Abstract: A dry storage systems for radioactive nuclear waste materials may include a double-walled canister system. The canister system may include a canister having a tubular inner shell defining an internal cavity for storing nuclear waste material, a first lid sealably welded to a first end of the inner shell, a primary base plate defining a peripheral edge portion and having an annular closure flange, and an annular full thickness butt weld formed at an abutment joint between the annular closure flange and a second end of the inner shell. The inner shell, first lid, and first end closure may collectively define a sealed primary pressure retention barrier. A tubular outer shell may adjoin the inner shell. The outer shell may be welded to the canister to form a hermetically sealed secondary pressure retention barrier.

Abstract: A vertical bundle air-cooled heat exchanger, a finned tube assembly for an air cooled condenser and method for forming the same, and a system for removing thermal energy generated by radioactive materials. In one aspect, an air cooled condenser sized for industrial and commercial application includes an inlet steam distribution header for conveying steam, a condensate outlet header for conveying condensate, an array of tube bundles each having a plurality of finned tube assemblies having a bare steel tube with an exposed outer surface and a set of aluminum fins brazed directly onto the tube by a brazing filler metal. The steel tubes may be spaced apart by the aluminum fins and have an inlet end fluidly coupled to the inlet steam distribution header and an outlet end fluidly coupled to the outlet header. A forced draft fan may be arranged to blow air through the tube bundles.

Abstract: A passively cooled stackable nuclear waste storage system may include a pair of vertically stacked radiation-shielded nuclear waste storage casks. Each cask has a cavity which holds a nuclear waste canister containing spent nuclear fuel or other high-level radioactive wastes. The lower cask may be founded on an above-grade concrete pad. The upper cask is vertically stacked on and detachably coupled to the lower cask. The upper cask comprises a perforated baseplate which establishes fluid communication between cavities of both casks and is configured to prevent radiation shine. One or both casks may include air inlet vents configured to draw ambient ventilation air into each respective cask cavity for cooling the nuclear waste. In operation, air is drawn inward into each cask cavity independently. Air heated in the lower cask rises into the upper cask where it mixes with air drawn into the upper cask and is returned to atmosphere.

Abstract: A nuclear waste cask in one embodiment includes an axially elongated cask body defining a longitudinally-extending opening forming an entrance to an internal storage cavity of the cask configured for holding radioactive nuclear waste materials. A closure lid detachably coupled to the cask body at the top opening seals the cavity. A cask locking mechanism includes a plurality of first locking protrusions spaced apart on the lid which are selectively interlockable with a plurality of second locking protrusions spaced apart on the cask body to lock the lid to the cask body. The first locking protrusions may be disposed on slideable locking bars moveable between locked and unlocked positions while the lid remains stationary on the cask body. Hydraulic or pneumatic actuators may be used to change position of the locking bars. The cask and lid may include other features such as impact absorbers and lifting elements.

Abstract: A container system for radioactive waste and method for using the same is provided. The system includes a canister configured for holding radioactive waste and a lid system. In one embodiment, the lid system comprises a two-part lid assembly including a confinement lid and a shielded lifting lid. The confinement lid is detachably mounted to the confinement lid. In use, the lifting lid supports the confinement lid for lifting and placement on the canister. The lifting lid further shields operators while the confinement lid is mounted to the canister. Thereafter, the lifting lid is removed and may be reused for confinement lid mountings on other canisters. In one embodiment, the confinement lid is bolted to the canister. The canister may be disposed in a protective overpack for transport and storage.

Abstract: A system for externally cooling a radiation shielded cask containing heat-emitting high level radioactive waste such as spent nuclear fuel. The system includes the cask defining an internal cavity configured to hold an unshielded canister containing the spent nuclear fuel. An annular cooling water header extends circumferentially around the entire circumference of the cylindrical sidewall of the cask. The header comprises plural dispensing outlets which direct cooling water onto the cask, thereby wetting the entire sidewall of the cask. The cooling water provides an external heat sink for absorbing the heat emitted through the external wall surface of the cask generated by the spent nuclear fuel. In various embodiments, the cooling water header may have a continuous annular structure, or be formed by two or more header segments. The header may be supported directly from the cask by detachably mounted brackets.

