A method of forming a sealed canister and a method of storing radioactive materials is provided. The method of forming includes placing a top plate on a top opening of a side wall, a bottom of the side wall being sealed to a base plate. The top plate includes a top surface with a top edge having a bevel and with a channel set in from the top edge. Finally, a weld is formed between the beveled top edge and the top opening of the side wall to seal the top plate to the side wall.

A method of forming a sealed canister and a method of storing radioactive materials is provided. The method of forming includes placing a top plate on a top opening of a side wall, a bottom of the side wall being sealed to a base plate. The top plate includes a top surface with a top edge having a bevel and with a channel set in from the top edge. Finally, a weld is formed between the beveled top edge and the top opening of the side wall to seal the top plate to the side wall.

A method of storing high level radioactive waste, and specifically a method of adjusting or controlling the temperature of ventilation air flowing through a storage cavity of a ventilated system. The method includes positioning a metal canister containing high level radioactive waste in a storage cavity of the ventilated system. The ventilated system includes a cask body, a cask lid, a plurality of inlet ducts, and at least one outlet duct so that ventilation air can flow from atmosphere into the storage cavity where it is heated and then back out to the atmosphere. The method includes progressively reducing a cross-sectional area of one or more of the inlet ducts and/or the outlet duct over time so that a rate at which the ventilation air is heated within he storage cavity is maintained above a predetermined threshold to mitigate the risk of stress corrosion cracking in the metal canister.

A method of storing high level radioactive waste, and specifically a method of adjusting or controlling the temperature of ventilation air flowing through a storage cavity of a ventilated system. The method includes positioning a metal canister containing high level radioactive waste in a storage cavity of the ventilated system. The ventilated system includes a cask body, a cask lid, a plurality of inlet ducts, and at least one outlet duct so that ventilation air can flow from atmosphere into the storage cavity where it is heated and then back out to the atmosphere. The method includes progressively reducing a cross-sectional area of one or more of the inlet ducts and/or the outlet duct over time so that a rate at which the ventilation air is heated within he storage cavity is maintained above a predetermined threshold to mitigate the risk of stress corrosion cracking in the metal canister.

A module for storing high level radioactive waste includes an outer shell, having a hermetically closed bottom end, and an inner shell forming a cavity and being positioned inside the outer shell to form a space therebetween. At least one divider extends from the top to the bottom of the inner shell to create a plurality of inlet passageways through the space, each inlet passageway connecting to a bottom portion of the cavity. A plurality of inlet ducts each connect at least one of the inlet passageways and ambient atmosphere, and each includes an inlet duct cover affixed atop a surrounding inlet wall, the inlet wall being peripherally perforated. A removable lid is positioned atop the inner shell and has at least one outlet passageway connecting the cavity and the ambient atmosphere, the lid and the top of the inner shell being configured to form a hermetic seal therebetween.

A module for storing high level radioactive waste includes an outer shell, having a hermetically closed bottom end, and an inner shell forming a cavity and being positioned inside the outer shell to form a space therebetween. At least one divider extends from the top to the bottom of the inner shell to create a plurality of inlet passageways through the space, each inlet passageway connecting to a bottom portion of the cavity. A plurality of inlet ducts each connect at least one of the inlet passageways and ambient atmosphere, and each includes an inlet duct cover affixed atop a surrounding inlet wall, the inlet wall being peripherally perforated. A removable lid is positioned atop the inner shell and has at least one outlet passageway connecting the cavity and the ambient atmosphere, the lid and the top of the inner shell being configured to form a hermetic seal therebetween.

A passively cooled storage module for spent nuclear fuel includes an elongated body including a top end, bottom end, sidewall, baseplate, detachable lid, and cavity for holding a fuel canister containing heat-emitting spent nuclear fuel assemblies. Cooling air inlet ducts spaced draw ambient cooling air radially inwards into a lower portion of the cavity. The air flows upwards in the cavity along the canister and is discharged from the top end of the module to atmosphere via natural circulation. The air inlet ducts may have a multi-angled and recurving configuration comprising one or more obliquely angled sections in one embodiment. The exterior inlet end openings of the inlet ducts are arranged at a higher elevation than the interior outlet end openings to prevent the ingress of standing and flood-related waters. The ducts and lid include radiation shielding features.

A passively cooled storage module for spent nuclear fuel includes an elongated body including a top end, bottom end, sidewall, baseplate, detachable lid, and cavity for holding a fuel canister containing heat-emitting spent nuclear fuel assemblies. Cooling air inlet ducts spaced draw ambient cooling air radially inwards into a lower portion of the cavity. The air flows upwards in the cavity along the canister and is discharged from the top end of the module to atmosphere via natural circulation. The air inlet ducts may have a multi-angled and recurving configuration comprising one or more obliquely angled sections in one embodiment. The exterior inlet end openings of the inlet ducts are arranged at a higher elevation than the interior outlet end openings to prevent the ingress of standing and flood-related waters. The ducts and lid include radiation shielding features.

A dry storage systems for radioactive nuclear waste materials in one embodiment includes a canister having a tubular shell defining an internal cavity for storing nuclear waste material, a lid sealably welded to one end the shell, and an end closure attached to a second end of the shell. The end closure includes a base plate having an upturned peripheral annular closure flange. In one embodiment, a circumferentially-extending butt joint is formed between the closure flange and the shell second end which is hermetically seals by a full through-wall thickness butt weld. Various embodiments may further include secondary pressure retention barriers enclosing the canister or select portions thereof most susceptible to failure under certain conditions.

A dry storage systems for radioactive nuclear waste materials in one embodiment includes a canister having a tubular shell defining an internal cavity for storing nuclear waste material, a lid sealably welded to one end the shell, and an end closure attached to a second end of the shell. The end closure includes a base plate having an upturned peripheral annular closure flange. In one embodiment, a circumferentially-extending butt joint is formed between the closure flange and the shell second end which is hermetically seals by a full through-wall thickness butt weld. Various embodiments may further include secondary pressure retention barriers enclosing the canister or select portions thereof most susceptible to failure under certain conditions.