Patent Number: 
Section: claims

1. A canister for storing radioactive materials, the canister comprising:a base plate;a side wall having a bottom sealed to the base plate; anda top plate including a top surface with a top edge having a bevel and with an annular channel set in from the top edge, wherein a weld is formed between the beveled top edge and a top of the side wall to seal the top plate to the side wall, andwherein the base plate, side wall, and top plate form a sealed vessel. 2. The canister of claim 1, wherein the base plate, side wall, and top plate form a hermetically sealed vessel. 3. The canister of claim 1, wherein the circumferential channel is approximately as deep as the bevel extends below the top surface. 4. The canister of claim 1, wherein the circumferential channel is deeper than the bevel extends below the top surface. 5. The canister of claim 1, wherein the top plate includes one or more ports therethrough. 6. The canister of claim 1, wherein at least one of the ports is disposed in the channel. 7. The canister of claim 1, wherein the side wall forms one of two walls of a double-walled canister. 8. The canister of claim 1, wherein the top plate is monolitihic. 9. The canister of claim 1, wherein the annular channel circumscribes a raised central portion and the annular channel is circumscribed by a perimeter portion. 10. The canister of claim 9, wherein the raised central portion and the perimeter portion each have a top surface that are substantially coplanar.