Abstract: An automatically adjusting seismic restraint system for nuclear fuel storage in one embodiment comprises a free-standing first fuel storage component (FSC) configured to contain nuclear fuel, and a stationary second FSC configured to receive the first fuel storage component. An inter-body gap formed between the FSCs includes at least one seismic restraint assembly. The assembly includes a stationary wedge member fixedly coupled to the second FSC and a movable loose wedge member engaged with and supported in place by the stationary wedge member. The stationary wedge member defines an inclined load bearing surface slideably engaged with a mating inclined load bearing surface of the loose wedge member. During a seismic event or thermal expansion of the first FSC, the first FSC moves towards the second FSC which shrinks the inter-body gap and the loose wedge member is vertically displaced relative to the stationary wedge member while maintaining engagement therewith.

Abstract: An underground ventilated system for storing nuclear waste materials. The system includes a storage module having an outer shell defining an internal cavity and an inner shell. A majority of the height of the outer shell may be disposed below grade. The outer shell may include a hermetically sealed bottom. First and second canisters are positioned in lower and upper portions within the cavity respectively in vertically stacked relationship. A centering and spacing ring assembly is interspersed between the first and second canisters to transfer the weight of the upper second canister to the lower first canister. The assembly may include centering lugs which laterally restrain the first and second canisters in case of a seismic event. A natural convection driven ventilated air system cools the canisters to remove residual decay heat to the atmosphere. In one non-limiting embodiment, the shells are made of steel.

Abstract: A radioactive nuclear waste storage system includes a cask comprising a hermetically sealed internal cavity configured for holding the waste such as spent nuclear fuel submerged in an inventory of water. One or more pressure surge capacitors disposed inside the cask include a vacuum cavity evacuated to sub-atmospheric conditions prior to storage of fuel in the cask. At least one rupture disk seals a vacuum chamber inside each capacitor. Each rupture disk is designed and constructed to burst at a predetermined burst pressure level occurring inside the cask external to the capacitor. This allows excess cask pressure occurring during a high pressure excursion resulting from abnormal operating conditions to bleed into capacitor, thereby returning the pressure inside the cask to acceptable levels. In one embodiment, the capacitors are located in peripheral regions of the cask cavity adjacent to the circumferential wall of the cask body.

Abstract: A passively cooled stackable nuclear waste storage system includes an at least partially below grade cavity enclosure container (CEC) and above grade cask. Each vessel includes a cavity holding a nuclear waste canister containing spent nuclear fuel or other high-level radioactive wastes. The CEC is founded on a below grade concrete base pad and cask is mounted on an above-grade concrete top pad in a vertically stacked arrangement. The upper cask comprises a perforated baseplate which establishes fluid communication between cavities of both casks and is configured to prevent radiation shine. One or both vessels include air inlets which draw ambient cooling air into their respective cavities for cooling the nuclear waste. Air heated in the lower CEC rises into the upper cask through the baseplate where it mixes with air drawn into the cask and is returned to atmosphere. The system increases storage capacity of new or existing facilities.

Abstract: A system for externally cooling a cask containing heat-emitting spent nuclear fuel includes the cask comprising a radiation shielding body defining an internal cavity configured to hold a canister containing the spent nuclear fuel. A continuously annular cooling jacket extends circumferentially around an external surface of the cask body. The cooling jacket may have a double shell construction including an internal cavity for a cooling medium which provides an external heat sink for absorbing heat radiated from the external wall surface of the cask generated by the spent nuclear fuel. The heat emitted by the spent nuclear fuel is absorbed by the cooling medium in the cooling jacket, thereby in turn cooling the cask. In one embodiment, the cooling medium may be dry ice which undergoes sublimation by absorbing the heat to change from solid to gaseous phase directly. The jacket may be formed of multiple segments.

Abstract: An apparatus for supporting radioactive fuel assemblies, such as spent nuclear fuel. In one aspect, the apparatus is in the form of a fuel rack having adjustable height pedestals. In another aspect, the apparatus is a canister including a first pressure vessel forming a first cavity and a second pressure vessel forming a second cavity, the first pressure vessel located in the second cavity of the second pressure vessel. An inner surface of the second pressure vessel may be in continuous surface contact with an outer surface of the first pressure vessel to form a dual-walled canister.

Abstract: A nuclear reactor support system that, in one embodiment, includes a reactor vessel, a reactor core disposed within the reactor vessel, an upper portion of the reactor vessel located above a ground plane and a lower portion of the reactor vessel located below the ground plane. The support system further includes a first flange fixedly attached to the upper portion of the reactor vessel and contacting the ground plane, the first flange supporting the reactor vessel, a second flange fixedly attached to the upper portion of the reactor vessel above the ground plane, the second flange spaced vertically apart from the first flange, and a plurality of welded lugs extending vertically between the first and second flanges. The first flange supports the entire weight of the reactor vessel in a cantilevered manner.

