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.

Abstract: A nuclear reactor in one embodiment includes a cylindrical body having an internal cavity, a nuclear fuel core, and a shroud disposed in the cavity. The shroud comprises an inner shell, an outer shell, and a plurality of intermediate shells disposed between the inner and outer shells. Pluralities of annular cavities are formed between the inner and outer shells which are filled with primary coolant such as demineralized water. The coolant-filled annular cavities may be sealed at the top and bottom and provide an insulating effect to the shroud. In one embodiment, the shroud may comprise a plurality of vertically-stacked self-supported shroud segments which are coupled together.

Abstract: A canister for storing spent nuclear fuel includes an elongated shell, baseplate enclosing the bottom end of the shell, and removable top lid bolted to the shell. The shell may have a dual thickness comprising a lower portion with first thickness and upper portion with greater second thickness by comparison. The upper portion is formed by an annular boss defining a fastening portion of the shell including plural threaded bores for engaging the lid bolting. The fastening portion may protrude radially outwards or inwards in different embodiments. The lid has a mounting flange receiving the bolts and is seated on the top end of shell. The mounting flange does not protrude radially beyond the outer surface of the fastener portion to minimize the diameter of the canister for placement inside an outer radiation shielded overpack or cask for transport/storage. The shell may optionally include cooling fins.

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 storage apparatus with radiation shielding for spent nuclear fuel includes a fuel basket comprising elongated fuel storage tubes each defining an open cell configured to hold a nuclear fuel assembly. Gamma radiation attenuation inserts are nested inside at least some of the storage tubes. The inserts each comprise elongated open-ended tubular bodies which may have a rectangular cuboid configuration with square cross section. The inserts are composed of a dense metallic material selected for blocking gamma radiation and may have high thermal conductivity for effective heat dissipation from the decaying nuclear fuel. Attenuation inserts can occupy some or all perimeter tubes to provide shielding against gamma radiation emanating in a lateral direction from the fuel basket. The inserts may include upper and lower securement features for detachable fixation to the storage tubes, and air/gas flow cutouts.

Abstract: A system and method for storing multiple canisters containing high level waste below grade that afford adequate ventilation of the spent fuel storage cavity. In one aspect, the invention is a ventilated system for storing high level waste emitting heat, the system comprising: an air-intake shell forming an air-intake cavity; a plurality of storage shells, each storage shell forming a storage cavity; a lid positioned atop each of the storage shells; an outlet vent forming a passageway between an ambient environment and a top portion of each of the storage cavities; and a network of pipes forming hermetically sealed passageways between a bottom portion of the air-intake cavity and at least two different openings at a bottom portion of each of the storage cavities such that blockage of a first one of the openings does not prohibit air from flowing from the air-intake cavity into the storage cavity via a second one of the openings.

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: Manufacturing methods for fabricating nuclear waste canisters used to store spent nuclear fuel assemblies are disclosed to mitigate stress corrosion cracking. The method may generally comprise providing one or more stainless steel sheets used to form a shell of the canister. The shell comprises open butt joints which are welded closed via full shell thickness type welds of preferably narrow profile. The welds and adjoining heat affect zone may then be subjected to mechanical through-thickness compaction, which converts a residual tensile stress field in the shell base material adjoining the weld to a compressive stress field for a full thickness of the shell. The crown of the external exposed portion of the weld is flattened by the compaction and may be coplanar with the exterior surface of the shell. Surface peening may optionally be performed on the welded zone after compaction.

Abstract: A system and method for drying cavities containing spent nuclear fuel is devised. The invention utilizes a non-intrusive procedure that is based on monitoring the dew point temperature of a non-reactive gas that is circulated through the cavity. In one aspect, the invention is a system for drying a cavity loaded with spent nuclear fuel comprising: a canister forming the cavity, the cavity having an inlet and an outlet; a source of non-reactive gas; means for flowing the non-reactive gas from the source of non-reactive gas through the cavity; and means for repetitively measuring the dew point temperature of the non-reactive gas exiting the cavity.

Abstract: A natural passively cooled ventilated cask includes a cavity which holds a canister containing heat and radiation emitting spent nuclear fuel assemblies. Cooling air inlet ducts draw ambient cooling air inwards into a lower portion of the cavity. The air heated by the canister flows upwards along the canister and is discharged from at least one air outlet duct formed by the cask lid to atmosphere via natural convective thermo-siphon flow. The air inlet ducts or at least one outlet duct in one embodiment may be fitted with an adjustable shutter plate which allows the flowrate of air entering the cask to be increased or decreased to maintain a predetermined canister maximum temperature limit selected in part to prevent the onset of stress corrosion cracking of the canister welds. Other embodiments may use a fixed orifice plate replaceable over time to maintain the minimum temperature.

Abstract: An air-cooled condenser system for steam condensing applications in a power plant Rankine cycle includes an air cooled condenser having a plurality of interconnected modular cooling cells. Each cell comprises a frame-supported fan, inlet steam header, outlet condensate headers, and tube bundle assemblies having optionally finned tubes extending between the headers. The tube bundle assemblies may fabricated into an A-shaped tube structure. The tube bundles are self-supporting without support from any part of the frame between top and bottom tubesheets of each bundle. The condensate headers may be slideably mounted to the frame for thermal expansion/contraction. Steam circulating in a closed flow loop on the tube side from a steam turbine is cooled in each cell by ambient air blown through the tube bundles, thereby forming liquid condensate returned to the Rankine cycle. The present design further provides a longitudinal and vertical thermal expansion restraint system.

Abstract: A heat exchanger for severe temperature and fluid flow conditions in one configuration includes a first longitudinal shell, a second longitudinal shell, and a transverse shell extending transversely between 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 an inlet and outlet tubesheet. A generally U-shaped assembly of shells is thus formed. The tube bundle has a complementary U-shaped configuration comprising a plurality of tubes which extend through the longitudinal and transverse shells between the tubesheets. An expansion joint fluidly couples each longitudinal shell to one of the tubesheets. The shell-side inlet and outlet nozzle may be fluidly coupled to the expansion joints for introducing and extracting the shell-side fluid from the heat exchanger. In another configuration, the heat exchanger may be L-shaped with tube bundle of the same configuration.

Abstract: A nuclear waste cask with impact protection includes impact limiters comprising deformable energy-absorbing perforated sleeves. An impact amelioration system for nuclear fuel storage components includes impact limiter assemblies at the bottom cask to canister interface including impact limiter plugs frictionally engaging corresponding plug holes formed in the cask closure plate. A nuclear waste fuel storage system includes an unventilated cask including a heavy free-floating radiation shielding lid loosely coupled the top end of the cask in a movable manner via the anchor bosses which provides cask overpressurization protection. A nuclear waste cask includes an axially elongated rectangular cuboid cask body having a cavity for holding nuclear waste materials and cask locking mechanism including first locking protrusions on the lid which are selectively interlockable with mating second locking protrusions on the cask body to lock the lid to the cask body.

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: 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.