layered constructs of lead and steel. 23. The canister apparatus of claim 20 wherein the body portion of the lid comprises a plug portion that extends into the cavity and a flange portion that forms a lid-to-body interface with a top edge of the tubular body. 24. The canister apparatus of claim 20 wherein the body portion of the lid further comprises a valved port for adjusting a water level within the cavity. 25. The canister apparatus of claim 19 wherein the chamber has a vacuum pressure. 26. The canister apparatus of claim 19 further comprising a fuel basket located within the cavity, the fuel basket comprising a gridwork of plates forming a plurality of axially extending cells. 27. The canister apparatus of claim 26 wherein the fuel basket is configured to facilitate a thermosiphon flow of fluid within the hermetically sealed cavity when spent nuclear fuel having a heat load is loaded in the cavity. 28. The canister apparatus of claim 26 wherein the fuel basket has a height that is less than a height of the hermetically sealed cavity. 29. The canister apparatus of claim 19 wherein the tubular body is thermally conductive. 30. The canister apparatus of claim 19 wherein the pressure relief device is a pressure relief valve or a rupture disk.