Abstract: A nuclear waste cask in one embodiment includes an axially elongated cask body defining a longitudinally-extending opening forming an entrance to an internal storage cavity of the cask configured for holding radioactive nuclear waste materials. A closure lid detachably coupled to the cask body at the top opening seals the cavity. A cask locking mechanism includes a plurality of first locking protrusions spaced apart on the lid which are selectively interlockable with a plurality of second locking protrusions spaced apart on the cask body to lock the lid to the cask body. The first locking protrusions may be disposed on slideable locking bars moveable between locked and unlocked positions while the lid remains stationary on the cask body. Hydraulic or pneumatic actuators may be used to change position of the locking bars. The cask and lid may include other features such as impact absorbers and lifting elements.

Abstract: 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.

Abstract: An underground passively ventilated nuclear waste storage system includes an array of cavity enclosure containers each including a cavity holding a nuclear waste canister containing radioactive waste generating heat. Each container comprises at least one pair of air inlets each fluidly coupled directly to separate vertical cooling air feeder shells spaced apart from the container. The feeder shell in fluid communication with ambient air operates to draw in ventilation air which flows to the container via natural convective thermo-siphon effect driven by heat emitted from the canister which heats the container cavity. The containers are arranged in a serial spaced apart manner in multiple parallel rows. The containers within each row are fluidly isolated from containers in other rows. Containers within each row are further fluidly isolated from other containers therein when the ventilation system operates. The containers may be part of a consolidated interim storage facility for radioactive waste.

Abstract: Systems and methods for storing spent nuclear fuel below grade that afford adequate ventilation of the spent fuel storage cavity. In one aspect, the invention is a system comprising: a shell forming a cavity for receiving a canister of spent nuclear fuel, at least a portion of the shell positioned below grade; and at least one inlet ventilation duct extending from an above grade inlet to a below grade outlet at or near a bottom of the cavity; the inlet ventilation duct connected to the shell so that the cavity is hermetically sealed to ingress of below grade fluids.

Abstract: A nuclear fuel storage system includes an outer canister and fuel basket positioned therein. The basket is formed by orthogonally arranged and interlocked slotted plates which collectively define exterior side surfaces of the basket and a grid array of open cells each configured to hold a fuel assembly. At least some slotted plates comprise cantilevered plate extensions protruding laterally beyond the side surfaces of the basket to define various shaped peripheral gaps between the basket and canister. The plate extensions are configured to engage the shell of the canister. Vertically elongated reinforcement members are inserted in the peripheral gaps and fixedly coupled to the basket. Reinforcement members may comprise elongated reinforcement plates and/or tubular shimming members which may be fixedly coupled to the slotted plate extensions. The reinforcement members structurally strengthen the fuel basket. The plate extensions further act as fins to enhance heat dissipation from the basket.

Abstract: A spent nuclear fuel storage facility. In one embodiment, the invention is directed to a storage facility including an array of storage containers. Each of the storage containers includes a body portion and a lid. The body portion has a storage cavity configured to hold a canister containing spent nuclear fuel. The lid, which may rest atop the body portion in a detachable manner, includes an inlet vent and an outlet vent. Each of the storage containers may be configured to draw air through the inlet vent and into the storage cavity where the air is warmed and passed through the outlet vent as heated air. The body portion of the storage containers may be positioned below grade and the lid of the storage containers may be positioned above grade.

Abstract: A heat exchanger in one aspect includes a longitudinal shell and a transverse shell oriented transversely thereto. A J-shaped tube bundle carrying a tube-side fluid extends through the longitudinal and transverse shells from a first tubesheet in the longitudinal shell to a second tubesheet in the transverse shell. The first and second tubesheets are oriented perpendicular to each other. In a related aspect a dual heat exchanger unit includes a first longitudinal shell, a second longitudinal shell, and a common transverse shell extending transversely between and fluidly coupled to the longitudinal shells. The longitudinal shells may be parallel to each other. The shells are fluidly coupled directly together to form a common shell-side space between pairs of inlet and outlet tubesheets. A pair of J-shaped tube bundles is disposed in the dual heat exchanger unit for heating two tube-side fluids.